Gut Microbial Composition in Mice Fed Different Amount of Rice Resistant Starch (P21-031-19)

Abstract

Abstract Objectives The aim of this study is to evaluate the effects of rice containing different levels of resistant starch on the gut microbiome using a rodent model. Methods Rice with low resistant starch (0.11%), medium resistant starch (1.07%) and high resistant starch (8.61%) were cooked, grounded into powders and used to formulate diet to represent all the carbohydrates in mice diet that consist of low fat (LF, 10 kcal %) or high fat (HF, 39 kcal %). C57BL/6 mice (n = 60, male, 5 weeks old) were randomly assigned to six feeding groups: (1) low-fat and low resistant starch diet (LL); (2) high-fat and low resistant starch diet (HL); (3) low-fat and medium resistant starch diet (LM); (4) high-fat and medium resistant starch diet (HM); (5) low-fat and high resistant starch diet (LH); (6) high-fat and high resistant starch diet (HH). Mice were fed with diets for 8 weeks then gut microbiome composition was determined using 16S rDNA sequencing of cecal contents. Results We found that the gut microbiome was significantly different at different levels of resistant starch (P < 0.01) but not at different fat levels. OTU (operational taxonomic unit) richness was reduced in LF and HF high-resistant groups as compared to others. OTU diversity was reduced in LF and HF medium and high-resistant groups as compared to low-resistant groups. Decreased Firmicutes to Bacteroidetes ratio, which related to lower risk of obesity, was observed in mice fed LF and HF high-resistant diet as compared to others. Moreover, at the family level, LF, HF high-resistant diet mainly increased the abundances of Bacteroidaceae and S24_7, the bacteria positively correlated with SCFAs (short-chain fatty acids) levels. We also observed a decrease in abundances of Odoribacteraceae, Rikenellaceae, Lachnospiraceae, Ruminococcaceae and Desulfovibrionaceae in LF and HF high resistant starch group. Desulfovibrionaceae and genus Odoribecter in Odoribacteraceae are reported to be opportunistic pathogens, Lachnospiraceae, Ruminococcaceae, Odoribacteraceae and Rikenellaceae are associated with obesity. Conclusions Overall, our results demonstrated that resistant starch exerted concentration-dependent effect on the gut microbiome in mice which may have protective effect against obesity. Funding Sources USDA, ARS.