Isolation, identification and potential probiotic characterization of lactic acid bacteria from Thai traditional fermented food

The probiotic potential of lactic acid bacteria (LAB) isolated from Thai traditional fermented food was investigated. Forty-two samples were collected from four markets in Phra Nakhon Si Ayutthaya Province. Out of 50 isolated LAB, 6 (a3, f4, f8, K1, K4 and K9) obtained from pla-ra and bamboo shoot pickle samples showed high tolerance to gastrointestinal tract conditions. These isolates were selected to identify and characterize their probiotic properties. Isolate a3 was identified as Weissella thailandensis, isolates f4 and f8 were identified as belonging to Enterococcus thailandicus and isolates K1, K4 and K9 were determined as Limosilactobacillus fermentum. All six LAB exhibited high autoaggregation ability (93.40–95.01%), while W. thailandensis isolate a3 showed potential for coaggregation in almost all the pathogenic bacteria tested. Cell-free supernatant (CFS) obtained from all isolates did not inhibit Staphylococcus aureus. CFS derived from L. fermentum isolate K4 showed the most efficient antimicrobial activity, in particular against Gram-negative bacteria, while L. fermentum isolate K4 presented high surface hydrophobicity in the presence of xylene and n-hexane. All LAB isolates were found to be resistant to clindamycin and nalidixic acid, whereas E. thailandicus isolate f8 exhibited resistance to most of the antibiotics tested. L. fermentum isolate K4 showed promise as a suitable probiotic candidate for future applications in the food industry due to tolerance to gastrointestinal tract conditions with high surface hydrophobicity and inhibited most of the pathogens tested.