Caldifarcimen microaerophilum gen. nov., sp. nov., a facultatively anaerobic, thermophilic bacterium of a novel bacterial phylum, Caldifarciminota phyl. nov., formerly called candidate phylum WOR-3, description of Caldifarciminaceae fam. nov., Caldifarciminales ord. nov. and Caldifarciminia classis nov.

内容摘要

A facultatively anaerobic, thermophilic, Gram-negative bacterium, strain sy37T, isolated from a deep-sea hydrothermal field and belonging to the candidate phylum WOR-3, was characterized in detail. The cells were non-motile long rods with pili and grew via respiration with 2-10% (v/v) oxygen and elemental sulphur as electron acceptors. Optimum growth was observed at 75 °C, pH 6.0 and 3.5% (w/v) NaCl with a doubling time of 10 h. iso-C17 : 0 was found to be the major fatty acid and menaquinone-8 was identified as the major respiratory quinone. The G+C content of the genomic DNA was 60.6 mol%. Based on the results of phylogenetic analyses of the 16S rRNA gene and genome sequences, together with the phenotypic characterization of strain sy37T, we propose the name Caldifarcimen microaerophilum gen. nov., sp. nov. for strain sy37T (=NBRC 116057T=BCRC 81450T). In addition, we propose the associated family, order, class and phylum as Caldifarciminaceae fam. nov., Caldifarciminales ord. nov., Caldifarciminia classis nov. and Caldifarciminota phyl. nov., respectively, in the bacterial kingdom Pseudomonadati.