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.
Strain VNs100T, a novel mesophilic, anaerobic, rod-coccoid-shaped bacterium, having a sheath-like outer structure (toga), was isolated from a water sample collected in the area of an underground gas storage aquifer. It was non-motile with cells appearing singly (2–4 µm long×1–2 µm wide), in pairs or as long chains and stained Gram-negative. Strain VNs100T was heterotrophic, able to use arabinose, cellobiose, fructose, galactose, glucose, lactose, lactate, mannose, maltose, raffinose, ribose, sucrose and xylose as energy sources only in the presence of elemental sulfur as terminal electron acceptor. Acetate, CO2 and sulfide were the end products of sugar metabolism. Hydrogen was not detected. Elemental sulfur, but not thiosulfate, sulfate or sulfite, were reduced to sulfide. Strain VNs100T grew at temperatures between 30 and 50 °C (optimum 45 °C), at pH values between 6.2 and 7.9 (optimum 7.3–7.5) and at NaCl concentrations between 0 and 15 g l−1 (optimum 2 g l−1). The DNA G+C content was 47.5 mol%. The main cellular fatty acid was C16 : 0. Phylogenetic analysis of the small subunit rRNA gene sequence indicated that strain VNs100T had as its closest relatives ‘ Mesotoga sulfurireducens’ (97.1 % similarity) and Mesotoga prima (similarity of 97.1 % and 97.7 % with each of its two genes, respectively) within the order Thermotogales . Hybridization between strain VNS100T and ‘M. sulfurireducens’ and between strain VNS100T and M. prima showed 12.9 % and 20.6 % relatedness, respectively. Based on phenotypic, phylogenetic and taxonomic characteristics, strain VNs100T is proposed as a representative of a novel species of the genus Mesotoga in the family Thermotogaceae , order Thermotogales . The name Mesotoga infera sp. nov. is proposed. The type strain is VNs100T ( = DSM 25546T = JCM 18154T).
The taxonomic properties of strain DC2c-G4T, a Gram-staining-negative, ovoid, gellan-gum-degrading bacterial isolate, were examined. Phylogenetic analysis based on 16S rRNA gene sequences identified this isolate as a member of the phylum Verrucomicrobia and closest to the genus Prosthecobacter . The 16S rRNA gene sequence similarities between this isolate and any of the type strains of species of the genus Prosthecobacter were less than 95 %. In addition, the absence of a single prostheca and the predominant menaquinone MK-7(H2) supported the differentiation of this isolate from the genus Prosthecobacter . Here, we propose Brevifollis gellanilyticus gen. nov., sp. nov. to accommodate the isolate. The type strain of the type species is DC2c-G4T ( = NBRC 108608T = CIP 110457T).