Exploring the Antibacterial Potency of Bacteriocins

Background: Increasing antibiotic resistance has intensified the search for alternative antimicrobial agents. Bacteriocins are ribosomally synthesized antimicrobial peptides that can exhibit targeted inhibitory activity against bacteria. Objective: To assess and compare the in vitro antibacterial activity of bacteriocin extracts obtained from four Lactobacillus isolates, designated IS1, IS2, IS4, and IS6, against Salmonella typhi, Bacillus subtilis, and Streptococcus mutans. Methods: Extracts from the four isolates were evaluated using broth microdilution and microbial growth inhibition assays. Optical density measurements and inhibitory activity were assessed using a ProMax5 ELISA microplate reader (USA). Minimum inhibitory concentration (MIC) and half-maximal inhibitory concentration (IC50) values were compiled for each isolate–test organism combination. Results and conclusion: The Lactobacillus-derived extracts exhibited isolate-dependent activity against the tested Gram-positive and Gram-negative organisms. Numerical MIC and IC50 values were reported for all four isolates against B. subtilis and S. mutans, whereas the values for IS1 against S. typhi were recorded as NA. The findings support further investigation of these extracts as potential antibacterial agents; confirmation of the reported concentration values and additional characterization are necessary before therapeutic applications can be established.