Nautilia lithotrophica gen. nov., sp. nov., a thermophilic sulfur-reducing epsilon-proteobacterium isolated from a deep-sea hydrothermal vent.

A novel, strictly anaerobic, thermophilic sulfur-reducing bacterium, strain 525T, was isolated from tubes of the deep-sea hydrothermal vent polychaete Alvinella pompejana, collected on the East Pacific Rise (13 degrees N). This organism grew in the temperature range 37-68 degrees C, the optimum being 53 degrees C, and in the pH range 6.4-7.4, the optimum being 6.8-7.0. The NaCl range for growth was 0.8-5.0%, the optimum being 3.0%. Strain 525T grew lithoautotrophically with H2 as energy source, S0 as electron acceptor and CO2 as carbon source. Alternatively, strain 525T was able to use formate as an energy source. The G+C content of the genomic DNA was 34.7 mol%. Phylogenetic analysis of the 16S rDNA gene sequence placed strain 525T in the epsilon-subclass of the Proteobacteria, where it forms a deep cluster with recently isolated relatives. On the basis of phenotypic and phylogenetic differences between strain 525T and its closest phylogenetic relatives, it is proposed that the new isolate should be described as a member of a new genus, Nautilia, for which the name Nautilia lithotrophica gen. nov., sp. nov. is proposed. The type strain is strain 525T (= DSM 13520T).