ORCID Profile
0000-0002-4638-0059
Current Organisation
University of Sydney
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Research Topics
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.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Food Packaging, Preservation and Safety | Food Sciences | Biochemistry And Cell Biology Not Elsewhere Classified | Microbiology | Horticultural Production not elsewhere classified | Infectious Diseases | Medical Parasitology | Clinical Sciences | Medical Microbiology | Bacteriology | Infectious Agents | Phycology | Microbial Genetics | Microbial Systematics, Taxonomy And Phylogeny | Water Treatment Processes | Plasma Physics; Fusion Plasmas; Electrical Discharges |
ANZSRC Socio-Economic Objective (SEO)
Infectious diseases | Food Safety | Higher education | Endocrine organs and diseases (incl. diabetes) | Biological sciences | Living resources (flora and fauna) | Industrial Machinery and Equipment | Expanding Knowledge in the Biological Sciences | Preventive medicine | Other
Related Links
Publications
Reassessing therapeutic antibodies for neglected and tropical diseases
Publisher: Public Library of Science (PLoS)
Date: 30-01-2020
Lineages derived from Cryptococcus neoformans type strain H99 support a link between the capacity to be pleomorphic and virulence
Publisher: Cold Spring Harbor Laboratory
Date: 10-02-2022
DOI: 10.1101/2022.02.09.479843
Abstract: The pathogenic yeast Cryptococcus neoformans causes nearly 200,000 deaths annually in immunocompromised in iduals. Cryptococcus cells can undergo substantial morphological change during mammalian infection, including increased capsule and cell size, the release of shed capsule, and the production of titan ( 10 μm), micro ( 2 μm) and irregular cells. We examined phenotypic variation under conditions designed to simulate in vivo stress in a collection of nine lineages derived from the C. neoformans type strain H99. These lineages are highly genetically similar but have a range of virulence levels. Strains from hypervirulent lineages had a larger average capsule size, greater variation in cell size, and an increased production of micro cells and shed capsule. We tested whether disruption of SGF29 , which encodes a component of the SAGA histone acetylation complex that has previously been implicated in the hypervirulence of some lineages, might also have a role in the production of morphological variants. Deletion of SGF29 in a lineage with intermediate virulence substantially increased its production of micro cells and released capsule, consistent with a switch to hypervirulence. We further examined SGF29 in a set of 52 clinical isolates and found loss-of-function mutations were significantly correlated with patient death. Expansion of a TA repeat in the second intron of SGF29 was positively correlated with cell and capsule size, suggesting it may also affect Sgf29 function. This study extends the evidence for a link between pleomorphism and virulence in Cryptococcus , with a likely role for epigenetic mechanisms mediated by SAGA-induced histone acetylation. Cryptococcosis is a devastating cause of death and disease worldwide. During infection, Cryptococcus cells can undergo substantial changes to their size and shape. In this study, we used a collection C. neoformans strains that are highly genetically similar but possess differing levels of virulence to investigate how morphological variation aligns with virulence. We found hypervirulent strains on average had larger capsules and greater variation in cell size, and also produced more micro cells and shed capsule. These hypervirulent strains possessed a mutation in SGF29 , which encodes a component of the SAGA complex involved in epigenetic regulation. Analysis of the SGF29 gene in a set of clinical isolates found strains with loss-of-function mutations were associated with higher patient death rates. The capacity to vary appears to be linked with virulence in Cryptococcus , and this can occur in the absence of genetic variation via epigenetic mechanisms.
A comparison of the nature and abundance of microsatellites in 14 fungal genomes
Publisher: Elsevier BV
Date: 11-2004
DOI: 10.1016/J.FGB.2004.08.004
Abstract: An overview of the character of microsatellites in 14 fungal genomes was obtained by analyzing databases containing complete or nearly complete genome sequences. Low GC content, rather than genome size, was the best predictor of high microsatellite density, although very long iterations of tandem repeats were less common in small genomes. Motif type correlated with %GC in that low-GC genomes were more likely to be dominated by A/T-rich motifs, and vice versa, although some exceptions were noted. The experimentally useful dinucleotide and trinucleotide arrays were analyzed in greater detail. Although these varied in sequence and length among fungal species, some that are likely to be universally useful were identified. This information will be useful for researchers wanting to identify the most useful microsatellites to analyze for the fungi included in this survey and provides a platform for choosing microsatellites to target in fungi that are not yet sequenced.
A set of electrophoretic molecular markers for strain typing and population genetic studies of Histoplasma capsulatum
Publisher: Wiley
Date: 1997
Abstract: A set of eleven biallelic and three multiallelic molecular markers have been developed to analyze populations of Histoplasma capsulatum. All markers are lified by polymerase chain reaction (PCR) and can be readily scored using minimal amounts of template DNA. The 11 biallelic loci have polymorphic restriction endonuclease sites or small insertions or deletions which may be assessed by agarose gel electrophoresis. These markers are inherited in an unambiguous manner and are ideal for assessing structure and gene flow within US populations of H. capsulatum, but are monomorphic in non-US populations. Both length and sequence variation are present in the multiallelic loci, which can be scored by direct sequencing, polyacrylamide gel electrophoresis, or single-strand conformation polymorphism (SSCP): As they are hypervariable, the multiallelic loci can be used to type isolates and to assess the level of genetic variation within populations. Preliminary results indicate that the three multiallelic markers presented are sufficient to distinguish isolates at the in idual level and are polymorphic in both US and non-US populations. This collection of molecular markers will be a useful tool in population and epidemiology studies of H. capsulatum.
Surface and flagella morphology of the motile form of Chromera velia revealed by field-emission scanning electron microscopy
Publisher: Elsevier BV
Date: 2011
DOI: 10.1016/J.PROTIS.2010.02.003
Abstract: Chromera velia(Chromerida Alveolata) is an autotrophic protist isolated from stony corals.Ch. veliapossesses a chloroplast thought to be most closely related to the apicoplasts of non-photosynthetic apicomplexa. Phylogenetic analyses placeCh. veliaas a close relative of parasitic apicomplexa and predatory colpodellids. We have used field-emission scanning electron microscopy of cells sputter-coated with gold or chromium and non-coated cells to characterise the surface ultrastructure of the motile form ofCh. velia. In overall morphology the biflagellatedCh. veliacells resemble the colpodellidColpodella edax, but with some notable differences. The ventral side of the flagellatedCh. veliacell has two grooves extending from the anterior flagella insertion point with a ridge rising towards the anterior apex of the cell. The anterior flagellum is shorter than the posterior flagellum and possesses a distinct, small curved appendage. The insertion point of the anterior flagellum is partly enclosed by a flap extending from the cell. The posterior flagellum is approximately four times the length of the cell and possesses mastigonemes. The combination of coating techniques proved superior to the commonly used gold coating to determine fine surface ultrastructure. This new ultrastructural information forCh. veliaallowed us to emend its diagnosis.
More missense in amyloid gene
Publisher: Springer Science and Business Media LLC
Date: 12-1992
DOI: 10.1038/NG1292-255
Augmenting Azoles with Drug Synergy to Expand The Antifungal Toolbox
Publisher: MDPI AG
Date: 18-03-2022
DOI: 10.20944/PREPRINTS202203.0262.V1
Abstract: Fungal infections impact the lives of at least 12 million people every year, killing over 1.5 million. Wide-spread use of fungicides and prophylactic antifungal therapy have driven resistance in many serious fungal pathogens, and there is an urgent need to expand the current antifungal ar-senal. Recent research has focused on improving azoles, our most successful class of antifungals, by looking for synergistic interactions with secondary compounds. Synergists can co-operate with azoles by targeting steps in related pathways, or they may act on mechanisms related to re-sistance like active efflux or on totally disparate pathways or processes. A variety of sources of potential synergists have been explored, including pre-existing antimicrobials, pharmaceuticals approved for other uses, bioactive natural compounds and phytochemicals, and novel synthetic compounds. Synergy can successfully widen the antifungal spectrum, decrease inhibitory dosag-es, reduce toxicity, and prevent the development of resistance. This review highlights the ersity of mechanisms that have been exploited for the purposes of azole synergy and demonstrates that synergy remains a promising approach for meeting the urgent need for novel antifungal strate-gies.
Looking for sex in the fungal pathogensCryptococcus neoformansandCryptococcus gattii
Publisher: Oxford University Press (OUP)
Date: 06-2006
DOI: 10.1111/J.1567-1364.2006.00087.X
Abstract: Why are we interested in understanding the mode of reproduction being used by the fungal pathogens Cryptococcus neoformans and Cryptococcus gattii? Empirical evidence has finally supported the long-held assumption that, by increasing the rate of adaptive evolution, sex increases the chances of long-term survival. Understanding the ability of pathogenic organisms to adapt to diagnostic and treatment regimes is also important in the fight against the diseases caused by these organisms. This review looks at the different approaches used to identify population structure in C. neoformans and C. gattii. These are sexual species however, recombination in natural populations has only recently been found. We highlight the importance of population selection and the value of both indirect molecular analysis and direct biological evidence for sexual recombination, when looking for the mode of reproduction in these fungal pathogens.
Phylogeography of the fungal pathogen Histoplasma capsulatum
Publisher: Wiley
Date: 31-10-2003
DOI: 10.1046/J.1365-294X.2003.01995.X
Abstract: Until recently, Histoplasma capsulatum was believed to harbour three varieties, var. capsulatum (chiefly a New World human pathogen), var. duboisii (an African human pathogen) and var. farciminosum (an Old World horse pathogen), which varied in clinical manifestations and geographical distribution. We analysed the phylogenetic relationships of 137 in iduals representing the three varieties from six continents using DNA sequence variation in four independent protein-coding genes. At least eight clades were idengified: (i) North American class 1 clade (ii) North American class 2 clade (iii) Latin American group A clade (iv) Latin American group B clade (v) Australian clade (vi) Netherlands (Indonesian?) clade (vii) Eurasian clade and (viii) African clade. Seven of eight clades represented genetically isolated groups that may be recognized as phylogenetic species. The sole exception was the Eurasian clade which originated from within the Latin American group A clade. The phylogenetic relationships among the clades made a star phylogeny. Histoplasma capsulatum var. capsulatum in iduals were found in all eight clades. The African clade included all of the H. capsulatum var. duboisii in iduals as well as in iduals of the other two varieties. The 13 in iduals of var. farciminosum were distributed among three phylogenetic species. These findings suggest that the three varieties of Histoplasma are phylogenetically meaningless. Instead we have to recognize the existence of genetically distinct geographical populations or phylogenetic species. Combining DNA substitution rates of protein-coding genes with the phylogeny suggests that the radiation of Histoplasma started between 3 and 13 million years ago in Latin America.
