Project description:Genomic characterization of a polymicrobial infection associated with a disease outbreak in Pacific white shrimp (Litopenaeus vannamei) Genome sequencing and assembly
Project description:The antimicrobial additive triclosan has been used in personal care products widely across the globe for decades. Triclosan resistance has been noted among Vibrio spp., but reports have been anecdotal and the extent of phenotypic triclosan resistance across the Vibrionaceae family has not been established. Here, triclosan resistance was determined for Vibrionaceae strains across nine distinct clades. Minimum inhibitory concentrations (MIC) were determined for 70 isolates from clinical (n = 6) and environmental sources (n = 64); only two were susceptible to triclosan. The mean MIC for all resistant Vibrionaceae was 53 µg mL-1 (range 3.1-550 µg mL-1), but was significantly different between clades (p < 0.001). The highest mean triclosan MIC was observed in the Splendidus clade (200 µg mL-1; n = 3). Triclosan mean MICs were 68.8 µg mL-1 in the Damselae clade and 45.3 µg mL-1 in the Harveyi clade. The lowest mean MIC was observed in the Cholerae clade with 14.4 µg mL-1, which was primarily represented by clinical strains. There were no significant differences in triclosan MIC among individual species or among environmental strains isolated from different locations. Overall, phenotypic triclosan resistance appears to be widespread across multiple clades of Vibrionaceae.
Project description:BackgroundThe steadily increasing number of prokaryotic genomes has accelerated the study of genome evolution; in particular, the availability of sets of genomes from closely related bacteria has facilitated the exploration of the mechanisms underlying genome plasticity. The family Vibrionaceae is found in the Gammaproteobacteria and is abundant in aquatic environments. Taxa from the family Vibrionaceae are diversified in their life styles; some species are free living, others are symbiotic, and others are human pathogens. This diversity makes this family a useful set of model organisms for studying bacterial evolution. This evolution is driven by several forces, among them gene duplication and lateral gene transfer, which are believed to provide raw material for functional redundancy and novelty. The resultant gene copy increase in one genome is then detected as lineage-specific expansion (LSE).ResultsHere we present the results of a detailed comparison of the genomes of eleven Vibrionaceae strains that have distinct life styles and distinct phenotypes. The core genome shared by all eleven strains is composed of 1,882 genes, which make up about 31%-50% of the genome repertoire. We further investigated the distribution and features of genes that have been specifically expanded in one unique lineage of the eleven strains. Abundant duplicate genes have been identified in the eleven Vibrionaceae strains, with 1-11% of the whole genomes composed lineage specific radiations. These LSEs occurred in two distinct patterns: the first type yields one or more copies of a single gene; we call this a single gene expansion. The second pattern has a high evolutionary impact, as the expansion involves two or more gene copies in a block, with the duplicated block located next to the original block (a contiguous block expansion) or at some distance from the original block (a discontiguous block expansion). We showed that LSEs involve genes that are tied to defense and pathogenesis mechanisms as well as in the fundamental life cycle of Vibrionaceae species.ConclusionOur results provide evidence of genome plasticity and rapid evolution within the family Vibrionaceae. The comparisons point to sources of genomic variation and candidates for lineage-specific adaptations of each Vibrionaceae pathogen or nonpathogen strain. Such lineage specific expansions could reveal components in bacterial systems that, by their enhanced genetic variability, can be tied to responses to environmental challenges, interesting phenotypes, or adaptive pathogenic responses to host challenges.