Probiotic characteristics and survival of a multi-strain lactic acid bacteria consortium in simulated gut model.

Abstract

Dahi, a traditional yet underexplored fermented milk product from Pakistan, harbors diverse lactic acid bacteria (LAB) that have potential as probiotics. These bacteria could be used for therapeutic purposes, beneficial modulation of gut microbiota, and in the formulation of functional foods and feeds. This study aimed to isolate and characterize probiotic LAB from dahi, assess their survival in simulated gastrointestinal conditions, and evaluate their safety and probiotic potential, both phenotypically and genotypically. A total of 143 isolates from 37 samples were evaluated for probiotic traits, including acid and bile tolerance, antibacterial activity, cholesterol-lowering capacity, and antioxidant activity. The strains were also tested for antibiotic sensitivity and safety through in vitro tests and genomic analysis. A multi-strain probiotic consortium was developed and tested for enhanced functionality. Out of 143 isolates, 62 LAB strains were identified. These strains demonstrated significant survival under acidic (pH 2) and bile conditions. Antibacterial activity against pathogens ranged from 51 to 88%. The strains exhibited high cholesterol removal (up to 98%) and antioxidant activity (up to 76%). Genomic analysis revealed the presence of key probiotic-related genes, including those for acid resistance, bile salt hydrolase, and adhesion. All strains were sensitive to EFSA-recommended antibiotics and exhibited no hemolytic or DNase activity, confirming their safety. The multi-strain consortium showed superior probiotic potential and survival in simulated gastrointestinal conditions. LAB strains isolated from dahi possess strong probiotic potential, confirmed through in vitro and genomic safety assessments. The multi-strain consortium holds promise for applications.