ORCID Profile
0000-0002-8526-6996
Current Organisations
University of Technology Sydney
,
Wellcome Trust Brighton and Sussex Centre for Global Health Research, Brighton and Sussex Medical School
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In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Microbiology | Microbial Ecology | Genetics | Microbial Genetics | Molecular evolution | Biochemistry and Cell Biology | Synthetic biology | Microbiology Not Elsewhere Classified | Microbiology not elsewhere classified | Systems Biology | Microbiology not elsewhere classified | Infectious Agents | Proteomics and Intermolecular Interactions (excl. Medical Proteomics) | Genomics | Bacteriology | Infectious Agents | Marine And Estuarine Ecology (Incl. Marine Ichthyology) | Microbial Ecology | Microbial genetics | Microbial ecology | Genomics | Bacteriology
Expanding Knowledge in the Biological Sciences | Biological sciences | Control of Animal Pests, Diseases and Exotic Species in Coastal and Estuarine Environments | Infectious Diseases |
Publisher: Public Library of Science (PLoS)
Date: 13-05-2009
Publisher: Elsevier BV
Date: 11-2018
Publisher: Informa UK Limited
Date: 03-2013
DOI: 10.1080/08927014.2013.772141
Abstract: Pseudomonas aeruginosa PAO1 wild type and a mucoid derivative (FRD1) which over produces alginate were used to foul reverse osmosis (RO) membranes. When operated at a constant flux, biofilm formation on the RO membrane resulted in a slow rise in transmembrane pressure (TMP) of 22% for the initial four days of operation, followed by a sharp increase of 159% over the following two days. The initial slow increase in TMP was probably due to the formation of a biofilm on the membrane surface, which then accelerated the rate of biofouling through the effect of concentration polarization. At later stages of operation, most of the bacterial biomass consisted of dead cells. The amount of extracellular polymeric substances appeared to correlate positively with the number of dead cells. The results indicate that prolonging the initial stage of slow TMP increase and avoiding the latter stage of accelerated TMP increase would provide a sustainable operation of the RO system. These results suggest that nutrient limitation could reduce biofilm accumulation and delay the increase in TMP.
Publisher: Elsevier BV
Date: 2019
Publisher: Elsevier BV
Date: 2015
Publisher: MDPI AG
Date: 09-09-2023
Publisher: Springer Science and Business Media LLC
Date: 04-07-2017
Publisher: American Society for Microbiology
Date: 15-07-2007
DOI: 10.1128/JB.01867-06
Abstract: Despite its notoriety as a human pathogen, Vibrio cholerae is an aquatic microbe suited to live in freshwater, estuarine, and marine environments where biofilm formation may provide a selective advantage. Here we report characterization of biofilms formed on abiotic and biotic surfaces by two non-O1/O139 V. cholerae strains, TP and SIO, and by the O1 V. cholerae strain N16961 in addition to the isolation of 44 transposon mutants of SIO and TP impaired in biofilm formation. During the course of characterizing the mutants, 30 loci which have not previously been associated with V. cholerae biofilms were identified. These loci code for proteins which perform a wide variety of functions, including amino acid metabolism, ion transport, and gene regulation. Also, when the plankton colonization abilities of strains N16961, SIO, and TP were examined, each strain showed increased colonization of dead plankton compared with colonization of live plankton (the dinoflagellate Lingulodinium polyedrum and the copepod Tigriopus californicus ). Surprisingly, most of the biofilm mutants were not impaired in plankton colonization. Only mutants impaired in motility or chemotaxis showed reduced colonization. These results indicate the presence of both conserved and variable genes which influence the surface colonization properties of different V. cholerae subspecies.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 2017
Publisher: American Society for Microbiology
Date: 07-1995
DOI: 10.1128/AEM.61.7.2624-2630.1995
Abstract: Using plate counts, total cell counts, and direct viable counts, we examined the fate of cells of Vibrio vulnificus placed into natural estuarine waters during both winter and summer months. Cells inoculated into membrane diffusion chambers and placed into estuarine waters entered into a viable but nonculturable (VBNC) state in January and February, when the water temperatures were low (average, 15 degrees C). In contrast, when cells in the VBNC state were placed into the same waters in the warmer months of August through November (average water temperature of ca. 21 degrees C), the cells appeared to undergo a rapid (typically, within 24 h) resuscitation to the fully culturable state. These results were independent of whether the cells were in the logarithmic or stationary phase and whether they were encapsulated or not. This study indicates that the inability to isolate V. vulnificus from cold estuarine sites may be accounted for by entrance of the cells into a VBNC state and that recovery from this state in natural environments may result from a temperature upshift.
Publisher: Public Library of Science (PLoS)
Date: 29-07-2015
Publisher: Oxford University Press (OUP)
Date: 05-09-2011
DOI: 10.1093/ICB/ICR115
Abstract: The sensory capacity of bacteria and macroalgae (seaweeds) is limited with respect to many modalities (visual, auditory) common in "higher" organisms such as animals. Thus, we expect that other modalities, such as chemical signaling and sensing, would play particularly important roles in their sensory ecology. Here, we discuss two ex les of chemical signaling in bacteria and seaweeds: (1) the role of chemical defenses and quorum-sensing (QS) regulatory systems in bacterial colonization and infection of the red alga Delisea pulchra and their ecological consequences, and (2) the regulation of dispersal and differentiation by nitric oxide (NO) in bacterial biofilms. Consistent with the goals of neuroecology, in both cases, we investigate the links between specific signal-mediated molecular mechanisms, and ecological outcomes, for populations or assemblages of bacteria or seaweeds. We conclude by suggesting that because of the fundamental role played by chemical signaling in bacteria, bacterial systems, either by themselves or in interactions with other organisms, have much to offer for understanding general issues in neuroecology. Thus, further integration of microbiology with the biology of eukaryotes would seem warranted and is likely to prove illuminating.
Publisher: Frontiers Media SA
Date: 2013
Publisher: Wiley
Date: 07-03-2014
Publisher: Springer Science and Business Media LLC
Date: 24-03-2016
Publisher: Inter-Research Science Center
Date: 04-08-2011
DOI: 10.3354/AME01518
Publisher: BMJ
Date: 24-08-2020
DOI: 10.1136/INJURYPREV-2019-043531
Abstract: While there is a long history of measuring death and disability from injuries, modern research methods must account for the wide spectrum of disability that can occur in an injury, and must provide estimates with sufficient demographic, geographical and temporal detail to be useful for policy makers. The Global Burden of Disease (GBD) 2017 study used methods to provide highly detailed estimates of global injury burden that meet these criteria. In this study, we report and discuss the methods used in GBD 2017 for injury morbidity and mortality burden estimation. In summary, these methods included estimating cause-specific mortality for every cause of injury, and then estimating incidence for every cause of injury. Non-fatal disability for each cause is then calculated based on the probabilities of suffering from different types of bodily injury experienced. GBD 2017 produced morbidity and mortality estimates for 38 causes of injury. Estimates were produced in terms of incidence, prevalence, years lived with disability, cause-specific mortality, years of life lost and disability-adjusted life-years for a 28-year period for 22 age groups, 195 countries and both sexes. GBD 2017 demonstrated a complex and sophisticated series of analytical steps using the largest known database of morbidity and mortality data on injuries. GBD 2017 results should be used to help inform injury prevention policy making and resource allocation. We also identify important avenues for improving injury burden estimation in the future.
Publisher: Elsevier BV
Date: 07-2014
DOI: 10.1016/J.WATRES.2014.03.052
Abstract: Forward osmosis membrane bioreactors (FOMBR) provide high quality permeate, however the propensity for membrane biofouling in FOMBRs is unknown. Here, FOMBRs were operated under high and low aeration and the membrane-associated biofilms were characterized by confocal laser scanning microscopy (CLSM) and rRNA gene-tagged pyrosequencing. CLSM images revealed that there was little biofilm formed under high aeration, while thick biofilms were observed on the membranes operated under low aeration. The ersity and richness of bacterial and archaeal communities as assessed by pyrosequencing varied under high and low aeration. The composition of the bacterial suspended sludge communities and the sessile biomass on the membrane surface, as assessed by non-metric multidimensional scaling, was significantly different under high aeration, but was more similar under low aeration. SIMPER analysis indicated that Pseudomonas, Aeromonas and Fluviicola preferentially attached to the membrane. The results presented here provide a comprehensive understanding of membrane biofouling in FOMBRs, which is essential for the development of effective control strategies.
Publisher: Elsevier BV
Date: 04-2022
Publisher: Elsevier BV
Date: 03-2018
Publisher: Frontiers Media SA
Date: 25-07-2022
DOI: 10.3389/FMICB.2022.928877
Abstract: Seawalls are important in protecting coastlines from currents, erosion, sea-level rise, and flooding. They are, however, associated with reduced bio ersity, due to their steep orientation, lack of microhabitats, and the materials used in their construction. Hence, there is considerable interest in modifying seawalls to enhance the settlement and ersity of marine organisms, as microbial biofilms play a critical role facilitating algal and invertebrate colonization. We assessed how different stone materials, ranging from aluminosilicates to limestone and concrete, affect biofilm formation. Metagenomic assessment of marine microbial communities indicated no significant impact of material on microbial ersity, irrespective of the erse surface chemistry and topography. Based on KEGG pathway analysis, surface properties appeared to influence the community composition and function during the initial stages of biofilm development, but this effect disappeared by Day 31. We conclude that marine biofilms converged over time to a generic marine biofilm, rather than the underlying stone substrata type playing a significant role in driving community composition.
Publisher: Springer Science and Business Media LLC
Date: 10-2021
DOI: 10.1038/S41591-021-01498-0
Abstract: Anemia is a globally widespread condition in women and is associated with reduced economic productivity and increased mortality worldwide. Here we map annual 2000–2018 geospatial estimates of anemia prevalence in women of reproductive age (15–49 years) across 82 low- and middle-income countries (LMICs), stratify anemia by severity and aggregate results to policy-relevant administrative and national levels. Additionally, we provide subnational disparity analyses to provide a comprehensive overview of anemia prevalence inequalities within these countries and predict progress toward the World Health Organization’s Global Nutrition Target (WHO GNT) to reduce anemia by half by 2030. Our results demonstrate widespread moderate improvements in overall anemia prevalence but identify only three LMICs with a high probability of achieving the WHO GNT by 2030 at a national scale, and no LMIC is expected to achieve the target in all their subnational administrative units. Our maps show where large within-country disparities occur, as well as areas likely to fall short of the WHO GNT, offering precision public health tools so that adequate resource allocation and subsequent interventions can be targeted to the most vulnerable populations.
