Comprehensive Evaluation of Safety, Functional Properties, and Immunomodulatory Activity of 19 Probiotic Strains Approved by the Ministry of Food and Drug Safety (MFDS).

The Ministry of Food and Drug Safety (MFDS) has approved 19 probiotic strains for use as functional food ingredients. Although the characteristics of individual strains have been previously reported, a comprehensive evaluation of all 19 MFDS-approved probiotic strains under a unified experimental framework has not yet been conducted. Therefore, this study systematically assessed the safety, probiotic properties, and immunomodulatory activity of the 19 MFDS-approved strains. Cytotoxicity, bile salt hydrolase (BSH) activity, D-lactate production, tolerance to simulated gastrointestinal tract (GIT) conditions, adhesion capacity, and immunomodulatory activity were evaluated. All strains showed no cytotoxicity toward Caco-2 cells. BSH activity was detected in 14 strains, whereas D-lactate production (1.14-28.88 mM) was observed only in Lactobacillaceae strains. The strains exhibited a broad range of GIT tolerance, with survival rates ranging from 23.55% to 95.58%. Lactobacillus gasseri, Bifidobacterium animalis subsp. lactis, and Bifidobacterium breve showed high survival rates (>80%), whereas Bifidobacterium bifidum and Streptococcus thermophilus exhibited relatively low tolerance (<40%). Adhesion capacity was generally similar among strains (59.84~87.82%), although B. bifidum showed the highest adhesion rate (87.82%). In contrast, Enterococcus faecium and Bifidobacterium longum subsp. longum exhibited relatively low adhesion capacities. Furthermore, 14 strains modulated immune responses in LPS-stimulated RAW 264.7 cells by regulating TNF-α and IL-6 secretion. Collectively, these findings demonstrate the overall safety and strain-specific functional properties of the 19 MFDS-approved probiotic strains and provide fundamental information for selecting suitable candidates for targeted probiotic applications.