Characterization and Functional Properties of Lactobacilli Isolated from Kefir Grains

As a natural, symbiotic consortium of bacteria and yeasts, kefir grains provide a unique source of new probiotic microorganisms. In this work, three new isolates of lactobacilli, Lactobacillus helveticus and two strains of Lacticaseibacillus paracasei, were isolated from kefir grains originating from the North Caucasus region of Russia, and they were identified with biochemical and genetic methods. The enzyme-activity profiles were described for all strains, and the antimicrobial resistance and genetic determinants of antibiotic resistance were screened. During fermentation of cow's milk, all three strains showed lower acid-forming activity but comparable proteolytic, antioxidant, and hypotensive activities in comparison with kefir starter culture.