Probiotic Potential of Lactic Acid Bacteria in Traditional Dairy Products: An In Vitro Assessment

The probiotic properties of lactic acid bacteria (LAB) vary depending on the specific strain. This study aimed to evaluate the probiotic potential of LAB present in traditional dairy products using in vitro techniques.

Bacterial isolates from 63 artisanal dairy product samples, which included 6 kefir, 22 cheese, and 35 yogurt products, were analyzed. The isolates were subjected to tests for acid resistance, bile tolerance, antibiotic resistance, acidification capacity, hydrophobicity, exopolysaccharide (EPS) production, and antimicrobial activity. The isolates that gave positive results in these analyses were subsequently identified through 16S rRNA gene sequencing.

The survival rates of the 93 isolates decreased significantly as the pH level lowered (p < 0.05), resulting in 76 isolates being classified as acid-resistant. The identical isolates also demonstrated tolerance to high concentrations of bile. Out of these, only 37 isolates were sensitive to all 12 antibiotics tested, while each isolate had varying levels of acidification capacity. Eight of these 37 isolates, which showed negative hydrophobicity ratios, were eliminated from further testing. All 29 remaining isolates exhibited EPS production, but only 17 showed an inhibitory effect against the selected pathogenic bacteria. Molecular identification of these 17 isolates revealed that 6 were Lactobacillus (Lact.) paracasei, 3 were Lact. crustorum, 2 were Lact. brevis, 2 were Lact. casei, 1 was Lact. plantarum, 1 was Lact. pentosus, 1 was Lact. helveticus, and 1 was Lact. rhamnosus.

The findings indicated that LAB strains naturally present in traditional dairy products possess significant probiotic characteristics. The direct use of the isolated strains in the development of functional foods and supplements within the local industry could contribute to the conservation and enhancement of the country's biodiversity and regional economic value. It is recommended that further comprehensive research be conducted to explore their potential for production and use as dietary supplements for humans.