A Single Key for Many Doors? Unlocking the Bio-chemical Potential of Lactobacillus bulgaricus Metabolic Postbiotic.

Postbiotics, defined as bioactive compounds derived from probiotics, have gained increasing attention for their potential health benefits. In this study, we investigated the bio-chemical properties and antimicrobial activities of Lactobacillus bulgaricus postbiotics. The postbiotics exhibited antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus with the MIC values of 50, 50, and 100 mg/mL, respectively. Antifungal assessments demonstrated growth inhibition of Candida species with the MIC ranged from 32 to 128 mg/mL and MIC ranged from 128 to 256 mg/mL as well as Aspergillus species with the MIC of 64 mg/mL and MIC of 128 mg/mL. The postbiotic showed no antiviral effects against SA-11 rotavirus at non-cytotoxic concentrations, and moderate antioxidant properties with a DPPH IC of 2.75 mg/mL, which was significantly weaker than quercetin. The postbiotic's chemical composition revealed high levels of acetic acid, lactic acid, and little amount of 3-phenyllactic acid, contributing to its antimicrobial effects. Additionally, biosurfactants present in the postbiotic exhibited hemolytic activity and potential antimicrobial effects. Cytotoxicity analysis on NIH/3T3 cell line revealed that concentrations below 50 mg/mL were non-toxic, whereas higher concentrations showed adverse effects on cell viability. Despite demonstrating significant bioactivity, our findings emphasize the necessity to modulate expectations regarding postbiotics. They hold promise as functional agents but exhibit moderate effects rather than extreme bioactivity. This study underscores the need for further research to optimize postbiotic applications in food and pharmaceutical industries.