Alkaline Peroxide Pretreatment of Corn Stover for Enzymatic Saccharification and Ethanol Production

Abstract

Abstract Alkaline hydrogen peroxide (AHP) pretreatment and enzymatic saccharification were evaluated for conversion of corn stover cellulose and hemicellulose to fermentable sugars. Corn stover used in this study contained 37.0±0.2% cellulose, 26.8±0.2% hemicellulose, and 18.0±0.1% lignin on dry basis. Under the optimum conditions of AHP pretreatment [2% H2O2 (v/v), pH 11.5, 35°C, 24 h] of corn stover (10%, w/v) and enzymatic saccharification (45°C, pH 5.0, 72 h) with 0.1% (w/v) Tween 20, a total of 558±12 mg of fermentable sugars was obtained per g stover, which is equivalent to 79.5% of theoretical sugar yield. Most of the lignin (82%) was removed from corn stover. The AHP pretreated and enzymatically saccharified corn stover hydrolyzate was fermented by recombinant Escherichia coli strain FBR 5 at pH 6.5 and 37°C for 96 h to produce 23.9±0.9 g ethanol from 56.6±1.6 g total sugars per L with an ethanol yield of 0.42 g/g available sugars and 0.24 g/g corn stover, which is equivalent to 67% of theoretical...