Publisher: BMJ
Date: 24-04-2020
DOI: 10.1136/INJURYPREV-2019-043494
Abstract: Past research in population health trends has shown that injuries form a substantial burden of population health loss. Regular updates to injury burden assessments are critical. We report Global Burden of Disease (GBD) 2017 Study estimates on morbidity and mortality for all injuries. We reviewed results for injuries from the GBD 2017 study. GBD 2017 measured injury-specific mortality and years of life lost (YLLs) using the Cause of Death Ensemble model. To measure non-fatal injuries, GBD 2017 modelled injury-specific incidence and converted this to prevalence and years lived with disability (YLDs). YLLs and YLDs were summed to calculate disability-adjusted life years (DALYs). In 1990, there were 4 260 493 (4 085 700 to 4 396 138) injury deaths, which increased to 4 484 722 (4 332 010 to 4 585 554) deaths in 2017, while age-standardised mortality decreased from 1079 (1073 to 1086) to 738 (730 to 745) per 100 000. In 1990, there were 354 064 302 (95% uncertainty interval: 338 174 876 to 371 610 802) new cases of injury globally, which increased to 520 710 288 (493 430 247 to 547 988 635) new cases in 2017. During this time, age-standardised incidence decreased non-significantly from 6824 (6534 to 7147) to 6763 (6412 to 7118) per 100 000. Between 1990 and 2017, age-standardised DALYs decreased from 4947 (4655 to 5233) per 100 000 to 3267 (3058 to 3505). Injuries are an important cause of health loss globally, though mortality has declined between 1990 and 2017. Future research in injury burden should focus on prevention in high-burden populations, improving data collection and ensuring access to medical care.
Publisher: American Society for Microbiology
Date: 17-05-2018
Abstract: Vibrio vulnificus , a ubiquitous inhabitant of coastal marine environments, has been isolated from a variety of sources. It is an opportunistic pathogen of both marine animals and humans. Here, the genome sequence of V. vulnificus Env1, an environmental isolate resistant to predation by the ciliate Tetrahymena pyriformis , is reported.
Publisher: Public Library of Science (PLoS)
Date: 28-07-2021
DOI: 10.1371/JOURNAL.PNTD.0008824
Abstract: Recent evidence suggests that, in some foci, elimination of onchocerciasis from Africa may be feasible with mass drug administration (MDA) of ivermectin. To achieve continental elimination of transmission, mapping surveys will need to be conducted across all implementation units (IUs) for which endemicity status is currently unknown. Using boosted regression tree models with optimised hyperparameter selection, we estimated environmental suitability for onchocerciasis at the 5 × 5-km resolution across Africa. In order to classify IUs that include locations that are environmentally suitable, we used receiver operating characteristic (ROC) analysis to identify an optimal threshold for suitability concordant with locations where onchocerciasis has been previously detected. This threshold value was then used to classify IUs (more suitable or less suitable) based on the location within the IU with the largest mean prediction. Mean estimates of environmental suitability suggest large areas across West and Central Africa, as well as focal areas of East Africa, are suitable for onchocerciasis transmission, consistent with the presence of current control and elimination of transmission efforts. The ROC analysis identified a mean environmental suitability index of 0·71 as a threshold to classify based on the location with the largest mean prediction within the IU. Of the IUs considered for mapping surveys, 50·2% exceed this threshold for suitability in at least one 5 × 5-km location. The formidable scale of data collection required to map onchocerciasis endemicity across the African continent presents an opportunity to use spatial data to identify areas likely to be suitable for onchocerciasis transmission. National onchocerciasis elimination programmes may wish to consider prioritising these IUs for mapping surveys as human resources, laboratory capacity, and programmatic schedules may constrain survey implementation, and possibly delaying MDA initiation in areas that would ultimately qualify.
Publisher: Public Library of Science (PLoS)
Date: 11-01-2018
Publisher: Elsevier BV
Date: 11-2018
Publisher: American Society for Microbiology
Date: 15-01-2013
DOI: 10.1128/AEM.02710-12
Abstract: Vibrio fischeri proliferates in a sessile, stable community known as a biofilm, which is one alternative survival strategy of its life cycle. Although this survival strategy provides adequate protection from abiotic factors, marine biofilms are still susceptible to grazing by bacteria-consuming protozoa. Subsequently, grazing pressure can be controlled by certain defense mechanisms that confer higher biofilm antipredator fitness. In the present work, we hypothesized that V. fischeri exhibits an antipredator fitness behavior while forming biofilms. Different predators representing commonly found species in aquatic populations were examined, including the flagellates Rhynchomonas nasuta and Neobodo designis (early biofilm feeders) and the ciliate Tetrahymena pyriformis (late biofilm grazer). V. fischeri biofilms included isolates from both seawater and squid hosts ( Euprymna and Sepiola species). Our results demonstrate inhibition of predation by biofilms, specifically, isolates from seawater. Additionally, antiprotozoan behavior was observed to be higher in late biofilms, particularly toward the ciliate T. pyriformis however, inhibitory effects were found to be widespread among all isolates tested. These results provide an alternative explanation for the adaptive advantage and persistence of V. fischeri biofilms and provide an important contribution to the understanding of defensive mechanisms that exist in the out-of-host environment.
Publisher: ASM Press
Date: 09-04-2014
Publisher: Research Square Platform LLC
Date: 19-01-2021
DOI: 10.21203/RS.3.RS-146426/V1
Abstract: Background Bacterial communities are responsible for biological nutrient removal and flocculation in engineered systems such as activated floccular sludge. Predators such as bacteriophage and protozoa exert significant predation pressure and cause bacterial mortality within these communities. However, the roles of bacteriophage and protozoan predation in impacting granulation process remain limited. Recent studies hypothesised that protozoa, particularly sessile ciliates, could have an important role in granulation as these ciliates were often observed in high abundance on surfaces of granules. Bacteriophages were hypothesized to contribute to granular stability through bacteriophage-mediated extracellular DNA release by lysing bacterial cells. This current study investigated the bacteriophage and protozoan communities throughout the granulation process. In addition, the importance of protozoan predation during granulation was also determined through chemical killing of protozoa in the floccular sludge. Results Four independent bioreactors seeded with activated floccular sludge were operated for aerobic granulation for 11 weeks. Changes in the phage, protozoa and bacterial communities were characterized throughout the granulation process. The filamentous phage, Inoviridae, increased in abundance at the initiation phase of granulation. However, the abundance shifted towards lytic phages during the maturation phase. In contrast, the abundance and ersity of protozoa decreased initially, possibly due to the reduction in settling time and subsequent washout. Upon the formation of granules, ciliated protozoa from the class Oligohymenophorea were the dominant group of protozoa based on metacommunity analysis. These protozoa had a strong, positive-correlation with the initial formation of compact aggregates prior to granule development. Furthermore, chemical inhibition of these ciliates in the floccular sludge delayed the initiation of granule formation. Analysis of the bacterial communities in the thiram treated sludge demonstrated that the recovery of ‘ Candidatus Accmulibacter’ was positively correlated with the formation of compact aggregates and granules. Conclusion Predation by bacteriophage and protozoa were positively correlated with the formation of aerobic granules. Increases in Inoviridae abundance suggested that filamentous phages may promote the structural formation of granules. Initiation of granules formation was delayed due to an absence of protozoa after chemical treatment. The presence of Candidatus Accumulibacter was necessary for the formation of granules in the absence of protozoa.
Publisher: Elsevier BV
Date: 06-2021
Publisher: American Society for Microbiology
Date: 18-06-2015
DOI: 10.1128/MICROBIOLSPEC.VE-0003-2014
Abstract: Members of the genus Vibrio are known to interact with phyto- and zooplankton in aquatic environments. These interactions have been proven to protect the bacterium from various environmental stresses, serve as a nutrient source, facilitate exchange of DNA, and to serve as vectors of disease transmission. This review highlights the impact of Vibrio -zooplankton interactions at the ecosystem scale and the importance of studies focusing on a wide range of Vibrio -zooplankton interactions. The current knowledge on chitin utilization (i.e., chemotaxis, attachment, and degradation) and the role of these factors in attachment to nonchitinous zooplankton is also presented.
Publisher: Springer Science and Business Media LLC
Date: 03-06-2021
DOI: 10.1038/S41562-021-01108-6
Abstract: Exclusive breastfeeding (EBF)—giving infants only breast-milk for the first 6 months of life—is a component of optimal breastfeeding practices effective in preventing child morbidity and mortality. EBF practices are known to vary by population and comparable subnational estimates of prevalence and progress across low- and middle-income countries (LMICs) are required for planning policy and interventions. Here we present a geospatial analysis of EBF prevalence estimates from 2000 to 2018 across 94 LMICs mapped to policy-relevant administrative units (for ex le, districts), quantify subnational inequalities and their changes over time, and estimate probabilities of meeting the World Health Organization’s Global Nutrition Target (WHO GNT) of ≥70% EBF prevalence by 2030. While six LMICs are projected to meet the WHO GNT of ≥70% EBF prevalence at a national scale, only three are predicted to meet the target in all their district-level units by 2030.
Publisher: Elsevier BV
Date: 06-2019
Publisher: Frontiers Media SA
Date: 21-01-2020
Publisher: Elsevier BV
Date: 08-2020
Publisher: American Society for Microbiology
Date: 15-01-2001
DOI: 10.1128/JB.183.2.758-762.2001
Abstract: Vibrio vulnificus contains homologues of the V. harveyi luxR and luxS genes. A null mutation in smcR ( luxR ) resulted in a defect in starvation survival, inhibition of starvation-induced maintenance of culturability that occurs when V. vulnificus is starved prior to low-temperature incubation, and increased expression of stationary-phase phenotypes.
Publisher: Elsevier BV
Date: 09-2014
Publisher: American Society for Microbiology
Date: 1987
DOI: 10.1128/AEM.53.1.193-195.1987
Abstract: We screened 44 lactose-positive Vibrio strains isolated from the marine environment for homology with a 3.2-kilobase DNA fragment encoding the Vibrio vulnificus cytotoxin-hemolysin gene. All 29 marine isolates identified as V. vulnificus on the basis of numerical taxonomy and DNA-DNA hybridization studies hybridized with the cytotoxin gene probe, as did all V. vulnificus reference strains. Homologous gene sequences were identified in no other lactose-positive marine vibrio isolates nor in 10 other Vibrio species.
Publisher: Springer Science and Business Media LLC
Date: 13-04-2023
DOI: 10.1007/S00338-023-02376-6
Abstract: Corals host abundant microbial communities, or microbiomes, that play essential roles in the function of the coral holobiont. We examined the mucus microbiome in corals within the port of Singapore, where corals persist despite intense anthropogenic impacts. The coral mucus microbiomes of Pectinia paeonia and Platygyra sinensis at three reef sites were tracked by 16S rRNA gene licon sequencing from January 2019 to January 2020. Both coral species displayed spatial and temporal differences in microbiome composition, suggesting site specificity and seasonality in microbiome composition consistent with the monsoons. The temporal shifts in relative abundance of dominant taxa were different between the two coral species. Nonetheless, Proteobacteria was the most abundant phylum in both coral species and was reduced during the southwest (SW) monsoon, while Cyanobacteria and Crenarchaeota increased. The presumptive beneficial endosymbiont Endozoicomonas was only associated with corals at the reef site located the farthest from the Singapore mainland. The coral microbiomes reflected seasonal changes, while the seawater displayed distinct temporal microbial compositions and site-specific differentiation within all s ling dates. The persistence of coral reefs within the port of Singapore highlights the adaptive ability of corals to respond to stressful environments, and this study provides further evidence that a flexible microbiome could be an important part of the strategy employed by corals to remain resilient.
