Microbes in pit mud play an important role on the quality and flavor of Chinese Luzhou-flavor liquor. Here, 54 bacterial strains were isolated from the pit mud of a 25 year-old fermentation pit, and a new butyrate-producing bacterium BTY6 was identified by polyphasic taxonomical method. Strain BTY6 is a strictly anaerobic, Gram-stain-positive, non-spore-forming，and short rod bacterium. Strain BTY6 has positive reactions for α-D-glucose, sucrose, maltose, D-fructose, D-cellobiose, α-D-lactose, D-galactose, L-lactic Acid, and so on. The major cellular fatty acids were C16 : 0 (54.85%),C16 : 0 N alcohol (9.61%), C17 : 0 10-methyl (7.06%) and C18 : 0 (4.71%). The genomic DNA G+C content of strain BTY6 was 48.52mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain BTY6 was most closely related to an uncultured Firmicutes bacterium HBG_A4R5-4 ( DQ837628 ) of the family Lachnospiraceae with 99.8% sequence similarity, but only had less than 93% sequence similarity with all cultured type species. Based on morphological observation, physiological and biochemical tests and phylogenetic analysis, strain BTY6 should represent a previously unknown subline within the family Lachnospiraceae.
