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

Two strictly anaerobic bacterial strains (YUAN-3T 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 x 1.5-8.0 microm) and occurred singly, in pairs and sometimes in chains of up to eight. Autoaggregative and autofluorescent growth of strain YUAN-3T and non-aggregative growth of strain X-29 were observed at 20-44 degrees 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-3T 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 <92 % 16S rRNA gene sequence similarity to currently known species. On the basis of polyphasic evidence from this study, it is proposed that the unknown bacterium should be classified in a new genus as a novel species, Ethanoligenens harbinense gen. nov., sp. nov. The type strain of Ethanoligenens harbinense is YUAN-3T (=JCM 12961T = CGMCC 1.5033T).