Publisher: Wiley
Date: 1997
Abstract: In this paper, we present results from studies on marine Vibrio species, in which complex adaptive responses have been investigated. The results of two-dimensional polyacrylamide gel electrophoresis serve to illustrate the usefulness of a global approach, and how it can be combined with other methodologies in order to achieve an improved understanding of the means by which bacteria adapt to alterations in environmental conditions. The overall strategies described in this paper are particularly useful for studies of bacteria for which efficient genetic tools, background genotypes and in depth physiological data are not yet available.
Publisher: Informa UK Limited
Date: 21-02-2014
DOI: 10.1080/08927014.2013.872778
Abstract: This study explored an antifouling (AF) concept based on deployment of microfabricated polydimethyl siloxane (PDMS) surfaces with 1-10 μm periodicity corrugated topographies in temperate marine waters. The effect of the surfaces on the development of microbial biofilms over 28 days and during different seasons, including both summer and winter, was examined using confocal laser scanning microscopy (CLSM) as well as terminal restriction fragment (T-RF) analysis for phylogenetic fingerprinting. The microscale topography significantly impacted biofilm development by altering the attachment pattern and reducing microcolony formation on the 1, 2 and 4 μm PDMS surfaces. Also, field deployments over 28 days showed a significant reduction in biovolume on the 4 and 10 μm PDMS surfaces despite altered environmental conditions. The microfabricated PDMS surfaces further significantly impacted on the community composition of the biofilms, as revealed by changes in T-RF profiles, at different stages of development. Moreover, altered biofilm resistance was demonstrated by exposing pre-established biofilms on 10 μm micro-fabricated surfaces to enhanced flagellate predation by a heterotrophic protist, Rhynchomonas nasuta. Pronounced changes in the overall marine microbial biofilm development as well as community composition warrant exploring substratum modification for marine AF applications.
Publisher: Informa UK Limited
Date: 21-10-2014
DOI: 10.1080/08927014.2014.971238
Abstract: Biofouling, the combined effect of microorganism and biopolymer accumulation, significantly reduces the process efficiency of membrane bioreactors (MBRs). Here, four biofilm components, alpha-polysaccharides, beta-polysaccharides, proteins and microorganisms, were quantified in MBRs. The biomass of each component was positively correlated with the transmembrane pressure increase in MBRs. Proteins were the most abundant biopolymer in biofilms and showed the fastest rate of increase. The spatial distribution and co-localization analysis of the biofouling components indicated at least 60% of the extracellular polysaccharide (EPS) components were associated with the microbial cells when the transmembrane pressure (TMP) entered the jump phase, suggesting that the EPS components were either secreted by the biofilm cells or that the deposition of these components facilitated biofilm formation. It is suggested that biofilm formation and the accumulation of EPS are intrinsically coupled, resulting in biofouling and loss of system performance. Therefore, strategies that control biofilm formation on membranes may result in a significant improvement of MBR performance.
Publisher: BMJ
Date: 08-01-2020
DOI: 10.1136/INJURYPREV-2019-043302
Abstract: The global burden of road injuries is known to follow complex geographical, temporal and demographic patterns. While health loss from road injuries is a major topic of global importance, there has been no recent comprehensive assessment that includes estimates for every age group, sex and country over recent years. We used results from the Global Burden of Disease (GBD) 2017 study to report incidence, prevalence, years lived with disability, deaths, years of life lost and disability-adjusted life years for all locations in the GBD 2017 hierarchy from 1990 to 2017 for road injuries. Second, we measured mortality-to-incidence ratios by location. Third, we assessed the distribution of the natures of injury (eg, traumatic brain injury) that result from each road injury. Globally, 1 243 068 (95% uncertainty interval 1 191 889 to 1 276 940) people died from road injuries in 2017 out of 54 192 330 (47 381 583 to 61 645 891) new cases of road injuries. Age-standardised incidence rates of road injuries increased between 1990 and 2017, while mortality rates decreased. Regionally, age-standardised mortality rates decreased in all but two regions, South Asia and Southern Latin America, where rates did not change significantly. Nine of 21 GBD regions experienced significant increases in age-standardised incidence rates, while 10 experienced significant decreases and two experienced no significant change. While road injury mortality has improved in recent decades, there are worsening rates of incidence and significant geographical heterogeneity. These findings indicate that more research is needed to better understand how road injuries can be prevented.
Publisher: Informa UK Limited
Date: 15-02-2012
Publisher: Springer Science and Business Media LLC
Date: 23-01-2015
Publisher: Springer Science and Business Media LLC
Date: 28-11-2011
DOI: 10.1038/NRMICRO2695
Abstract: In most environments, bacteria reside primarily in biofilms, which are social consortia of cells that are embedded in an extracellular matrix and undergo developmental programmes resulting in a predictable biofilm 'life cycle'. Recent research on many different bacterial species has now shown that the final stage in this life cycle includes the production and release of differentiated dispersal cells. The formation of these cells and their eventual dispersal is initiated through erse and remarkably sophisticated mechanisms, suggesting that there are strong evolutionary pressures for dispersal from an otherwise largely sessile biofilm. The evolutionary aspect of biofilm dispersal is now being explored through the integration of molecular microbiology with eukaryotic ecological and evolutionary theory, which provides a broad conceptual framework for the ersity of specific mechanisms underlying biofilm dispersal. Here, we review recent progress in this emerging field and suggest that the merging of detailed molecular mechanisms with ecological theory will significantly advance our understanding of biofilm biology and ecology.
Publisher: Elsevier BV
Date: 07-2013
Publisher: Frontiers Media SA
Date: 22-01-2020
Publisher: Public Library of Science (PLoS)
Date: 07-07-2017
Publisher: Public Library of Science (PLoS)
Date: 06-12-2018
Publisher: Springer Science and Business Media LLC
Date: 15-02-2016
DOI: 10.1038/SREP20717
Abstract: While many studies of coral bleaching report on broad, regional scale responses, fewer examine variation in susceptibility among coral taxa and changes in community structure, before, during and after bleaching on in idual reefs. Here we report in detail on the response to bleaching by a coral community on a highly disturbed reef site south of mainland Singapore before, during and after a major thermal anomaly in 2010. To estimate the capacity for resistance to thermal stress, we report on: a) overall bleaching severity during and after the event, b) differences in bleaching susceptibility among taxa during the event and c) changes in coral community structure one year before and after bleaching. Approximately two thirds of colonies bleached, however, post-bleaching recovery was quite rapid and, importantly, coral taxa that are usually highly susceptible were relatively unaffected. Although total coral cover declined, there was no significant change in coral taxonomic community structure before and after bleaching. Several factors may have contributed to the overall high resistance of corals at this site including Symbiodinium affiliation, turbidity and heterotrophy. Our results suggest that, despite experiencing chronic anthropogenic disturbances, turbid shallow reef communities may be remarkably resilient to acute thermal stress.
Publisher: Public Library of Science (PLoS)
Date: 07-01-2016
Publisher: Wiley
Date: 26-03-2008
Publisher: Elsevier BV
Date: 12-2011
Publisher: Springer Science and Business Media LLC
Date: 26-09-2006
DOI: 10.1007/S00216-006-0761-2
Abstract: Bacteria are able to coordinate gene expression as a community through the secretion and detection of signalling molecules so that the members of the community can simultaneously express specific behaviours. This mechanism of regulation of behaviour appears to be a key trait for adaptation to specific environments and has been shown to regulate a variety of important phenotypes, from virulence factor production to biofilm formation to symbiosis related behaviours such as bioluminescence. The ability to communicate and communally regulate gene expression is hypothesised to have evolved as a way for organisms to delay expression of phenotypes until numerical supremacy is reached. For ex le, in the case of infection, if an invading microorganism were to express virulence factors too early, the host may be able to mount a successful defence and repel the invaders. There is growing evidence that bacterial quorum sensing (QS) systems are involved in cross-kingdom signalling with eukaryotic organisms and that eukaryotes are capable of actively responding to bacteria in their environment by detecting and acting upon the presence of these signalling molecules. Likewise, eukaryotes produce compounds that can interfere with QS systems in bacteria by acting as agonists or antagonists. An exciting new field of study, biomimetics, takes inspiration from nature's models and attempts to design solutions to human problems, and biomimics of QS systems may be one such solution. This article presents the acylated homoserine lactone and autoinducer 2 QS systems in bacteria, the means of intercepting or interfering with bacterial QS systems evolved by eukaryotes, and the rational design of synthetic antagonists.
Publisher: Elsevier BV
Date: 07-2012
Publisher: Oxford University Press (OUP)
Date: 09-2016
Publisher: Springer Science and Business Media LLC
Date: 08-01-2021
DOI: 10.1186/S12916-020-01876-4
Abstract: Human immunodeficiency virus (HIV) remains a public health priority in Latin America. While the burden of HIV is historically concentrated in urban areas and high-risk groups, subnational estimates that cover multiple countries and years are missing. This paucity is partially due to incomplete vital registration (VR) systems and statistical challenges related to estimating mortality rates in areas with low numbers of HIV deaths. In this analysis, we address this gap and provide novel estimates of the HIV mortality rate and the number of HIV deaths by age group, sex, and municipality in Brazil, Colombia, Costa Rica, Ecuador, Guatemala, and Mexico. We performed an ecological study using VR data ranging from 2000 to 2017, dependent on in idual country data availability. We modeled HIV mortality using a Bayesian spatially explicit mixed-effects regression model that incorporates prior information on VR completeness. We calibrated our results to the Global Burden of Disease Study 2017. All countries displayed over a 40-fold difference in HIV mortality between municipalities with the highest and lowest age-standardized HIV mortality rate in the last year of study for men, and over a 20-fold difference for women. Despite decreases in national HIV mortality in all countries—apart from Ecuador—across the period of study, we found broad variation in relative changes in HIV mortality at the municipality level and increasing relative inequality over time in all countries. In all six countries included in this analysis, 50% or more HIV deaths were concentrated in fewer than 10% of municipalities in the latest year of study. In addition, national age patterns reflected shifts in mortality to older age groups—the median age group among decedents ranged from 30 to 45 years of age at the municipality level in Brazil, Colombia, and Mexico in 2017. Our subnational estimates of HIV mortality revealed significant spatial variation and erging local trends in HIV mortality over time and by age. This analysis provides a framework for incorporating data and uncertainty from incomplete VR systems and can help guide more geographically precise public health intervention to support HIV-related care and reduce HIV-related deaths.
