Coculture of <i>Bifidobacterium bifidum</i> G9‐1 With Butyrate‐Producing Bacteria Promotes Butyrate Production

Supplementation with Bifidobacterium bifidum G9-1 (BBG9-1) has been established to enhance the production of butyrate, a short-chain fatty acid (SCFA) known for its beneficial effects in alleviating constipation. We hypothesized that BBG9-1 alters gut microbiota such that bacteria that produce butyric acid from lactate and acetate become more abundant. In this study, we sought to determine whether BBG9-1 promotes the growth of butyrate-producing bacteria and thereby enhances butyrate production. BBG9-1 was cocultured with different butyrate-producing bacteria to compare differences in the SCFA production of cocultures and monocultures. We indeed detected significant increases in the production of SCFAs in cocultures compared to monocultures. Moreover, lactate and butyrate production increased in a time-dependent manner in the BBG9-1 and Faecalibacterium prausnitzii ID 6052 coculture. In addition, acetate production in cocultures initially increased until 16 h, followed by a decline between 20 and 24 h, and a subsequent significant increase at 48 h. Comparatively, lactate and acetate production in the BBG9-1 and Anaerostipes caccae JCM 13470^T coculture peaked at 16 h and declined thereafter, and butyrate production increased in a time-dependent manner. In contrast, lactate, acetate, and butyrate production in the BBG9-1 and Roseburia hominis JCM 17582^T coculture increased in a time-dependent manner. These findings indicate that butyrate-producing bacteria increase butyrate production by utilizing BBG9-1-produced lactate and acetate. Thus, the butyrate-mediated physiological activity of BBG9-1 could be attributed to an indirect enhancement of butyrate production.