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Silke Pradella - One of the best experts on this subject based on the ideXlab platform.
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Genome of the R-body producing marine alphaproteobacterium Labrenzia alexandrii type strain (DFL-11^T)
Standards in Genomic Sciences, 2013Co-Authors: Anne Fiebig, Jorn Petersen, Silke Pradella, Orsola Pauker, Victoria Michael, Heinrich Lünsdorf, Markus Göker, Hans-peter Klenk, Irene Wagner-döblerAbstract:Labrenzia alexandrii Biebl et al. 2007 is a marine member of the family Rhodobacteraceae in the order Rhodobacterales , which has thus far only partially been characterized at the genome level. The bacterium is of interest because it lives in close association with the toxic dinoflagellate Alexandrium lusitanicum . Ultrastructural analysis reveals R-bodies within the bacterial cells, which are primarily known from obligate endosymbionts that trigger “killing traits” in ciliates ( Paramecium spp.). Genomic traits of L. alexandrii DFL-11^T are in accordance with these findings, as they include the reb genes putatively involved in R-body synthesis. Analysis of the two extrachromosomal elements suggests a role in heavy-metal resistance and exopolysaccharide formation, respectively. The 5,461,856 bp long genome with its 5,071 protein-coding and 73 RNA genes consists of one chromosome and two plasmids, and has been sequenced in the context of the M arine M icrobial I nitiative.
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Genome of the R-body producing marine alphaproteobacterium Labrenzia alexandrii type strain (DFL-11(T)).
Standards in Genomic Sciences, 2013Co-Authors: Anne Fiebig, Jorn Petersen, Silke Pradella, Orsola Pauker, Victoria Michael, Heinrich Lünsdorf, Markus Göker, Hans-peter Klenk, Irene Wagner-döblerAbstract:Labrenzia alexandrii Biebl et al. 2007 is a marine member of the family Rhodobacteraceae in the order Rhodobacterales, which has thus far only partially been characterized at the genome level. The bacterium is of interest because it lives in close association with the toxic dinoflagellate Alexandrium lusitanicum. Ultrastructural analysis reveals R-bodies within the bacterial cells, which are primarily known from obligate endosymbionts that trigger “killing traits” in ciliates (Paramecium spp.). Genomic traits of L. alexandrii DFL-11T are in accordance with these findings, as they include the reb genes putatively involved in R-body synthesis. Analysis of the two extrachromosomal elements suggests a role in heavy-metal resistance and exopolysaccharide formation, respectively. The 5,461,856 bp long genome with its 5,071 protein-coding and 73 RNA genes consists of one chromosome and two plasmids, and has been sequenced in the context of the Marine Microbial Initiative.
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origin and evolution of a novel dnaa like plasmid replication type in Rhodobacterales
Molecular Biology and Evolution, 2011Co-Authors: Jorn Petersen, Henner Brinkmann, Martine Berger, Thorsten Brinkhoff, Orsola Pauker, Silke PradellaAbstract:Large extrachromosomal elements are widespread among Alphaproteobacteria, but it is unclear how up to a dozen lowcopy plasmids can stably coexist within the same cell. We systematically analyzed the distribution of different replicons in about 40 completely sequenced genomes of the Roseobacter clade (Rhodobacterales) and surprisingly identified a novel plasmid replicon type. The conserved replication module comprises the characteristic partitioning operon (parAB) and a hitherto unknown replicase. The latter shows a weak homology to the chromosomal replication initiator DnaA and was accordingly named ‘‘DnaA-like.’’ Phylogenetic analyses of the adjacent parAB genes document a common ancestry with repA- and repB-type plasmids and moreover indicate the presence of two dnaA-like compatibility groups. This conclusion is supported by conserved palindrome sequences within the replication module that probably represent crucial centromeric anchors for plasmid partitioning. The functionality of dnaA-like replicons was proven by transformation experiments in Phaeobacter gallaeciensis BS107 (DSM 17395). This Roseobacter strain furthermore allows the phenotypical monitoring of plasmid incompatibility, based on a 262-kb dnaA-like replicon required for the brown pigmentation of the bacterium. Uptake of an incompatible construct induces its loss, hence resulting in white colonies. Accordingly, we could substantiate the in silico predictions about stable maintenance of dnaA-like plasmids and thereby functionally validate our approach of plasmid classification based on phylogenetic analyses.
