The improvement of microbiota pattern by ingestion of soybean fermentation broth

The human gut microbiota may be viewed as an organ, executing numerous functions in metabolism, development of the immune system and host defence against pathogens. Soybean fermentation broth (SFB) was fermented using a coculture system of Lactobacillus and yeast, consisting of a mixture of soybean extracts and the secondary metabolites of these microorganisms. As proved by our previous report, the SFB is favouring a Th1 cell response that may be preventing some diseases such as allergic. In this study, the pattern of intestinal microbiota in the faeces of 25 healthy humans with or without the ingestion of SFB was evaluated. The beneficial and pathogenic bacteria found in the faeces were Bifidobacterium spp. and Clostridium perfringens, respectively. After SFB ingestion for 5 weeks, the number of Bifidobacterium spp. and total anaerobic bacteria increased, whereas those of C. perfringens decreased. The ratio of the number of C. perfringens to that of total anaerobic bacteria decreased to 27–35% in two SFB groups compared with a placebo group. In addition, the ratio of the number of Bifidobacterium spp. at the sixth wk after SFB ingestion once per day to that at the initial stage (0 week) increased by approximately 18% and was significantly different from that of the placebo group. In conclusion, the gut microbiota composition improves with an increase in Bifidobacterium spp. and a decrease in C. perfringens after SFB ingestion for 5 weeks. This microbiota pattern in gut might be related with the improvement of allergic response.