The Potential of Honey as a Prebiotic Food to Re-engineer the Gut Microbiome Toward a Healthy State
Publisher: Frontiers Media SA
Date: 28-07-2022
Abstract: Honey has a long history of use for the treatment of digestive ailments. Certain honey types have well-established bioactive properties including antibacterial and anti-inflammatory activities. In addition, honey contains non-digestible carbohydrates in the form of oligosaccharides, and there is increasing evidence from in vitro , animal, and pilot human studies that some kinds of honey have prebiotic activity. Prebiotics are foods or compounds, such as non-digestible carbohydrates, that are used to promote specific, favorable changes in the composition and function of the gut microbiota. The gut microbiota plays a critical role in human health and well-being, with disturbances to the balance of these organisms linked to gut inflammation and the development and progression of numerous conditions, such as colon cancer, irritable bowel syndrome, obesity, and mental health issues. Consequently, there is increasing interest in manipulating the gut microbiota to a more favorable balance as a way of improving health by dietary means. Current research suggests that certain kinds of honey can reduce the presence of infection-causing bacteria in the gut including Salmonella , Escherichia coli , and Clostridiodes difficile , while simultaneously stimulating the growth of potentially beneficial species, such as Lactobacillus and Bifidobacteria. In this paper, we review the current and growing evidence that shows the prebiotic potential of honey to promote healthy gut function, regulate the microbial communities in the gut, and reduce infection and inflammation. We outline gaps in knowledge and explore the potential of honey as a viable option to promote or re-engineer a healthy gut microbiome.
Survey of Vietnamese Peanuts, Corn and Soil for the Presence of Aspergillus flavus and Aspergillus parasiticus
Publisher: Springer Science and Business Media LLC
Date: 20-08-2009
DOI: 10.1007/S11046-009-9221-9
Abstract: Aspergillus flavus and Aspergillus parasiticus cause perennial infection of agriculturally important crops in tropical and subtropical areas. Invasion of crops by these fungi may result in contamination of food and feed by potent carcinogenic aflatoxins. Consumption of aflatoxin contaminated foods is a recognised risk factor for human hepatocellular carcinoma (HCC) and may contribute to the high incidence of HCC in Southeast Asia. This study conducted a survey of Vietnamese crops (peanuts and corn) and soil for the presence of aflatoxigenic fungi and used microsatellite markers to investigate the genetic ersity of Vietnamese Aspergillus strains. From a total of 85 s les comprising peanut (25), corn (45) and soil (15), 106 strains were isolated. Identification of strains by colony morphology and aflatoxin production found all Vietnamese strains to be A. flavus with no A. parasiticus isolated. A. flavus was present in 36.0% of peanut s les, 31.1% of corn s les, 27.3% of farmed soil s les and was not found in virgin soil s les. Twenty-five per cent of the strains produced aflatoxins. Microsatellite analysis revealed a high level of genetic ersity in the Vietnamese A. flavus population. Clustering, based on microsatellite genotype, was unrelated to aflatoxin production, geographic origin or substrate origin.
Development of polymorphic microsatellite markers for Cryptococcus neoformans
Publisher: Wiley
Date: 29-08-2008
DOI: 10.1111/J.1755-0998.2008.02196.X
Abstract: Cryptococcus neoformans is a haploid basidiomycetous yeast that causes life-threatening infections in patients with and without impaired immune function. Present typing systems for C. neoformans are limited by either poor standardization or high cost. We present eleven microsatellite loci that were developed from the published genomes of C. neoformans var. neoformans, and are applicable to the varieties and hybrids within C. neoformans.
Molecular typing of pathogenic fungi
Publisher: Oxford University Press (OUP)
Date: 2000
Time-Course Proteome Analysis Reveals the Dynamic Response of Cryptococcus gattii Cells to Fluconazole
Publisher: Public Library of Science (PLoS)
Date: 06-08-2012
Manuka-type honeys can eradicate biofilms produced byStaphylococcus aureusstrains with different biofilm-forming abilities
Publisher: PeerJ
Date: 25-03-2014
DOI: 10.7717/PEERJ.326
Rifampicin-manuka honey combinations are superior to other antibiotic-manuka honey combinations in eradicating Staphylococcus aureus biofilms
Publisher: Frontiers Media SA
Date: 11-01-2018
Clonal Reproduction and Limited Dispersal in an Environmental Population of Cryptococcus neoformans var. gattii Isolates from Australia
Publisher: American Society for Microbiology
Date: 02-2003
DOI: 10.1128/JCM.41.2.703-711.2003
Abstract: Cryptococcus neoformans var. gattii is a causative agent of cryptococcosis and is thought to have a specific ecological association with a number of Eucalyptus species in Australia. However, the role that the tree plays in the life cycle of the fungus and the nature of the infectious propagule are not well understood. This study set out to examine whether sexual recombination is occurring in a natural population of C. neoformans var. gattii and whether the fungus disseminates between colonized trees. Thirty C. neoformans var. gattii isolates, consisting of both the α and a mating types, were collected from 13 Eucalyptus camaldulensis trees growing along a riverbank in Renmark, South Australia. The genetic ersity within the population was studied by using lified fragment length polymorphism fingerprinting, and each isolate was assigned a unique multilocus genotype. Population genetic analyses of the multilocus data found no evidence of genetic exchange between members of the population, indicating a clonal population structure. Canonical variate analysis was then used to study the relationship between isolates from different colonized trees. Isolates from in idual trees were strongly correlated, and it appeared that dispersal between trees was not occurring to any appreciable extent. These results suggest that the eucalypt may not be the primary niche for C. neoformans var. gattii but that the decaying wood present in hollows on these trees may provide a favorable substrate for extensive clonal propagation of the yeast cells.
Cellular plasticity of pathogenic fungi during infection
Publisher: Public Library of Science (PLoS)
Date: 04-06-2020
The importance of superoxide anion for Escherichia coli biofilm removal using plasma-activated water
Publisher: Elsevier BV
Date: 06-2023
Latitudinal variability in symbiont specificity within the widespread scleractinian coral Plesiastrea versipora
Publisher: Springer Science and Business Media LLC
Date: 06-2001
Honey has an antifungal effect against Candida species
Publisher: Oxford University Press (OUP)
Date: 2006
DOI: 10.1080/13693780500417037
Abstract: The incidence of Candida infections is escalating worldwide. The serious nature of these infections is compounded by increasing levels of drug resistance. We report that certain honeys have significant antifungal activity against clinical isolates of Candida species. Importantly, the minimum inhibitory concentration of these honeys would be achievable in a clinical setting.
Species in the Cryptococcus gattii Complex Differ in Capsule and Cell Size following Growth under Capsule-Inducing Conditions.
Publisher: American Society for Microbiology
Date: 28-12-2016
Abstract: Infections with the fungal pathogen Cryptococcus gattii have been increasing in recent years. Recently, four different species have been described within C. gattii , which correspond to four previously known molecular genotypes (VGI to VGIV). Examining traits related to infection and disease is important for determining whether these different species have clinical relevance. This study examined variation in attributes that are important for infecting and surviving in the host, including tolerance to various stresses, yeast cell size, and the amount of polysaccharide capsule that covers the cell. The cell size and capsule size were significantly different and inversely correlated across the species. Thermotolerance was highest in C. deuterogattii (VGII), the only species known to cause outbreaks, while most strains of the species C. bacillisporus (VGIII) and C. tetragattii (VGIV) grew poorly at 37°C. These findings argue for increased acceptance of the new species and may be useful for informing diagnosis and prognosis in clinical infection.
Surveillance for azole resistance in clinical and environmental isolates of Aspergillus fumigatus in Australia and cyp51A homology modelling of azole-resistant isolates
Publisher: Oxford University Press (OUP)
Date: 29-05-2018
DOI: 10.1093/JAC/DKY187
Abstract: The prevalence of azole resistance in Aspergillus fumigatus is uncertain in Australia. Azole exposure may select for resistance. We investigated the frequency of azole resistance in a large number of clinical and environmental isolates. A. fumigatus isolates [148 human, 21 animal and 185 environmental strains from air (n = 6) and azole-exposed (n = 64) or azole-naive (n = 115) environments] were screened for azole resistance using the VIPcheck™ system. MICs were determined using the Sensititre™ YeastOne YO10 assay. Sequencing of the Aspergillus cyp51A gene and promoter region was performed for azole-resistant isolates, and cyp51A homology protein modelling undertaken. Non-WT MICs/MICs at the epidemiological cut-off value of one or more azoles were observed for 3/148 (2%) human isolates but not amongst animal, or environmental, isolates. All three isolates grew on at least one azole-supplemented well based on VIPcheck™ screening. For isolates 9 and 32, the itraconazole and posaconazole MICs were 1 mg/L (voriconazole MICs 0.12 mg/L) isolate 129 had itraconazole, posaconazole and voriconazole MICs of >16, 1 and 8 mg/L, respectively. Soil isolates from azole-exposed and azole-naive environments had similar geometric mean MICs of itraconazole, posaconazole and voriconazole (P > 0.05). A G54R mutation was identified in the isolates exhibiting itraconazole and posaconazole resistance, and the TR34/L98H mutation in the pan-azole-resistant isolate. cyp51A modelling predicted that the G54R mutation would prevent binding of itraconazole and posaconazole to the haem complex. Azole resistance is uncommon in Australian clinical and environmental A. fumigatus isolates further surveillance is indicated.
Mixing postharvest fungicides and sanitizers results in unpredictable survival of microbes that affect cantaloupes
Publisher: Elsevier BV
Date: 10-2021
The Antifungal and Synergistic Effect of Bisphosphonates in Cryptococcus
Publisher: American Society for Microbiology
Date: 20-01-2021
DOI: 10.1128/AAC.01753-20
Abstract: New treatment strategies are required for cryptococcosis, a leading mycosis in HIV-AIDS patients. Following the identification of Cryptococcus proteins differentially expressed in response to fluconazole, we targeted farnesyl pryrophosphate synthetase (FPPS), an enzyme in the squalene biosynthesis pathway, using nitrogenous bisphosphonates. We hypothesized that these would disrupt squalene synthesis and thereby produce synergy with fluconazole, which acts on a downstream pathway that requires squalene.
Isolates of Cryptococcus neoformans from Infected Animals Reveal Genetic Exchange in Unisexual, α Mating Type Populations
Publisher: American Society for Microbiology
Date: 10-2008
DOI: 10.1128/EC.00097-08
Abstract: Sexual reproduction and genetic exchange are important for the evolution of fungal pathogens and for producing potentially infective spores. Studies to determine whether sex occurs in the pathogenic yeast Cryptococcus neoformans var . grubii have produced enigmatic results, however: basidiospores are the most likely infective propagules, and clinical isolates are fertile and genetically erse, consistent with a sexual species, but almost all populations examined consist of a single mating type and have little evidence for genetic recombination. The choice of population is critical when looking for recombination, particularly when significant asexual propagation is likely and when latency may complicate assessing the origin of an isolate. We therefore selected isolates from infected animals living in the region of Sydney, Australia, with the assumption that the relatively short life spans and limited travels of the animal hosts would provide a very defined population. All isolates were mating type α and were of molecular genotype VNI or VNII. A lack of linkage disequilibrium among loci suggested that genetic exchange occurred within both genotype groups. Four diploid VNII isolates that produced filaments and basidium-like structures when cultured in proximity to an a mating type strain were found. Recent studies suggest that compatible α-α unions can occur in C. neoformans var. neoformans populations and in populations of the sibling species Cryptococcus gattii . As a mating type strains of C. neoformans var. grubii have never been found in Australia, or in the VNII molecular type globally, the potential for α-α unions is evidence that α-α unisexual mating maintains sexual recombination and ersity in this pathogen and may produce infectious propagules.
