ORCID Profile
0000-0003-2417-2969
Current Organisation
Nanyang Technical University
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In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Marine and Estuarine Ecology (incl. Marine Ichthyology) | Environmental Rehabilitation (excl. Bioremediation) | Ecosystem Function | Environmental Science and Management |
Coastal and Estuarine Flora, Fauna and Biodiversity | Rehabilitation of Degraded Coastal and Estuarine Environments | Ecosystem Assessment and Management of Marine Environments
Publisher: Elsevier BV
Date: 09-2008
Publisher: Frontiers Media SA
Date: 21-05-2021
DOI: 10.3389/FMICB.2021.671092
Abstract: The type VI secretion system (T6SS) operons of Vibrio cholerae contain extraordinarily erse arrays of toxic effector and cognate immunity genes, which are thought to play an important role in the environmental lifestyle and adaptation of this human pathogen. Through the T6SS, proteinaceous “spears” tipped with antibacterial effectors are injected into adjacent cells, killing those not possessing immunity proteins to these effectors. Here, we investigate the T6SS-mediated dynamics of bacterial competition within a single environmental population of V. cholerae . We show that numerous members of a North American V. cholerae population possess strain-specific repertoires of cytotoxic T6SS effector and immunity genes. Using pairwise competition assays, we demonstrate that the vast majority of T6SS-mediated duels end in stalemates between strains with different T6SS repertoires. However, horizontally acquired effector and immunity genes can significantly alter the outcome of these competitions. Frequently observed horizontal gene transfer events can both increase or reduce competition between distantly related strains by homogenizing or ersifying the T6SS repertoire. Our results also suggest temperature-dependent outcomes in T6SS competition, with environmental isolates faring better against a pathogenic strain under native conditions than under those resembling a host-associated environment. Taken altogether, these interactions produce density-dependent fitness effects and a constant T6SS-mediated arms race in in idual V. cholerae populations, which could ultimately preserve intraspecies ersity. Since T6SSs are widespread, we expect within-population ersity in T6SS repertoires and the resulting competitive dynamics to be a common theme in bacterial species harboring this machinery.
Publisher: Public Library of Science (PLoS)
Date: 05-12-2011
Publisher: Springer Science and Business Media LLC
Date: 27-02-2011
DOI: 10.1038/NCHEM.1002
Publisher: Frontiers Media SA
Date: 29-05-2018
Publisher: Oxford University Press (OUP)
Date: 12-05-2011
Publisher: MDPI AG
Date: 16-12-2020
Abstract: Vibrio metoecus is a recently described aquatic bacterium and opportunistic pathogen, closely related to and often coexisting with Vibrio cholerae. To study the relative abundance and population dynamics of both species in aquatic environments of cholera-endemic and cholera-free regions, we developed a multiplex qPCR assay allowing simultaneous quantification of total V. metoecus and V. cholerae (including toxigenic and O1 serogroup) cells. The presence of V. metoecus was restricted to s les from regions that are not endemic for cholera, where it was found at 20% of the abundance of V. cholerae. In this environment, non-toxigenic O1 serogroup V. cholerae represents almost one-fifth of the total V. cholerae population. In contrast, toxigenic O1 serogroup V. cholerae was also present in low abundance on the coast of cholera-endemic regions, but sustained in relatively high proportions throughout the year in inland waters. The majority of cells from both Vibrio species were recovered from particles rather than free-living, indicating a potential preference for attached versus planktonic lifestyles. This research further elucidates the population dynamics underpinning V. cholerae and its closest relative in cholera-endemic and non-endemic regions through culture-independent quantification from environmental s les.