Publisher: Elsevier BV
Date: 08-2019
Publisher: Springer Science and Business Media LLC
Date: 08-01-2020
DOI: 10.1038/S41586-019-1878-8
Abstract: Childhood malnutrition is associated with high morbidity and mortality globally 1 . Undernourished children are more likely to experience cognitive, physical, and metabolic developmental impairments that can lead to later cardiovascular disease, reduced intellectual ability and school attainment, and reduced economic productivity in adulthood 2 . Child growth failure (CGF), expressed as stunting, wasting, and underweight in children under five years of age (0–59 months), is a specific subset of undernutrition characterized by insufficient height or weight against age-specific growth reference standards 3–5 . The prevalence of stunting, wasting, or underweight in children under five is the proportion of children with a height-for-age, weight-for-height, or weight-for-age z -score, respectively, that is more than two standard deviations below the World Health Organization’s median growth reference standards for a healthy population 6 . Subnational estimates of CGF report substantial heterogeneity within countries, but are available primarily at the first administrative level (for ex le, states or provinces) 7 the uneven geographical distribution of CGF has motivated further calls for assessments that can match the local scale of many public health programmes 8 . Building from our previous work mapping CGF in Africa 9 , here we provide the first, to our knowledge, mapped high-spatial-resolution estimates of CGF indicators from 2000 to 2017 across 105 low- and middle-income countries (LMICs), where 99% of affected children live 1 , aggregated to policy-relevant first and second (for ex le, districts or counties) administrative-level units and national levels. Despite remarkable declines over the study period, many LMICs remain far from the ambitious World Health Organization Global Nutrition Targets to reduce stunting by 40% and wasting to less than 5% by 2025. Large disparities in prevalence and progress exist across and within countries our maps identify high-prevalence areas even within nations otherwise succeeding in reducing overall CGF prevalence. By highlighting where the highest-need populations reside, these geospatial estimates can support policy-makers in planning interventions that are adapted locally and in efficiently directing resources towards reducing CGF and its health implications.
Publisher: American Society for Microbiology
Date: 12-1984
DOI: 10.1128/AEM.48.6.1243-1245.1984
Abstract: Bacterial populations attached to intestinal linings of shallow-water fish were compared to those free in the lumen for response to hydrostatic pressure and ability to degrade a variety of substrates. Results suggested that, unlike reports on gut-associated deep-sea bacteria, the two shallow-water populations were not significantly different in their pressure or substrate responsiveness.
Publisher: Springer Science and Business Media LLC
Date: 16-10-2019
DOI: 10.1038/S41586-019-1545-0
Abstract: Since 2000, many countries have achieved considerable success in improving child survival, but localized progress remains unclear. To inform efforts towards United Nations Sustainable Development Goal 3.2—to end preventable child deaths by 2030—we need consistently estimated data at the subnational level regarding child mortality rates and trends. Here we quantified, for the period 2000–2017, the subnational variation in mortality rates and number of deaths of neonates, infants and children under 5 years of age within 99 low- and middle-income countries using a geostatistical survival model. We estimated that 32% of children under 5 in these countries lived in districts that had attained rates of 25 or fewer child deaths per 1,000 live births by 2017, and that 58% of child deaths between 2000 and 2017 in these countries could have been averted in the absence of geographical inequality. This study enables the identification of high-mortality clusters, patterns of progress and geographical inequalities to inform appropriate investments and implementations that will help to improve the health of all populations.
Publisher: Springer Science and Business Media LLC
Date: 03-07-2014
Publisher: Public Library of Science (PLoS)
Date: 09-09-2014
Publisher: American Medical Association (AMA)
Date: 12-2019
Publisher: Informa UK Limited
Date: 2006
DOI: 10.1080/08927010600691879
Abstract: It has been suggested that Vibrio vulnificus attaches to plankton and algae and is found in large numbers in the environment. Factors affecting attachment, biofilm formation and morphology of V. vulnificus have not been thoroughly investigated. This study evaluated the role of quorum sensing (QS) and environmental conditions on biofilm development of V. vulnificus. It was found that biofilm development by V. vulnificus was affected by nutrient and glucose concentration, but not by NaCl concentration or temperature under the conditions used here. Moreover, biofilm development of a QS mutant strain proceeded rapidly and sloughing occurred earlier than for the isogenic parent strain. There was a significant loss of viability for the QS mutant biofilm early in development. Hence, it is hypothesised that factors regulated by the QS system play a role in proper biofilm development and maintenance of V. vulnificus. Furthermore, it is shown that biofilm development varied among isolates.
Publisher: Springer Science and Business Media LLC
Date: 05-1994
DOI: 10.1007/BF01573208
Publisher: Elsevier BV
Date: 03-2015
DOI: 10.1016/J.JES.2014.07.025
Abstract: Biofilm formation, one of the primary causes of biofouling, results in reduced membrane flux or increased transmembrane pressure and thus represents a major impediment to the wider implementation of membrane bioreactor (MBR) technologies for water purification. Most studies have focused on the role of bacteria in membrane fouling as they are the most dominant and best studied organisms present in the MBR. In contrast, there is limited information on the role of the archaeal community in biofilm formation in MBRs. This study investigated the composition of the archaeal community during the process of biofouling in an MBR. The archaeal community was observed to have lower richness and ersity in the biofilm than the sludge during the establishment of biofilms at low transmembrane pressure (TMP). Clustering of the communities based on the Bray-Curtis similarity matrix indicated that a subset of the sludge archaeal community formed the initial biofilms. The archaeal community in the biofilm was mainly composed of Thermoprotei, Thermoplasmata, Thermococci, Methanopyri, Methanomicrobia and Halobacteria. Among them, the Thermoprotei and Thermoplasmata were present at higher relative proportions in the biofilms than they were in the sludge. Additionally, the Thermoprotei, Thermoplasmata and Thermococci were the dominant organisms detected in the initial biofilms at low TMP, while as the TMP increased, the Methanopyri, Methanomicrobia, Aciduliprofundum and Halobacteria were present at higher abundances in the biofilms at high TMP.
Publisher: Oxford University Press (OUP)
Date: 31-10-2017
Publisher: Springer Science and Business Media LLC
Date: 30-09-2019
Publisher: American Society for Microbiology
Date: 30-04-2015
Abstract: Shewanella sp. CP20 is a marine bacterium that survives ingestion by Tetrahymena pyriformis and is expelled from the protozoan within membrane-bound vacuoles, where the bacterial cells show long-term survival. Here, we report the draft genome sequence of Shewanella sp. CP20 and discuss the potential mechanisms facilitating intraprotozoan survival.
Publisher: Elsevier BV
Date: 02-2012
DOI: 10.1016/J.JTBI.2011.10.007
Abstract: Biofilms are currently recognised as the predominant bacterial life-style and it has been suggested that biofilm development is influenced by a number of different processes such as adhesion, detachment, mass transport, quorum sensing, cell death and active dispersal. One of the least understood processes and its effects on biofilm development is cell death. However, experimental studies suggest that bacterial death is an important process during biofilm development and many studies show a relationship between cell death and dispersal in microbial biofilms. We present a model of the process of cell death during biofilm development, with a particular focus on the spatial localisation of cell death or cell damage. Three rules governing cell death or cell damage were evaluated which compared the effects of starvation, damage accumulation, and viability during biofilm development and were also used to design laboratory based experiments to test the model. Results from model simulations show that actively growing biofilms develop steep nutrient gradients within the interior of the biofilm that affect neighbouring microcolonies resulting in cell death and detachment. Two of the rules indicated that high substrate concentrations lead to accelerated cell death, in contrast to the third rule, based on the accumulation of damage, which predicted earlier cell death for biofilms grown with low substrate concentrations. Comparison of the modelling results with experimental results suggests that cell death is favoured under low nutrient conditions and that the accumulation of damage may be the main cause of cell death during biofilm development.
Publisher: Elsevier BV
Date: 09-2014
Publisher: American Society for Microbiology
Date: 11-1986
DOI: 10.1128/AEM.52.5.1209-1211.1986
Abstract: We report the existence of a bioluminescent strain of the human pathogen Vibrio vulnificus. The isolate was obtained from blood following a fatal wound infection and thus represents the first description of an infection caused by a luminescent bacterium.
Publisher: American Society for Microbiology
Date: 08-03-2022
DOI: 10.1128/AEM.02322-21
Abstract: Pseudomonas aeruginosa is an opportunistic pathogen that causes both acute infections in plants and animals, including humans, and chronic infections in immunocompromised and cystic fibrosis patients. This bacterium is commonly found in soils and water, where bacteria are constantly under threat of being consumed by bacterial predators, e.g., protozoa.
Publisher: Oxford University Press (OUP)
Date: 15-02-2015
DOI: 10.1111/JAM.12759
Publisher: Springer Science and Business Media LLC
Date: 19-06-2021
DOI: 10.1007/S00248-021-01793-W
Abstract: As corals continue to decline globally, particularly due to climate change, it is vital to understand the extent to which their microbiome may confer an adaptive resilience against environmental stress. Corals that survive on the urban reefs of Singapore are ideal candidates to study the association of scleractinians with their microbiome, which in turn can inform reef conservation and management. In this study, we monitored differences in the microbiome of Pocillopora acuta colonies reciprocally transplanted between two reefs, Raffles and Kusu, within the Port of Singapore, where corals face intense anthropogenic impacts. Pocillopora acuta had previously been shown to host distinct microbial communities between these two reefs. Amplicon sequencing (16S rRNA) was used to assess the coral microbiomes at 1, 2, 4, and 10 days post-transplantation. Coral microbiomes responded rapidly to transplantation, becoming similar to those of the local corals at the destination reef within one day at Raffles and within two days at Kusu. Elevated nitrate concentrations were detected at Raffles for the duration of the study, potentially influencing the microbiome’s response to transplantation. The persistence of corals within the port of Singapore highlights the ability of corals to adapt to stressful environments. Further, coral resilience appears to coincide with a dynamic microbiome which can undergo shifts in composition without succumbing to dysbiosis.
Publisher: No publisher found
Date: 2016
DOI: 10.1016/J.MIMET.2016.06.008 10.1016/J.MIMET.2016.06.008. EPUB 2016 JUN 11.
