Assessing lactococcal and enterococcal strains derived from traditionally fermented kefir and nabeez for their prospects as probiotics

Consumers' healthy lifestyle practices have heightened the appeal of minimally processed foods, especially the fermented kind. Kefir and nabeez with numerous benefits are world-famous beverages. This study aimed to explore the enterococcal and lactococcal probiotic strains associated with these beverages. Artisanal recipes were used to make kefir and nabeez, and bacteria were isolated using classical culturing techniques. The isolates were screened based on antimicrobial potential, safety and probiotic attributes. The bacterial isolates obtained from three fermented beverages, milk kefir, water kefir and nabeez, were assessed for safety concerns, and those deemed safe were tested for antagonistic potential. Strains of Enterococcus durans (NPL1395 MK , NPL1396 MK and NPL1480 MK ), Enterococcus faecium (NPL1390 MK , NPL1420 WK and NPL1427 Nb ) and Lactococcus lactis (NPL1426 Nb , NPL1428 Nb and NPL1436 Nb ) demonstrated interesting antimicrobial characteristics against food-borne pathogens. Strains from milk kefir and nabeez could tolerate strong acidic and bile stress. All strains were susceptible to lysozyme and phenol at the concentrations tested but demonstrated significant antioxidant potentials, exopolysaccharide production and bile salt hydrolase activities. Cholesterol assimilation was most significant in milk kefir and nabeez strains, which also had good adherence and biofilm formation. Statistical analysis of performance data using the principal component analysis identified L. lactis strain NPL1428 Nb as the best. It exhibited good potential to persist in the human gut based on its ability to tolerate in vitro mixtures simulating the gastrointestinal tract digestive fluids, using the static digestion model. Therefore, strain NPL1428 Nb of traditional fermented beverage provenance has good prospects for use in probiotic product development.