Probiotic Potential and Quorum Quenching Activity of Lactic Acid Bacteria Isolated from Indigenous Fermented Foods

Abstract

Objectives: The present study isolate lactic acid bacteria (LAB) from diverse traditional Indian fermented foods and evaluate their functional probiotic potential by assessing probiotic attributes, safety profiles and quorum-quenching (QQ) activity. Materials and Methods: Fifteen LAB strains were isolated from indigenous Indian fermented foods. The isolates were evaluated for gastrointestinal tolerance through simulated stress tests involving mild (pH 4.0) to extreme (pH 2.0) acidic conditions and 0.5% bile salts. Functional assays assessed colonisation potential through cell surface hydrophobicity and auto-aggregation. Safety was evaluated using haemolysis assays and susceptibility testing against clinically relevant antibiotics targeting cell-wall and protein synthesis. Crude secondary metabolite extracts were screened for QQ activity using a Chromobacterium violaceum biosensor by measuring inhibition of violacein production. Results: All 15 isolates survived simulated gastrointestinal stress under pH 4.0 and 0.5% bile salt conditions. Strain JUFB showed the highest overall survival, including under extreme acid stress (pH 2.0), and exhibited the greatest cell surface hydrophobicity and auto-aggregation, indicating stronger colonisation-associated potential. Safety assessment confirmed that all isolates were non-haemolytic (γ-haemolysis) and susceptible to the tested antibiotics. Crude extracts from JUFF, JUBM and JUFB showed quorum-quenching activity by inhibiting violacein production in the C. violaceum biosensor without evident bactericidal effects. Conclusion: The evaluated LAB isolates, particularly JUFB, demonstrated favourable in vitro probiotic viability and preliminary safety attributes. Their quorum-quenching activity suggests potential for disrupting bacterial communication and supports further investigation of selected isolates and metabolites for anti-virulence and anti-biofilm applications.