AUTHOR=Pi Xionge , Teng Weilin , Fei Dibo , Zhao Gang , Liu Wei 

TITLE=Effects of Live Combined Bacillus subtilis and Enterococcus faecium on Gut Microbiota Composition in C57BL/6 Mice and in Humans

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=12

YEAR=2022

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2022.821662

DOI=10.3389/fcimb.2022.821662

ISSN=2235-2988

ABSTRACT=<p>Probiotics, prebiotics, and synbiotics can alleviate metabolic syndrome by altering the composition of the gut microbiota. Live combined <italic>Enterococcus faecium</italic> and <italic>Bacillus subtilis</italic> has been indicated to promote growth and reduce inflammation in animal models. However, the modulatory effects of live combined <italic>B. subtilis</italic> R-179 and <italic>E. faecium</italic> R-026 (LCBE) on human microbiota remain unclear. The current study examined the growth of these two strains in the presence of various oligosaccharides and assessed the effects of this probiotic mixture on human and murine gut microbiota <italic>in vitro</italic> and <italic>in vivo</italic>. Oligosaccharides improved the growth of <italic>E. faecium</italic> R-026 and <italic>B. subtilis</italic> R-179 as well as increased their production of short-chain fatty acids. <italic>E. faecium</italic> R-026 or <italic>B. subtilis</italic> R-179 co-incubated with <italic>Bifidobacterium</italic> and <italic>Clostridium</italic> significantly increased the number of the anaerobic bacteria <italic>Bifidobacterium longum</italic> and <italic>Clostridium butyricum</italic> by <italic>in vitro</italic> fermentation. Moreover, LCBE significantly reduced plasma cholesterol levels in mouse models of hyperlipidemia. LCBE combined with galacto-oligosaccharides led to a significant decrease in the Firmicutes/Bacteroidetes ratio and a significant increase in the relative abundance of <italic>Akkermansia</italic> and <italic>Bifidobacteria</italic> after treating mice with LCBE (0.23 g/day) for eight weeks. Furthermore, <italic>in vitro</italic> fermentation also showed that both the single strains and the two-strain mixture modulated human gut microbiota, resulting in increased <italic>Lactobacillus</italic> and <italic>Bifidobacteria</italic>, and decreased <italic>Escherichia-Shigella</italic>. Overall, these results suggest that LCBE can improve host health by reducing the level of cholesterol in mouse models by modifying the composition of the gut microbiota.</p>