Regulatory Effects of Pediococcus Pentosaceus JASB0677 Isolated from Naturally Fermented Yak Yogurt on In Vitro Rumen...

This study aimed to isolate and identify a fiber-degrading probiotic strain from traditional yak yogurt on the Qinghai-Tibet Plateau and evaluate its effects on rumen fermentation and microbial metabolism. Through carboxymethyl cellulose (CMC) screening, filter paper degradation, and straw degradation tests, a lactic acid bacterium-Pediococcus pentosaceus JASB0677-was obtained, with a straw degradation rate of 18.74%. P. pentosaceus JASB0677 exhibited tolerance to simulated gastric (pH 3.0, 1% pepsin, survival rate: 69.01%) and intestinal juices (pH 8.0, 1% trypsin, 63.18%) and showed bile salt resistance at 0.1%, 0.2%, and 0.3% concentrations (survival rates: 79.05%, 63.34%, and 52.32%, respectively). It also demonstrated strong antibacterial activity, with an inhibition zone diameter of 20.03 mm against Salmonella, and antioxidant activity, with 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radical scavenging rates of 46.52% and 39.17%, respectively. In vitro rumen fermentation revealed that P. pentosaceus JASB0677 significantly increased acetate and total volatile fatty acids (TVFAs) concentrations while reducing ammonia nitrogen levels (p < 0.05). 16 S rRNA sequencing revealed that P. pentosaceus JASB0677 altered the rumen microbial composition by increasing the relative abundance of Proteobacteria, Actinobacteria, Enterobacter, Klebsiella, and Christensenellaceae_R-7_group. Metabolomic analysis revealed significant modulation of several metabolic pathways, especially those related to amino acid and lipid metabolism. Correlation analysis indicated that acetate and TVFAs concentrations were significantly positively correlated with the abundances of Proteobacteria, Actinobacteria, Enterobacter, and Klebsiella, as well as specific metabolites including mevalonic acid and L-leucine, while ammonia nitrogen showed the opposite trend (p < 0.05). These results suggest that P. pentosaceus JASB0677 is a promising candidate functional feed additive for enhancing fiber utilization, maintaining microbial homeostasis, and improving rumen fermentation in ruminants.