In-vitro evaluation of probiotics isolated from traditionally fermented South Indian rice varieties using earthen pot

An increasing demand for health-promoting foods beyond their nutrients and taste has led to a rise in recognition of probiotic rich fermented food. In this study, the probiotic bacteria isolated from three varieties of traditionally fermented rice water were identified using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Upon identification, the isolates were characterized for their probiotic properties by evaluating their tolerance ability towards low pH, gastric juice, bile, and haemolytic activity. Four different probiotic species belonging to the Lactic Acid Bacteria (LAB) group were grown during fermentation, namely, Lactococcus lactis, Lactococcus taiwanensis, Lactococcus lactis ssp. lactis, and Lactococcus lactis ssp. tructae. All the isolates showed a higher survival rate at pH 3.0 and 0.3% bile. In simulated gastric juice at pH 2.5, the Lactococcus lactis (36.33%) from raw rice survived up till 60 min. The isolates from raw rice and parboiled white ponni rice maintained survivability in gastric juice at pH 3.0 for 15 min, whereas Lactococcus lactis from raw rice has a better tolerance for up to 60 min. Furthermore, the absence of β-haemolytic activity ensures the avirulent nature of the strain. Therefore, fermented rice water enriched in probiotics will improve the intestinal flora with beneficial bacteria via a symbiotic relationship.