Cryptococcus strains with different pathogenic potentials have diverse protein secretomes
Publisher: American Society for Microbiology
Date: 06-2015
DOI: 10.1128/EC.00052-15
Abstract: Secreted proteins are the frontline between the host and pathogen. In mammalian hosts, secreted proteins enable invasive infection and can modulate the host immune response. Cryptococcosis, caused by pathogenic Cryptococcus species, begins when inhaled infectious propagules establish to produce pulmonary infection, which, if not resolved, can disseminate to the central nervous system to cause meningoencephalitis. Strains of Cryptococcus species differ in their capacity to cause disease, and the mechanisms underlying this are not well understood. To investigate the role of secreted proteins in disease, we determined the secretome for three genome strains of Cryptococcus species, including a hypovirulent and a hypervirulent strain of C. gattii and a virulent strain of C. neoformans . Sixty-seven unique proteins were identified, with different numbers and types of proteins secreted by each strain. The secretomes of the virulent strains were largely limited to proteolytic and hydrolytic enzymes, while the hypovirulent strain had a erse secretome, including non-conventionally secreted canonical cytosolic and immunogenic proteins that have been implicated in virulence. The hypovirulent strain cannot establish pulmonary infection in a mouse model, but strains of this genotype have caused human meningitis. To directly test brain infection, we used intracranial inoculation and found that the hypovirulent strain was substantially more invasive than its hypervirulent counterpart. We suggest that immunogenic proteins secreted by this strain invoke a host response that limits pulmonary infection but that there can be invasive growth and damage if infection reaches the brain. Given their known role in virulence, it is possible that non-conventionally secreted proteins mediate this process.
Increasing Lovastatin Production by Re-routing the Precursors Flow of Aspergillus terreus via Metabolic Engineering
Publisher: Springer Science and Business Media LLC
Date: 21-09-2021
DOI: 10.1007/S12033-021-00393-W
Abstract: Lovastatin is an anti-cholesterol medicine that is commonly prescribed to manage cholesterol levels, and minimise the risk of suffering from heart-related diseases. Aspergillus terreus (ATCC 20542) supplied with carbohydrates or sugar alcohols can produce lovastatin. The present work explored the application of metabolic engineering in A. terreus to re-route the precursor flow towards the lovastatin biosynthetic pathway by simultaneously overexpressing the gene for acetyl-CoA carboxylase (acc) to increase the precursor flux, and eliminate ( +)-geodin biosynthesis (a competing secondary metabolite) by removing the gene for emodin anthrone polyketide synthase (gedC). Alterations to metabolic flux in the double mutant (gedCΔ*acc
Improved lovastatin production by inhibiting (+)-geodin biosynthesis in Aspergillus terreus
Publisher: Elsevier BV
Date: 09-2019
DOI: 10.1016/J.NBT.2019.04.003
Abstract: Lovastatin is widely prescribed to reduce elevated levels of cholesterol and prevent heart-related diseases. Cultivation of Aspergillus terreus (ATCC 20542) with carbohydrates or low-value feedstocks such as glycerol produces lovastatin as a secondary metabolite and (+)-geodin as a by-product. An A. terreus mutant strain was developed (gedCΔ) with a disrupted (+)-geodin biosynthesis pathway. The gedCΔ mutant was created by inserting the antibiotic marker hygromycin B (hyg) within the gedC gene that encodes emodin anthrone polyketide synthase (PKS), a primary gene responsible for initiating (+)-geodin biosynthesis. The effects of emodin anthrone PKS gene disruption on (+)-geodin and lovastatin biosynthesis and the production of the precursors acetyl-CoA and malonyl-CoA were investigated with cultures based on glycerol alone and in combination with lactose. The gedCΔ strain showed improved lovastatin production, particularly when cultivated on the glycerol-lactose mixture, increasing lovastatin production by 80% (113 mg/L) while simultaneously inhibiting (+)-geodin biosynthesis compared to the wild-type strain. This study thus shows that suppression of the (+)-geodin pathway increases lovastatin yield and demonstrates a practical approach of manipulating carbon flux by modulating enzyme activity.
Most Cases of Cryptococcal Meningitis in HIV-Uninfected Patients in Vietnam Are Due to a Distinct Amplified Fragment Length Polymorphism-Defined Cluster of Cryptococcus neoformans var. grubii VN1
Publisher: American Society for Microbiology
Date: 02-2011
DOI: 10.1128/JCM.01985-10
Abstract: Cryptococcal disease most commonly occurs in patients with an underlying immune deficit, most commonly HIV infection, and is due to Cryptococcus neoformans var. grubii . Occasionally disease due to this variety occurs in apparently immunocompetent patients. The relationship between strains infecting immunosuppressed and immunocompetent patients is not clear. Amplified fragment length polymorphism (AFLP) analysis was used to characterize the relationship between strains infecting HIV-infected and uninfected patients. Isolates from 51 HIV-uninfected patients and 100 HIV-infected patients with cryptococcal meningitis were compared. C. neoformans var. grubii VNI was responsible for infections in 73% of HIV-uninfected and 100% of HIV-infected patients. AFLP analysis defined two distinct clusters, VNIγ and VNIδ. The majority (84%) of isolates from HIV-uninfected patients were VNIγ, compared with only 38% of isolates from HIV-infected patients (odds ratio, 8.30 95% confidence interval [CI], 3.04 to 26.6 P 0.0001). In HIV-uninfected patients, underlying disease was less frequent in those with VNIγ infections. Two clusters of C. neoformans var. grubii VN1 are responsible for the majority of cases of cryptococcal meningitis in Vietnam. The distribution of these clusters differs according to the immune status of the host.
The Antifungal Activity of Lactoferrin and Its Derived Peptides: Mechanisms of Action and Synergy with Drugs against Fungal Pathogens.
Publisher: Frontiers Media SA
Date: 18-01-2017
No mutation in codon 713 of the amyloid precursor gene in schizophrenic patients
Publisher: Oxford University Press (OUP)
Date: 1993
DOI: 10.1093/HMG/2.3.321
Overexpression of acetyl-CoA carboxylase in Aspergillus terreus to increase lovastatin production
Publisher: Elsevier BV
Date: 09-2018
DOI: 10.1016/J.NBT.2018.04.008
Abstract: The present work describes the application of homologous recombination techniques in a wild-type Aspergillus terreus (ATCC 20542) strain to increase the flow of precursors towards the lovastatin biosynthesis pathway. A new strain was generated to overexpress acetyl-CoA carboxylase (ACCase) by replacing the native ACCase promoter with a strong constitutive PadhA promoter from Aspergillus nidulans. Glycerol and a mixture of lactose and glycerol were used independently as the carbon feedstock to determine the degree of response by the A. terreus strains towards the production of acetyl-CoA, and malonyl-CoA. The new strain increased the levels of malonyl-CoA and acetyl-CoA by 240% and 14%, respectively, compared to the wild-type strain. As a result, lovastatin production was increased by 40% and (+)-geodin was decreased by 31% using the new strain. This study shows for the first time that the metabolism of Aspergillus terreus can be manipulated to attain higher levels of precursors and valuable secondary metabolites.
Phenotypic variability correlates with clinical outcome in cryptococcus isolates obtained from botswanan hiv/aids patients
Publisher: American Society for Microbiology
Date: 07-11-2018
Abstract: Cryptococcosis results in hundreds of thousands of deaths annually, predominantly in sub-Saharan Africa. Cryptococcus is an encapsulated yeast, and during infection, cells have the capacity for substantial morphological changes, including capsule enlargement and shedding and variations in cell shape and size. In this study, we examined 70 Cryptococcus isolates causing meningitis in HIV/AIDS patients in Botswana in order to look for associations between phenotypic variation and clinical symptoms. Four variant phenotypes were seen across strains: giant cells of ≥15 µm, micro cells of ≤1 µm, shed extracellular capsule, and irregularly shaped cells. We found that “large” and “small” phenotypes were associated with differing disease symptoms, indicating that their production may be important during the disease process. Overall, our study indicates that Cryptococcus strains that can switch on cell types under different situations may be more able to sustain infection and resist the host response.
An effective sanitizer for fresh produce production:In situplasma activated water treatment inactivates pathogenic bacteria and maintains the quality of cucurbit fruit
Publisher: Cold Spring Harbor Laboratory
Date: 04-01-2023
DOI: 10.1101/2023.01.03.522676
Abstract: The effect of plasma activated water (PAW) generated with a dielectric barrier discharge diffusor (DBDD) system on microbial load and organoleptic quality of cucamelons was investigated and compared to the established sanitizer, sodium hypochlorite (NaOCl). Pathogenic serotypes of Escherichia coli , Salmonella enterica , and Listeria monocytogenes were inoculated onto the surface of cucamelons (6.5 log CFU g −1 ) and into the wash water (6 log CFU mL −1 ). PAW treatment involved 2 minutes in situ with water activated at 1500 Hz and 120 V, and air as the feed gas NaOCl treatment was a wash with 100 ppm total chlorine and the control treatment was a wash with tap water. PAW treatment produced a 3 log CFU g −1 reduction of pathogens on the cucamelon surface without negatively impacting quality or shelf life. NaOCl treatment reduced the pathogenic bacteria on the cucamelon surface by 3-4 log CFU g −1 , however, this treatment also reduced fruit shelf life and quality. Both systems reduced 6 log CFU ml −1 pathogens in the wash water to below detectable limits. The critical role of superoxide anion radical (·O 2 − ) in the antimicrobial power of DBDD-PAW was demonstrated through a scavenger assay, and chemistry modelling confirmed that ·O 2 − generation readily occurs in DBDD-PAW generated with the employed settings. Modelling of the physical forces produced during plasma treatment showed that bacteria likely experience strong local electric fields and polarization. We hypothesize that these physical effects synergise with reactive chemical species to produce the acute antimicrobial activity seen with the in situ PAW system. Plasma activated water (PAW) is an emerging sanitizer in the fresh food industry, where food safety must be achieved without a thermal kill step. Here we demonstrate PAW generated in situ to be a competitive sanitizer technology, providing a significant reduction of pathogenic and spoilage micro-organisms while maintaining the quality and shelf life of the produce item. Our experimental results are supported by modelling of the plasma chemistry and applied physical forces, which show that the system can generate highly reactive superoxide radicals and strong electric fields that combine to produce potent antimicrobial power. In situ PAW has promise in industrial applications as it only requires low power (12 W), tap water and air. Moreover, it does not produce toxic by-products or hazardous effluent waste, making it a sustainable solution for fresh food safety.
