Ethanoligenens harbinense gen. nov., sp. nov., isolated from molasses wastewater

Abstract

Two strictly anaerobic bacterial strains (YUAN-3^T and X-29) were isolated from anaerobic activated sludge of molasses wastewater in a continuous stirred-tank reactor. The strains were Gram-positive, non-spore-forming, mesophilic and motile. Cells were regular rods (0·4–0·8×1·5–8·0 μm) and occurred singly, in pairs and sometimes in chains of up to eight. Autoaggregative and autofluorescent growth of strain YUAN-3^T and non-aggregative growth of strain X-29 were observed at 20–44 °C and pH 3·5–9·0. Both strains hydrolysed gelatin and aesculin and fermented several kinds of mono-, di- and oligosaccharides. Fermentation end products formed from glucose were acetate, ethanol, hydrogen and carbon dioxide. The predominant cellular fatty acids were the branched-chain fatty acids iso-C_16 : 0 (44·18 %) and iso-C_12 : 0 (26·67 %). The DNA G+C contents of strains YUAN-3^T and X-29 were 47·8 and 49·0 mol%, respectively. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the isolates represent a novel phyletic sublineage within the Clostridium cellulosi rRNA cluster, with Ethanoligenens harbinense gen. nov., sp. nov. The type strain of Ethanoligenens harbinense is YUAN-3^T (=JCM 12961^T=CGMCC 1.5033^T).