Publisher: Springer Science and Business Media LLC
Date: 15-10-2022
DOI: 10.1038/S41396-021-01134-2
Abstract: Predation by heterotrophic protists drives the emergence of adaptive traits in bacteria, and often these traits lead to altered interactions with hosts and persistence in the environment. Here we studied adaptation of the cholera pathogen, Vibrio cholerae during long-term co-incubation with the protist host, Acanthamoeba castellanii . We determined phenotypic and genotypic changes associated with long-term intra-amoebal host adaptation and how this impacts pathogen survival and fitness. We showed that adaptation to the amoeba host leads to temporal changes in multiple phenotypic traits in V. cholerae that facilitate increased survival and competitive fitness in amoeba. Genome sequencing and mutational analysis revealed that these altered lifestyles were linked to non-synonymous mutations in conserved regions of the flagellar transcriptional regulator, flrA . Additionally, the mutations resulted in enhanced colonisation in zebrafish, establishing a link between adaptation of V. cholerae to amoeba predation and enhanced environmental persistence. Our results show that pressure imposed by amoeba on V. cholerae selects for flrA mutations that serves as a key driver for adaptation. Importantly, this study provides evidence that adaptive traits that evolve in pathogens in response to environmental predatory pressure impact the colonisation of eukaryotic organisms by these pathogens.
Publisher: MDPI AG
Date: 15-08-2021
DOI: 10.3390/V13081614
Abstract: It has been shown that the filamentous phage, Pf4, plays an important role in biofilm development, stress tolerance, genetic variant formation and virulence in Pseudomonas aeruginosa PAO1. These behaviours are linked to the appearance of superinfective phage variants. Here, we have investigated the molecular mechanism of superinfection as well as how the Pf4 phage can control host gene expression to modulate host behaviours. Pf4 exists as a prophage in PAO1 and encodes a homologue of the P2 phage repressor C and was recently named Pf4r. Through a combination of molecular techniques, ChIPseq and transcriptomic analyses, we show a critical site in repressor C (Pf4r) where a mutation in the site, 788799A G (Ser4Pro), causes Pf4r to lose its function as the immunity factor against reinfection by Pf4. X-ray crystal structure analysis shows that Pf4r forms symmetric homo-dimers homologous to the E.coli bacteriophage P2 RepC protein. A mutation, Pf4r*, associated with the superinfective Pf4r variant, found at the dimer interface, suggests dimer formation may be disrupted, which derepresses phage replication. This is supported by multi-angle light scattering (MALS) analysis, where the Pf4r* protein only forms monomers. The loss of dimerisation also explains the loss of Pf4r’s immunity function. Phenotypic assays showed that Pf4r increased LasB activity and was also associated with a slight increase in the percentage of morphotypic variants. ChIPseq and transcriptomic analyses suggest that Pf4r also likely functions as a transcriptional regulator for other host genes. Collectively, these data suggest the mechanism by which filamentous phages play such an important role in P. aeruginosa biofilm development.
Publisher: Microbiology Society
Date: 07-2003
Abstract: Quorum sensing systems serve as a means of ‘census taking’ of conspecific and non-conspecific bacteria in the near vicinity. The acylated homoserine lactone (AHL) quorum sensing system has been proposed to be primarily an intra-specific communication system, while the AI-2 autoinducer signalling system is proposed to be an interspecific communication system. Here it is shown that AI-2-like signalling in two marine Vibrio species, Vibrio vulnificus and ‘ Vibrio angustum ’ S14, induces the core response phenotypes of starvation adaptation and stress resistance, and that a signal antagonist can competitively inhibit these phenotypes. Furthermore, the signals produced by a range of Vibrio species have the ability to induce these phenotypes in V. vulnificus and ‘ V. angustum ’ S14, indicating that, at least in Vibrio species, AI-2-like signalling systems function as interspecies communication systems capable of ‘cross-talk’ and of regulating environmentally relevant phenotypes.
Publisher: F1000 Research Ltd
Date: 15-12-2017
DOI: 10.12688/WELLCOMEOPENRES.12483.2
Abstract: Background : In 2011, the World Health Organization recognized podoconiosis as one of the neglected tropical diseases. Nonetheless, the magnitude of podoconiosis and the geographical distribution of the disease is poorly understood. Based on a nationwide mapping survey and geostatistical modelling, we predict the prevalence of podoconiosis and estimate the number of cases across Ethiopia. Methods : We used nationwide data collected in Ethiopia between 2008 and 2013. Data were available for 141,238 in iduals from 1,442 communities in 775 districts from all nine regional states and two city administrations. We developed a geostatistical model of podoconiosis prevalence among adults (in iduals aged 15 years or above), by combining environmental factors. The number of people with podoconiosis was then estimated using a gridded map of adult population density for 2015. Results : Podoconiosis is endemic in 345 districts in Ethiopia: 144 in Oromia, 128 in Southern Nations, Nationalities and People’s [SNNP], 64 in Amhara, 4 in Benishangul Gumuz, 4 in Tigray and 1 in Somali Regional State. Nationally, our estimates suggest that 1,537,963 adults (95% confidence intervals, 290,923-4,577,031 adults) were living with podoconiosis in 2015. Three regions (SNNP, Oromia and Amhara) contributed 99% of the cases. The highest proportion of in iduals with podoconiosis resided in the SNNP (39%), while 32% and 29% of people with podoconiosis resided in Oromia and Amhara Regional States, respectively. Tigray and Benishangul Gumuz Regional States bore lower burdens, and in the remaining regions, podoconiosis was almost non-existent. Conclusions : The estimates of podoconiosis cases presented here based upon the combination of currently available epidemiological data and a robust modelling approach clearly show that podoconiosis is highly endemic in Ethiopia. Given the presence of low cost prevention, and morbidity management and disability prevention services, it is our collective responsibility to scale-up interventions rapidly.
Publisher: F1000 Research Ltd
Date: 04-09-2017
DOI: 10.12688/WELLCOMEOPENRES.12483.1
Abstract: Background: In 2011, the World Health Organization recognized podoconiosis as one of the neglected tropical diseases. Nonetheless, the number of people with podoconiosis and the geographical distribution of the disease is poorly understood. Based on a nationwide mapping survey and geostatistical modelling, we predict the prevalence of podoconiosis and estimate the number of cases across Ethiopia. Methods: We used nationwide data collected in Ethiopia between 2008 and 2013. Data were available for 141,238 in iduals from 1,442 villages in 775 districts from all nine regional states and two city administrations. We developed a geostatistical model of podoconiosis prevalence among adults (in iduals aged 15 years or above), by combining environmental factors. The number of people with podoconiosis was then estimated using a gridded map of adult population density for 2015. Results: Podoconiosis is endemic in 345 districts in Ethiopia: 144 in Oromia, 128 in Southern Nations, Nationalities and People’s [SNNP], 64 in Amhara, 4 in Benishangul Gumuz, 4 in Tigray and 1 in Somali Regional State. Nationally, our estimates suggest that 1,537,963 adults (95% confidence intervals, 290,923-4,577,031 adults) were living with podoconiosis in 2015. Three regions (SNNP, Oromia and Amhara) contributed 99% of the cases. The highest proportion of in iduals with podoconiosis resided in the SNNP (39%), while 32% and 29% of people with podoconiosis resided in Oromia and Amhara Regional States, respectively. Tigray and Benishangul Gumuz Regional States bore lower burdens, and in the remaining regions, podoconiosis was almost non-existent. Discussion: The estimates of podoconiosis cases presented here based upon the combination of currently available epidemiological data and a robust modelling approach clearly show that podoconiosis is highly endemic in Ethiopia. Given the presence of low cost prevention, and morbidity management and disability prevention services, it is our collective responsibility to scale-up interventions rapidly.
Publisher: American Society for Microbiology
Date: 28-02-2023
DOI: 10.1128/AEM.01741-22
Abstract: Biofilms have been shown to protect bacterial cells from predation by protists. Biofilm studies have traditionally used single species systems, which have provided information on the mechanisms and regulation of biofilm formation and dispersal, and the effects of predation on these biofilms.
Publisher: Wiley
Date: 25-08-2010
DOI: 10.1111/J.1365-2958.2010.07286.X
Abstract: Vibrio2009, the third international conference on the biology of Vibrios, was held in Rio de Janeiro, Brazil, in November 2009. This conference united researchers studying various aspects of pathogenesis, symbiosis and environmental persistence of this erse group of marine bacteria. Through many of the presentations, it became apparent how horizontal gene transfer and genetic flexibility has driven the incredible ersity of these microbes. Interestingly, unifying themes of behaviour could be seen in the interaction(s) of Vibrios with other organisms, such as with other bacteria, corals, invertebrates and humans. Presentations illuminated the idea that the path towards symbiosis is not that different from the path towards disease, and that alterations in environmental conditions, such as climate change, can tip the balance and change the Vibrio interactions from benign to pathogenic.
Publisher: Springer International Publishing
Date: 2023
Publisher: BMJ
Date: 08-01-2020
DOI: 10.1136/INJURYPREV-2019-043296
Abstract: The epidemiological transition of non-communicable diseases replacing infectious diseases as the main contributors to disease burden has been well documented in global health literature. Less focus, however, has been given to the relationship between sociodemographic changes and injury. The aim of this study was to examine the association between disability-adjusted life years (DALYs) from injury for 195 countries and territories at different levels along the development spectrum between 1990 and 2017 based on the Global Burden of Disease (GBD) 2017 estimates. Injury mortality was estimated using the GBD mortality database, corrections for garbage coding and CODEm—the cause of death ensemble modelling tool. Morbidity estimation was based on surveys and inpatient and outpatient data sets for 30 cause-of-injury with 47 nature-of-injury categories each. The Socio-demographic Index (SDI) is a composite indicator that includes lagged income per capita, average educational attainment over age 15 years and total fertility rate. For many causes of injury, age-standardised DALY rates declined with increasing SDI, although road injury, interpersonal violence and self-harm did not follow this pattern. Particularly for self-harm opposing patterns were observed in regions with similar SDI levels. For road injuries, this effect was less pronounced. The overall global pattern is that of declining injury burden with increasing SDI. However, not all injuries follow this pattern, which suggests multiple underlying mechanisms influencing injury DALYs. There is a need for a detailed understanding of these patterns to help to inform national and global efforts to address injury-related health outcomes across the development spectrum.
Publisher: The Electrochemical Society
Date: 2017
DOI: 10.1149/2.0521709JES
Publisher: Elsevier BV
Date: 12-2014
Publisher: Wiley
Date: 06-03-2015
Publisher: Frontiers Media SA
Date: 23-11-2022
Publisher: Microbiology Society
Date: 07-1996
DOI: 10.1099/13500872-142-7-1675
Abstract: The response of the estuarine human pathogen Vibrio vulnificus to starvation for carbon, nitrogen or phosphorus, or all three nutrients simultaneously (multiple-nutrient), was examined with respect to the maintenance of culturability during incubation at low temperature. V. vulnificus showed similar survival patterns during starvation for the in idual nutrients when kept at 24 degrees C. On the other hand, cultures prestarved at 24 degrees C and then shifted to 5 degrees C maintained culturability at low temperature in a starvation-condition-dependent manner. Carbon and multiple-nutrient starvation were indistinguishable in their ability to mediate maintenance of culturability in the cold. Prolonged starvation for phosphorus had a similar effect, but nitrogen starvation did not allow for maintenance of culturability. Extracellular factors produced during starvation were not observed to have an effect on the culturability of cells incubated at low temperature. Protein synthesis during starvation for in idual nutrients was analysed by two-dimensional PAGE of pulse-labelled proteins. Carbon and multiple-nutrient starvation gave nearly identical protein induction patterns involving at least 34 proteins, indicating that carbon starvation determines both responses. Nitrogen starvation for 1 h induced 24 proteins, while phosphorus starvation induced a set of 10 proteins after 1 h and about 40 proteins after 18 h. It is suggested that starvation for carbon or phosphorus induces maintenance of culturability of V. vulnificus incubated at low temperature via the synthesis of distinct sets of starvation-specific proteins.
