Tepidiforma bonchosmolovskayae gen. nov., sp. nov., a moderately thermophilic Chloroflexi bacterium from a Chukotka hot spring (Arctic, Russia), representing a novel class, Tepidiformia, which includes the previously uncultivated lineage OLB14

Abstract

A novel aerobic moderately thermophilic bacterium, strain 3753O^T, was isolated from a Chukotka hot spring (Arctic, Russia) using the newly developed technology of laser engineering of microbial systems. Сells were regular short rods, 0.4×0.8-2.0 µm in size, with a monoderm-type envelope and a single flagellum. The temperature and pH ranges for growth were 42-60 °C and pH 6.5-8.5, the optima being 50-54 °C and pH 7.3. Strain 3753O^T grew chemoorganoheterotrophically on a number of carbohydrates or peptidic substrates and volatile fatty acids, and chemolithoautotrophically with siderite (FeCO₃) as the electron donor. The major cellular fatty acid was branched C_{19 : 0}. Phosphatidylethanolamine, phosphatidylglycerol and two unidentified phospholipids as well as two yellow carotenoid-type pigments were detected in the polar lipid extract. Strain 3753O^T was inhibited by chloramphenicol, polymyxin B, vancomycin, streptomycin, neomycin and kanamycin, but resistant to the action of novobiocin and ampicillin. The DNA G+C content was 69.9 mol%. The 16S rRNA gene as well as 51 conservative protein sequence-based phylogenetic analyses placed strain 3753O^T within the previously uncultivated lineage OLB14 in the phylum <i>Chloroflexi</i>. Taking into account the phylogenetic position as well as phenotypic properties of the novel isolate, the novel genus and species <i>Tepidiforma bonchosmolovskayae</i> gen. nov.<i>,</i> sp. nov., within the <i>Tepidiformaceae</i> fam. nov., the <i>Tepidiformales</i> ord. nov. and the <i>Tepidiformia</i> classis nov. are proposed. The type strain of <i>Tepidiforma bonchosmolovskayae</i> is 3753O^T (=VKM B-3389^T=KTCT 72284^T).