Publisher: MyJove Corporation
Date: 11-03-2015
DOI: 10.3791/52455
Publisher: American Society for Microbiology
Date: 2007
DOI: 10.1128/AEM.01177-06
Abstract: Several characteristics of the 16S rRNA gene, such as its essential function, ubiquity, and evolutionary properties, have allowed it to become the most commonly used molecular marker in microbial ecology. However, one fact that has been overlooked is that multiple copies of this gene are often present in a given bacterium. These intragenomic copies can differ in sequence, leading to identification of multiple ribotypes for a single organism. To evaluate the impact of such intragenomic heterogeneity on the performance of the 16S rRNA gene as a molecular marker, we compared its phylogenetic and evolutionary characteristics to those of the single-copy gene rpoB . Full-length gene sequences and gene fragments commonly used for denaturing gradient gel electrophoresis were compared at various taxonomic levels. Heterogeneity found between intragenomic 16S rRNA gene copies was concentrated in specific regions of rRNA secondary structure. Such “heterogeneity hot spots” occurred within all gene fragments commonly used in molecular microbial ecology. This intragenomic heterogeneity influenced 16S rRNA gene tree topology, phylogenetic resolution, and operational taxonomic unit estimates at the species level or below. rpoB provided comparable phylogenetic resolution to that of the 16S rRNA gene at all taxonomic levels, except between closely related organisms (species and subspecies levels), for which it provided better resolution. This is particularly relevant in the context of a growing number of studies focusing on subspecies ersity, in which single-copy protein-encoding genes such as rpoB could complement the information provided by the 16S rRNA gene.
Publisher: Springer Science and Business Media LLC
Date: 23-03-2020
DOI: 10.1038/S41396-020-0631-5
Abstract: With each cell ision, phytoplankton create new space for primary colonization by marine bacteria. Although this surface microenvironment is available to all planktonic bacterial colonizers, we show the assembly of bacterial consortia on a cosmopolitan marine diatom to be highly specific and reproducible. While phytoplankton–bacteria interactions play fundamental roles in marine ecosystems, namely primary production and the carbon cycle, the ecological paradigm behind epiphytic microbiome assembly remains poorly understood. In a replicated and repeated primary colonization experiment, we exposed the axenic diatom Thalassiosira rotula to several complex and compositionally different bacterial inocula derived from phytoplankton species of varying degrees of relatedness to the axenic Thalassiosira host or natural seawater. This revealed a convergent assembly of erse and compositionally different bacterial inocula, containing up to 2071 operational taxonomic units (OTUs), towards a stable and reproducible core community. Four of these OTUs already accounted for a cumulative abundance of 60%. This core community was dominated by Rhodobacteraceae (30.5%), Alteromonadaceae (27.7%), and Oceanospirillales (18.5%) which was qualitatively and quantitatively most similar to its conspecific original. These findings reject a lottery assembly model of bacterial colonization and suggest selective microhabitat filtering. This is likely due to diatom host traits such as surface properties and different levels of specialization resulting in reciprocal stable-state associations.
Publisher: Springer Science and Business Media LLC
Date: 11-10-2021
DOI: 10.1007/S00248-021-01838-0
Abstract: Cholera has been endemic to the Ganges Delta for centuries. Although the causative agent, Vibrio cholerae, is autochthonous to coastal and brackish water, cholera occurs continually in Dhaka, the inland capital city of Bangladesh which is surrounded by fresh water. Despite the persistence of this problem, little is known about the environmental abundance and distribution of lineages of V. cholerae, the most important being the pandemic generating (PG) lineage consisting mostly of serogroup O1 strains. To understand spatial and temporal dynamics of PG lineage and other lineages belonging to the V. cholerae species in surface water in and around Dhaka City, we used qPCR and high-throughput licon sequencing. Seven different freshwater sites across Dhaka were investigated for six consecutive months, and physiochemical parameters were measured in situ. Total abundance of V. cholerae was found to be relatively stable throughout the 6-month s ling period, with 2 × 10
Publisher: Elsevier BV
Date: 03-2022
DOI: 10.1016/J.PHYTOCHEM.2021.113052
Abstract: Dunaliella tertiolecta is a marine microalgae that has been studied extensively as a potential carbon-neutral biofuel source (Tang et al., 2011). Microalgae oil contains high quantities of energy-rich fatty acids and lipids, but is not yet commercially viable as an alternative fuel. Carefully optimised growth conditions, and more recently, algal-bacterial co-cultures have been explored as a way of improving the yield of D. tertiolecta microalgae oils. The relationship between the host microalgae and bacterial co-cultures is currently poorly understood. Here, a complete workflow is proposed to analyse the global metabolomic profile of co-cultured D. tertiolectra and Phaeobacter italicus R11, which will enable researchers to explore the chemical nature of this relationship in more detail. To the best of the authors' knowledge this study is one of the first of its kind, in which a pipeline for an entirely untargeted analysis of the algal metabolome is proposed using a practical s le preparation, introduction, and data analysis routine.
