Abstract:

Objective: To exploit the resource of rice bran and investigate the regulation role of supernatant of Bacillus nattofermented rice bran (SBRB) for intestinal tract system in mice. Methods: The culture supernatant of Bacillus natto in rice bran fermentation medium was co-cultured with Bacillus bifidus. Mice were treated with SBRB via a gavage tube and the quantity of normal flora of intestinal tract in mice was detected. Results: Individual Bacillus natto could not promote the growth of Bacillus bifidus under anaerobic environment in vitro. However, both SBRB and aqueous extract of rice bran (AERB) could promote the growth of Bacillus bifidus by 65.2% and 17.8%, respectively. After enzymatic digestion by pepsin and trypsin, 51.6% promotion capacity of SBRB was remained. Similarly, the growth promotion of anaerobic bacteria and growth inhibition of aerobic bacteria were also observed in the intestinal tract in mice treated with SBRB. Individual application of Bacillus natto and its fermentation broth exhibited a regulatory effect on normal flora of intestinal tract in mice. In additions, a synergistic effect of combinatorial application on normal flora of intestinal tract in mice was also observed. Conclusion: SBRB has the function for regulating intestinal tract flora and has a promising potential to be used as synbiotic preparation.

Key words: Bacillus natto, rice bran, regulating intestinal tract, synbiotics