RESUMO
Vibrio mimicus is a gram-negative bacterium responsible for diseases in humans. Three strains of V. mimicus identified as V. mimicus 87, V. mimicus 92 and V. mimicus 93 were isolated from a shrimp processing facility in Guaymas, Sonora, Mexico. The strains were analyzed using several molecular techniques and according to the cluster analysis they were different, their similarities ranged between 51.3% and 71.6%. ERIC-PCR and RAPD (vmh390R) were the most discriminatory molecular techniques for the differentiation of these strains. The complete genomes of two strains (V. mimicus 87, renamed as CAIM 1882, and V. mimicus 92, renamed as CAIM 1883) were sequenced. The sizes of the genomes were 3.9 Mb in both strains, with 2.8 Mb in ChI and 1.1 Mb in ChII. A 12.7% difference was found in the proteome content (BLAST matrix). Several virulence genes were detected (e.g. capsular polysaccharide, an accessory colonization factor and genes involved in quorum-sensing) which were classified in 16 categories. Variations in the gene content between these genomes were observed, mainly in proteins and virulence genes (e.g., hemagglutinin, mobile elements and membrane proteins). According to these results, both strains were different, even when they came from the same source, giving an insight of the diversity of V. mimicus. The identification of various virulence genes, including a not previously reported V. mimicus gene (acfD) in ChI in all sequenced strains, supports the pathogenic potential of this species. Further analysis will help to fully understand their potential virulence, environmental impact and evolution.
Assuntos
Manipulação de Alimentos , Microbiologia de Alimentos , Penaeidae/microbiologia , Vibrio mimicus/isolamento & purificação , Microbiologia da Água , Animais , Proteínas de Bactérias/genética , Técnicas de Tipagem Bacteriana , Impressões Digitais de DNA/métodos , DNA Bacteriano/análise , DNA Bacteriano/genética , Contaminação de Alimentos , Congelamento , Genes Bacterianos , Proteínas Hemolisinas/genética , México , Técnica de Amplificação ao Acaso de DNA Polimórfico , Ribotipagem , Alinhamento de Sequência , Análise de Sequência de DNA , Especificidade da Espécie , Vibrio mimicus/classificação , Vibrio mimicus/genética , Vibrio mimicus/patogenicidade , Virulência/genéticaRESUMO
Vibrio cholerae and Vibrio mimicus have similar phenotypes and genomes making rapid differentiation of these two species difficult. The first standard multilocus sequence analysis (MLSA) scheme for the identification of these species is described. A collection of 45 representative isolates from different geographical regions and hosts was examined using segments of the housekeeping genes pyrH, recA and rpoA. Overall, the closest phylogenetic neighbours of these species were Vibrio furnissii and Vibrio fluvialis. V. cholerae and V. mimicus formed separate species clusters on the basis of each gene, suggesting that these genes are useful as identification markers. These species clusters arose by the accumulation of point mutations. The pyrH gene showed the highest resolution for differentiating V. cholerae and V. mimicus. The maximum interspecies pyrH gene sequence similarity was 91 %. Clearly, V. mimicus strains were more heterogeneous than V. cholerae strains at the three loci. It is suggested that vibrio species may be defined on the basis of MLSA data. A vibrio species was defined as a group of strains forming a monophyletic group on the basis of these loci and with an intraspecific sequence similarity of at least 95 %. V. cholerae and V. mimicus isolates can be readily identified through the open database resource 'The Taxonomy of Vibrios' (http://www.taxvibrio.lncc.br/).