Publisher: American Society for Microbiology
Date: 25-08-2016
Abstract: Strains of Sulfitobacter spp., Erythrobacter sp., and Marinobacter sp. were isolated from a polymicrobial culture of the naked (N-type) haptophyte Emiliania huxleyi strain CCMP1516. The genomes encode genes for the production of phytohormones, vitamins, and the consumption of their hosts' metabolic by-products, suggesting symbiotic interactions within this polymicrobial culture.
Publisher: Springer Science and Business Media LLC
Date: 21-05-2015
Publisher: Frontiers Media SA
Date: 13-06-2016
Publisher: American Society for Microbiology
Date: 18-05-2017
Abstract: Two strains of Bacillus , B. cereus E41 and B. anthracis F34, were isolated from a salt lake in Aïn M’lila-Oum El Bouaghi, eastern Algeria, and Ain Baida-Ouargla, southern Algeria, respectively. Their genomes display genes for the production of several bioactive secondary metabolites, including polyhydroxyalkanoate, iron siderophores, lipopeptides, and bacteriocins.
Publisher: Springer International Publishing
Date: 2017
Publisher: Inter-Research Science Center
Date: 08-2008
DOI: 10.3354/AME01215
Publisher: Cold Spring Harbor Laboratory
Date: 28-09-2021
DOI: 10.1101/2021.09.27.461748
Abstract: Dunaliella tertiolecta is a marine microalgae that has been studied extensively as a potential carbon-neutral biofuel source [1]. Microalgae oil contains high quantities of energy-rich fatty acids and lipids, but is not yet commercially viable as an alternative fuel. Carefully optimised growth conditions, and more recently, algal-bacterial co-cultures have been explored as a way of improving the yield of Dunaliella tertiolecta microalgae oils. The relationship between the host microalgae and bacterial co-cultures is currently poorly understood. Here, a complete workflow is proposed to analyse the global metabolomic profile of co-cultured Dunaliella tertiolectra and Phaeobacter italicus R11 , which will enable researchers to explore the chemical nature of this relationship in more detail. A method for direct microalgae s le introduction is proposed. Advanced chemometric tools can extract, useful and discriminating metabolomic features even from very noisy complex datasets.
Publisher: Frontiers Media SA
Date: 25-06-2021
DOI: 10.3389/FMICB.2021.683109
Abstract: The family Rhodobacteraceae consists of alphaproteobacteria that are metabolically, phenotypically, and ecologically erse. It includes the roseobacter clade, an informal designation, representing one of the most abundant groups of marine bacteria. The rapid pace of discovery of novel roseobacters in the last three decades meant that the best practice for taxonomic classification, a polyphasic approach utilizing phenotypic, genotypic, and phylogenetic characteristics, was not always followed. Early efforts for classification relied heavily on 16S rRNA gene sequence similarity and resulted in numerous taxonomic inconsistencies, with several poly- and paraphyletic genera within this family. Next-generation sequencing technologies have allowed whole-genome sequences to be obtained for most type strains, making a revision of their taxonomy possible. In this study, we performed whole-genome phylogenetic and genotypic analyses combined with a meta-analysis of phenotypic data to review taxonomic classifications of 331 type strains (under 119 genera) within the Rhodobacteraceae family. Representatives of the roseobacter clade not only have different environmental adaptions from other Rhodobacteraceae isolates but were also found to be distinct based on genomic, phylogenetic, and in silico -predicted phenotypic data. As such, we propose to move this group of bacteria into a new family, Roseobacteraceae fam. nov. In total, reclassifications resulted to 327 species and 128 genera, suggesting that misidentification is more problematic at the genus than species level. By resolving taxonomic inconsistencies of type strains within this family, we have established a set of coherent criteria based on whole-genome-based analyses that will help guide future taxonomic efforts and prevent the propagation of errors.