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diversity and evolution of repabc type plasmids in Rhodobacterales
Environmental Microbiology, 2009Co-Authors: Jorn Petersen, Henner Brinkmann, Silke PradellaAbstract:: The repABC operon is the prevalent replication unit of alphaproteobacterial plasmids. Their semi-autonomy is ensured by the essential replicase gene repC as well as the repAB partitioning cassette. While conserved repAB modules are widespread among bacterial plasmids and homologues are even responsible for chromosome partitioning, repC genes are exclusively present in Alphaproteobacteria. RepABC operons contain two strong incompatibility regions, namely a small regulative antisense RNA gene (inc alpha) and a palindromic centromere region (inc beta), which were previously used to classify these replicons. The present survey pursued a complementary strategy essentially following the rationale that all plasmids identified from a single bacterium are per se compatible. We established a novel classification scheme for plasmids based on comprehensive phylogenetic analyses of repC, repA and repB genes. Our case study is focused on the Roseobacter clade (Rhodobacterales), one of the most successful lineages of the marine bacterioplankton. Its global significance was shown in several studies and the interest in these organisms is reflected by more than 40 upcoming genome projects. Based on phylogenetic RepC analyses we identified nine compatibility groups that are expected to stably coexist within the same cell. This prediction is supported by RepA and RepB phylogenies, moreover independent evidence is delivered by the group specificity of highly conserved palindromes (inc beta).
Stephen J Giovannoni - One of the best experts on this subject based on the ideXlab platform.
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Maritimibacter alkaliphilus gen. nov., sp. nov., a genome-sequenced marine bacterium of the Roseobacter clade in the order Rhodobacterales.
International journal of systematic and evolutionary microbiology, 2020Co-Authors: Yoejin Choo, Stephen J GiovannoniAbstract:A Gram-negative, chemoheterotrophic, strictly aerobic, alkaliphilic, rod-shaped marine bacterium, designated HTCC2654(T), was isolated from the western Sargasso Sea by using a dilution-to-extinction culturing method. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain HTCC2654(T) belonged to the Roseobacter clade of the order Rhodobacterales. The 16S rRNA gene sequence similarity of the strain with respect to other members of the Roseobacter clade ranged from 90.4 to 95.1 %. In the phylogenetic analyses, the strain formed an independent phyletic line and could not be assigned to any other known genera of the Rhodobacterales. The DNA G+C content of strain HTCC2654(T) was 61.7 mol% by HPLC and 64.1 mol% from genome sequences. The predominant constituents of the cellular fatty acids were C(16 : 0) 2-OH (27.3 %), 11-methyl C(18 : 1) omega 7c (19.6 %) and C(18 : 1) omega 7c (17.3 %), and the major polar lipids were phosphatidylethanolamine, phosphatidylglycerol and phosphatidylcholine, which served to differentiate the strain from other members of the Roseobacter clade. On the basis of the taxonomic data obtained in this study, strain HTCC2654(T) represents a novel genus and species, for which the name Maritimibacter alkaliphilus gen. nov., sp. nov. is proposed. The type strain is HTCC2654(T) (=KCCM 42376(T)=NBRC 102057(T)).
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Pelagibaca bermudensis gen. nov., sp. nov., a novel marine bacterium within the Roseobacter clade in the order Rhodobacterales.
International journal of systematic and evolutionary microbiology, 2020Co-Authors: Stephen J GiovannoniAbstract:A Gram-negative, chemoheterotrophic, facultatively anaerobic, slightly halophilic, oval-shaped marine bacterium, designated HTCC2601T, was isolated from the western Sargasso Sea by high-throughput culturing involving dilution to extinction. Although the 16S rRNA gene sequence similarity between the isolate and Salipiger mucosus was 96.5 %, phylogenetic analyses using different treeing algorithms clearly indicated that the strain forms a distinct lineage within a clade containing the recently classified genera Salipiger and Palleronia in the order Rhodobacterales of the Alphaproteobacteria. The DNA-DNA relatedness between strain HTCC2601T and S. mucosus was 26.3 %. Strain HTCC2601T utilized a wide range of carbohydrates, including hexose monomers, sugar alcohols, organic acids and amino acids, as sole carbon sources. The DNA G+C content of strain HTCC2601T was 65.4 mol%, and the predominant constituents of the cellular fatty acids were 18 : 1omega7c (79.7 %) and 11-methyl 18 : 1omega7c (7.5 %). The strain differed from members of the closely related genera Salipiger and Palleronia in its morphological, biochemical and ecological characteristics. On the basis of the taxonomic data obtained in this study, a novel genus and species, Pelagibaca bermudensis gen. nov., sp. nov., is proposed; HTCC2601T (=KCTC 12554T = JCM 13377T) is the type strain of Pelagibaca bermudensis.
