Lebetimonas acidiphila gen. nov., sp. nov., a novel thermophilic, acidophilic, hydrogen-oxidizing chemolithoautotroph within the 'Epsilonproteobacteria', isolated from a deep-sea hydrothermal fumarole in the Mariana Arc.

A novel thermophilic, acidophilic bacterium, designated strain Pd55T, was isolated from a self-temperature-recording in situ colonization system deployed in a hydrothermal diffusing flow (maximum temperature of 78 degrees C) at the TOTO caldera in the Mariana Arc. Cells of strain Pd55T were motile, short rods with a single polar flagellum. Growth was observed between 30 and 68 degrees C (optimum growth at 50 degrees C; 120 min doubling time) and between (initial) pH 4.2 and 7.0 (optimum at pH 5.2). The isolate was a strictly anaerobic chemolithoautotroph capable of using molecular hydrogen as sole energy source and carbon dioxide as sole carbon source. Elemental sulfur served as the sole electron acceptor to support growth. The G+C content of the genomic DNA was 34.0 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the isolate was related to members of the genera Nautilia and Caminibacter, although it appeared to be a novel lineage prior to the divergence between Nautilia and Caminibacter. Strain Pd55T could also be differentiated from Nautilia and Caminibacter species on the basis of its physiological properties. It is, therefore, proposed that strain Pd55T (=JCM 12420T=DSM 16356T) represents the type strain of a novel species in a new genus, Lebetimonas acidiphila gen. nov., sp. nov.