Probiotic potential of lactic acid bacteria isolated from yaks

Abstract The prevalence of bacterial digestive diseases in plateau animals has caused considerable losses to the Tibetan livestock industry. Therefore, this study aimed to isolate safe lactic acid bacteria (LAB) with beneficial probiotic properties to protect yaks from intestinal diseases. After 16S rDNA matching, four strains of Lactobacillus fermentum (A4), Pediococcus pentosaceus (A3.4 and A1.2), and Pediococcus acidilactici (B1.9) were isolated from the intestinal tissues and content of healthy yaks. The results indicated that A4 was more tolerant to bile salt (0.3%), while A3.4 had better stability in an acidic (pH = 3.0) environment. The results of the antibacterial activity test suggested that the isolates inhibited most pathogenic bacteria by up to 20%, except for A3.4, which inhibited Pasteurella and Staphylococcus aureus by more than 20%. Moreover, the results of the antioxidant test demonstrated that A4 and A3.4 had potent antioxidant activity. In addition, the drug sensitivity test revealed that the isolates were susceptible to commonly used antibiotics. In terms of safety, the isolates promoted growth, enhanced intestinal development, and protected the intestinal barrier without causing any adverse effects. In conclusion, LAB isolated from yak intestinal contents are potential probiotics with excellent antibacterial properties.