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Oceanicola granulosus gen. nov., sp. nov. and Oceanicola batsensis sp. nov., poly-beta-hydroxybutyrate-producing marine bacteria in the order 'Rhodobacterales'.
International journal of systematic and evolutionary microbiology, 2020Co-Authors: Stephen J GiovannoniAbstract:Three Gram-negative, chemoheterotrophic, non-motile, rod-shaped bacterial strains that accumulate poly-beta-hydroxybutyrate granules were isolated from the Bermuda Atlantic Time-series Study site by high-throughput culturing methods and characterized by polyphasic approaches. DNA-DNA hybridization, DNA G+C content and phylogenetic analyses based on 16S rRNA gene sequences divided the three isolates into two distinct genospecies that were clearly differentiated by fatty acid profiles, carbon source utilization patterns, antibiotic susceptibility and biochemical characteristics. The strains utilized a wide range of substrates, including pentoses, hexoses, oligosaccharides, sugar alcohols, organic acids and amino acids. DNA G+C contents were 71.5, 70.9 and 67.3 mol% for strains HTCC2516T, HTCC2523 and HTCC2597T, respectively. The most dominant fatty acid was 18 : 1omega7c in strains HTCC2516T and HTCC2523, and cyclo 19 : 0 in strain HTCC2597T. The type strains HTCC2516T and HTCC2597T were clearly differentiated by the presence or absence of 12 : 0, 12 : 1omega11c, 14 : 0, 15 : 0 and methyl 18 : 1. Phylogenetic analyses indicated that the strains formed a distinct monophyletic lineage within the Roseobacter clade in the order 'Rhodobacterales' of the Alphaproteobacteria, and which did not associate with any of the described genera. Genotypic and phenotypic differences of the isolates from the previously described genera support the description of Oceanicola granulosus gen. nov., sp. nov. with the type strain HTCC2516T (=ATCC BAA-861T=DSM 15982T=KCTC 12143T) and of Oceanicola batsensis sp. nov. with the type strain HTCC2597T (=ATCC BAA-863T=DSM 15984T=KCTC 12145T).
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maritimibacter alkaliphilus gen nov sp nov a genome sequenced marine bacterium of the roseobacter clade in the order Rhodobacterales
International Journal of Systematic and Evolutionary Microbiology, 2007Co-Authors: Yoejin Choo, Stephen J GiovannoniAbstract:A Gram-negative, chemoheterotrophic, strictly aerobic, alkaliphilic, rod-shaped marine bacterium, designated HTCC2654T, was isolated from the western Sargasso Sea by using a dilution-to-extinction culturing method. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain HTCC2654T belonged to the Roseobacter clade of the order Rhodobacterales. The 16S rRNA gene sequence similarity of the strain with respect to other members of the Roseobacter clade ranged from 90.4 to 95.1 %. In the phylogenetic analyses, the strain formed an independent phyletic line and could not be assigned to any other known genera of the Rhodobacterales. The DNA G+C content of strain HTCC2654T was 61.7 mol% by HPLC and 64.1 mol% from genome sequences. The predominant constituents of the cellular fatty acids were C16 : 0 2-OH (27.3 %), 11-methyl C18 : 1 ω7c (19.6 %) and C18 : 1 ω7c (17.3 %), and the major polar lipids were phosphatidylethanolamine, phosphatidylglycerol and phosphatidylcholine, which served to differentiate the strain from other members of the Roseobacter clade. On the basis of the taxonomic data obtained in this study, strain HTCC2654T represents a novel genus and species, for which the name Maritimibacter alkaliphilus gen. nov., sp. nov. is proposed. The type strain is HTCC2654T (=KCCM 42376T=NBRC 102057T).
