Vulcanibacillus modesticaldus gen. nov., sp. nov., a strictly anaerobic, nitrate-reducing bacterium from deep-sea hydrothermal vents

Abstract

A novel anaerobic, moderately thermophilic, spore-forming bacterium, designated strain BRT, was isolated from deep-sea hydrothermal core samples collected at the Rainbow vent field on the Mid-Atlantic Ridge (36° 14′ N 33° 54′ W). The cells were found to be rod-shaped, non-motile, Gram-positive and spore-forming. The organism grew in the temperature range 37–60 °C, with an optimum at 55 °C, and at pH values in the range 6–8.5, with an optimum around pH 7. NaCl concentrations for growth were in the range 10–40 g l−1, with an optimum at 20–30 g l−1. Strain BRTgrew chemo-organoheterotrophically with carbohydrates, proteinaceous substrates and organic acids with nitrate as electron acceptor. The novel isolate was not able to ferment. The G+C content of the genomic DNA was 34.5 mol%. Phylogenetic analysis of the 16S rRNA gene sequence placed strain BRTin theBacillaceaewithin the class ‘Bacilli’. On the basis of the phenotypic and phylogenetic data, this isolate should be described as a member of a novel genus, for which the nameVulcanibacillusgen. nov. is proposed. The type species isVulcanibacillus modesticaldussp. nov., with the type strain BRT(=DSM 14931T=JCM 12998T).