Ardenticatena maritima gen. nov., sp. nov., a ferric iron- and nitrate-reducing bacterium of the phylum ‘ Chloroflexi ’ isolated from an iron-rich coastal hydrothermal field, and description of Ardenticatenia classis nov.

Abstract

A novel thermophilic, chemoheterotrophic, Gram-negative-staining, multicellular filamentous bacterium, designated strain 110ST, was isolated from an iron-rich coastal hydrothermal field in Japan. The isolate is facultatively aerobic and chemoheterotrophic. Phylogenetic analysis using 16S rRNA gene sequences nested strain 110ST in a novel class-level clone cluster of the phylum ‘ Chloroflexi ’. The isolate grows by dissimilatory iron- and nitrate-reduction under anaerobic conditions, which is the first report of these abilities in the phylum ‘ Chloroflexi ’. The organism is capable of growth with oxygen, ferric iron and nitrate as a possible electron acceptor, has a wide range of growth temperatures, and tolerates higher NaCl concentrations for growth compared to the other isolates in the phylum. Using phenotypic and phylogenetic data, strain 110ST ( = JCM 17282T = NBRC 107679T = DSM 23922T = KCTC 23289T = ATCC BAA-2145T) is proposed as the type strain of a novel species in a new genus, Ardenticatena maritima gen. nov., sp. nov. In addition, as strain 110ST apparently constitutes a new class of the phylum ‘ Chloroflexi ’ with other related uncultivated clone sequences, we propose Ardenticatenia classis nov. and the subordinate taxa Ardenticatenales ord. nov. and Ardenticatenaceae fam. nov.