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pelagibaca bermudensis gen nov sp nov a novel marine bacterium within the roseobacter clade in the order Rhodobacterales
International Journal of Systematic and Evolutionary Microbiology, 2006Co-Authors: Stephen J GiovannoniAbstract:A Gram-negative, chemoheterotrophic, facultatively anaerobic, slightly halophilic, oval-shaped marine bacterium, designated HTCC2601T, was isolated from the western Sargasso Sea by high-throughput culturing involving dilution to extinction. Although the 16S rRNA gene sequence similarity between the isolate and Salipiger mucosus was 96·5 %, phylogenetic analyses using different treeing algorithms clearly indicated that the strain forms a distinct lineage within a clade containing the recently classified genera Salipiger and Palleronia in the order Rhodobacterales of the Alphaproteobacteria. The DNA–DNA relatedness between strain HTCC2601T and S. mucosus was 26·3 %. Strain HTCC2601T utilized a wide range of carbohydrates, including hexose monomers, sugar alcohols, organic acids and amino acids, as sole carbon sources. The DNA G+C content of strain HTCC2601T was 65·4 mol%, and the predominant constituents of the cellular fatty acids were 18 : 1ω7c (79·7 %) and 11-methyl 18 : 1ω7c (7·5 %). The strain differed from members of the closely related genera Salipiger and Palleronia in its morphological, biochemical and ecological characteristics. On the basis of the taxonomic data obtained in this study, a novel genus and species, Pelagibaca bermudensis gen. nov., sp. nov., is proposed; HTCC2601T (=KCTC 12554T=JCM 13377T) is the type strain of Pelagibaca bermudensis.
Stephanie M Rosales - One of the best experts on this subject based on the ideXlab platform.
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Rhodobacterales and rhizobiales are associated with stony coral tissue loss disease and its suspected sources of transmission
Frontiers in Microbiology, 2020Co-Authors: Stephanie M Rosales, Abigail S Clark, Lindsay K Huebner, Rob Ruzicka, Erinn M MullerAbstract:: In 2014, Stony Coral Tissue Loss Disease (SCTLD) was first detected off the coast of Miami, FL, United States, and continues to persist and spread along the Florida Reef Tractr (FRT) and into the Caribbean. SCTLD can have up to a 61% prevalence in reefs and has affected at least 23 species of scleractinian corals. This has contributed to the regional near-extinction of at least one coral species, Dendrogyra cylindrus. Initial studies of SCTLD indicate microbial community shifts and cessation of lesion progression in response to antibiotics on some colonies. However, the etiology and abiotic sources of SCTLD transmission are unknown. To characterize SCTLD microbial signatures, we collected tissue samples from four affected coral species: Stephanocoenia intersepta, Diploria labyrinthiformis, Dichocoenia stokesii, and Meandrina meandrites. Tissue samples were from apparently healthy (AH) corals, and unaffected tissue (DU) and lesion tissue (DL) on diseased corals. Samples were collected in June 2018 from three zones: (1) vulnerable (ahead of the SCTLD disease boundary in the Lower Florida Keys), (2) endemic (post-outbreak in the Upper Florida Keys), and (3) epidemic (SCTLD was active and prevalent in the Middle Florida Keys). From each zone, sediment and water samples were also collected to identify whether they may serve as potential sources of transmission for SCTLD-associated microbes. We used 16S rRNA gene amplicon high-throughput sequencing methods to characterize the microbiomes of the coral, water, and sediment samples. We identified a relatively higher abundance of the bacteria orders Rhodobacterales and Rhizobiales in DL tissue compared to AH and DU tissue. Also, our results showed relatively higher abundances of Rhodobacterales in water from the endemic and epidemic zones compared to the vulnerable zone. Rhodobacterales and Rhizobiales identified at higher relative abundances in DL samples were also detected in sediment samples, but not in water samples. Our data indicate that Rhodobacterales and Rhizobiales may play a role in SCTLD and that sediment may be a source of transmission for Rhodobacterales and Rhizobiales associated with SCTLD lesions.
