RESUMO
Antibiotic resistance is an increasingly prevalent problem worldwide. Probiotics are live microorganisms that provide health benefits to human beings and animals and also antimicrobial activity against pathogens and might be an antibiotic alternative. The gastrointestinal tract of animals can be a suitable source of finding novel antimicrobial agents, where the vast majority of gut microbes inhabit and a plurality of antimicrobial producers exhibit either a wide or narrow spectrum. Animals that live in Northwest China might possess a special commensal community in the gut. Therefore, the purpose of this study was to assess the effects of three probiotic strains (including Lactobacillus salivarius ZLP-4b from swine, Lactobacillus plantarum FBL-3a from beef cattle, and Bacillus velezensis JT3-1 from yak), which were isolated from livestock in this area, on the overall growth performance, immune function, and gut microbiota of mice. The results showed that the L. salivarius ZLP-4b group not only improved the growth performance but also amended the intestinal mucosa morphology of mice. Furthermore, the supplementation of L. plantarum FBL-3a and L. salivarius ZLP-4b strains significantly increased the content of anti-inflammatory cytokines IL-4 and IL-10 but decreased the pro-inflammatory factor IL-17A. The levels of pro-inflammatory factors IL-6, IL-17A, and TNF-α were also decreased by the B. velezensis JT3-1 group pretreatment. The 16S rDNA sequence results showed that the probiotic administration could increase the proportion of Firmicutes/Bacteroidetes intestinal microbes in mice. Furthermore, the relative abundance of Lactobacillus was boosted in the JT3-1- and ZLP-4b-treated groups, and that of opportunistic pathogens (including Proteobacteria and Spirochaetes) was diminished in all treated groups compared with the control group. In conclusion, B. velezensis JT3-1 and L. salivarius ZLP-4b supplementation enhanced the overall performance, intestinal epithelial mucosal integrity, and immune-related cytokines and regulated the intestinal microbiota in mice.
