Screening of Probiotic Lactic Acid Bacteria Isolated from Fermented Pak-Sian for Use as a Starter Culture.

The objective of this research was to evaluate the probiotic properties of lactic acid bacteria (LAB) isolated from fermented Pak-Sian, a traditional Thai food in the northeastern region of Thailand (Kalasin, Sakon Nakhon, Maha Sarakham, and Khon Kaen Provinces). A total of 61 LAB isolates isolated from selective MRS agar were screened by SDS-PAGE and identified by 16S rDNA analysis. Seventeen bacterial strains were found consisting of Pediococcus pentosaceus (6 strains) Lactiplantibacillus plantarum (5 strains), Levilactobacillus brevis (1 strain), Lactobacillus fermentum (3 strains), and Weissella cibaria (2 strains). A PH tree grouped 17 LAB strains into 5 clusters with three clusters only recorded from Sakon Nakhon Province. All strains were tested for probiotic properties. Results showed that 14 strains had the ability to resist pH 2.5 as resistant to bile salts and survive in gastric juices and the intestinal tract. LAB demonstrated antimicrobial activity against 4 pathogens: Staphylococcus aureus TISTR746, Salmonella typhimurium TISTR1472, Escherichia coli ATCC25922, and Bacillus cereus TISTR1449. Most LAB strains were resistant to all antibiotics tested, while some Lactobacillus strains were moderately susceptible to chloramphenicol, rifampicin, and ampicillin. None of the 14 strains produced biogenic amine and eight showed no hemolysis activity, indicating the safety of these strains. These 8 strains were selected to determine mucin adhesion capacity. Lactobacillus fermentum SK324 and Levilactobacillus brevis SK335 showed the highest adhesion capacity of 2.39 and 2.34%, respectively. These two strains showed promise as alternative starter cultures to improve probiotic health benefits of local fermented Pak-Sian products as a functional food.