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Alien vs. predator: bacterial challenge alters coral microbiomes unless controlled by Halobacteriovorax predators
PeerJ, 2017Co-Authors: Rory M. Welsh, Stephanie M Rosales, Jesse R. Zaneveld, Jérôme P. Payet, Ryan Mcminds, Steven L. Hubbs, Rebecca Vega ThurberAbstract:: Coral microbiomes are known to play important roles in organismal health, response to environmental stress, and resistance to disease. The coral microbiome contains diverse assemblages of resident bacteria, ranging from defensive and metabolic symbionts to opportunistic bacteria that may turn harmful in compromised hosts. However, little is known about how these bacterial interactions influence the mechanism and controls of overall structure, stability, and function of the microbiome. We sought to test how coral microbiome dynamics were affected by interactions between two bacteria: Vibrio coralliilyticus, a known temperature-dependent pathogen of some corals, and Halobacteriovorax, a unique bacterial predator of Vibrio and other gram-negative bacteria. We challenged reef-building coral with V. coralliilyticus in the presence or absence of Halobacteriovorax predators, and monitored microbial community dynamics with 16S rRNA gene profiling time-series. Vibrio coralliilyticus inoculation increased the mean relative abundance of Vibrios by greater than 35% from the 4 to 8 hour time point, but not in the 24 & 32 hour time points. However, strong secondary effects of the Vibrio challenge were also observed for the rest of the microbiome such as increased richness (observed species), and reduced stability (increased beta-diversity). Moreover, after the transient increase in Vibrios, two lineages of bacteria (Rhodobacterales and Cytophagales) increased in coral tissues, suggesting that V. coralliilyticus challenge opens niche space for these known opportunists. Rhodobacterales increased from 6.99% (±0.05 SEM) to a maximum mean relative abundance of 48.75% (±0.14 SEM) in the final time point and Cytophagales from
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Alien vs. Predator: Pathogens open niche space for opportunists, unless controlled by predators
2015Co-Authors: Rory M. Welsh, Stephanie M Rosales, Jérôme P. Payet, Ryan Mcminds, Steven L. Hubbs, Jesse R.r. Zaneveld, Rebecca L Vega ThurberAbstract:Coral microbiomes are known to play important roles in organismal health, response to environmental stress, and resistance to disease. Pathogens invading the coral microbiome encounter diverse assemblages of resident bacteria, ranging from defensive and metabolic symbionts to opportunistic bacteria that may turn harmful in compromised hosts. However, little is known about how these bacterial interactions influence the overall structure, stability, and function of the microbiome during the course of pathogen challenge. We sought to test how coral microbiome dynamics were affected by interactions between two of its members: Vibrio coralliilyticus, a known temperature-dependent coral pathogen, and Halobacteriovorax, a unique bacterial predator of Vibrio and other gram-negative bacteria. We challenged specimens of the important reef-building coral Montastraea cavernosa with Vibrio coralliilyticus pathogens in the presence or absence of Halobacteriovorax predators, and monitored microbial community dynamics with 16S rRNA gene time-series. In addition to its direct effects on corals, pathogen challenge reshaped coral microbiomes in ways that allowed for secondary blooms of opportunistic bacteria. As expected, Vibrio coralliilyticus addition increased the infiltration of Vibrio into coral tissues. This increase of Vibrios in coral tissue was accompanied by increased richness, and reduced stability (increased beta-diversity) of the rest of the microbiome, suggesting strong secondary effects of pathogen invasion on commensal and mutualistic coral bacteria. Moreover, after an initial increase in Vibrios, two opportunistic lineages (Rhodobacterales and Cytophagales) increased in coral tissues, suggesting that this pathogen opens niche space for opportunists. Based on the keystone role of predators in many ecosystems, we hypothesized that Halobacteriovorax predators might help protect corals by consuming gram-negative pathogens. In keeping with a protective role, Halobacteriovorax addition alone had only minor effects on the microbiome, and no infiltration of Halobacteriovorax into coral tissues was detected in amplicon libraries. Simultaneous challenge with both pathogen and predator eliminated detectable V. corallyticus infiltration into coral tissue samples, ameliorated changes to the rest of the coral microbiome, and prevented secondary blooms of opportunistic Rhodobacterales and Cytophagales. Thus, we show that primary infection by a coral pathogen is sufficient to cause increases in opportunists, as seen in correlational studies. These data further provide a proof-of-principle demonstration that, under certain circumstances, host-associated bacterial predators can mitigate the ability of pathogens to infiltrate host tissue, and stabilize the microbiome against complex secondary changes that favor growth of opportunistic lineages.