Publisher: Elsevier BV
Date: 09-2014
Publisher: Frontiers Media SA
Date: 22-02-2021
Publisher: Proceedings of the National Academy of Sciences
Date: 15-09-2009
Abstract: Many marine bacteria have evolved to grow optimally at either high (copiotrophic) or low (oligotrophic) nutrient concentrations, enabling different species to colonize distinct trophic habitats in the oceans. Here, we compare the genome sequences of two bacteria, Photobacterium angustum S14 and Sphingopyxis alaskensis RB2256, that serve as useful model organisms for copiotrophic and oligotrophic modes of life and specifically relate the genomic features to trophic strategy for these organisms and define their molecular mechanisms of adaptation. We developed a model for predicting trophic lifestyle from genome sequence data and tested ,000 proteins representing million nucleotides of sequence data from 126 genome sequences with metagenome data of whole environmental s les. When applied to available oceanic metagenome data (e.g., the Global Ocean Survey data) the model demonstrated that oligotrophs, and not the more readily isolatable copiotrophs, dominate the ocean's free-living microbial populations. Using our model, it is now possible to define the types of bacteria that specific ocean niches are capable of sustaining.
Publisher: Elsevier BV
Date: 2000
DOI: 10.1007/PL00012150
Publisher: Humana Press
Date: 2007
DOI: 10.1007/978-1-60327-032-8_5
Abstract: Bacteria communicate with other members of their community through the secretion and perception of small chemical cues or signals. The recognition of a signal normally leads to the expression of a large suite of genes, which in some bacteria are involved in the regulation of virulence factors, and as a result, these signaling compounds are key regulatory factors in many disease processes. Thus, it is of interest when studying pathogens to understand the mechanisms used to control the expression of virulence genes so that strategies might be devised for the control of those pathogens. Clearly, the ability to interfere with this process of signaling represents a novel approach for the treatment of bacterial infections. There is a broad range of compounds that bacteria can use for signaling purposes, including fatty acids, peptides, N-acylated homoserine lactones, and the signals collectively called autoinducer 2 (AI-2). This chapter will focus on the latter two signaling systems as they are present in a range of medically relevant bacteria, and here we describe assays for determining whether an organism produces a particular signal and assays that can be used to identify inhibitors of the signaling cascade. Lastly, the signal detection and inhibition assays will be directly linked to the expression of virulence factors of specific pathogens.
Publisher: Elsevier BV
Date: 09-2020
Publisher: Springer Science and Business Media LLC
Date: 21-07-2017
Publisher: Public Library of Science (PLoS)
Date: 14-08-2012
Publisher: Elsevier BV
Date: 10-2020
Publisher: Springer Science and Business Media LLC
Date: 27-01-2013
Publisher: Informa UK Limited
Date: 2006
Publisher: Springer Science and Business Media LLC
Date: 03-08-2017
Publisher: Springer Science and Business Media LLC
Date: 07-09-2022
DOI: 10.1186/S12916-022-02486-Y
Abstract: Onchocerciasis is a disease caused by infection with Onchocerca volvulus , which is transmitted to humans via the bite of several species of black fly, and is responsible for permanent blindness or vision loss, as well as severe skin disease. Predominantly endemic in parts of Africa and Yemen, preventive chemotherapy with mass drug administration of ivermectin is the primary intervention recommended for the elimination of its transmission. A dataset of 18,116 geo-referenced prevalence survey datapoints was used to model annual 2000–2018 infection prevalence in Africa and Yemen. Using Bayesian model-based geostatistics, we generated spatially continuous estimates of all-age 2000–2018 onchocerciasis infection prevalence at the 5 × 5-km resolution as well as aggregations to the national level, along with corresponding estimates of the uncertainty in these predictions. As of 2018, the prevalence of onchocerciasis infection continues to be concentrated across central and western Africa, with the highest mean estimates at the national level in Ghana (12.2%, 95% uncertainty interval [UI] 5.0–22.7). Mean estimates exceed 5% infection prevalence at the national level for Cameroon, Central African Republic, Democratic Republic of the Congo (DRC), Guinea-Bissau, Sierra Leone, and South Sudan. Our analysis suggests that onchocerciasis infection has declined over the last two decades throughout western and central Africa. Focal areas of Angola, Cameroon, the Democratic Republic of the Congo, Ethiopia, Ghana, Guinea, Mali, Nigeria, South Sudan, and Uganda continue to have mean microfiladermia prevalence estimates exceeding 25%. At and above this level, the continuation or initiation of mass drug administration with ivermectin is supported. If national programs aim to eliminate onchocerciasis infection, additional surveillance or supervision of areas of predicted high prevalence would be warranted to ensure sufficiently high coverage of program interventions.
Publisher: Oxford University Press (OUP)
Date: 07-2023
Abstract: Protozoa are eukaryotic organisms that play a crucial role in nutrient cycling and maintaining balance in the food web. Predation, symbiosis and parasitism are three types of interactions between protozoa and bacteria. However, not all bacterial species are equally susceptible to protozoan predation as many are capable of defending against predation in numerous ways and may even establish either a symbiotic or parasitic life-style. Biofilm formation is one such mechanism by which bacteria can survive predation. Structural and chemical components of biofilms enhance resistance to predation compared to their planktonic counterparts. Predation on biofilms gives rise to phenotypic and genetic heterogeneity in prey that leads to trade-offs in virulence in other eukaryotes. Recent advances, using molecular and genomics techniques, allow us to generate new information about the interactions of protozoa and biofilms of prey bacteria. This review presents the current state of the field on impacts of protozoan predation on biofilms. We provide an overview of newly gathered insights into (i) molecular mechanisms of predation resistance in biofilms, (ii) phenotypic and genetic ersification of prey bacteria, and (iii) evolution of virulence as a consequence of protozoan predation on biofilms.
Publisher: Springer Science and Business Media LLC
Date: 26-03-2020
Publisher: Elsevier BV
Date: 03-2015
DOI: 10.1016/J.WATRES.2014.12.001
Abstract: In this study gravity-driven membrane (GDM) ultrafiltration is investigated for the pretreatment of seawater before reverse osmosis (RO). The impacts of temperature (21 ± 1 and 29 ± 1 °C) and hydrostatic pressure (40 and 100 mbar) on dynamic flux development and biofouling layer structure were studied. The data suggested pore constriction fouling was predominant at the early stage of filtration, during which the hydrostatic pressure and temperature had negligible effects on permeate flux. With extended filtration time, cake layer fouling played a major role, during which higher hydrostatic pressure and temperature improved permeate flux. The permeate flux stabilized in a range of 3.6 L/m(2) h (21 ± 1 °C, 40 mbar) to 7.3 L/m(2) h (29 ± 1 °C, 100 mbar) after slight fluctuations and remained constant for the duration of the experiments (almost 3 months). An increase in biofouling layer thickness and a variable biofouling layer structure were observed over time by optical coherence tomography and confocal laser scanning microscopy. The presence of eukaryotic organisms in the biofouling layer was observed by light microscopy and the microbial community structure of the biofouling layer was analyzed by sequences of 16S rRNA genes. The magnitude of permeate flux was associated with the combined effect of the biofouling layer thickness and structure. Changes in the biofouling layer structure were attributed to (1) the movement and predation behaviour of the eukaryotic organisms which increased the heterogeneous nature of the biofouling layer (2) the bacterial debris generated by eukaryotic predation activity which reduced porosity (3) significant shifts of the dominant bacterial species over time that may have influenced the biofouling layer structure. As expected, most of the particles and colloids in the feed seawater were removed by the GDM process, which led to a lower RO fouling potential. However, the dissolved organic carbon in the permeate was not be reduced, possibly because some microbial species (e.g. algae) could convert CO2 into organic substances. To further improve the removal efficiency of the organic carbon, combining carrier biofilm processes with a submerged GDM filtration system is proposed.
Publisher: Cold Spring Harbor Laboratory
Date: 25-02-2020
DOI: 10.1101/2020.02.25.964320
Abstract: The opportunistic pathogen, Pseudomonas aeruginosa , is ubiquitous in the environment, and in humans is capable of causing acute and chronic infections. P. aeruginosa , when co-incubated with the bacterivorous amoeba, Acanthamoeba castellanii , for extended periods, produced genetic and phenotypic variants. Sequencing of late-stage amoeba-adapted P. aeruginosa isolates demonstrated single nucleotide polymorphisms within genes that encode known virulence factors, and this correlated with a reduction in expression of virulence traits. Virulence towards the nematode, Caenorhabditis elegans , was attenuated in late-stage amoeba-adapted P. aeruginosa compared to early stage amoeba-adapted and non-adapted counterparts. Late-stage amoeba-adapted P. aeruginosa lost competitive fitness compared to non-adapted counterparts when grown in nutrient rich media. However, non-adapted P. aeruginosa were rapidly cleared by amoeba predation, whereas late-stage amoeba-adapted isolates remained in higher numbers 24 h after ingestion by amoeba. In addition, there was reduced uptake by macrophage of amoeba-adapted isolates and reduced uptake by human neutrophils as well as increased survival in the presence of neutrophils. Our findings indicate that the selection imposed by amoeba on P. aeruginosa resulted in reduced virulence over time. Importantly, the genetic and phenotypic traits possessed by late-stage amoeba-adapted P. aeruginosa are similar to what is observed for isolates obtained from chronic cystic fibrosis infections. This notable overlap in adaptation to different host types suggests similar selection pressures among host cell types. Pseudomonas aeruginosa is an opportunistic pathogen that causes both acute infections in plants and animals, including humans and also causes chronic infections in immune compromised and cystic fibrosis patients. This bacterium is commonly found in soils and water where bacteria are constantly under threat of being consumed by the bacterial predators, protozoa. To escape being killed, bacteria have evolved a suite of mechanisms that protect them from being consumed or digested. Here we examined the effect of long-term predation on the genotype and phenotypes expressed by P. aeruginosa. We show that long-term co-incubation with protozoa resulted in mutations in the bacteria that made them less pathogenic. This is particularly interesting as we see similar mutations arise in bacteria associated with chronic infections. Thus, predation by protozoa and long term colonization of the human host may represent similar environments that select for similar losses in gene functions.