Synergy and antagonism between iron chelators and antifungal drugs in Cryptococcus
Publisher: Elsevier BV
Date: 10-2016
DOI: 10.1016/J.IJANTIMICAG.2016.06.012
Abstract: Fungal infections remain very difficult to treat, and developing new antifungal drugs is difficult and expensive. Recent approaches therefore seek to augment existing antifungals with synergistic agents that can lower the therapeutic dose, increase efficacy and prevent resistance from developing. Iron limitation can inhibit microbial growth, and iron chelators have been employed to treat fungal infections. In this study, chequerboard testing was used to explore combinations of iron chelators with antifungal agents against pathogenic Cryptococcus spp. with the aim of determining how disruption to iron homeostasis affects antifungal susceptibility. The iron chelators ethylenediaminetetraacetic acid (EDTA), deferoxamine (DFO), deferiprone (DFP), deferasirox (DSX), ciclopirox olamine and lactoferrin (LF) were paired with the antifungal agents hotericin B (AmB), fluconazole, itraconazole, voriconazole and caspofungin. All chelators except for DFO increased the efficacy of AmB, and significant synergy was seen between AmB and LF for all Cryptococcus strains. Addition of exogenous iron rescued cells from the antifungal effect of LF alone but could not prevent inhibition by AmB + LF, indicating that synergy was not due primarily to iron chelation but to other properties of LF that were potentiated in the presence of AmB. Significant synergy was not seen consistently for other antifungal-chelator combinations, and EDTA, DSX and DFP antagonised the activity of azole drugs in strains of Cryptococcus neoformans var. grubii. This study highlights the range of interactions that can be induced by chelators and indicates that most antifungal drugs are not enhanced by iron limitation in Cryptococcus.
Unique antimicrobial activity in honey from the Australian honeypot ant (Camponotus inflatus)
Publisher: PeerJ
Date: 26-07-2023
DOI: 10.7717/PEERJ.15645
Abstract: Honey produced by the Australian honeypot ant ( C onotus inflatus ) is valued nutritionally and medicinally by Indigenous peoples, but its antimicrobial activity has never been formally studied. Here, we determine the activity of honeypot ant honey (HPAH) against a panel of bacterial and fungal pathogens, investigate its chemical properties, and profile the bacterial and fungal microbiome of the honeypot ant for the first time. We found HPAH to have strong total activity against Staphylococcus aureus but not against other bacteria, and strong non-peroxide activity against Cryptococcus and Aspergillus sp. When compared with therapeutic-grade jarrah and manuka honey produced by honey bees, we found HPAH to have a markedly different antimicrobial activity and chemical properties, suggesting HPAH has a unique mode of antimicrobial action. We found the bacterial microbiome of honeypot ants to be dominated by the known endosymbiont genus Candidatus Blochmannia (99.75%), and the fungal microbiome to be dominated by the plant-associated genus Neocelosporium (92.77%). This study demonstrates that HPAH has unique antimicrobial characteristics that validate its therapeutic use by Indigenous peoples and may provide a lead for the discovery of novel antimicrobial compounds.
Inactivation of foodborne viruses: Opportunities for cold atmospheric plasma
Publisher: Elsevier BV
Date: 06-2022
Antibacterial activity of honey from the Australian stingless bee Trigona carbonaria
Publisher: Elsevier BV
Date: 07-2008
Genome Variation in Cryptococcus gattii, an Emerging Pathogen of Immunocompetent Hosts
Publisher: American Society for Microbiology
Date: 03-2011
Abstract: Cryptococcus gattii recently emerged as the causative agent of cryptococcosis in healthy in iduals in western North America, despite previous characterization of the fungus as a pathogen in tropical or subtropical regions. As a foundation to study the genetics of virulence in this pathogen, we sequenced the genomes of a strain (WM276) representing the predominant global molecular type (VGI) and a clinical strain (R265) of the major genotype (VGIIa) causing disease in North America. We compared these C. gattii genomes with each other and with the genomes of representative strains of the two varieties of Cryptococcus neoformans that generally cause disease in immunocompromised people. Our comparisons included chromosome alignments, analysis of gene content and gene family evolution, and comparative genome hybridization (CGH). These studies revealed that the genomes of the two representative C. gattii strains (genotypes VGI and VGIIa) are colinear for the majority of chromosomes, with some minor rearrangements. However, multiortholog phylogenetic analysis and an evaluation of gene/sequence conservation support the existence of speciation within the C. gattii complex. More extensive chromosome rearrangements were observed upon comparison of the C. gattii and the C. neoformans genomes. Finally, CGH revealed considerable variation in clinical and environmental isolates as well as changes in chromosome copy numbers in C. gattii isolates displaying fluconazole heteroresistance. IMPORTANCE Isolates of Cryptococcus gattii are currently causing an outbreak of cryptococcosis in western North America, and most of the cases occurred in the absence of coinfection with HIV. This pattern is therefore in stark contrast to the current global burden of one million annual cases of cryptococcosis, caused by the related species Cryptococcus neoformans , in the HIV/AIDS population. The genome sequences of two outbreak-associated major genotypes of C. gattii reported here provide insights into genome variation within and between cryptococcal species. These sequences also provide a resource to further evaluate the epidemiology of cryptococcal disease and to evaluate the role of pathogen genes in the differential interactions of C. gattii and C. neoformans with immunocompromised and immunocompetent hosts.
The role of honey in the ecology of the hive: Nutrition, detoxification, longevity, and protection against hive pathogens
Publisher: Frontiers Media SA
Date: 25-07-2022
Abstract: Honey is the source of energy for the European honey bee, Apis mellifera . Beyond simple nutrition and a hedge against the seasonal, geographic, and chemical unpredictability of nectar, honey has properties that protect the hive against various stresses. Enzyme-mediated detoxification during honey ripening neutralizes potentially toxic phytochemicals, and bees that consume honey have enhanced tolerance to other ingested toxins. Catalase and antioxidant phenolics protect honey bees from oxidative damage caused by reactive oxygen species, promoting their longevity. Phytochemical components of honey and microRNAs have the potential to influence developmental pathways, with diet playing a large role in honey bee caste determination. Components of honey mediate stress response and promote cold tolerance during overwintering. Honey has a suite of antimicrobial mechanisms including osmotic pressure, low water activity, low pH, hydrogen peroxide, and plant-, honey bee-, and microbiota-derived compounds such as phytochemicals and antimicrobial peptides. Certain types of honey, particularly polyfloral honeys, have been shown to inhibit important honey bee pathogens including the bacteria responsible for American and European Foulbrood, the microsporidian Nosema ceranae , and the fungi responsible for Stonebrood. Understanding the erse functional properties of honey has far-ranging implications for honey bee and hive health and management by beekeepers.
Phenotypic Switching and Genetic Diversity of Cryptococcus neoformans
Publisher: American Society for Microbiology
Date: 06-2001
DOI: 10.1128/JCM.39.6.2060-2064.2001
Abstract: Niger seed agar was used as a primary plating medium for the isolation of Cryptococcus neoformans from cerebrospinal fluid specimens from AIDS patients with untreated primary cryptococcosis. The medium was used as the primary means to detect variations in the colony morphology of the yeast. To search for phenotypic and genetic variations, nine patients in idually harboring two or three types of colony morphology were studied. Intrain idual isolates from nine patients had minor variations in the API 20C profile, and the MICs of one or more antifungal agents ( hotericin B, fluconazole, and itraconazole) for isolates from three patients were significantly different. Intrain idual isolates from three patients had minor karyotype differences, and one showed a dramatic chromosomal length polymorphism. In addition, three serial isolates from a patient with two episodes of infection showed similar karyotypes, confirming persistent infection by the same strain. Random lified polymorphic DNA products were identical for all isolates (including three isolates from a relapse case). Our results provided evidence suggesting that (i) in humans, C. neoformans may undergo phenotypic and genetic changes during early infection prior to antifungal agent administration (ii) dramatic variations in electrophoretic karyotypes and in phenotypes, as demonstrated during the early infection of one patient, may be due to infection by different strains and (iii) the use of niger seed agar as a primary plating medium is useful for studying antifungal susceptibility, phenotypic switching, genetic ersity, and multiple-strain infections.
Inhibition of Dermatophyte Fungi by Australian Jarrah Honey
Publisher: MDPI AG
Date: 11-02-2021
DOI: 10.3390/PATHOGENS10020194
Abstract: Superficial dermatophyte infections, commonly known as tineas, are the most prevalent fungal ailment and are increasing in incidence, leading to an interest in alternative treatments. Many floral honeys possess antimicrobial activity due to high sugar, low pH, and the production of hydrogen peroxide (H2O2) from the activity of the bee-derived enzyme glucose oxidase. Australian jarrah (Eucalyptus marginata) honey produces particularly high levels of H2O2 and has been found to be potently antifungal. This study characterized the activity of jarrah honey on fungal dermatophyte species. Jarrah honey inhibited dermatophytes with minimum inhibitory concentrations (MICs) of 1.5–3.5% (w/v), which increased to ≥25% (w/v) when catalase was added. Microscopic analysis found jarrah honey inhibited the germination of Trichophyton rubrum conidia and scanning electron microscopy of mature T. rubrum hyphae after honey treatment revealed bulging and collapsed regions. When treated hyphae were stained using REDOX fluorophores these did not detect any internal oxidative stress, suggesting jarrah honey acts largely on the hyphal surface. Although H2O2 appears critical for the antifungal activity of jarrah honey and its action on fungal cells, these effects persisted when H2O2 was eliminated and could not be replicated using synthetic honey spiked with H2O2, indicating jarrah honey contains agents that augment antifungal activity.
