Hydrogenispora ethanolica gen. nov., sp. nov., an anaerobic carbohydrate-fermenting bacterium from anaerobic sludge

Abstract

An anaerobic, spore-forming, ethanol-hydrogen-coproducing bacterium, designated LX-B^T, was isolated from an anaerobic sludge treating herbicide wastewater. Cells of strain LX-B^Twere non-motile rods (0.3–0.5×3.0–18.0 µm). Spores were terminal with a bulged sporangium. Growth occurred at 20–50 °C (optimum 37–45 °C), pH 5.0–8.0 (optimum pH 6.0–7.7) and 0–2.5 % (w/v) NaCl. The strain could grow fermentatively on glucose, maltose, arabinose, fructose, xylose, ribose, galactose, mannose, raffinose, sucrose, pectin, starch, glycerol, fumarate, tryptone and yeast extract. The major end-products of glucose fermentation were acetate, ethanol and hydrogen. Yeast extract was not required but stimulated growth. Nitrate, sulfate, thiosulfate, elemental sulfur, sulfite, anthraquinone-2,6-disulfonate, fumarate and Fe (III) nitrilotriacetate were not used as terminal electron acceptors. The G+C content of the genomic DNA was 56.1 mol%. The major cellular fatty acids were anteiso-C_15 : 0, iso-C_14 : 0and C_16 : 0. The most abundant polar lipids of strain LX-B^Twere diphosphatidylglycerol and phosphatidylglycerol. 16S rRNA gene sequence analysis revealed that it belongs to an as-yet-unidentified taxon at the order- or class-level (OPB54) within the phylum Firmicutes , showing 86.5 % sequence similarity to previously described species of the Desulfotomaculum cluster. The nameHydrogenispora ethanolicagen. nov., sp. nov. is proposed to accommodate strain LX-B^T( = DSM 25471^T = JCM 18117^T = CGMCC 1.5175^T) as the type strain.