| Description: |
Nitratiruptor sp. (strain SB155-2) is a deep-sea vent microaerobic bacterium phylogenetically associated with the epsilon proteobacteria. This strain was isolated in the vicinity of a deep-sea vent occurring in the Iheya North hydrothermal field, in Okinawa, Japan. This rod-shaped bacterium grows chemolithoautotrophically and can utilize a wide spectrum of electron donors and acceptors (i.e. hydrogen, sulfur compounds, nitrate and oxygen). It can occupy different ecological niches, and its metabolic versatility probably enables it to adapt to the geochemical variability in deep-sea hydrothermal environments. Furthermore, fitting to its metal-rich niche, this strain contains a wide array of mineral transport systems including detoxification mechanisms of heavy metals such as arsenate, cadmium, and copper. It probably has some symbiotic relationship with vent animals. Nitratiruptor sp. (strain SB155-2) genome lacks orthologs of virulence genes of pathogenic epsilon proteobacteria, such as type IV secretion pathway and cag pathogenicity island genes. However, it possesses many virulence genes that were identified in pathogenic epsilon proteobacteria, including genes for virulence factor mviN, hemolysin, invasion antigen ciaB, and lytic murein transglycosylase. Some of the most remarkable virulence genes in deep-sea vent epsilon proteobacteria belong to the N-linked glycosylation (NLG) gene cluster. It is increasingly recognized that pathogenic epsilon proteobacteria have virulence determinants that are not classified as virulence genes in general but do play important roles in virulence. For example, Helicobacter species have a H2-uptake hydrogenase encoded outside the pathogenicity island, which is essential for its efficient initial colonization. Interestingly, strain SB155-2 has three different hydrogenases (one each of H2-uptake type, H2-sensing type, and H2-evolving type). |
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