Characterization of Potential Proteolytic Lactic Acid Bacteria with Probiotic Properties Isolated from Mam Products - Vietnamese Fish and Whole Shrimp Fermented Foods

Mam is a naturally fermented aquatic product from Vietnam that contains diverse lactic acid bacteria (LAB) communities. This study characterized and selected proteolytic LAB with probiotic potential isolated from four Mam sources. Among the 42 isolates, 26 were LAB, and 17 exhibited proteolytic activity (2.69–19.63 U/mg), classified into low, medium, and high groups using K-means clustering. Four promising proteolytic LABs were identified: Lactiplantibacillus pentosus S02, Lp. plantarum S12, Lp. plantarum T06, and Companilactobacillus futsaii T21. They were non-hemolytic and showed no irregular antibiotic resistance. Lp. plantarum T06 demonstrated the best bile salt tolerance (52.22% survival after 3 h), whereas Lp. plantarum S12 exhibited the best antibacterial activity against Bacillus cereus (25.07 mm). They inhibited even Gram-negative pathogens. Overall, the selected proteolytic LAB, highlighted as Lp. plantarum T06, exhibited desirable safety and probiotic properties, suggesting their potential as probiotic starters or for bioactive compound production after more in-depth safety evaluations.