Publisher: Elsevier BV
Date: 05-2000
DOI: 10.1016/S0378-1119(00)00117-7
Abstract: Vibrio vulnificus is an opportunistic pathogen that exhibits numerous virulence factors, including the secretion of a zinc metalloprotease and the production of a capsule. We have cloned and sequenced a gene from V. vulnificus that is a homologue of the positive transcriptional regulator, luxR, of the lux operon in Vibrio harveyi. This gene encodes a putative, single complete open reading frame designated smcR, which shares greater than 75% nucleotide identity with luxR of V. harveyi. The deduced amino acid sequence of the putative SmcR protein is more than 90% identical and 95% similar to that of LuxR of V. harveyi, suggesting that V. vulnificus possesses a member of the family of signal-response genes recently described in Vibrio cholerae and in Vibrio parahaemolyticus. Our data also demonstrate that, in addition to V. vulnificus, all six Vibrio spp. tested contained genes that hybridized with the luxR probe. We also present evidence that this regulatory protein was inherited from a common ancestor, and that the gene is ancient and widespread in marine Vibrio spp.
Publisher: American Medical Association (AMA)
Date: 07-2015
Publisher: Elsevier BV
Date: 08-2015
Publisher: Springer Science and Business Media LLC
Date: 20-04-2020
DOI: 10.1038/S41591-020-0807-6
Abstract: A double burden of malnutrition occurs when in iduals, household members or communities experience both undernutrition and overweight. Here, we show geospatial estimates of overweight and wasting prevalence among children under 5 years of age in 105 low- and middle-income countries (LMICs) from 2000 to 2017 and aggregate these to policy-relevant administrative units. Wasting decreased overall across LMICs between 2000 and 2017, from 8.4% (62.3 (55.1–70.8) million) to 6.4% (58.3 (47.6–70.7) million), but is predicted to remain above the World Health Organization’s Global Nutrition Target of % in over half of LMICs by 2025. Prevalence of overweight increased from 5.2% (30 (22.8–38.5) million) in 2000 to 6.0% (55.5 (44.8–67.9) million) children aged under 5 years in 2017. Areas most affected by double burden of malnutrition were located in Indonesia, Thailand, southeastern China, Botswana, Cameroon and central Nigeria. Our estimates provide a new perspective to researchers, policy makers and public health agencies in their efforts to address this global childhood syndemic.
Publisher: American Society for Microbiology
Date: 07-2006
DOI: 10.1128/JB.00141-06
Publisher: Elsevier BV
Date: 10-2020
Publisher: American Society for Microbiology
Date: 26-10-2023
DOI: 10.1128/AEM.01095-23
Publisher: Springer Science and Business Media LLC
Date: 16-05-2022
DOI: 10.1038/S41396-022-01249-0
Abstract: Vibrio cholerae , the bacterial pathogen responsible for the diarrheal disease cholera, resides in the aquatic environment between outbreaks. For bacteria, genetic variation by lateral gene transfer (LGT) is important for survival and adaptation. In the aquatic environment, V. cholerae is predominantly found in biofilms associated with chitinous organisms or with chitin “rain”. Chitin induces competency in V. cholerae , which can lead to LGT. In the environment, V. cholerae is also subjected to predation pressure by protist. Here we investigated whether protozoal predation affected LGT using the integron as a model. Integrons facilitate the integration of mobile DNA (gene cassettes) into the bacterial chromosome. We report that protozoal predation enhances transformation of a gene cassette by as much as 405-fold. We show that oxidative radicals produced in the protozoal phagosome induces the universal SOS response, which in turn upregulates the integron-integrase, the recombinase that facilitates cassette integration. Additionally, we show that during predation, V. cholerae requires the type VI secretion system to acquire the gene cassette from Escherichia coli . These results show that protozoal predation enhances LGT thus producing genetic variants that may have increased capacity to survive grazing. Additionally, the conditions in the food vacuole may make it a “hot spot” for LGT by accumulating erse bacteria and inducing the SOS response helping drive genetic ersification and evolution.
Publisher: Oxford University Press (OUP)
Date: 14-06-2016
Publisher: Elsevier BV
Date: 2017
Publisher: Elsevier BV
Date: 03-2018
Publisher: American Society for Microbiology
Date: 25-01-2022
DOI: 10.1128/AEM.01665-21
Abstract: Bacteria in the environment, including Vibrio spp., interact with protozoan predators. To defend against predation, bacteria evolve antipredator mechanisms ranging from changing morphology, biofilm formation, and secretion of toxins or virulence factors.
Publisher: Springer Science and Business Media LLC
Date: 2002
Abstract: It now seems clear that starvation adaptation is important for cells to initiate long-term survival under conditions of not only nutrient depletion but to develop resistance to other stresses, most notably oxidative stress. Clearly, oxidative stress is a condition likely to be perceived by many bacteria, for ex le, in the form of reactive oxygen species derived from metabolic processes or from near-UV exposure. We have found evidence for a large degree of overlap in the cell's use of global regulators to deal with both starvation and oxidative stress. Both SpoT and AI-2 signalling pathways are important regulators of starvation and stress adaptation as well as the alternative sigma factor, RpoE. We also present evidence that suggests that AI-2 signalling can mediate starvation adaptation at the molecular level by increasing the stability of the mRNAs so that cells are prepared for rapid response to nutrient addition. Moreover, such extracellular signals mediate intraspecies communication to enable enhanced survival and stress resistance of neighbouring bacterial cells. It is likely that bacteria rely on a suite of effects between cells and on transcription, translation and post-translationalprocesses, mediated by global regulators and signalling molecules, to meet their needs for growth and survival.
Publisher: Elsevier BV
Date: 12-2019
Publisher: Public Library of Science (PLoS)
Date: 19-06-2017
Publisher: Oxford University Press (OUP)
Date: 11-11-2020
Abstract: Difficulties in reliably diagnosing podoconiosis have severely limited the scale-up and uptake of the World Health Organization–recommended morbidity management and disability prevention interventions for affected people. We aimed to identify a set of clinical features that, combined into an algorithm, allow for diagnosis of podoconiosis. We identified 372 people with lymphoedema and administered a structured questionnaire on signs and symptoms associated with podoconiosis and other potential causes of lymphoedema in northern Ethiopia. All in iduals were tested for Wuchereria bancrofti–specific immunoglobulin G4 in the field using Wb123. Based on expert diagnosis, 344 (92.5%) of the 372 participants had podoconiosis. The rest had lymphoedema due to other aetiologies. The best-performing set of symptoms and signs was the presence of moss on the lower legs and a family history of leg swelling, plus the absence of current or previous leprosy, plus the absence of swelling in the groin, plus the absence of chronic illness (such as diabetes mellitus or heart or kidney diseases). The overall sensitivity of the algorithm was 91% (95% confidence interval [CI] 87.6 to 94.4) and specificity was 95% (95% CI 85.45 to 100). We developed a clinical algorithm of clinical history and physical examination that could be used in areas suspected or endemic for podoconiosis. Use of this algorithm should enable earlier identification of podoconiosis cases and scale-up of interventions.
Publisher: Springer Science and Business Media LLC
Date: 14-11-2016
Publisher: Elsevier BV
Date: 09-2020
Publisher: Elsevier BV
Date: 06-2020
Publisher: Springer Science and Business Media LLC
Date: 25-04-2018
Publisher: American Society for Microbiology
Date: 07-1997
DOI: 10.1128/AEM.63.7.2754-2758.1997
Abstract: Low-temperature-induced nonculturable cells of the human pathogenic bacterium Vibrio vulnificus retained significant amounts of nucleic acids for more than 5 months. Upon permeabilization of fixed cells, however, an increasing number of cold-incubated cells released the nucleic acids. This indicates substantial degradation of DNA and RNA in nonculturable cells prior to fixation. Treatment of permeabilized cells with DNase and RNase allowed differential staining of DNA and RNA with the nucleic acid dye 4',6-diamidino-2-phenylindole (DAPI). Epifluorescence microscopy revealed that the could-induced nonculturable populations of V. vulnificus are highly heterogeneous with regard to their nucleic acid content. The fraction of nonculturable cells which maintained DNA and RNA structures decreased gradually during cold incubation. After 5 months at 5 degrees C, less than 0.05% of the cells could be observed to retain DNA and RNA. In parallel with the loss of nucleic acids, an increase in the concentrations of UV-absorbing material in the culture supernatants was observed in nonculturable-cell suspensions. It is hypothesized that there are two phases of the formation of nonculturable cells of V. vulnificus: the first involves a loss of culturability with maintenance of cellular integrity and intact RNA and DNA (and thus possibly viability), and the second is typified by a gradual degradation of nucleic acids, the products of which partly remain inside the cells and partly diffuse into the extracellular space. A small number of nonculturable cells, however, retain DNA and RNA, and thus may be viable despite having reduced culturability.
Publisher: Springer Science and Business Media LLC
Date: 27-03-2021
DOI: 10.1186/S12866-021-02156-8
Abstract: Bacterial communities are responsible for biological nutrient removal and flocculation in engineered systems such as activated floccular sludge. Predators such as bacteriophage and protozoa exert significant predation pressure and cause bacterial mortality within these communities. However, the roles of bacteriophage and protozoan predation in impacting granulation process remain limited. Recent studies hypothesised that protozoa, particularly sessile ciliates, could have an important role in granulation as these ciliates were often observed in high abundance on surfaces of granules. Bacteriophages were hypothesized to contribute to granular stability through bacteriophage-mediated extracellular DNA release by lysing bacterial cells. This current study investigated the bacteriophage and protozoan communities throughout the granulation process. In addition, the importance of protozoan predation during granulation was also determined through chemical killing of protozoa in the floccular sludge. Four independent bioreactors seeded with activated floccular sludge were operated for aerobic granulation for 11 weeks. Changes in the phage, protozoa and bacterial communities were characterized throughout the granulation process. The filamentous phage, Inoviridae, increased in abundance at the initiation phase of granulation. However, the abundance shifted towards lytic phages during the maturation phase. In contrast, the abundance and ersity of protozoa decreased initially, possibly due to the reduction in settling time and subsequent washout. Upon the formation of granules, ciliated protozoa from the class Oligohymenophorea were the dominant group of protozoa based on metacommunity analysis. These protozoa had a strong, positive-correlation with the initial formation of compact aggregates prior to granule development. Furthermore, chemical inhibition of these ciliates in the floccular sludge delayed the initiation of granule formation. Analysis of the bacterial communities in the thiram treated sludge demonstrated that the recovery of ‘ Candidatus Accumulibacter’ was positively correlated with the formation of compact aggregates and granules. Predation by bacteriophage and protozoa were positively correlated with the formation of aerobic granules. Increases in Inoviridae abundance suggested that filamentous phages may promote the structural formation of granules. Initiation of granules formation was delayed due to an absence of protozoa after chemical treatment. The presence of ‘ Candidatus Accumulibacter’ was necessary for the formation of granules in the absence of protozoa.