Highly Recombinant VGII Cryptococcus gattii Population Develops Clonal Outbreak Clusters through both Sexual Macroevolution and Asexual Microevolution
Publisher: American Society for Microbiology
Date: 29-08-2014
Abstract: An outbreak of the fungal pathogen Cryptococcus gattii began in the Pacific Northwest (PNW) in the late 1990s. This outbreak consists of three clonal subpopulations: VGIIa/major, VGIIb/minor, and VGIIc/novel. Both VGIIa and VGIIc are unique to the PNW and exhibit increased virulence. In this study, we sequenced the genomes of isolates from these three groups, as well as global isolates, and analyzed a total of 53 isolates. We found that VGIIa/b/c populations show evidence of clonal expansion in the PNW. Whole-genome sequencing provided evidence that VGIIb originated in Australia, while VGIIa may have originated in South America, and these were likely independently introduced. Additionally, the VGIIa outbreak lineage may have arisen from a less virulent clade that contained a mutation in the MSH2 ortholog, but this appears to have reverted in the VGIIa outbreak strains, suggesting that a transient mutator phenotype may have contributed to adaptation and evolution of virulence in the PNW outbreak. PNW outbreak isolates share genomic islands, both between the clonal lineages and with global isolates, indicative of sexual recombination. This suggests that VGII C. gattii has undergone sexual reproduction, either bisexual or unisexual, in multiple locales contributing to the production of novel, virulent subtypes. We also found that the genomes of two basal VGII isolates from HIV + patients contain an introgression tract spanning three genes. Introgression substantially contributed to intra-VGII polymorphism and likely occurred through sexual reproduction with VGI. More broadly, these findings illustrate how both microevolution and sexual reproduction play central roles in the development of infectious outbreaks from avirulent or less virulent progenitors. IMPORTANCE Cryptococcus gattii is the causative agent responsible for ongoing infections in the Pacific Northwest of the United States and western Canada. The incidence of these infections increased dramatically in the 1990s and remains elevated. These infections are attributable to three clonal lineages of C. gattii , VGIIa, VGIIb, and VGIIc, with only VGIIa identified once previously in the Pacific Northwest prior to the start of the outbreak, albeit in a less virulent form. This study addresses the origin and emergence of this outbreak, using whole-genome sequencing and comparison of both outbreak and global isolates. We show that VGIIa arose mitotically from a less virulent clonal group, possibly via the action of a mutator phenotype, while VGIIb was likely introduced from Australia, and VGIIc appears to have emerged in the United States or in an unders led locale via sexual reproduction. This work shows that multiple processes can contribute to the emergence of an outbreak.
Environmental sampling forCryptococcus neoformansvar.gattiifrom the Blue Mountains National Park, Sydney, Australia
Publisher: Oxford University Press (OUP)
Date: 2002
Abstract: The environmental association of Cryptococcus neoformans var. gattii with decaying wood in tropical and subtropical regions of the world is well documented. In Australia, the yeast appears confined to certain species of Eucalyptus or very closely related tree species. In this study, we attempted to isolate C. n. var. gattii from different gum tree species in the Blue Mountains National Park. Out of 99 s les from 9 different tree species, only 3 yielded viable yeast colonies 2 were from turpentine gums (Syncarpia glomulifera) and 1 was from a decayed stump of an unknown species. All of the colonized trees occurred in close proximity in urbanized areas of the Park, and all isolates shared identical DNA fingerprinting profiles. We suggest that domestic animal vectors may be responsible for the introduction and transmission of the yeast in this region, but that propagation and dispersal are very limited. This study indicates that C. n. var. gattii may occur on trees and in areas that were not previously expected to host it. However, the low incidence in the Blue Mountains National Park means this yeast is unlikely to pose any hazards to humans and animals living in or visiting this area.
The Effect of New Zealand Kanuka, Manuka and Clover Honeys on Bacterial Growth Dynamics and Cellular Morphology Varies According to the Species
Publisher: Public Library of Science (PLoS)
Date: 13-02-2013
Synergism between Medihoney and Rifampicin against Methicillin-Resistant Staphylococcus aureus (MRSA)
Publisher: Public Library of Science (PLoS)
Date: 28-02-2013
Lactoferrin-Derived Peptide Lactofungin Is Potently Synergistic with Amphotericin B
Publisher: American Society for Microbiology
Date: 21-09-2020
DOI: 10.1128/AAC.00842-20
Abstract: Lactoferrin (LF) is an iron-binding glycoprotein with broad-spectrum antimicrobial activity. Previously, we discovered that LF synergistically enhanced the antifungal efficacy of hotericin B (AMB) across a variety of yeast species and subsequently hypothesized that this synergy was enhanced by the presence of small peptides derived from the whole LF molecule. In this study, LF was digested with pepsin under a range of conditions. The resulting hydrolysates exhibited enhanced synergy with AMB compared to its synergy with undigested LF.
Phylogenetic analysis of the light-harvesting system in Chromera velia
Publisher: Springer Science and Business Media LLC
Date: 10-12-2012
DOI: 10.1007/S11120-011-9710-9
Abstract: Chromera velia is a newly discovered photosynthetic eukaryotic alga that has functional chloroplasts closely related to the apicoplast of apicomplexan parasites. Recently, the chloroplast in C. velia was shown to be derived from the red algal lineage. Light-harvesting protein complexes (LHC), which are a group of proteins involved in photon capture and energy transfer in photosynthesis, are important for photosynthesis efficiency, photo-adaptation/accumulation and photo-protection. Although these proteins are encoded by genes located in the nucleus, LHC peptides migrate and function in the chloroplast, hence the LHC may have a different evolutionary history compared to chloroplast evolution. Here, we compare the phylogenetic relationship of the C. velia LHCs to LHCs from other photosynthetic organisms. Twenty-three LHC homologues retrieved from C. velia EST sequences were aligned according to their conserved regions. The C. velia LHCs are positioned in four separate groups on trees constructed by neighbour-joining, maximum likelihood and Bayesian methods. A major group of seventeen LHCs from C. velia formed a separate cluster that was closest to dinoflagellate LHC, and to LHC and fucoxanthin chlorophyll-binding proteins from diatoms. One C. velia LHC sequence grouped with LI1818/LI818-like proteins, which were recently identified as environmental stress-induced protein complexes. Only three LHC homologues from C. velia grouped with the LHCs from red algae.
The Development of Genetic Markers from Fungal Genome Initiatives
Publisher: Elsevier
Date: 2004
Genetic structure of populations of Fusarium proliferatum in soils associated with Livistona mariae palms in Little Palm Creek, Northern Territory, Australia
Publisher: CSIRO Publishing
Date: 2004
DOI: 10.1071/BT03158
Abstract: Fusarium proliferatum (Matsushima) Nirenberg (teleomorph = Gibberella intermedia) is a member of a group of closely related and agriculturally important fungal plant pathogens known as the 'Gibberella fujikuroi species complex'. The genetic structure of populations of F. proliferatum in non-agricultural soils collected from Finke Gorge National Park, Northern Territory, Australia, was investigated. F. proliferatum was isolated from soils from the root zone of Livistona mariae palms. Amplified fragment length polymorphism (AFLP) analysis of 77 isolates distinguished 73 unique haplotypes with an overall genetic similarity of 0.94. Cluster and bootstrap analysis indicated the population was composed of two well supported groups, possibly of clonal origin. Statistical analysis of the distribution of genotypes in the study area showed there were clear spatial sub isions of genotypic ersity (P 0.001) indicating limited mixing of genotypes.
Evidence of Recombination in Mixed-Mating-Type and α-Only Populations of Cryptococcus gattii Sourced from Single Eucalyptus Tree Hollows
Publisher: American Society for Microbiology
Date: 04-2008
DOI: 10.1128/EC.00020-08
Abstract: Disease caused by the pathogenic yeast Cryptococcus gattii begins with the inhalation of an infectious propagule. As C. gattii is heavily encapsulated, this propagule is most likely to be a basidiospore. However, most C. gattii strains are infertile in laboratory crosses, and population studies indicate that recombination and dispersal are very restricted. In addition, strains of the α mating type predominate, which would not be expected in a mating population. C. gattii comprises four genetically distinct molecular genotypes, designated VGI to VGIV. C. gattii molecular type VGI has a strong association with Eucalyptus camaldulensis and can be found in high numbers in E. camaldulensis hollows. Previous work on isolates obtained from E. camaldulensis suggested that environmental populations of C. gattii are highly fragmented, have limited ability to disperse, and are confined to in idual tree hollows. In the current study, we examined large numbers of isolates from three separate hollows for evidence of recombination. In two hollows, the α and a mating types were present in approximately equal numbers. The third hollow had α cells only and was from a region where a isolates have never been found. Statistical analysis of multilocus genotypes revealed recombining subpopulations in the three Eucalyptus hollows. Recombination was equally present in the α- a and α-only populations. This is consistent with recent studies that have found evidence suggestive of α-α mating in C. gattii and Cryptococcus neoformans and raises the possibility this may be a widespread phenomenon, allowing these fungi to recombine despite a paucity of a mating partners.
Honey can inhibit and eliminate biofilms produced by Pseudomonas aeruginosa
Publisher: Springer Science and Business Media LLC
Date: 03-12-2019
DOI: 10.1038/S41598-019-54576-2
Abstract: Chronic wound treatment is becoming increasingly difficult and costly, further exacerbated when wounds become infected. Bacterial biofilms cause most chronic wound infections and are notoriously resistant to antibiotic treatments. The need for new approaches to combat polymicrobial biofilms in chronic wounds combined with the growing antimicrobial resistance crisis means that honey is being revisited as a treatment option due to its broad-spectrum antimicrobial activity and low propensity for bacterial resistance. We assessed four well-characterised New Zealand honeys, quantified for their key antibacterial components, methylglyoxal, hydrogen peroxide and sugar, for their capacity to prevent and eradicate biofilms produced by the common wound pathogen Pseudomonas aeruginosa . We demonstrate that: (1) honey used at substantially lower concentrations compared to those found in honey-based wound dressings inhibited P. aeruginosa biofilm formation and significantly reduced established biofilms (2) the anti-biofilm effect of honey was largely driven by its sugar component (3) cells recovered from biofilms treated with sub-inhibitory honey concentrations had slightly increased tolerance to honey and (4) honey used at clinically obtainable concentrations completely eradicated established P. aeruginosa biofilms. These results, together with their broad antimicrobial spectrum, demonstrate that manuka honey-based wound dressings are a promising treatment for infected chronic wounds, including those with P. aeruginosa biofilms.
A cost-effective colourimetric assay for quantifying hydrogen peroxide in honey
Publisher: Microbiology Society
Date: 12-2019
The unusual antibacterial activity of medical-grade Leptospermum honey: antibacterial spectrum, resistance and transcriptome analysis.
Publisher: Springer Science and Business Media LLC
Date: 10-06-2009
DOI: 10.1007/S10096-009-0763-Z
Abstract: There is an urgent need for new, effective agents in topical wound care, and selected honeys show potential in this regard. Using a medical-grade honey, eight species of problematic wound pathogens, including those with high levels of innate or acquired antibiotic resistance, were killed by 4.0-14.8% honey, which is a concentration that can be maintained in the wound environment. Resistance to honey could not be induced under conditions that rapidly induced resistance to antibiotics. Escherichia coli macroarrays were used to determine the response of bacterial cells to a sub-lethal dose of honey. The pattern of gene expression differed to that reported for other antimicrobial agents, indicating that honey acts in a unique and multifactorial way 78 (2%) genes were upregulated and 46 (1%) genes were downregulated more than two-fold upon exposure to the medical-grade honey. Most of the upregulated genes clustered into distinct functional regulatory groups, with many involved in stress responses, and the majority of downregulated genes encoded for products involved in protein synthesis. Taken together, these data indicate that honey is an effective topical antimicrobial agent that could help reduce some of the current pressures that are promoting antibiotic resistance.
