Decoding the Applications of Microbial Metabolites: Insights into the Antibacterial Potential of Lactobacillus acidophilus Postbiotics.

Postbiotics, bioactive metabolites produced by probiotic bacteria, have garnered attention for their diverse health benefits, particularly their antimicrobial properties. This study evaluates the antibacterial efficacy of lactic acid bacteria (LAB), selecting Lactobacillus acidophilus postbiotics as the most effective against various pathogenic microorganisms, and focusing on their potential use in topical formulations. In vitro assays were conducted to assess their antimicrobial activity, including minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), well diffusion assay, antibiofilm activity, preservative effectiveness testing, and time-kill assay. The L. acidophilus postbiotic, was identified and quantified by a validated HPLC method, effectively inhibited the growth of Escherichia coli, Staphylococcus aureus, Candida albicans, Pseudomonas aeruginosa, and Aspergillus niger. Furthermore, the formulation containing postbiotics exhibited self-preservative properties. The study also highlights distinct antibacterial effects against Corynebacterium acnes in supernatant, lyophilized, and spray-dried models, with the lyophilized form exhibiting the greatest antimicrobial activity. Based on these results, L. acidophilus postbiotics are a promising candidate for topical applications. They may serve as supportive or complementary components to existing antibiotics and preservative systems, pending further validation.