Publisher: American Society for Microbiology
Date: 15-09-2016
DOI: 10.1128/AEM.01177-16
Abstract: Vibrio cholerae is a ubiquitous aquatic microbe in temperate and tropical coastal areas. It is a erse species, with many isolates that are harmless to humans, while others are highly pathogenic. Most notable among them are strains belonging to the pandemic O1/O139 serogroup lineage, which contains the causative agents of cholera. The environmental selective regimes that led to this ersity are key to understanding how pathogens evolve in environmental reservoirs. A local population of V. cholerae and its close relative Vibrio metoecus from a coastal pond and lagoon system was extensively s led during two consecutive months across four size fractions (480 isolates). In stark contrast to previous studies, the observed population was highly clonal, with 60% of V. cholerae isolates falling into one of five clonal complexes, which varied in abundance in the short temporal scale s led. V. cholerae clonal complexes had significantly different distributions across size fractions and the two environments s led, the pond and the lagoon. Sequencing the genomes of 20 isolates representing these five V. cholerae clonal complexes revealed different evolutionary trajectories, with considerable variations in gene content with potential ecological significance. Showing genotypic differentiation and differential spatial distribution, the dominant clonal complexes are likely ecologically ergent. Temporal variation in the relative abundance of these complexes suggests that transient blooms of specific clones could dominate local ersity. IMPORTANCE Vibrio cholerae is commonly found in coastal areas worldwide, with only a single group of this bacterium capable of causing severe cholera outbreaks. However, the potential to evolve the ability to cause disease exists in many strains of this species in its aquatic reservoir. Understanding how pathogenic bacteria evolve requires the study of their natural environments. By extensive s ling in a geographically restricted location in the United States, we found that most cells of a V. cholerae population belong to only a small number of strains. Analysis of their genome composition and spatial distribution indicates differential environmental adaptations between these strains. Other strains exist in smaller numbers, and the population was found to be temporally varied. This suggests frequent bloom and collapse cycles on a time scale of weeks. These population dynamics make it possible that more virulent strains could stochastically rise to large numbers, allowing for infection to occur.
Publisher: Springer New York
Date: 2013
Publisher: Wiley
Date: 06-02-2020
Abstract: Populations of the bacterium Vibrio cholerae consist of dozens of distinct lineages, with primarily (but not exclusively) members of the pandemic generating lineage capable of causing the diarrhoeal disease cholera. Assessing the composition and temporal dynamics of such populations requires extensive isolation efforts and thus only rarely covers large geographic areas or timeframes exhaustively. We developed a culture‐independent licon sequencing strategy based on the protein‐coding gene viuB (vibriobactin utilization) to study the structure of a V . cholerae population over the course of a summer. We show that the 26 co‐occurring V . cholerae lineages continuously compete for limited space on nutrient‐rich particles where only a few of them can grow to large numbers. Differential abundance of lineages between locations and size‐fractions associated with a particle‐attached or free‐swimming lifestyle could reflect adaptation to various environmental niches. In particular, a major V . cholerae lineage occasionally grows to large numbers on particles but remain undetectable using isolation‐based methods, indicating selective culturability for some members of the species. We thus demonstrate that isolation‐based studies may not accurately reflect the structure and complex dynamics of V . cholerae populations and provide a scalable high‐throughput method for both epidemiological and ecological approaches to studying this species.