Open Source Drug Discovery with the Malaria Box Compound Collection for Neglected Diseases and Beyond
Publisher: Public Library of Science (PLoS)
Date: 28-07-2016
Phylogenetic Placement and Host Specificity of Mycorrhizal Isolates Belonging to AG-6 and AG-12 in the Rhizoctonia solani Species Complex
Publisher: Informa UK Limited
Date: 07-2001
DOI: 10.2307/3761825
Lineages derived from Cryptococcus neoformans type strain H99 support a link between the capacity to be pleomorphic and virulence
Publisher: American Society for Microbiology
Date: 26-04-2022
Abstract: Cryptococcosis is a devastating cause of death and disease worldwide. During infection, Cryptococcus cells can undergo substantial changes to their size and shape.
Survey of Vietnamese coffee beans for the presence of ochratoxigenic Aspergilli
Publisher: Springer Science and Business Media LLC
Date: 03-2007
DOI: 10.1007/S11046-007-0099-0
Abstract: Vietnamese coffee beans were investigated for the presence of ochratoxigenic Aspergilli. Ninety-three percent of the coffee s les studied were positive for A. niger. No other ochratoxigenic species were present. HPLC analysis determined that 8.7% of the A. niger strains were positive for ochratoxin A (OA) production. There was no significant difference in the level of contamination or incidence of toxigenic strains in s les that had been rejected by manual sorting and those that were destined for human consumption. No OA-producing fungi were uncovered in a fresh coffee bean s le analysed, suggesting that the OA problem most likely occurs post-harvest.
Molecular genotype analysis of natural toxigenic and nontoxigenic isolates of Aspergillus flavus and A. parasiticus
Publisher: Elsevier BV
Date: 11-1999
Clinical and environmental isolates of Cryptococcus gattii from Australia that retain sexual fecundity
Publisher: American Society for Microbiology
Date: 08-2005
DOI: 10.1128/EC.4.8.1410-1419.2005
Abstract: Cryptococcus gattii is a primary pathogenic yeast that causes disease in both animals and humans. It is closely related to Cryptococcus neoformans and erged from a common ancestor ∼40 million years ago. While C. gattii has a characterized sexual cycle dependent upon a dimorphic region of the genome known as the MAT locus, mating has rarely been observed in this species. In this study, we identify for the first time clinical (both human and veterinary) and environmental isolates from Australia that retain sexual fecundity. A collection of 120 isolates from a variety of geographic locations was analyzed for molecular type, mating type, and the ability to develop mating structures when cocultured with fertile tester strains. Nine isolates produced dikaryotic filaments with paired nuclei, fused cl connections, and basidiospores. DNA sequence analysis of three genes ( URA5 , the MATα-specific SXI1 α gene, and the MAT a -specific SXI2 a gene) revealed little or no variability in URA5 and SXI2 a , respectively. However across the 108 MATα strains sequenced, the SXI1 α gene was found to exist as 11 different alleles. Phylogenetic analysis found most variation to occur in the more fertile genotypes. Although some lineages of Australian C. gattii have retained the ability to mate, the majority of isolates were sterile, suggesting that asexuality is the dominant mode of propagation in these populations.
Therapeutic Manuka Honey: No Longer So Alternative.
Publisher: Frontiers Media SA
Date: 20-04-2016
The antibacterial activity of honey derived from Australian flora
Publisher: Public Library of Science (PLoS)
Date: 28-03-2011
Development and clinical application of a panfungal PCR assay to detect and identify Fungal DNA in tissue specimens
Publisher: American Society for Microbiology
Date: 02-2007
DOI: 10.1128/JCM.01862-06
Abstract: Given the rise in the incidence of invasive fungal infections (IFIs) and the expanding spectrum of fungal pathogens, early and accurate identification of the causative pathogen is essential. We developed a panfungal PCR assay that targets the internal transcribed spacer 1 (ITS1) region of the ribosomal DNA gene cluster to detect fungal DNA in fresh and formalin-fixed, paraffin-embedded (PE) tissue specimens from patients with culture-proven ( n = 38) or solely histologically proven ( n = 24) IFIs. PCR products were sequenced and compared with sequences in the GenBank database to identify the causal pathogen. The molecular identification was correlated with results from histological examination and culture. The assay successfully detected and identified the fungal pathogen in 93.6% and 64.3% of culture-proven and solely histologically proven cases of IFI, respectively. A erse range of fungal genera were identified, including species of Candida , Cryptococcus , Trichosporon , Aspergillus , Fusarium , Scedosporium , Exophiala , Exserohilum , Apophysomyces , Actinomucor , and Rhizopus . For five specimens, molecular analysis identified a pathogen closely related to that identified by culture. All PCR-negative specimens ( n = 10) were PE tissues in which fungal hyphae were visualized. The results support the use of the panfungal PCR assay in combination with conventional laboratory tests for accurate identification of fungi in tissue specimens.
Factors affecting the production and measurement of hydrogen peroxide in honey samples
Publisher: Microbiology Society
Date: 03-2021
Abstract: Many Australian native honeys possess significant antimicrobial properties due to the production of hydrogen peroxide (H 2 O 2 ) by glucose oxidase, an enzyme derived from the honeybee. The level of H 2 O 2 produced in different honey s les is highly variable, and factors governing its production and stability are not well understood. In this study, highly active Australian honeys that had been stored for years lost up to 54 % of their antibacterial activity, although almost all retained sufficient activity to be considered potentially therapeutically useful. We used a simple colourimetric assay to quantify H 2 O 2 production. Although we found a significant correlation between H 2 O 2 production and antibacterial activity across erse honey s les, variation in H 2 O 2 only explained 47 % of the variation observed in activity, limiting the assay as a screening tool and highlighting the complexity of the relationship between H 2 O 2 and the killing power of honey. To further examine this, we tested whether H 2 O 2 detection in honey was being inhibited by pigmented compounds and if H 2 O 2 might be directly degraded in some honey s les. We found no correlation between H 2 O 2 detection and honey colour. Some honey s les rapidly lost endogenous and spiked H 2 O 2 , suggesting that components in honey, such as catalase or antioxidant polyphenols, may degrade or quench H 2 O 2 . Despite this rapid loss of H 2 O 2 , these honeys had significant peroxide-based antibacterial activity, indicating a complex relationship between H 2 O 2 and other honey components that may act synergistically to augment activity.
The evolutionary history of Symbiodinium and scleractinian hosts - Symbiosis, diversity, and the effect of climate change
Publisher: Elsevier BV
Date: 27-09-2006
The Antimicrobial Efficacy Of Plasma Activated Water Is Modulated By Reactor Design And Water Composition
Publisher: Cold Spring Harbor Laboratory
Date: 15-07-2021
DOI: 10.1101/2021.07.14.452435
Abstract: Plasma activated water (PAW) contains a cocktail of reactive oxidative species and free radicals and has demonstrated efficacy as a sanitizer for fresh produce, however there is a need for further optimization. The antimicrobial efficacy of PAW produced by a bubble spark discharge (BSD) reactor and a dielectric barrier discharge-diffuser (DBDD) reactor operating at atmospheric conditions with air, discharge frequencies of 500, 1000 and 1500 Hz, and MilliQ and tap water, was investigated with model organisms Listeria innocua and Escherichia coli . Optimal conditions were subsequently employed for pathogenic bacteria Listeria monocytogenes, E. coli and Salmonella enterica . PAW generated with the DBDD reactor reduced more than 6-log CFU of bacteria within 1 minute of treatment. The BSD-PAW, while attaining high CFU reduction was less effective, particularly for L. innocua . Analysis of physicochemical properties revealed BSD-PAW had a greater variety of reactive species than DBDD-PAW. Scavenger assays were employed to specifically sequester reactive species, including the short-lived superoxide (·O 2 - ) radical that could not be directly measured in the PAW. This demonstrated a critical role of superoxide for the inactivation of both E. coli and L. innocua by DBDD-PAW, while in BSD-PAW it had a role in L. innocua inactivation only. Overall, this study demonstrates the potential of DBDD-PAW in fresh produce, where there is a need for sterilization while minimizing chemical inputs and residues and maintaining food quality. Highly effective PAW was generated using air as a processing gas and tap water, making this a feasible and cost-effective option. There is a growing demand for fresh food produced with minimal processing, however guaranteeing microbial safety in the absence of a thermal kill step is challenging. Plasma-activated water (PAW) is a promising novel antimicrobial but its use in high-risk applications like the sanitization of fresh produce requires further optimization. This study demonstrated the importance of reactor design in the production of reactive species in PAW with capacity to kill bacteria. Very effective PAW was generated using a dielectric barrier discharge-diffuser (DBDD) system, with antimicrobial activity attributed to the presence of superoxide radicals. The DBBD reactor used air as a processing gas and tap water, highlighting the potential of this approach as a cost-effective and green alternative to chemical treatment methods that are currently used in food decontamination.
The effect of standard heat and filtration processing procedures on antimicrobial activity and hydrogen peroxide levels in honey
Publisher: Frontiers Media SA
Date: 2012
First Reported Case of Cryptococcus gattii in the Southeastern USA: Implications for Travel-Associated Acquisition of an Emerging Pathogen
Publisher: Public Library of Science (PLoS)
Date: 10-06-2009
Molecular markers reveal cryptic sex in the human pathogen Coccidioides immitis.
Publisher: Proceedings of the National Academy of Sciences
Date: 23-01-1996
Abstract: Coccidioides immitis, cause of a recent epidemic of "Valley fever" in California, is typical of many eukaryotic microbes in that mating and meiosis have yet to be reported, but it is not clear whether sex is truly absent or just cryptic. To find out, we have undertaken a population genetic study using PCR lification, screening for single-strand conformation polymorphisms, and direct DNA sequencing to find molecular markers with nucleotide-level resolution. Both population genetic and phylogenetic analyses indicate that C. immitis is almost completely recombining. To our knowledge, this study is the first to find molecular evidence for recombination in a fungus for which no sexual stage has yet been described. These results motivate a directed search for mating and meiosis and illustrate the utility of single-strand conformation polymorphism and sequencing with arbitrary primer pairs in molecular population genetics.
Stability of coral-endosymbiont associations during and after a thermal stress event in the southern Great Barrier Reef
Publisher: Springer Science and Business Media LLC
Date: 21-05-2009
Amplified Single-Nucleotide Polymorphisms and a (GA) Microsatellite Marker Reveal Genetic Differentiation between Populations of Histoplasma capsulatum from the Americas
Publisher: Elsevier BV
Date: 10-2201
Augmenting Azoles with Drug Synergy to Expand the Antifungal Toolbox
Publisher: MDPI AG
Date: 14-04-2022
DOI: 10.3390/PH15040482
Abstract: Fungal infections impact the lives of at least 12 million people every year, killing over 1.5 million. Wide-spread use of fungicides and prophylactic antifungal therapy have driven resistance in many serious fungal pathogens, and there is an urgent need to expand the current antifungal arsenal. Recent research has focused on improving azoles, our most successful class of antifungals, by looking for synergistic interactions with secondary compounds. Synergists can co-operate with azoles by targeting steps in related pathways, or they may act on mechanisms related to resistance such as active efflux or on totally disparate pathways or processes. A variety of sources of potential synergists have been explored, including pre-existing antimicrobials, pharmaceuticals approved for other uses, bioactive natural compounds and phytochemicals, and novel synthetic compounds. Synergy can successfully widen the antifungal spectrum, decrease inhibitory dosages, reduce toxicity, and prevent the development of resistance. This review highlights the ersity of mechanisms that have been exploited for the purposes of azole synergy and demonstrates that synergy remains a promising approach for meeting the urgent need for novel antifungal strategies.
