Biotransformation of daidzein to equol by crude enzyme from Asaccharobacter celatus AHU1763 required an anaerobic environment.

Asaccharobacter celatus AHU1763 is a Gram-positive, obligate anaerobic, non-spore forming, rod-shaped bacteria that was successfully isolated from rat cecal content. Daizein was converted to equol via dihydrodaidzein by this bacterium. A crude enzyme that converted daidzein to dihydrodaidzein was detected mainly in the culture supernatant. The ability of this enzyme dropped after the culture supernatant was exposed to a normal atmospheric environment for even 5 min. Furthermore, the enzyme responsible for changing dihydrodaidzein to equol was detected mainly in the cell debris, which required anaerobic conditions for its activity.