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Saccharification of kans grass biomass by a novel fractional hydrolysis method followed by co-culture fermentation for bioethanol production

Mishra, Archana, Ghosh, Sanjoy
Renewable energy 2020 v.146 pp. 750-759
Scheffersomyces, Zymomonas mobilis, biomass, coculture, ethanol, ethanol production, fermentation, grasses, hydrolysates, hydrolysis, lignocellulose, pentoses, reducing sugars, renewable energy sources, saccharification, sulfuric acid, toxicity
Present work is focused mainly on recovering maximum amount of soluble pentose and hexose sugars separately, direct from the kans grass (lignocellulosic biomass) by a novel fractional hydrolysis process (pretreatment + hydrolysis + detoxification) with minimum toxic products generation. Effect of biomass loading and preheating time on the fractional hydrolysis process was studied along with various strategies up to 30% H2SO4 (v/v) to reduce the number of stages for acid use minimisation. 84.88% of total reducing sugar present in the kans grass biomass was extracted as separate pentose and hexose sugar fractions with negligible toxics. Zymomonas mobilis and Scheffersomyces shehatae were used during co-culture fermentation; 92.13% of the sugar present in xylose-rich fraction (initial sugar: 21.87 g/L) and 96.32% of glucose-rich fraction (initial sugar: 40.32 g/L) were utilised to produce 25.0 g/L ethanol from the kans grass biomass hydrolysate; thereby achieving 78.6% of the maximum theoretical ethanol production with an average yield of 0.435.