Some potential beneficial properties of Lacticaseibacillus paracasei subsp. paracasei and Leuconostoc mesenteroides strains originating from raw milk and kefir grains

In this study, some potential beneficial properties and probiotic characteristics of Lacticaseibacillus paracasei subsp. paracasei and Leuconostoc mesenteroides strains were investigated in 48 isolates, which were isolated from raw cow's and sheep's milk and kefir grains. The study aimed to determine the antimicrobial properties, antibiotic resistance profiles, antioxidant properties, proteolytic activities, bile salt resistance levels, and bile salt deconjugation activities of L. paracasei and Leu. mesenteroides strains. L. paracasei strains showed a higher antimicrobial activity profile than Leu. mesenteroides strains. L. paracasei strains were not sensitive to novobiocin (5 µg) and bacitracin (10 µg), while Leu. mesenteroides ZT8 showed resistance only to polymyxin B (300 µg). L. paracasei strains showed higher antioxidant activity compared to Leu. mesenteroides strains. L. paracasei SMM1 strain showed strong growth in the presence of 0.25% bile salt, whereas Leu. mesenteroides ZT8 and Leu. mesenteroides ZX3 showed poor growth. Neither L. paracasei nor Leu. mesenteroides strains were able to develop at 0.5%–1% bile salt concentration. Bile salt deconjugation ability was lower in Leu. mesenteroides strains, and Leu. mesenteroides ZT8 produced deconjugation from taurodeoxycholic acid. It was remarkable that Leu. mesenteroides strains showed higher proteolytic activity. Leu. mesenteroides ZT8 strain showed the highest hydrophobicity. Evaluating the obtained results, it was seen that the characteristics of Leu. mesenteroides and L. paracasei strains differed according to the source and strain from which they were isolated. It was determined that both types were suitable for industrial use. NOVELTY IMPACT STATEMENT: Isolation and identification of Lacticaseibacillus paracasei subsp. paracasei and Leuconostoc mesenteroides strains derived from raw milks and kefir grains. Biochemical properties of dairy orgin L. paracasei and Leu. mesenteroides strains. Probiotic potential of L. paracasei and Leu. mesenteroides strains isolated from dairy environment.