Abstract: Bacterial diarhea causes serious loses for the sheep industry. Antibiotic resistance acquired by diarheal bacteria is still a nurdle in the care of animal health. Thus, it is urgent to develop effective alternatives to antibiotics for controlling bacterial diarrhea. We initially isolated Bacillus spp. from Xinjiang fine wool sheep fecal and determined their properties of hemolysis and tolerance to acid and bile salts to identify potential candidates. Subsequently, we studied the position of a candidatein phylogenetic trees by 16S rRNA sequences and its susceptibility to antibiotics, ability to inhibit diarrheal bacteria, andoxicity, as well as its effects on animal health. Fourteen Bacillus spp. strains were isolated from sheep fecal. We identifiedhe non-hemolysis B63 strain, which exhibited a high tolerance to acid and bile salts. Phylogenetic analysis indicated that the B63 strain is a new strain of Bacillus licheniformis. The B. licheniformis B63 strain was prompt to form spores, susceptible commonly used antibiotics, and able to inhibit diarrhea-associated bacteria, including Escherichia coli, Staphvlococcus aureus, and Salmonella typhi. Animal studies determined that B. licheniformis B63 at 4 × 108 CFU/mL was non-toxic to mice and SD rats. Supplement with B. licheniformis B63 promoted the body weight gain of mice, reduced the inflammatory interleukin 6, and increased the jejunum villus height of SD rats. The newly isolated, non-hemolysis, spore-forming B.icheniformis B63 strain should be considered an optimal strain for the development of an effective probiotic supplement tocontrol diarrheal diseases and promote the health of sheep and other animals.
Keywords: Sheep · Bacillus licheniformis B63 · Probiotic · Bacterial diarrhea
编辑：安崇霄 审核人：
