Antimicrobial properties of postbiotics of different LAB against multidrug resistance bacteria
It was shown the comparative antimicrobial activity of postbiotics (bacteriocins and exopolysaccharides) isolated from lactic acid bacteria (LAB) strains of genus Enterococcus and Lactobacillus against three broad panelsof human pathogens. The antimicrobial activity was assessed in a concentration-dependent manner and compared with that of conventional antibiotics. Selected and purified bacteriocins from strains of L. rhamnosus 2012 and E. faecium KE5, for which an MIC of 5 mg/mL was established against S. typhimurium G-38 via the serial dilution method, exhibited the strongest antimicrobial activity across a broad panel of pathogens when tested at this concentration using agar diffusion assays. Postbiotics displayed strain-specific inhibitory effects, highlighting their narrower antimicrobial spectrum relative to antibiotics. It was shown that conventional antibiotics demonstrated broad-spectrum efficacy against susceptible strains but known failures against multidrug-resistant (MDR) isolates. Differences in antimicrobial effects between postbiotics may depend on their interaction with the cell membrane of pathogens. These findings suggest that LAB-derived postbiotics could serve as complementary antimicrobial agents (with antibiotics or another bioactive substance), which may have applications in nutritional and preventive frameworks.