Enhanced ethanol production through salt pre-conditioning of S.cerevisiae MTCC 11815

Salt preconditioning provides an alternate to very high gravity fermentation for increasing osmotolerance and thermotolerance of yeast. In the current study, a fermenting yeast strain (Saccharomyces cerevisiae MTCC 11815) was sequentially preconditioned at 4% (w/v) NaCl in a synthetic medium and optimized using RSM on the basis of osmotolerance and thermotolerance for maximum ethanol production. A maximum ethanol of 12.53% (v/v) was observed at a temperature of 35ºC with high residual Brix of 17°B from initial 39°B. Further, ethanol fermentation carried out between 20 to 30°B revealed 24°B as optimum with an ethanol production of 12.4% (v/v) and residual brix of 3.5°B. Validation studies on sugarcane juice as well as on molasses (10L) recorded the optimized fermentation parameters (Brix 24°B, Inoculum size 7.5% (v/v) and DAHP 0.3% (w/v)) with ethanol production of 12.4% (v/v) on sugar cane juice and 10.6% (v/v) on molasses having fermentation efficiencies of 86.10% and 81.20% by pre-conditioned S.cerevisiae MTCC 11815 cells.