Publisher: American Society for Microbiology
Date: 15-12-2007
DOI: 10.1128/AEM.01543-07
Abstract: Bacteria that produce inhibitory compounds on the surface of marine algae are thought to contribute to the defense of the host plant against colonization of fouling organisms. However, the number of bacterial cells necessary to defend against fouling on the plant surface is not known. Pseudoalteromonas tunicata and Phaeobacter sp. strain 2.10 (formerly Roseobacter gallaeciensis ) are marine bacteria often found in association with the alga Ulva australis and produce a range of extracellular inhibitory compounds against common fouling organisms. P. tunicata and Phaeobacter sp. strain 2.10 biofilms with cell densities ranging from 10 2 to 10 8 cells cm −2 were established on polystyrene petri dishes. Attachment and settlement assays were performed with marine fungi (uncharacterized isolates from U. australis ), marine bacteria ( Pseudoalteromonas gracilis , Alteromonas sp., and Cellulophaga fucicola ), invertebrate larvae ( Bugula neritina ), and algal spores ( Polysiphonia sp.) and gametes ( U. australis ). Remarkably low cell densities (10 2 to 10 3 cells cm −2 ) of P. tunicata were effective in preventing settlement of algal spores and marine fungi in petri dishes. P. tunicata also prevented settlement of invertebrate larvae at densities of 10 4 to 10 5 cells cm −2 . Similarly, low cell densities (10 3 to 10 4 cells cm −2 ) of Phaeobacter sp. strain 2.10 had antilarval and antibacterial activity. Previously, it has been shown that abundance of P. tunicata on marine eukaryotic hosts is low ( × 10 3 cells cm −2 ) (T. L. Skovhus et al., Appl. Environ. Microbiol. 70:2373-2382, 2004). Despite such low numbers of P. tunicata on U. australis in situ, our data suggest that P. tunicata and Phaeobacter sp. strain 2.10 are present in sufficient quantities on the plant to inhibit fouling organisms. This strongly supports the hypothesis that P. tunicata and Phaeobacter sp. strain 2.10 can play a role in defense against fouling on U. australis at cell densities that commonly occur in situ.
Publisher: Annual Reviews
Date: 12-2003
DOI: 10.1146/ANNUREV.GENET.37.050503.084247
Abstract: ▪ Abstract Lateral gene transfer (LGT) is now known to be a major force in the evolution of prokaryotic genomes. To date, most analyses have focused on either (a) verifying phylogenies of in idual genes thought to have been transferred, or (b) estimating the fraction of in idual genomes likely to have been introduced by transfer. Neither approach does justice to the ability of LGT to effect massive and complex transformations in basic biology. In some cases, such transformation will be manifested as the patchy distribution of a seemingly fundamental property (such as aerobiosis or nitrogen fixation) among the members of a group classically defined by the sharing of other properties (metabolic, morphological, or molecular, such as small subunit ribosomal RNA sequence). In other cases, the lineage of recipients so transformed may be seen to comprise a new group of high taxonomic rank (“class” or even “phylum”). Here we review evidence for an important role of LGT in the evolution of photosynthesis, aerobic respiration, nitrogen fixation, sulfate reduction, methylotrophy, isoprenoid biosynthesis, quorum sensing, flotation (gas vesicles), thermophily, and halophily. Sometimes transfer of complex gene clusters may have been involved, whereas other times separate exchanges of many genes must be invoked.
Publisher: Springer Science and Business Media LLC
Date: 04-02-2019
DOI: 10.1038/S41598-018-37062-Z
Abstract: Our understanding of diseases has been transformed by the realisation that people are holobionts, comprised of a host and its associated microbiome(s). Disease can also have devastating effects on populations of marine organisms, including dominant habitat formers such as seaweed holobionts. However, we know very little about how interactions between microorganisms within microbiomes - of humans or marine organisms – affect host health and there is no underpinning theoretical framework for exploring this. We applied ecological models of succession to bacterial communities to understand how interactions within a seaweed microbiome affect the host. We observed succession of surface microbiomes on the red seaweed Delisea pulchra in situ , following a disturbance, with communities ‘recovering’ to resemble undisturbed states after only 12 days. Further, if this recovery was perturbed, a bleaching disease previously described for this seaweed developed. Early successional strains of bacteria protected the host from colonisation by a pathogenic, later successional strain. Host chemical defences also prevented disease, such that within-microbiome interactions were most important when the host’s chemical defences were inhibited. This is the first experimental evidence that interactions within microbiomes have important implications for host health and disease in a dominant marine habitat-forming organism.
