Propionylated Resistant Starch: In Vitro Fecal Fermentation Properties And Gut Microbiota Regulation Of High-fat Diet-fed Mice

Acylated starch has a wide range of beneficial effects on colon health,including low energy intake,intestinal p H and high concentration of short-chain fatty acids(SCFAs).In addition,acylated starch can promote the growth of some beneficial bacteria.In recent years,acylated starch has attracted special attention for its ability to deliver specific SCFAs to the colon in a consistent and predictable manner,so its potential application in the treatment and prevention of some metabolic diseases such as obesity has aroused great concern.In this study,high-amylose maize starch was used to produce propionylated resistant starch.In vitro fecal fermentation was first conducted on the feces of the general and the Bacteroides-dominated individuals.It was found that propionylated resistant starch could release high amount of propionate specifically to the colon and promote the relative abundance of Roseburia and Bacteroides respectively.Subsequently,animal experiments were conducted to verify that propionylated resistant starch has anti-obesity effects on high-fat diet-fed mice.Propionate levels in the feces of mice increased significantly after 8 weeks intervention.Also,the relative abundance of bacteria Ruminococcus increased.The research results provided a basis for the development of new drugs and health care products.We fabricated propionylated resistant starches with different degrees of substitution(DS),and monitored the in vitro human fecal fermentation profiles.Propionylated modification did not change the slow gas production properties of high-amylose maize starch throughout the whole fermentation period.The final concentration of propionate(13.68-21.10 m M)produced by propionylated resistant starch fermentation enhanced gradually with increase of DS value,resulting from the release of introduced propionyl groups.Certain beneficial gut microbiota such as Roseburia and Blautia were obviously promoted,suggesting that propionylated resistant starch could regulate the composition of gut microbiota.Fecal samples of 7 volunteers with Bacteroides-dominated gut microbiota were collected,and propionylated resistant starch with different DS were fermented in batches.The changes of gas production and microbiota of individuals after 12 h and 24 h fermentation with different DS were determined.Also,the function of gut microbiota was predicted.The results showed that propionylated resistant starch with different DS showed similar and slow fermentation rate after both 12 h and 24 h fermentation time.Both gut microbiomes and their response to dietary carbohydrates are highly individualized,and they are homeostatic and resilient to change.After 24 h fermentation,the relative abundance of Bacteroidetes at the phylum level and Bacteroides at the genus level enhanced gradually with increase of DS value.PICRUSt comparison showed that propionylated resistant starch promoted some relevant gut microbiota which was associated with glycan biosynthesis and metabolism.The experimental mice were divided into 4 groups and named as normal diet,high-fat diet,high-amylose maize starch diet and propionylated resistant starch diet.After eight weeks of feeding,the changes of body weight,liver and adipose tissues,oral glucose tolerance,blood fat index,inflammatory factors,SCFAs content and gut microbiota were determined.The results showed that propionylated resistant starch have anti-obesity effects on high-fat diet-fed mice,and body weight loss was mainly associated with liver and epididymal white adipose tissue.Propionylated resistant starch can significantly decrease the fasting blood glucose and alleviate the dyslipidemia in obese mice.Propionate content in the feces of mice fed with propionylated resistant starch diet increased significantly.The sequencing of 16 S r RNA gene and PCo A analysis further showed that propionylated resistant starch could promote the abundance of beneficial bacteria Ruminococcus,and reduce the abundance of some harmful bacteria such as Oscillospira and Helicobacter,suggesting that propionylated starch could regulate the gut microbiota disorder caused by high-fat diet.