Jorn Petersen - One of the best experts on this subject based on the ideXlab platform.
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Genome of the R-body producing marine alphaproteobacterium Labrenzia alexandrii type strain (DFL-11^T)
Standards in Genomic Sciences, 2013Co-Authors: Anne Fiebig, Jorn Petersen, Silke Pradella, Orsola Pauker, Victoria Michael, Heinrich Lünsdorf, Markus Göker, Hans-peter Klenk, Irene Wagner-döblerAbstract:Labrenzia alexandrii Biebl et al. 2007 is a marine member of the family Rhodobacteraceae in the order Rhodobacterales , which has thus far only partially been characterized at the genome level. The bacterium is of interest because it lives in close association with the toxic dinoflagellate Alexandrium lusitanicum . Ultrastructural analysis reveals R-bodies within the bacterial cells, which are primarily known from obligate endosymbionts that trigger “killing traits” in ciliates ( Paramecium spp.). Genomic traits of L. alexandrii DFL-11^T are in accordance with these findings, as they include the reb genes putatively involved in R-body synthesis. Analysis of the two extrachromosomal elements suggests a role in heavy-metal resistance and exopolysaccharide formation, respectively. The 5,461,856 bp long genome with its 5,071 protein-coding and 73 RNA genes consists of one chromosome and two plasmids, and has been sequenced in the context of the M arine M icrobial I nitiative.
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Genome of the R-body producing marine alphaproteobacterium Labrenzia alexandrii type strain (DFL-11(T)).
Standards in Genomic Sciences, 2013Co-Authors: Anne Fiebig, Jorn Petersen, Silke Pradella, Orsola Pauker, Victoria Michael, Heinrich Lünsdorf, Markus Göker, Hans-peter Klenk, Irene Wagner-döblerAbstract:Labrenzia alexandrii Biebl et al. 2007 is a marine member of the family Rhodobacteraceae in the order Rhodobacterales, which has thus far only partially been characterized at the genome level. The bacterium is of interest because it lives in close association with the toxic dinoflagellate Alexandrium lusitanicum. Ultrastructural analysis reveals R-bodies within the bacterial cells, which are primarily known from obligate endosymbionts that trigger “killing traits” in ciliates (Paramecium spp.). Genomic traits of L. alexandrii DFL-11T are in accordance with these findings, as they include the reb genes putatively involved in R-body synthesis. Analysis of the two extrachromosomal elements suggests a role in heavy-metal resistance and exopolysaccharide formation, respectively. The 5,461,856 bp long genome with its 5,071 protein-coding and 73 RNA genes consists of one chromosome and two plasmids, and has been sequenced in the context of the Marine Microbial Initiative.
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origin and evolution of a novel dnaa like plasmid replication type in Rhodobacterales
Molecular Biology and Evolution, 2011Co-Authors: Jorn Petersen, Henner Brinkmann, Martine Berger, Thorsten Brinkhoff, Orsola Pauker, Silke PradellaAbstract:Large extrachromosomal elements are widespread among Alphaproteobacteria, but it is unclear how up to a dozen lowcopy plasmids can stably coexist within the same cell. We systematically analyzed the distribution of different replicons in about 40 completely sequenced genomes of the Roseobacter clade (Rhodobacterales) and surprisingly identified a novel plasmid replicon type. The conserved replication module comprises the characteristic partitioning operon (parAB) and a hitherto unknown replicase. The latter shows a weak homology to the chromosomal replication initiator DnaA and was accordingly named ‘‘DnaA-like.’’ Phylogenetic analyses of the adjacent parAB genes document a common ancestry with repA- and repB-type plasmids and moreover indicate the presence of two dnaA-like compatibility groups. This conclusion is supported by conserved palindrome sequences within the replication module that probably represent crucial centromeric anchors for plasmid partitioning. The functionality of dnaA-like replicons was proven by transformation experiments in Phaeobacter gallaeciensis BS107 (DSM 17395). This Roseobacter strain furthermore allows the phenotypical monitoring of plasmid incompatibility, based on a 262-kb dnaA-like replicon required for the brown pigmentation of the bacterium. Uptake of an incompatible construct induces its loss, hence resulting in white colonies. Accordingly, we could substantiate the in silico predictions about stable maintenance of dnaA-like plasmids and thereby functionally validate our approach of plasmid classification based on phylogenetic analyses.
