Caloranaerobacter azorensis gen. nov., sp nov., an anaerobic thermophilic bacterium isolated from a deep-sea hydrothermal vent

A thermophilic, anaerobic, chemo-organotrophic bacterium, designated MV1087 (T), was isolated from a deep-sea hydrothermal chimney sample collected fro m the Mid-Atlantic Ridge. The cells were straight, motile and stained Gram- negative. Growth was observed from 45 to 65 degreesC, with an optimum aroun d 65 degreesC. No growth was observed at 40 or 70 degreesC. Growth was obse rved from pH 5.5 to 9.0 and the optimum pH was around 7. The salinity range for growth was 10-100 g sea salt l(-1) (corresponding to 6.5-65 g NaCl l(- 1)) with an optimum at 30 g sea salt l(-1) (20 g NaCl l(-1)). Strain MV1087 (T) was heterotrophic, able to ferment proteinaceous substrates, such as br ain/heart infusion and gluten, and carbohydrates, such as glucose, xylan an d starch. The DNA G+C content was 27 mol%. Phylogenetic analyses using 16S rDNA sequences indicated that strain MV1087(T) belonged to cluster XII of t he Clostridium subphylum. Due to its phenotypic and genotypic characteristi cs, isolate MV1087(T) is proposed as a novel species of a new genus, Calora naerobacter azorensis gen. nov., sp. nov. The type strain is MV1087(T) (= C NCM I-2543(T) = DSM 13643(T)).