Screening and characterization of probiotic lactic acid bacteria from Korean fermented foods for functional food development

• One hundred LAB strains were isolated from Korean fermented food samples. • Four L. mesenteroides strains showed in vitro strong probiotic potential. • L. mesenteroides RP3 produced EPS, a functional bioactive exopolysaccharide. • None of the strains showed hemolytic or gelatinase production activity. • Safety and probiotic traits support the use of these strains in food applications. Fermented foods are rich sources of beneficial microbes, particularly lactic acid bacteria (LAB), which contribute to significant health benefits through their probiotic properties. This study aimed to isolate and characterize probiotic LAB from traditional Korean fermented foods, including four types of kimchi, two salted fish products, and a rice punch. One hundred LAB strains were isolated and screened for probiotic potential through in vitro assays, which assessed acid and bile tolerance, digestive enzyme resistance, cell surface properties, antimicrobial activity, stress tolerance, and extracellular enzyme production. Four of the isolated strains— Leuconostoc mesenteroides RP1, RP3, SFI6, and SS5—exhibited exceptional probiotic features, including high survival rates under gastrointestinal (GI) conditions (76.95%–77.47% at pH 2.5, 51.61%–74.04% in 0.08% bile, 46.15%–91.95% in pepsin, and 56.72%–98.76% in pancreatin); mucosal cell adhesion ability (17.82%–24.39% hydrophobicity and 16.27%–29.74% autoaggregation); strong antimicrobial activity against various pathogens (13.66–21.00 mm inhibition zones), and high stress resilience (7–8 log 10 CFU/mL). Additionally, L. mesenteroides RP3 demonstrated exopolysaccharide production, a desirable trait for food and gut health applications. The safety evaluation confirmed the absence of hemolytic and gelatinase activities, with antibiotic susceptibility profiles consistent with species-specific intrinsic resistance. The whole genome sequencing (WGS) of the strains confirmed their identity as L. mesenteroides . This study is notable for identifying novel probiotic strains from rice punch, a relatively understudied fermented beverage in probiotic research. These findings highlight the probiotic and functional potential of LAB strains derived from fermented Korean foods for use in functional food development.