Publisher: Humana Press
Date: 2009
DOI: 10.1007/978-1-60327-853-9_6
Abstract: The integron includes a site-specific recombination system capable of integrating and expressing genes contained in structures called mobile gene cassettes. Integrons were originally identified on mobile elements from pathogenic bacteria and were found to be a major reservoir of antibiotic-resistance genes. Integrons are now known to be ancient structures that are phylogenetically erse and, to date, have been found in approximately 9% of sequenced bacterial genomes. Overall, gene ersity in cassettes is extraordinarily high, suggesting that the integron/gene cassette system has a broad role in adaptation rather than being confined to simply conferring resistance to antibiotics. In this chapter, we provide a review of the integron/gene cassette system highlighting characteristics associated with this system, ersity of elements contained within it, and their importance in driving bacterial evolution and consequently adaptation. Ideas on the evolution of gene cassettes and gene cassette arrays are discussed.
Publisher: Frontiers Media SA
Date: 08-06-2016
Publisher: Wiley
Date: 15-10-2010
DOI: 10.1111/J.1462-2920.2010.02356.X
Abstract: Host-pathogen interactions have been widely studied in humans and terrestrial plants, but are much less well explored in marine systems. Here we show that a marine macroalga, Delisea pulchra, utilizes a chemical defence - furanones - to inhibit colonization and infection by a novel bacterial pathogen, Ruegeria sp. R11, and that infection by R11 is temperature dependent. Ruegeria sp. R11 formed biofilms, invaded and bleached furanone-free, but not furanone-producing D. pulchra thalli, at high (24°C) but not low (19°C) temperatures. Bleaching is commonly observed in natural populations of D. pulchra near Sydney, Australia, during the austral summer when ocean temperatures are at their peak and the chemical defences of the alga are reduced. Furanones, produced by D. pulchra as a chemical defence, inhibit quorum sensing (QS) in bacteria, and this may play a role in furanone inhibition of R11 infection of furanone-free thalli as R11 produces QS signals. This interplay between temperature, an algal chemical defence mechanism and bacterial virulence demonstrates the complex impact environmental change can have on an ecosystem.
Publisher: American Society for Microbiology
Date: 25-08-2016
Abstract: Strains of Rhodobacteraceae , Sphingomonadales , Alteromonadales , and Bacteroidetes were isolated from a polymicrobial culture of the coccolith-forming (C-type) haptophyte Emiliania huxleyi strain M217 . The genomes encode genes for the production of algal growth factors and the consumption of their hosts' metabolic by-products, suggesting that the polymicrobial culture harbors many symbiotic interactions.
Publisher: Springer Science and Business Media LLC
Date: 2011
Publisher: Oxford University Press (OUP)
Date: 23-11-2017
Abstract: In this study, we identified a new Bacillus strain isolated from an Algerian salty lake that produces metabolites that are active against Gram-positive and Gram-negative bacteria, as well as fungal pathogens. The draft genome sequence of the strain is presented herein. Genome sequence analysis identified the strain to be B. amyloliquefaciens subspecies plantarum F11, and showed that the strain carries the gene clusters for the production of a number of bioactive and surface-active compounds. These include the lipopeptides surfactin and fengycin, antibacterial polyketides macrolactin and bacillaene, and a putative novel lanthipeptide, among others. Through an activity-guided purification method using hydrophobic interaction chromatographic techniques, we confirmed the ability of the strain to produce fengycin lipopeptides. The identities of the isolated fengycin homologs were ascertained through tandem mass spectrometry.
