| The intestine of organisms is colonized by many microorganisms,which regulate the balance of various metabolisms in the body.Diet is one of the key factors affecting intestinal microbiota,and studies have found that food-derived peptides can regulate the growth and metabolism of intestinal microbiota.Yak(Bos grunnirns)is a kind of valuable livestock breed in China.Yak bone is rich in collagen,and many biological activities of yak bone collagen peptide(YBCP)had been reported.However,no study has been conducted to investigate its regulation on intestinal microbiota.In this study,combined with 16 S rRNA gene sequencing technology,bioinformatics and non-targeted metabolomics,the effects of YBCP on intestinal microbiota were investigated through simulated colonic fermentation in vitro and animal experiments in vivo.The main research contents and results are as follows:(1)The changes of YBCP after gastrointestinal digestion and its effects on intestinal microbiota were investigated by simulating gastrointestinal digestion and colonic fermentation in vitro.The results showed that the molecular weight distribution of YBCP did not change during simulated gastric digestion,while it changed significantly during simulated intestinal digestion.The total free amino acid concentration of YBCP after digestion increased more than 5 times compared to that before digestion.The samples were sequenced by 16 S rRNA after 24 h of in vitro anaerobic fermentation.The results showed that the abundance of Bifidobacterium increased by 70.58% and 52.51% in the low and medium YBCP addition groups,respectively.In addition,the total content of short-chain fatty acids increased by 31.66%,48.90%,and 71.36%in the three YBCP-added groups,respectively.This suggests that YBCP may have a regulatory effect on intestinal microbiota and the production of SCFAs.(2)The effects of YBCP on the regulation of intestinal microbiota and its metabolites were further verified by in vivo animal experiments.After 4 weeks of dietary intervention,the intestinal microbial composition of mice in the YBCP gavage group showed significant changes.In the intestinal microbiota of mice in the medium dose group,the ratio of Firmicutes to Bacteroidetes(F/B)decreased by 36.53%,the abundance of Lachnospiraceae decreased by 29.83%,and the abundance of S24-7 and Bacteroidaceae increased by 66.72% and 73.26%,respectively.Meanwhile,the functional prediction of intestinal microbiota suggested that there was a significant increase in the abundance of “energy metabolism”,“lipid metabolism” and“other amino acid metabolism” in the medium dose group.The above results suggest that YBCP can regulate the structure of intestinal microbiota and may have the potential to regulate lipid metabolism and inhibit obesity.(3)The inhibitory effects of YBCP on high-fat diet-induced obesity were investigated.The results showed that after 12 weeks of continuous intervention,YBCP supplementation could significantly inhibit the rapid weight gain of mice with a high-fat diet.Meanwhile,YBCP supplementation could reduce triglyceride(TG),high-density lipoprotein cholesterol(HDL-C)and lipopolysaccharide(LPS)level in mice serum,and enhance glucose tolerance in obese mice.Analysis of intestinal microbiota composition showed that,at the phylum level,YBCP intervention reduced the F/B radio in obese mice.At the family level,the abundance of Lachnospiraceae showed a decreasing trend.At the genus level,the abundance of uncultured＿bacterium＿f＿Muribaculaceae and Alistipes,which were negatively correlated with obesity-related phenotypes,increased significantly.The non-targeted metabolomic analysis showed that YBCP could regulate the metabolism of linoleic acid,phenylalanine,arginine,proline,tryptophan and arginine biosynthesis in mice with a high-fat diet.Combined amplicon sequencing with non-targeted metabolomics analysis indicated that YBCP may affect lipid metabolism in mice on a high-fat diet by influencing the amino acid metabolism of intestinal microbiota. |
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