Acetanaerobacterium elongatum gen. nov., sp. nov., from paper mill waste water

Two mesophilic anaerobic bacterial strains (Z7(T) and Z1) were isolated from waste water sludge of the Xinanzhang paper mill, Beijing, China. The strains were Gram-positive, non-spore-forming and motile. Cells were thin rods (0.2-0.4x4.0-8.0 microm). Growth of the strains was observed at 20-42 degrees C and pH 5.0-7.5. Both strains hydrolysed gelatin and aesculin and fermented several kinds of mono-, di- and oligosaccharides. The fermentation end products formed from glucose were acetate, ethanol, hydrogen and carbon dioxide. The predominant cellular fatty acids were the branched-chain fatty acids isoC(15 : 0) (42.83 %) and isoC(14 : 0) (32.11 %). The DNA G+C contents of strains Z7(T) and Z1 were 50.4 and 48.6 mol%, respectively. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the isolates represent a new phyletic sublineage within the Clostridium leptum rRNA cluster, with <91 % 16S rRNA gene sequence similarity to currently described species. On the basis of polyphasic evidence from this study, Acetanaerobacterium elongatum gen. nov., sp. nov., a novel genus and species, is proposed, with strain Z7(T) (=JCM 12359(T)=AS 1.5012(T)) as the type strain.