Clostridium pabulibutyricum sp. nov., a butyric-acid-producing organism isolated from high-moisture grass silage.

A Gram-stain-variable, strictly anaerobic, rod-shaped, catalase-negative and endospore-forming bacterial strain, designated MJC39, was isolated from grass silage preserved in Hokkaido, Japan. Growth occurred at 20-42 °C, pH 5.0-7.0 and NaCl concentrations up to 2 % (w/v). The isolated strain MJC39 produced butyric acid in peptone yeast extract medium with glucose. The DNA G+C content of strain MJC39 was 34.4±0.2 mol%. The major cellular fatty acids (>10 %) were C14 : 0, C16 : 0 and summed feature 3 (including C16 : 1ω7c/C16 : 1ω6c). No respiratory quinones were detected. The polar lipids of strain MJC39 were phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, one unidentified lipid, one unidentified aminolipid, two unidentified glycolipids, one unidentified phospholipid, one unidentified aminoglycolipid and one unidentified phosphoaminoglycolipid. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain MJC39 was a member of the genus Clostridium and is closely related to Clostridium tyrobutyricum JCM 11008 (95.8 % similarity) and Clostridium algifaecis MB9-7 (95.5 % similarity). Based on the genotypic, phenotypic and chemotaxonomic characteristics, strain MJC39 represents a novel species of the genus Clostridium, for which the name Clostridium pabulibutyricum sp. nov. is proposed. The type strain is MJC39 (=JCM 31506=DSM 103944).