Abstract: In order to explore the effects of in vitro fermentation of quinoa water insoluble dietary fiber and exogenous addition of lactic acid bacteria on the gut microbiota and short-chain fatty acids (SCFAs), fecal filtrate (FF) from healthy subjects either alone or in combination with Lactobacillus plantarum was used to ferment quinoa water insoluble dietary fiber in vitro. The production of SCFAs was determined by gas chromatography (GC), and the changes in microbial community structure and abundance in the fermentation broth were analyzed by 16S rDNA sequencing. The results showed that the addition of quinoa insoluble dietary fiber and L. plantarum could change the structure and abundance of the gut microbiota. At the phylum level, the addition of quinoa insoluble dietary fiber and L. plantarum increased the abundance of Bacteroidota after 12 h of fermentation. At the genus level, quinoa insoluble dietary fiber increased the abundance of beneficial bacteria (Prevotella). Compared with the in vitro fermentation of quinoa water insoluble dietary fiber with FF, the exogenous addition of L. plantarum significantly increased the production of SCFAs. In summary, the in vitro fermentation of quinoa water insoluble dietary fiber by L. plantarum could significantly change the abundance and diversity of the intestinal microbiota, and promote the production of SCFAs, which is beneficial to intestinal health.

Key words: dietary fiber, in vitro fermentation, gut microbiota, short-chain fatty acids