Deep-sea hydrothermal vent bacteria related to human pathogenic Vibrio species

During Alvin and Nautile dives in 1999, samples were collected from water surrounding sulfide chimneys of a hydrothermal vent along the East Pacific Rise and four mesophilic bacteria were isolated, including a novel Vibrio species, Vibrio antiquarius. Genomic, functional, and phylogenetic analyses indicate an intriguing blend of genomic features related to adaptation and animal symbiotic association, and also revealed the presence of virulence genes commonly found in Vibrio species pathogenic for humans. The presence of these virulence genes in an ecologically distinct Vibrio species was surprising. It is concluded that pathogenicity genes serve a far more fundamental ecological role than solely causation of human disease.

Vibrio species are both ubiquitous and abundant in marine coastal waters, estuaries, ocean sediment, and aquaculture settings worldwide. We report here the isolation, characterization, and genome sequence of a novel Vibrio species, Vibrio antiquarius, isolated from a mesophilic bacterial community associated with hydrothermal vents located along the East Pacific Rise, near the southwest coast of Mexico. Genomic and phenotypic analysis revealed V. antiquarius is closely related to pathogenic Vibrio species, namely Vibrio alginolyticus, Vibrio parahaemolyticus, Vibrio harveyi, and Vibrio vulnificus, but sufficiently divergent to warrant a separate species status. The V. antiquarius genome encodes genes and operons with ecological functions relevant to the environment conditions of the deep sea and also harbors factors known to be involved in human disease caused by freshwater, coastal, and brackish water vibrios. The presence of virulence factors in this deep-sea Vibrio species suggests a far more fundamental role of these factors for their bacterial host. Comparative genomics revealed a variety of genomic events that may have provided an important driving force in V. antiquarius evolution, facilitating response to environmental conditions of the deep sea.                          

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