Effect of Saccharomyces boulardii and Bacillus subtilis B10 on gut microbiota modulation in broilers

The gut microbiota plays important roles in animal overall health and productiveness. Balancing host gut microbiota by probiotics has been documented. Our previous study showed that Saccharomyces boulardii (Sb) and Bacillus subtilis B10 (Bs) significantly improve growth performance and modulate the intestinal histomorphology in broilers. To increase the knowledge regarding Sb and Bs, this study investigated the effects of these 2 probiotic strains on the gut microbiota in broilers. Three hundred 1-day-old Sanhuang broilers (Chinese cross breed) were randomly divided into 3 groups, each group with 5 replications (n = 20). The control group (CK) was fed a basal diet containing an antibiotic (virginiamycin, 20 mg/kg) and the other 2 groups received Sb and Bs (1 × 10⁸ cfu/kg of feed) in addition to the basal diet. After 72 d of treatment, pyrosequencing revealed that the bacterial communities varied along the section of intestinal tract in the control and Bs groups, but not in the Sb group. No difference in microbial diversity was observed among 3 groups. The major phyla observed along the GI tract of broilers (particularly in the duodenum and cecum) were Firmicutes, Bacteroidetes, Proteobacteria, and Verrucomicrobia, which were considered potentially growth performance-related. Bacteroidetes, Proteobacteria, and Verrucomicrobia were observed at a much higher abundance in the jejunums and ileums of the Sb group (P < 0.05). In addition, the jejunal microbial communities formed 3 different clusters at either the genus level or the category of metabolism among the groups, based on the principal component analyses. These data indicated that Sb and Bs can modulate the microbial ecosystem, and subsequently enhance the health status of broilers.