Comparative anti-microbial and anti-biofilm activities of postbiotics derived from kefir and normal raw milk lactic acid bacteria against bovine mastitis pathogens

Abstract

Bovine mastitis, caused by pathogens including Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa, and Escherichia coli, poses a significant challenge to the dairy industry. This study aimed to investigate the underlying mechanisms of the anti-microbial and anti-biofilm activities of postbiotics derived from lactic acid bacteria against bovine mastitis pathogens. Kefir-derived Lentilactobacillus kefiri LK1 produced significantly more lactic acid than normal raw milk-derived Enterococcus faecium EFM2, which was attributed to differences in biochemical activities. At an optimum concentration of 25%, both L. kefiri LK1 (POS_LK1) and E. faecium EFM2 postbiotics (POS_EFM2) exhibited anti-microbial and anti-biofilm activities by modulating hydrophobicity, auto-aggregation, and exopolysaccharide (EPS) production phenotypes and genotypes of bovine mastitis pathogens. POS_LK1 treatment reduced auto-aggregation and EPS production by E. faecalis and downregulated wspA and pelA expression in P. aeruginosa compared to those in POS_EFM2. Therefore, our results suggest that POS_LK1 could be used in the dairy industry as an anti-biofilm agent to effectively prevent pathogenic biofilm-induced bovine mastitis.