Publisher: Microbiology Society
Date: 07-2020
DOI: 10.1099/JMM.0.001208
Publisher: Elsevier BV
Date: 06-2020
Publisher: Oxford University Press (OUP)
Date: 10-02-2015
Abstract: This review synthesizes recent and past observations on filamentous phages and describes how these phages contribute to host phentoypes. For ex le, the CTXφ phage of Vibrio cholerae encodes the cholera toxin genes, responsible for causing the epidemic disease, cholera. The CTXφ phage can transduce non-toxigenic strains, converting them into toxigenic strains, contributing to the emergence of new pathogenic strains. Other effects of filamentous phage include horizontal gene transfer, biofilm development, motility, metal resistance and the formation of host morphotypic variants, important for the biofilm stress resistance. These phages infect a wide range of Gram-negative bacteria, including deep-sea, pressure-adapted bacteria. Many filamentous phages integrate into the host genome as prophage. In some cases, filamentous phages encode their own integrase genes to facilitate this process, while others rely on host-encoded genes. These differences are mediated by different sets of 'core' and 'accessory' genes, with the latter group accounting for some of the mechanisms that alter the host behaviours in unique ways. It is increasingly clear that despite their relatively small genomes, these phages exert signficant influence on their hosts and ultimately alter the fitness and other behaviours of their hosts.
Publisher: Public Library of Science (PLoS)
Date: 18-02-2013
Publisher: Frontiers Media SA
Date: 17-05-2018
Publisher: Proceedings of the National Academy of Sciences
Date: 02-11-2005
Abstract: Persistence of the opportunistic bacterial pathogen Vibrio cholerae in aquatic environments is the principal cause for seasonal occurrence of cholera epidemics. This causality has been explained by postulating that V. cholerae forms biofilms in association with animate and inanimate surfaces. Alternatively, it has been proposed that bacterial pathogens are an integral part of the natural microbial food web and thus their survival is constrained by protozoan predation. Here, we report that both explanations are interrelated. Our data show that biofilms are the protective agent enabling V. cholerae to survive protozoan grazing while their planktonic counterparts are eliminated. Grazing on planktonic V. cholerae was found to select for the biofilm-enhancing rugose phase variant, which is adapted to the surface-associated niche by the production of exopolymers. Interestingly, grazing resistance in V. cholerae biofilms was not attained by exopolymer production alone but was accomplished by the secretion of an antiprotozoal factor that inhibits protozoan feeding activity. We identified that the cell density-dependent regulator hapR controls the production of this factor in biofilms. The inhibitory effect of V. cholerae biofilms was found to be widespread among toxigenic and nontoxigenic isolates. Our results provide a mechanistic explanation for the adaptive advantage of surface-associated growth in the environmental persistence of V. cholerae and suggest an important contribution of protozoan predation in the selective enrichment of biofilm-forming strains in the out-of-host environment.
Publisher: Frontiers Media SA
Date: 02-12-2014
Publisher: Elsevier BV
Date: 10-2020
Publisher: Springer Science and Business Media LLC
Date: 13-11-2008
Publisher: Springer Science and Business Media LLC
Date: 21-07-2017
Publisher: CSIRO Publishing
Date: 2006
DOI: 10.1071/MA06115
Abstract: Bacterial communication has risen to prominence in microbiology as a dynamic research topic, both because of its role in microbial ecology and evolution and for the opportunity it offers to control pathogenic microbial activity. Bacterial communication has evolved from the metabolic processes of prokaryotic cellular life, in which the biosynthesis and breakdown of chemical compounds in central metabolism generates secondary metabolites with ambiguous utility in natural selection.
Publisher: Springer Science and Business Media LLC
Date: 25-12-2019
DOI: 10.1038/S41586-019-1872-1
Abstract: Educational attainment is an important social determinant of maternal, newborn, and child health 1–3 . As a tool for promoting gender equity, it has gained increasing traction in popular media, international aid strategies, and global agenda-setting 4–6 . The global health agenda is increasingly focused on evidence of precision public health, which illustrates the subnational distribution of disease and illness 7,8 however, an agenda focused on future equity must integrate comparable evidence on the distribution of social determinants of health 9–11 . Here we expand on the available precision SDG evidence by estimating the subnational distribution of educational attainment, including the proportions of in iduals who have completed key levels of schooling, across all low- and middle-income countries from 2000 to 2017. Previous analyses have focused on geographical disparities in average attainment across Africa or for specific countries, but—to our knowledge—no analysis has examined the subnational proportions of in iduals who completed specific levels of education across all low- and middle-income countries 12–14 . By geolocating subnational data for more than 184 million person-years across 528 data sources, we precisely identify inequalities across geography as well as within populations.
Publisher: Elsevier BV
Date: 09-2012
Publisher: Springer Science and Business Media LLC
Date: 22-09-2021
DOI: 10.1186/S12866-021-02318-8
Abstract: Biofilms disperse in response to specific environmental cues, such as reduced oxygen concentration, changes in nutrient concentration and exposure to nitric oxide. Interestingly, biofilms do not completely disperse under these conditions, which is generally attributed to physiological heterogeneity of the biofilm. However, our results suggest that genetic heterogeneity also plays an important role in the non-dispersing population of P. aeruginosa in biofilms after nutrient starvation. In this study, 12.2% of the biofilm failed to disperse after 4 d of continuous starvation-induced dispersal. Cells were recovered from the dispersal phase as well as the remaining biofilm. For 96 h starved biofilms, rugose small colony variants (RSCV) were found to be present in the biofilm, but were not observed in the dispersal effluent. In contrast, wild type and small colony variants (SCV) were found in high numbers in the dispersal phase. Genome sequencing of these variants showed that most had single nucleotide mutations in genes associated with biofilm formation, e.g. in wspF, pilT , fha1 and aguR . Complementation of those mutations restored starvation-induced dispersal from the biofilms. Because c-di-GMP is linked to biofilm formation and dispersal, we introduced a c-di-GMP reporter into the wild-type P. aeruginosa and monitored green fluorescent protein (GFP) expression before and after starvation-induced dispersal. Post dispersal, the microcolonies were smaller and significantly brighter in GFP intensity, suggesting the relative concentration of c-di-GMP per cell within the microcolonies was also increased. Furthermore, only the RSCV showed increased c-di-GMP, while wild type and SCV were no different from the parental strain. This suggests that while starvation can induce dispersal from the biofilm, it also results in strong selection for mutants that overproduce c-di-GMP and that fail to disperse in response to the dispersal cue, starvation.
Publisher: Elsevier BV
Date: 09-2012
Publisher: Elsevier BV
Date: 10-2014
Publisher: Elsevier BV
Date: 08-2016
DOI: 10.1016/J.MIMET.2016.06.008
Abstract: Quantitative real-time polymerase chain reaction (qRT-PCR) is a reliable technique for quantifying mRNA levels when normalised by a stable reference gene/s. Many putative reference genes are known to be affected by physiological stresses, such as nutrient limitation and hence may not be suitable for normalisation. In this study of Pseudomonas aeruginosa, the expression of 13 commonly used reference genes, rpoS, proC, recA, rpsL, rho, oprL, anr, tipA, nadB, fabD, C, algD and gyrA, were analysed for changes in expression under carbon starvation and nutrient replete conditions. The results showed that rpoS was the only stably expressed housekeeping gene during carbon starvation. In contrast, other commonly used housekeeping genes were shown to vary by as much as 10-100 fold under starvation conditions. This study has identified a suitable reference gene for qRT-PCR in P. aeruginosa during carbon starvation. The results presented here highlight the need to validate housekeeping genes under the chosen experimental conditions.
Publisher: Oxford University Press (OUP)
Date: 03-2011
DOI: 10.1111/J.1574-6941.2011.01067.X
Abstract: Previous laboratory experiments revealed that Vibrio cholerae A1552 biofilms secrete an antiprotozoal factor that prevents Rhynchomonas nasuta from growing and thus prevents grazing losses. The antiprotozoal factor is regulated by the quorum-sensing response regulator, HapR. Here, we investigate whether the antiprotozoal activity is ecologically relevant. Experiments were conducted in the field as well as under field-like conditions in the laboratory to assess the grazing resistance of V. cholerae A1552 and N16961 (natural frameshift mutation in hapR) biofilms to R. nasuta and Cafeteria roenbergensis. In laboratory experiments exposing the predators to V. cholerae grown in seawater containing high and low glucose concentrations, we determined that V. cholerae biofilms showed increased resistance towards grazing by both predators as glucose levels decreased. The relative resistance of the V. cholerae strains to the grazers under semi-field conditions was similar to that observed in situ. Therefore, the antipredator defense is environmentally relevant and not lost when biofilms are grown in an open system in the marine environment. The hapR mutant still exhibited some resistance to both predators and this suggests that V. cholerae may coordinate antipredator defenses by a combination of density-dependent regulation and environmental sensing to protect itself from predators in its natural habitat.
Publisher: Informa UK Limited
Date: 31-01-2013
DOI: 10.1080/08927014.2012.760069
Abstract: Membrane fouling by bacterial biofilms remains a key challenge for membrane-based water purification systems. Here, the optimal biofilm dispersal potential of three nitric oxide (NO) donor compounds, viz. sodium nitroprusside, 6-(2-hydroxy-1-methyl-2-nitrosohydrazino)-N-methyl-1-hexanamine (MAHMA NONOate) and 1-(hydroxy-NNO-azoxy)-L-proline, disodium salt, was investigated using Pseudomonas aeruginosa PAO1 as a model organism. Dispersal was quantitatively assessed by confocal microscopy [bacterial cells and the components of the extracellular polymeric substances (EPS) (polysaccharides and extracellular DNA)] and colony-forming unit counts. The three NO donor compounds had different optimal exposure times and concentrations, with MAHMA NONOate being the optimal NO donor compound. Biofilm dispersal correlated with a reduction in both bacterial cells and EPS. MAHMA NONOate also reduced single species biofilms formed by bacteria isolated from industrial membrane bioreactor and reverse osmosis membranes, as well as in isolates combined to generate mixed species biofilms. The data present strong evidence for the application of these NO donor compounds for prevention of biofouling in an industrial setting.
Location: United States of America
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: Ethiopia
Start Date: 05-2017
End Date: 05-2020
Amount: $379,500.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2007
End Date: 12-2010
Amount: $335,102.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2010
End Date: 12-2012
Amount: $310,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2023
End Date: 12-2025
Amount: $519,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2016
End Date: 12-2016
Amount: $550,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 02-2014
End Date: 07-2017
Amount: $315,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2023
End Date: 12-2023
Amount: $682,792.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2011
End Date: 03-2014
Amount: $340,000.00
Funder: Australian Research Council
View Funded Activity