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diversity and evolution of repabc type plasmids in Rhodobacterales
Environmental Microbiology, 2009Co-Authors: Jorn Petersen, Henner Brinkmann, Silke PradellaAbstract:: The repABC operon is the prevalent replication unit of alphaproteobacterial plasmids. Their semi-autonomy is ensured by the essential replicase gene repC as well as the repAB partitioning cassette. While conserved repAB modules are widespread among bacterial plasmids and homologues are even responsible for chromosome partitioning, repC genes are exclusively present in Alphaproteobacteria. RepABC operons contain two strong incompatibility regions, namely a small regulative antisense RNA gene (inc alpha) and a palindromic centromere region (inc beta), which were previously used to classify these replicons. The present survey pursued a complementary strategy essentially following the rationale that all plasmids identified from a single bacterium are per se compatible. We established a novel classification scheme for plasmids based on comprehensive phylogenetic analyses of repC, repA and repB genes. Our case study is focused on the Roseobacter clade (Rhodobacterales), one of the most successful lineages of the marine bacterioplankton. Its global significance was shown in several studies and the interest in these organisms is reflected by more than 40 upcoming genome projects. Based on phylogenetic RepC analyses we identified nine compatibility groups that are expected to stably coexist within the same cell. This prediction is supported by RepA and RepB phylogenies, moreover independent evidence is delivered by the group specificity of highly conserved palindromes (inc beta).
Erinn M Muller - One of the best experts on this subject based on the ideXlab platform.
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Rhodobacterales and rhizobiales are associated with stony coral tissue loss disease and its suspected sources of transmission
Frontiers in Microbiology, 2020Co-Authors: Stephanie M Rosales, Abigail S Clark, Lindsay K Huebner, Rob Ruzicka, Erinn M MullerAbstract:: In 2014, Stony Coral Tissue Loss Disease (SCTLD) was first detected off the coast of Miami, FL, United States, and continues to persist and spread along the Florida Reef Tractr (FRT) and into the Caribbean. SCTLD can have up to a 61% prevalence in reefs and has affected at least 23 species of scleractinian corals. This has contributed to the regional near-extinction of at least one coral species, Dendrogyra cylindrus. Initial studies of SCTLD indicate microbial community shifts and cessation of lesion progression in response to antibiotics on some colonies. However, the etiology and abiotic sources of SCTLD transmission are unknown. To characterize SCTLD microbial signatures, we collected tissue samples from four affected coral species: Stephanocoenia intersepta, Diploria labyrinthiformis, Dichocoenia stokesii, and Meandrina meandrites. Tissue samples were from apparently healthy (AH) corals, and unaffected tissue (DU) and lesion tissue (DL) on diseased corals. Samples were collected in June 2018 from three zones: (1) vulnerable (ahead of the SCTLD disease boundary in the Lower Florida Keys), (2) endemic (post-outbreak in the Upper Florida Keys), and (3) epidemic (SCTLD was active and prevalent in the Middle Florida Keys). From each zone, sediment and water samples were also collected to identify whether they may serve as potential sources of transmission for SCTLD-associated microbes. We used 16S rRNA gene amplicon high-throughput sequencing methods to characterize the microbiomes of the coral, water, and sediment samples. We identified a relatively higher abundance of the bacteria orders Rhodobacterales and Rhizobiales in DL tissue compared to AH and DU tissue. Also, our results showed relatively higher abundances of Rhodobacterales in water from the endemic and epidemic zones compared to the vulnerable zone. Rhodobacterales and Rhizobiales identified at higher relative abundances in DL samples were also detected in sediment samples, but not in water samples. Our data indicate that Rhodobacterales and Rhizobiales may play a role in SCTLD and that sediment may be a source of transmission for Rhodobacterales and Rhizobiales associated with SCTLD lesions.