Publisher: Springer Science and Business Media LLC
Date: 14-02-2008
Publisher: Microbiology Society
Date: 10-2016
Abstract: Four Vibrio spp. isolates from the historical culture collection at the Centers for Disease Control and Prevention, obtained from human blood specimens (n=3) and river water (n=1), show characteristics distinct from those of isolates of the most closely related species, Vibrio navarrensis and Vibrio vulnificus, based on phenotypic and genotypic tests. They are specifically adapted to survival in both freshwater and seawater, being able to grow in rich media without added salts as well as salinities above that of seawater. Phenotypically, these isolates resemble V. navarrensis, their closest known relative with a validly published name, but the group of isolates is distinguished from V. navarrensis by the ability to utilize l-rhamnose. Average nucleotide identity and percent DNA-DNA hybridization values obtained from the pairwise comparisons of whole-genome sequences of these isolates to V. navarrensis range from 95.4-95.8 % and 61.9-64.3 %, respectively, suggesting that the group represents a different species. Phylogenetic analysis of the core genome, including four protein-coding housekeeping genes (pyrH, recA, rpoA and rpoB), places these four isolates into their own monophyletic clade, distinct from V. navarrensis and V. vulnificus. Based on these differences, we propose these isolates represent a novel species of the genus Vibrio, for which the name Vibrio cidicii sp. nov. is proposed strain LMG 29267T (=CIP 111013T=2756-81T), isolated from river water, is the type strain.
Publisher: Georg Thieme Verlag KG
Date: 07-2012
Publisher: Springer Science and Business Media LLC
Date: 21-03-2019
DOI: 10.1038/S41598-018-36847-6
Abstract: The model coccolithophore, Emiliania huxleyi , forms expansive blooms dominated by the calcifying cell type, which produce calcite scales called coccoliths. Blooms last several weeks, after which the calcified algal cells rapidly die, descending into the deep ocean. E. huxleyi bloom collapse is attributed to E. huxleyi viruses (EhVs) that infect and kill calcifying cells, while other E. huxleyi pathogens, such as bacteria belonging to the roseobacter clade, are overlooked. EhVs kill calcifying E. huxleyi by inducing production of bioactive viral-glycosphingolipids (vGSLs), which trigger algal programmed cell death (PCD). The roseobacter Phaeobacter inhibens was recently shown to interact with and kill the calcifying cell type of E. huxleyi , but the mechanism of algal death remains unelucidated. Here we demonstrate that P. inhibens kills calcifying E. huxleyi by inducing a highly specific type of PCD called apoptosis-like-PCD (AL-PCD). Host death can successfully be abolished in the presence of a pan-caspase inhibitor, which prevents the activation of caspase-like molecules. This finding differentiates P. inhibens and EhV pathogenesis of E. huxleyi , by demonstrating that bacterial-induced AL-PCD requires active caspase-like molecules, while the viral pathogen does not. This is the first demonstration of a bacterium inducing AL-PCD in an algal host as a killing mechanism.
Location: United States of America
Start Date: 2018
End Date: 2024
Funder: Natural Sciences and Engineering Research Council of Canada
View Funded ActivityStart Date: 2021
End Date: 2023
Funder: Ministry of Education - Singapore
View Funded ActivityStart Date: 2014
End Date: 2015
Funder: Natural Sciences and Engineering Research Council
View Funded ActivityStart Date: 2017
End Date: 2018
Funder: Natural Sciences and Engineering Research Council
View Funded ActivityStart Date: 2012
End Date: 2013
Funder: Natural Sciences and Engineering Research Council
View Funded ActivityStart Date: 2012
End Date: 2017
Funder: Natural Sciences and Engineering Research Council
View Funded ActivityStart Date: 2017
End Date: 2018
Funder: Natural Sciences and Engineering Research Council
View Funded ActivityStart Date: 2011
End Date: 2013
Funder: Canada Foundation for Innovation
View Funded ActivityStart Date: 06-2022
End Date: 06-2025
Amount: $643,998.00
Funder: Australian Research Council
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