Bioconversion of Saccharum spontaneum (wild sugarcane) hemicellulosic hydrolysate into ethanol by mono and co-cultures of Pichia stipitis NCIM3498 and thermotolerant Saccharomyces cerevisiae-VS 3

Abstract

The lignocellulosic biomass is a low-cost renewable resource for eco-benign liquid fuel 'ethanol'. To resolve the hydrolysis of mixed sugars in lignocellulosic substrate Saccharum spontaneum, the microbial co-cultures of Pichia stipitis NCIM 3498 and thermotolerant Saccharomyces cerevisiae-VS(3) were analyzed for efficient bioconversion of mixed sugars into ethanol. Among the hydrolysis conditions, the acid hydrolysis released maximum sugars along with furans, phenolics and acetic acid. The acidic hydrolysate was detoxified and fermented by monocultures of P. stipitis NCIM3498 (P.S.) and thermotolerant S. cerevisiae VS(3) (S.C.), and co-culture of P.S. (7.5 mL) and S.C. (2.5 mL). Before the fermentation of hemicellulose acid hydrolysate, both the monocultures (P.S. and S.C.), and varying ratios of P.S. and S.C. microorganisms in co-cultures #1, #2 and #3 were grown on simulated synthetic medium. The ethanol yield from monocultures of P.S. (0.44 ± 0.021 g/g), S.C. (0.22 ± 0.01 g/g) and co-culture #3 (0.49 ± 0.02 g/g) revealed unique characteristics of each mono and co-culture technology. The fermentation of hemicellulose acid hydrolysate with monocultures of P.S., S.C. and co-culture #3 produced 12.08 ± 0.72 g/L, 1.40 ± 0.07 g/L, and 15.0 ± -0.92 g/L ethanol, respectively.