Biofilm inhibition and antagonism of Klebsiella pneumoniae by probiotic lactic acid bacteria (LAB) isolated from raw cow milk

Lactic acid bacteria (LAB) with their potential health benefits are naturally prevalent in dairy and fermented food products. This probiotic microbiota can be an alternative biological tool for controlling other pathogenic bacteria. The study aimed to isolate lactic acid bacteria (LAB) from raw cow milk and evaluate their probiotic potential. Twelve gram-positive isolates showing tolerance to bile salt, acid, and low pH were identified by 16S rRNA sequencing, which revealed the isolates belong to the genera including Lactococcus, Enterococcus, Streptococcus, Bacillus, and Weissella. In case of probiotic potential, the isolates exhibited arrays of probiotic properties: autoaggregation (33.65-84.63 %), co-aggregation (8.17-83.22 %), cell surface hydrophobicity for both polar (13.37-90.24 %) and non-polar solvents (5.52-53.58 %) and able to form biofilm (75 % weak, 16.67 % moderate and 8.33 % strong). Statistical analysis revealed the correlation pattern between the probiotic properties and showed a significant strong positive correlation between cell surface hydrophobicity and aggregation. Additionally, three isolates L. lactis, W. confusa, and E. gallinarum that were sensitive to antibiotics, able to produce biofilm, and did not contain virulence genes were able to reduce the biofilm formation of pathogen K. pneumoniae (1.3-4 log) in the co-culture assay. These Findings suggest that LAB from the raw cow milk could serve as a natural biocontrol agent for preventing and controlling K. pneumoniae biofilm formation and pave the way for innovative intervention of LAB in food safety and clinical settings.