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Comparative genomic analysis reveals evidence of two novel Vibrio species closely related to V. cholerae.

ABSTRACT: In recent years genome sequencing has been used to characterize new bacterial species, a method of analysis available as a result of improved methodology and reduced cost. Included in a constantly expanding list of Vibrio species are several that have been reclassified as novel members of the Vibrionaceae. The description of two putative new Vibrio species, Vibrio sp. RC341 and Vibrio sp. RC586 for which we propose the names V. metecus and V. parilis, respectively, previously characterized as non-toxigenic environmental variants of V. cholerae is presented in this study.Based on results of whole-genome average nucleotide identity (ANI), average amino acid identity (AAI), rpoB similarity, MLSA, and phylogenetic analysis, the new species are concluded to be phylogenetically closely related to V. cholerae and V. mimicus. Vibrio sp. RC341 and Vibrio sp. RC586 demonstrate features characteristic of V. cholerae and V. mimicus, respectively, on differential and selective media, but their genomes show a 12 to 15% divergence (88 to 85% ANI and 92 to 91% AAI) compared to the sequences of V. cholerae and V. mimicus genomes (ANI <95% and AAI <96% indicative of separate species). Vibrio sp. RC341 and Vibrio sp. RC586 share 2104 ORFs (59%) and 2058 ORFs (56%) with the published core genome of V. cholerae and 2956 (82%) and 3048 ORFs (84%) with V. mimicus MB-451, respectively. The novel species share 2926 ORFs with each other (81% Vibrio sp. RC341 and 81% Vibrio sp. RC586). Virulence-associated factors and genomic islands of V. cholerae and V. mimicus, including VSP-I and II, were found in these environmental Vibrio spp.Results of this analysis demonstrate these two environmental vibrios, previously characterized as variant V. cholerae strains, are new species which have evolved from ancestral lineages of the V. cholerae and V. mimicus clade. The presence of conserved integration loci for genomic islands as well as evidence of horizontal gene transfer between these two new species, V. cholerae, and V. mimicus suggests genomic islands and virulence factors are transferred between these species.

SUBMITTER: Haley BJ

PROVIDER: S-EPMC2889950 | biostudies-literature | 2010 May

REPOSITORIES: biostudies-literature

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Comparative genomic analysis reveals evidence of two novel Vibrio species closely related to V. cholerae.

Haley Bradd J BJ Grim Christopher J CJ Hasan Nur A NA Choi Seon-Young SY Chun Jongsik J Brettin Thomas S TS Bruce David C DC Challacombe Jean F JF Detter J Chris JC Han Cliff S CS Huq Anwar A Colwell Rita R RR

BMC microbiology 20100527

<h4>Background</h4>In recent years genome sequencing has been used to characterize new bacterial species, a method of analysis available as a result of improved methodology and reduced cost. Included in a constantly expanding list of Vibrio species are several that have been reclassified as novel members of the Vibrionaceae. The description of two putative new Vibrio species, Vibrio sp. RC341 and Vibrio sp. RC586 for which we propose the names V. metecus and V. parilis, respectively, previously ...[more]

PMID: 20507608

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Project description:BackgroundAkkermansia muciniphila is an important bacterium that resides on the mucus layer of the intestinal tract. Akkermansia muciniphila has a high abundance in human feces and plays an important role in human health.ObjectiveIn this article, 23 whole genome sequences of the Akkermansia genus were comparatively studied.MethodsPhylogenetic trees were constructed with three methods: All amino acid sequences of each strain were used to construct the first phylogenetic tree using the web server of Composition Vector Tree Version 3. The matrix of Genome-to-Genome Distances which were obtained from GGDC 2.0 was used to construct the second phylogenetic tree using FastME. The concatenated single-copy core gene-based phylogenetic tree was generated through MEGA. The single-copy genes were obtained using OrthoMCL. Population structure was assessed by STRUCTURE 2.3.4 using the SNPs in core genes. PROKKA and Roary were used to do pan-genome analyses. The biosynthetic gene clusters were predicted using antiSMASH 4.0. IalandViewer 4 was used to detect the genomic islands.ResultsThe results of comparative genomic analysis revealed that: (1) The 23 Akkermansia strains formed 4 clades in phylogenetic trees. The A. muciniphila strains isolated from different geographic regions and ecological niches, formed a closely related clade. (2) The 23 Akkermansia strains were divided into 4 species based on digital DNA-DNA hybridization (dDDH) values. (3) Pan-genome of A. muciniphila is in an open state and increases with addition of new sequenced genomes. (4) SNPs were not evenly distributed throughout the A. muciniphila genomes. The genes in regions with high SNP density are related to metabolism and cell wall/membrane envelope biogenesis. (5) The thermostable outer-membrane protein, Amuc_1100, was conserved in the Akkermansia genus, except for Akkermansia glycaniphila PytT.ConclusionOverall, applying comparative genomic and pan-genomic analyses, we classified and illuminated the phylogenetic relationship of the 23 Akkermansia strains. Insights of the evolutionary, population structure, gene clusters and genome islands of Akkermansia provided more information about the possible physiological and probiotic mechanisms of the Akkermansia strains, and gave some instructions for the in-depth researches about the use of Akkermansia as a gut probiotic in the future.