Hypervirulence and cross-resistance to a clinical antifungal are induced by an environmental fungicide in Cryptococcus gattii
Publisher: Elsevier BV
Date: 10-2020
The potential for honey in the management of wounds and infection
Publisher: Elsevier BV
Date: 03-2005
DOI: 10.1071/HI05024
Biodeterioration of pre-treated polypropylene by Aspergillus terreus and Engyodontium album
Publisher: Springer Science and Business Media LLC
Date: 14-04-2023
DOI: 10.1038/S41529-023-00342-9
Abstract: Polypropylene (PP) has raised severe environmental issues concerning its non-degradability, with a current recycling rate of only 1%. This current study utilises Aspergillus terreus ATCC 20542 and Engyodontium album BRIP 61534a to break down PP while focusing on pre-treatment. Polypropylene granule (GPP), film (FPP) and metallised film (MFPP) are pre-treated by either UV, heat, or Fenton’s reagent. UV and heat-treated MFPP by A. terreus exhibits notable weight loss percentage (25.29% and 22.13%, respectively). Biomass production, reduction rate, Fourier transform infrared (FTIR), and scanning electron microscopy (SEM) analyses further validate the degradation rate. A. terreus incubated with UV-treated MFPP produced a relatively high biomass yield of 1.07 mg/ml. Reduction in carbonyl index and surface morphological changes reveal consistent biodeterioration evidence. This investigation demonstrates that A. terreus and E. album can grow on, change, and utilise PP as a carbon source with pre-treatments’ aid, promoting the biological pathways for plastic waste treatment.
Lactoferrin Is Broadly Active against Yeasts and Highly Synergistic with Amphotericin B
Publisher: American Society for Microbiology
Date: 21-04-2020
DOI: 10.1128/AAC.02284-19
Abstract: Lactoferrin (LF) is a multifunctional milk protein with antimicrobial activity against a range of pathogens. While numerous studies report that LF is active against fungi, there are considerable differences in the level of antifungal activity and the capacity of LF to interact with other drugs. Here we undertook a comprehensive evaluation of the antifungal spectrum of activity of three defined sources of LF across 22 yeast and 24 mold species and assessed its interactions with six widely used antifungal drugs.
Comparative transcriptomic analyses of Z ymoseptoria tritici strains show complex lifestyle transitions and intraspecific variability in transcription profiles
Publisher: Wiley
Date: 08-02-2016
DOI: 10.1111/MPP.12333
Industry partnerships drive food safety research for fresh produce in Australia and New Zealand
Publisher: International Society for Horticultural Science (ISHS)
Date: 04-2023
Specific non-peroxide antibacterial effect of manuka honey on the Staphylococcus aureus proteome
Publisher: Elsevier BV
Date: 07-2012
DOI: 10.1016/J.IJANTIMICAG.2012.03.012
Abstract: Manuka honey, derived from the New Zealand flowering plant Leptospermum scoparium, shows promise as a topical antibacterial agent and effective chronic wound dressing. The aim of this study was to determine the non-peroxide antibacterial effects of this honey on the proteome of the common wound pathogen Staphylococcus aureus. Proteomic analysis was performed on cells treated for a short time with manuka honey compared with the proteome of untreated cells as well as cells treated with a Leptospermum honey s le without antibacterial activity. Treatment with manuka honey resulted in a significant decrease in the bacterial cell growth rate as well as downregulation of ten and upregulation of two proteins. Nine of these proteins were also differentially expressed by cells treated with the inactive Leptospermum honey, but to a lesser degree, and the rate of bacterial growth was not affected. The differentially expressed proteins have roles in ribosomal function, protein synthesis, metabolic processes and transcription. Manuka honey uniquely caused downregulation of two proteins [dihydrolipoamide dehydrogenase (DLD) and elongation factor Tu (EF-Tu)] associated with two of these pathways as well as upregulation of one stress-related protein [cold shock protein C (CspC)]. The proteomic profile following treatment with manuka honey differed from the profiles of other antibacterial agents, indicating a unique mode of action and its potential value as a novel antimicrobial agent.
Diversity of the Trichocomaceae in the Katandra Nature Reserve, Central Coast, NSW, Australia
Publisher: Elsevier BV
Date: 09-2005
DOI: 10.1017/S0953756205003540
Abstract: The ersity of the family Trichocomaceae, which includes the major anamorph genera Aspergillus and Penicillium, was studied in the Katandra Nature Reserve, Central Coast, NSW, Australia. Soil, living leaves, leaf litter and detritus were examined by both direct and dilution plating techniques. Fungi were isolated on dichloran Rose Bengal chlor henicol agar, and dichloran 18 % glycerol agar, media suitable for cultivation of many species within this family. Species of Trichocomaceae were isolated from all sites and all substrates examined. A high ersity was found, with more than 50 known species identified, and an equal number of undescribed species detected. More species of Penicillium were recovered than other genera, with Aspergillus species the next most common. Most of the species recovered were anamorphs, though 16 known and unknown ascosporic species were also isolated from heated and unheated soil. Soils, leaf litter, a scat from a native herbivore and leaves of living native plants yielded higher ersity than insects, worms or introduced plants. More species belonging to the family were isolated from soil in dry sclerophyll forest than in rainforest. Conversely, native rainforest plants harboured more ersity than the dry sclerophyll forest plants examined.
Highly organized structure in the non-coding region of the psbA minicircle from clade C Symbiodinium
Publisher: Microbiology Society
Date: 11-2003
Abstract: The chloroplast genes of dinoflagellates are distributed among small, circular dsDNA molecules termed minicircles. In this paper, we describe the structure of the non-coding region of the psbA minicircle from Symbiodinium: DNA sequence was obtained from five Symbiodinium strains obtained from four different coral host species (Goniopora tenuidens, Heliofungia actiniformis, Leptastrea purpurea and Pocillopora damicornis), which had previously been determined to be closely related using LSU rDNA region D1/D2 sequence analysis. Eight distinct sequence blocks, consisting of four conserved cores interspersed with two metastable regions and flanked by two variable regions, occurred at similar positions in all strains. Inverted repeats (IRs) occurred in tandem or "twin" formation within two of the four cores. The metastable regions also consisted of twin IRs and had modular behaviour, being either fully present or completely absent in the different strains. These twin IRs are similar in sequence to double-hairpin elements (DHEs) found in the mitochondrial genomes of some fungi, and may be mobile elements or may serve a functional role in recombination or replication. Within the central unit (consisting of the cores plus the metastable regions), all IRs contained perfect sequence inverses, implying they are highly evolved. IRs were also present outside the central unit but these were imperfect and possessed by in idual strains only. A central adenine-rich sequence most closely resembled one in the centre of the non-coding part of Amphidinium operculatum minicircles, and is a potential origin of replication. Sequence polymorphism was extremely high in the variable regions, suggesting that these regions may be useful for distinguishing strains that cannot be differentiated using molecular markers currently available for Symbiodinium.
Climate change and the emergence of fungal pathogens
Publisher: Public Library of Science (PLoS)
Date: 29-04-2021
Repurposing drugs to fast-track therapeutic agents for the treatment of cryptococcosis
Publisher: PeerJ
Date: 04-05-2018
DOI: 10.7717/PEERJ.4761
Abstract: Many infectious diseases disproportionately affect people in the developing world. Cryptococcal meningitis is one of the most common mycoses in HIV-AIDS patients, with the highest burden of disease in sub-Saharan Africa. Current best treatment regimens still result in unacceptably high mortality rates, and more effective antifungal agents are needed urgently. Drug development is h ered by the difficulty of developing effective antifungal agents that are not also toxic to human cells, and by a reluctance among pharmaceutical companies to invest in drugs that cannot guarantee a high financial return. Drug repurposing, where existing drugs are screened for alternative activities, is becoming an attractive approach in antimicrobial discovery programs, and various compound libraries are now commercially available. As these drugs have already undergone extensive optimisation and passed regulatory hurdles this can fast-track their progress to market for new uses. This study screened the Screen-Well Enzo library of 640 compounds for candidates that phenotypically inhibited the growth of Cryptococcus deuterogattii . The anthelminthic agent flubendazole, and L-type calcium channel blockers nifedipine, nisoldipine and felodipine, appeared particularly promising and were tested in additional strains and species. Flubendazole was very active against all pathogenic Cryptococcus species, with minimum inhibitory concentrations of 0.039–0.156 μg/mL, and was equally effective against isolates that were resistant to fluconazole. While nifedipine, nisoldipine and felodipine all inhibited Cryptococcus , nisoldipine was also effective against Candida, Saccharomyces and Aspergillus . This study validates repurposing as a rapid approach for finding new agents to treat neglected infectious diseases.
Low Levels of Hive Stress Are Associated with Decreased Honey Activity and Changes to the Gut Microbiome of Resident Honey Bees
Publisher: American Society for Microbiology
Date: 17-08-2023
DOI: 10.1128/SPECTRUM.00742-23
Abstract: Honey bees serve as pollinators for many plants and crops worldwide and produce valuable hive products such as honey and wax. Various sources of stress can disrupt honey bee colonies, affecting their health and productivity.
Antibiotic-specific differences in the response of Staphylococcus aureus to treatment with antimicrobials combined with manuka honey
Publisher: Frontiers Media SA
Date: 27-01-2015
Clonality and Recombination in Genetically Differentiated Subgroups of Cryptococcus gattii
Publisher: American Society for Microbiology
Date: 08-2005
DOI: 10.1128/EC.4.8.1403-1409.2005
Abstract: Cryptococcus gattii is a pathogenic yeast that together with Cryptococcus neoformans causes cryptococcosis in humans and animals. High numbers of viable C. gattii propagules can be obtained from certain species of Australian Eucalyptus camaldulensis trees, and an epidemiological link between Eucalyptus colonization and human exposure has been proposed. However, the highest prevalence of C. gattii cryptococcosis occurs in Papua New Guinea and in regions of Australia where the eucalypt species implicated to date are not endemic. This study investigated the population structure of three geographically distinct clinical and veterinary populations of C. gattii from Australia and Papua New Guinea. All populations that consisted of a genotype found frequently in Australia (VGI) were strongly clonal and were highly differentiated from one another. Two populations of the less common VGII genotype from Sydney and the Northern Territory had population structures inferring recombination. In addition, there was some evidence of reduced genetic differentiation between these geographically remote regions. In a companion study presented in this issue, VGII isolates were overwhelmingly more fertile than those of the VGI genotype, giving biological support to the indirect assessment of sexual exchange. It appears that the VGI genotype propagates clonally on eucalypts in Australia and on an unknown substrate in Papua New Guinea, with infection initiated by an unidentified infectious propagule. VGII isolates are completing their life cycles and may be dispersed via sexually produced basidiospores, which are also likely to initiate respiratory infection.
