In vitro simulated digestion and fecal fermentation of exopolysaccharides from Lacticaseibacillus paracasei GL1

The prebiotic properties of two purified fractions (GL1-E1 and GL1-E2) of exopolysaccharides (EPSs) from Lacticaseibacillus paracasei GL1 were investigated through in vitro fermentation of pure and human fecal cultures. The results indicated that the simulated digestion under saliva, gastric, and small intestinal conditions had no effect on GL1-E1 and GL1-E2. Additionally, GL1-E1 and GL1-E2 can be used as substrates for Lactobacillus and Lactococcus growth. It was also found that both were gradually degraded and utilized by the gut microbiota. As fermentation proceeded, the pH continued to decrease. Additionally, the total short-chain fatty acid (SCFA) production significantly increased, especially the major SCFA of formic, lactic, and acetic acid. Furthermore, GL1-E1 and GL1-E2 could significantly regulate the composition of the gut microbiota, by increasing the relative abundances of Bacteroides and Phascolarctobacterium, and decreasing the pathogenic bacteria Escherichia-Shigella, Klebsiella, and Fusobacterium. These results suggest that GL1-E1 and GL1-E2 have the potential to be developed as a prebiotic.