Project description:The PFGRC has developed a cost effective alternative to complete genome sequencing in order to study the genetic differences between closely related species and/or strains. The comparative genomics approach combines Gene Discovery (GD) and Comparative Genomic Hybridization (CGH) techniques, resulting in the design and production of species microarrays that represent the diversity of a species beyond just the sequenced reference strain(s) used in the initial microarray design. These species arrays may then be used to interrogate hundreds of closely related strains in order to further unravel their evolutionary relationships. Many infectious agents that cause emerging and re-emerging diseases appear to evolve from non-virulent forms. We still lack a clear understanding about the natural history of various microbial agents that cause human infectious diseases and the events leading to acquisition of their pathogenic potential. There have been seven pandemics of V. cholerae throughout the history of the mankind. To date, the world population is still experiencing the seventh one which started in the early 1960s. From almost 200 recognized V. cholerae serotypes, the majority of these epidemics are associated with primarily O1 serotype. However there is evidence that this species is undergoing some phenotypic changes during the last decades. Such examples include shifts in some metabolic pathways used for biotyping, phage sensitivity profiling and the acquisition of plasmids that carry multiple genes conferring antimicrobial resistance. Furthermore, the recent emergence of a non-O1 serotype (‘Bengal strain’, classified serologically as O139) has prompted the experts to think that perhaps this genotype will be the predominant one in the upcoming (eighth) pandemic. Besides the O1 and O139, the non-O1 and non-O139 V. cholerae stains are occasionally associated with other severe forms of gastrointestinal disease in humans. Interestingly, many of these non-canonical strains lack the genes encoding the typical virulence factors for this species such as the Cholera-toxin (ctx) and toxin co-regulated pilus (tcpA). Therefore it has been hypothesized that this group of non-canonical V. cholerae pathogens consist of several sub-clones that elicit disease via unknown virulence determinants and underlying mechanisms. The flow of genetic information within this group motivated us to identify novel genes for the purpose of creating a "species" DNA microarray to better understand the ancestral relationships among its members. Based on preliminary genotyping (MLST, and CGH using a single-genome-based array), 10 diverse V. cholerae and one V. mimicus were selected for sequencing. Sequence information obtained from this project, and from other publicly available sources, led to the development of a comprehensive species microarray for V. cholerae group members. The availability of the V. cholerae species DNA microarray has allowed us to carry out a collaborative CGH genotyping project to validate this microarray as well as understand the phylogenomic relationships among members of V. cholerae group.

Project description:BackgroundMembers of the genus Bacillus are important plant growth-promoting rhizobacteria that serve as biocontrol agents. Bacillus paralicheniformis MDJK30 is a PGPR isolated from the peony rhizosphere and can suppress plant-pathogenic bacteria and fungi. To further uncover the genetic mechanism of the plant growth-promoting traits of MDJK30 and its closely related strains, we used comparative genomics to provide insights into the genetic diversity and evolutionary relationship between B. paralicheniformis and B. licheniformis.ResultsA comparative genomics analysis based on B. paralicheniformis MDJK30 and 55 other previously reported Bacillus strains was performed. The evolutionary position of MDJK30 and the evolutionary relationship between B. paralicheniformis and B. licheniformis were evaluated by studying the phylogeny of the core genomes, a population structure analysis and ANI results. Comparative genomic analysis revealed various features of B. paralicheniformis that contribute to its commensal lifestyle in the rhizosphere, including an opening pan genome, a diversity of transport and the metabolism of the carbohydrates and amino acids. There are notable differences in the numbers and locations of the insertion sequences, prophages, genomic islands and secondary metabolic synthase operons between B. paralicheniformis and B. licheniformis. In particular, we found most gene clusters of Fengycin, Bacitracin and Lantipeptide were only present in B. paralicheniformis and were obtained by horizontal gene transfer (HGT), and these clusters may be used as genetic markers for distinguishing B. paralicheniformis and B. licheniformis.ConclusionsThis study reveals that MDJK30 and the other strains of lineage paralicheniformis present plant growth-promoting traits at the genetic level and can be developed and commercially formulated in agriculture as PGPR. Core genome phylogenies and population structure analysis has proven to be a powerful tool for differentiating B. paralicheniformis and B. licheniformis. Comparative genomic analyses illustrate the genetic differences between the paralicheniformis-licheniformis group with respect to rhizosphere adaptation.

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Comparative genomic analysis reveals evidence of two novel Vibrio species closely related to V. cholerae.

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Comparative genomic analysis reveals evidence of two novel Vibrio species closely related to V. cholerae.

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