Induction of salt tolerance in Lactococcus lactis ssp. cremoris by adaptation

Efforts were made to induce salt tolerance in Lactococcus lactis ssp. cremoris by adaptation (passaging) method. The object was to get the acclamatized salt tolerant culture to have desired performance even under adverse conditions for the production of more acid (lactic acid) leading to reduction in total manufacturing time and improvement in better protein digestion and palatability in cultured milk. Salt concentration ranging from 0 to 6.0% were incorporated in Elliker's broth with known concentration of cells (i.e. optical density adjusted at 0.3) and incubated at 30°C for 48 h. After the adaptation through passaging in higher salt concentration, the mutant culture was evaluated for growth, titratable acidity and proteolytic activity. The threshold value of this culture was at 3% salt concentration in Elliker's broth. Passaging of the culture led to increase in the rate of acid production by more than 25% in milk with 3% NaCl. Use of Lactococcus lactis ssp. cremoris C1-S3 (mutant culture) is recommended for commercial production of cheese as the culture is fastidious and exhibited sustained metabolic activity.