Adlercreutzia equolifaciens gen. nov., sp nov., an equol-producing bacterium isolated from human faeces, and emended description of the genus Eggerthella

Nine strains capable of metabolizing isoflavones to equol were isolated from human faeces. Four of the strains were characterized by determining phenotypic and biochemical features and their phylogenetic position based on 16S rRNA gene sequence analysis. These strains were related to Eggerthella sinensis HKU14(T) with about 93% 16S rRNA gene sequence similarity; they were asaccharolytic, obligately anaerobic, non-spore-forming, non-motile and Gram-positive coccobacilli. In enzyme activity tests, arginine dihydrolase, arginine and leucine arylamidases were positive but nitrate reduction, urease and P-glucosidase were negative. The major menaquinone was DMMK-6 (dimethylmenaquinone-6), while that of members of the genus Eggerthella was MMK-6 (methylmenaquinone-6). Furthermore, the cell-wall pepticloglycan type of these strains was A1 gamma, while that of members of the genus Eggerthella was A4 gamma. On the basis of these data, a new genus, Adlercreutzia gen. nov., is proposed with one species, Adlercreutzia equolifaciens sp. nov. The type strain of Adlercreutzia equolifaciens is FJC-B9(T) (=JCM 14793(T) =DSM 19450(T) =CCUG 54925(T)).