Abstract: In this study, the probiotic characteristics of Lactobacillus plantarum SWUN5815, a bacteriocin-producing strain isolated from yak, were evaluated by measuring its antibacterial activity, acid and salt tolerance, adhesion ability and effect on body mass gain and intestinal mucosal immunity in mice. The results showed that the strain had potent broad-spectrum antimicrobial activity against the foodborne pathogenic microorganisms of yak. The survival rates of this strain were 58.2% at pH 2, 86.9% at pH 3, 66.8% at bile salt concentration of 0.3%, and it had strong acid and salt resistance. Its adhesion rate to Caco-2 cells was 42%; it was sensitive to common antibiotics without drug resistance. L. plantarum SWUN5815 could significantly increase body mass gain in mice (P < 0.01), and also significantly enhance the expression level of intestinal SIgA in mice (P < 0.01). In summary, L. plantarum SWUN5815 can well adapt to the gastrointestinal environment, effectively improve body mass gain and immune function in mice, thus serving as a candidate probiotic strain.

Key words: yak, Lactobacillus plantarum, probiotic properties