Evaluation of food effects on fecal microbiota in vitro

Abstract

Various microorganisms have been inhabited in the human gastrointestinal tract, bacteria live in the colon are mostly related with both diet and disease. The studies have been continuously conducted to correlate functional food or materials with gut microbiota to cure and prevent the unhealthy state by performing an animal experiment or clinical trials. These studies are often laborious, expensive and may involve ethical issues. Meanwhile, several studies have developed the system to simulate digestion and fermentation in vitro using functional substance. In this study, the digestion and fecal bacterial fermentation using cheonggukjang (CGJ) were performed and the shift of microbiota was investigated to compare food effects both in vitro and in vivo based on 16S rRNA gene of bacteria. We measured main SCFAs such as acetate, propionate, and butyrate as food effects, while yeast and peptone were removed from basal nutrient media of fermentation because of the usage as an energy source for bacteria. The fermentation time was kept as 2 hours to observe the fermentation effect by CGJ. Different shifts in microbiota in response to CGJ were observed in vitro and in vivo assays, however, similar alteration of microbiota was shown in vitro in some donors. At phylum level, Bacteroidetes were significantly decreased whereas Actinobacteria increased in both tests (P<0.05). Several bacteria shown a common increment or decrement pattern at OTU level, while different patterns were observed in vitro and in vivo. In conclusion, there may involve limitations of in vivo reproduction but it worked well to evaluate food effects on microbiota. For further studies, it is suggested to use variety of foods and diverse fecal samples to investigate microbiota shifts.