In Vitro Susceptibility of the Yeast Pathogen Cryptococcus to Fluconazole and Other Azoles Varies with Molecular Genotype
Publisher: American Society for Microbiology
Date: 11-2010
DOI: 10.1128/JCM.01271-10
Abstract: Cryptococcosis is primarily caused by Cryptococcus neoformans and Cryptococcus gattii. These two pathogenic species each ide into four distinct molecular genotypes. In this study, we examined whether genotype influenced susceptibility to antifungal drugs used to treat cryptococcosis using the broth microdilution method described by the Clinical and Laboratory Standards Institute. C. gattii isolates belonging to molecular genotype VGII had significantly higher MIC values for flucytosine and all azole antifungal agents tested, particularly fluconazole, than isolates of other C. gattii genotypes. In an extended analysis of fluconazole susceptibility, VGII isolates from the north and west of Australia required higher drug levels for inhibition than those from Vancouver Island, Canada. Within C. neoformans , genotype VNII had significantly lower geometric mean MICs for fluconazole than genotype VNI. These results indicate that cryptococcal species, molecular genotype, and region of origin may be important when deciding treatment options for cryptococcosis.
A photosynthetic alveolate closely related to apicomplexan parasites
Publisher: Springer Science and Business Media LLC
Date: 21-02-2008
DOI: 10.1038/NATURE06635
Abstract: Many parasitic Apicomplexa, such as Plasmodium falciparum, contain an unpigmented chloroplast remnant termed the apicoplast, which is a target for malaria treatment. However, no close relative of apicomplexans with a functional photosynthetic plastid has yet been described. Here we describe a newly cultured organism that has ultrastructural features typical for alveolates, is phylogenetically related to apicomplexans, and contains a photosynthetic plastid. The plastid is surrounded by four membranes, is pigmented by chlorophyll a, and uses the codon UGA to encode tryptophan in the psbA gene. This genetic feature has been found only in coccidian apicoplasts and various mitochondria. The UGA-Trp codon and phylogenies of plastid and nuclear ribosomal RNA genes indicate that the organism is the closest known photosynthetic relative to apicomplexan parasites and that its plastid shares an origin with the apicoplasts. The discovery of this organism provides a powerful model with which to study the evolution of parasitism in Apicomplexa.
The antimicrobial efficacy of plasma‐activated water against Listeria and E. coli is modulated by reactor design and water composition
Publisher: Oxford University Press (OUP)
Date: 04-2022
DOI: 10.1111/JAM.15429
Abstract: This study aimed to compare the efficacy of plasma-activated water (PAW) generated by two novel plasma reactors against pathogenic foodborne illness organisms. The antimicrobial efficacy of PAW produced by a bubble spark discharge (BSD) reactor and a dielectric barrier discharge-diffuser (DBDD) reactor operating at atmospheric conditions with air, multiple discharge frequencies and Milli-Q and tap water, was investigated with model organisms Listeria innocua and Escherichia coli in situ. Optimal conditions were subsequently employed for pathogenic bacteria Listeria monocytogenes, E. coli and Salmonella enterica. DBDD-PAW reduced more than 6-log of bacteria within 1 min. The BSD-PAW, while attaining high log reduction, was less effective. Analysis of physicochemical properties revealed that BSD-PAW had a greater variety of reactive species than DBDD-PAW. Scavenger assays designed to specifically sequester reactive species demonstrated a critical role of superoxide, particularly in DBDD-PAW. DBDD-PAW demonstrated rapid antimicrobial activity against pathogenic bacteria, with superoxide the critical reactive species. This study demonstrates the potential of DBDD-PAW produced using tap water and air as a feasible and cost-effective option for antimicrobial applications, including food safety.
Sexual Reproduction of Human Fungal Pathogens
Publisher: Cold Spring Harbor Laboratory
Date: 08-2014
The antibacterial activity of Australian Leptospermum honey correlates with methylglyoxal levels
Publisher: Public Library of Science (PLoS)
Date: 28-12-2016
Predominance of Trichophyton interdigitale revealed in podiatric nail dust collections in Eastern Australia
Publisher: Springer Science and Business Media LLC
Date: 22-07-2020
DOI: 10.1007/S11046-019-00363-6
Abstract: Toenail onychomycosis caused by dermatophytes is a significant medical and financial worldwide burden. Relatively scant research has been undertaken as to the predominant species and strains causing this condition in Australia, which is a unique isolated continent with erse geographical, climatic and population regions. Four regions were selected in Eastern Australia: Far North Queensland, Rural Victoria, Melbourne Metropolitan and Tasmania. From each of these areas, communal nail dust bags from podiatric physicians' work were collected and analysed. A total of 32 dust bags were collected: 10 from Far North Queensland, 8 from Melbourne Metropolitan, 8 from Rural Victoria and 6 from Tasmania. Dermatophyte test medium was used to isolate dermatophytes from the dust, and the colonies were subcultured to Potato Dextrose Agar. Of the bags collected, in total 69% were positive for dermatophytes: 40% from Far North Queensland, 75% from Melbourne Metropolitan, 88% from Rural Victoria and 83% from Tasmania. The internal transcribed spacer (ITS) region of ribosomal DNA was used to identify and compare isolates. A total of 148 dermatophyte strains were identified. The predominant species isolated was Trichophyton interdigitale (125 isolates), which was found in all four regions. This species was further sub ided into four ITS genotypes: the first two were present in all regions, but the third was found only in the Melbourne Metropolitan area and the fourth only in Tasmania. Only one strain of Trichophyton rubrum was found and only in Rural Victoria. Eighteen isolates of Arthroderma quadrifidum were cultured from Rural Victoria and Tasmania and were further classified into three ITS genotypes. Some isolates rarely reported in clinical material were identified as Paraphyton cookei, Arthroderma tuberculatum and Arthroderma crocatum. A potentially new species of Arthroderma was also found in Melbourne Metropolitan. These findings reveal a unique dermatophyte fingerprint in toenails for Eastern Australia.
The Detection of Nonhybrid, Trisomic, and Triploid Offspring in Sexual Progeny of a Mating of Phytophthora infestans
Publisher: Elsevier BV
Date: 04-1999
Restriction fragment length polymorphisms of mitochondrial DNA of Phytophthora infestans
Publisher: Elsevier BV
Date: 12-1990
Phenotypic Variability Correlates with Clinical Outcome in Cryptococcus Isolates Obtained from Botswanan HIV/AIDS Patients
Publisher: Cold Spring Harbor Laboratory
Date: 16-09-2018
DOI: 10.1101/418897
Abstract: Pathogenic species of Cryptococcus cause hundreds of thousands of deaths annually. Considerable phenotypic variation is exhibited during infection, including increased capsule size, capsule shedding, giant cells (≥ 15 μm) and micro cells (≤ 1 μm). We examined 70 clinical isolates of Cryptococcus neoformans and Cryptococcus tetragattii from HIV/AIDS patients in Botswana to determine if the capacity to produce morphological variants was associated with clinical parameters. Isolates were cultured under conditions designed to simulate in vivo stresses. Substantial variation was seen across morphological and clinical data. Giant cells were more common in C. tetragattii, while micro cells and shed capsule occurred in C. neoformans only. Phenotypic variables fell into two groups associated with differing symptoms. The production of “large” phenotypes (greater cell and capsule size and giant cells) was associated with higher CD4 count and was negatively correlated with intracranial pressure indicators, suggesting these are induced in early-stage infection. “Small” phenotypes (micro cells and shed capsule) were associated with lower CD4 counts, negatively correlated with meningeal inflammation indicators and positively correlated with intracranial pressure indicators, suggesting they are produced later during infection and may contribute to immune suppression and promote proliferation and dissemination. These trends persisted at the species level, indicating that they were not driven by association with particular Cryptococcus species. Isolates possessing giant cells, micro cells, and shed capsule were rare, but strikingly were associated with patient death (p=0.0165). Our data indicate that pleomorphism is an important driver in Cryptococcus infection. Cryptococcosis results in hundreds of thousands of deaths annually, predominantly in sub-Saharan Africa. Cryptococcus is an encapsulated yeast, and during infection cells have the capacity for substantial morphological changes, including capsule enlargement and shedding, and variations in cell shape and size. In this study we examined 70 Cryptococcus isolates causing meningitis in HIV/AIDS patients in Botswana in order to look for associations between phenotypic variation and clinical symptoms. Four variant phenotypes were seen across strains: giant cells ≥ 15 μm, micro cells ≤ 1 μm, shed extracellular capsule, and irregularly shaped cells. We found “large” and “small” phenotypes were associated with differing disease symptoms, indicating that their production may be important during the disease process. Overall, our study indicates that Cryptococcus strains that can switch on cell types under different situations may be more able to sustain infection and resist the host response.
Effect of Nutrient Concentration and Salinity on Immotile-Motile Transformation of Chromera velia
Publisher: Wiley
Date: 20-07-2010
DOI: 10.1111/J.1550-7408.2010.00495.X
Abstract: Chromera velia (Chromerida: Alveolata) is a photosynthetic, unicellular organism closely related to parasitic apicomplexa. Diurnal rhythmicity of an immotile-motile transformation has been observed but its role in the life cycle remains largely unknown. Using a multiwell system, we show that salinity and f-medium concentration significantly affect the percentage of motile C. velia cells. An inverse relationship between salinity and motility in C. velia occurred, and flagellation was also suppressed at high nutrient levels. These results suggest a low salinity environment with relatively low nutrient levels enables flagellate transformation during the diurnal cycle of C. velia.
Chromera et al.: Novel Photosynthetic Alveolates and Apicomplexan Relatives
Publisher: Springer Vienna
Date: 08-10-2013
An Effective Sanitizer for Fresh Produce Production: In Situ Plasma-Activated Water Treatment Inactivates Pathogenic Bacteria and Maintains the Quality of Cucurbit Fruit
Publisher: American Society for Microbiology
Date: 17-08-2023
DOI: 10.1128/SPECTRUM.00034-23
Abstract: Plasma-activated water (PAW) is an emerging sanitizer in the fresh food industry, where food safety must be achieved without a thermal kill step. Here, we demonstrate PAW generated in situ to be a competitive sanitizer technology, providing a significant reduction of pathogenic and spoilage microorganisms while maintaining the quality and shelf life of the produce item.
Symbiont acquisition strategy drives host-symbiont associations in the southern Great Barrier Reef
Publisher: Springer Science and Business Media LLC
Date: 09-08-2008
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Imperial College London
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