Identification and Probiotic Characterization of Lactiplantibacillus pentosus Isolated from Pla-som, A Traditional Thai Fermented Fish of Phayao Province, Thailand

Pla-som is a product from traditional food preservation method that has grown to become a popular product in Thailand's Phayao Province. In the current study, lactic acid bacteria (LAB) were isolated and assessed for their probiotic properties. A total of 20 isolates were selected and based on morphological and some biochemical testing. Among these, 2 strains, PY13 and PY 41, were able to survive at pH 2.0, 7% NaCl and 0.3% bile salt conditions. These strains were further evaluated for antibiotic susceptibility, antagonistic activity, hemolysis activity, aggregation activities and β-galactosidase production. The results showed that both strains possessed an aggregation activity, β-galactosidase, non-hemolysis activity, and inhibition to the growth of Gram-positive (Staphylococcus aureus and Enterococcus faecalis) and Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa). The antibiotic susceptibility test showed susceptibility to most tested antibiotics except for vancomycin and ciprofloxacin. The selected LAB strains were identified by 16S rRNA sequencing as Lactiplantibacillus pentosus. The study demonstrated the probiotic potential of isolated LAB strains, suggesting that they might be used as food products and dietary supplements