Ethanol Production from Alkaline Peroxide Pretreated Enzymatically Saccharified Wheat Straw

Wheat straw used in this study contained 44.24 ± 0.28% cellulose and 25.23 ± 0.11% hemicellulose. Alkaline H2O2 pretreatment and enzymatic saccharification were evaluated for conversion of wheat straw cellulose and hemicellulose to fermentable sugars. The maximum yield of monomeric sugars from wheat straw (8.6%, w/v) by alkaline peroxide pretreatment (2.15% H2O2, v/v; pH 11.5; 35 °C; 24 h) and enzymatic saccharification (45 °C, pH 5.0, 120 h) by three commercial enzyme preparations (cellulase, β‐glucosidase, and xylanase) using 0.16 mL of each enzyme preparation per g of straw was 672 ± 4 mg/g (96.7% yield). During the pretreatment, no measurable quantities of furfural and hydroxymethyl furfural were produced. The concentration of ethanol (per L) from alkaline peroxide pretreated enzyme saccharified wheat straw (66.0 g) hydrolyzate by recombinant Escherichia coli strain FBR5 at pH 6.5 and 37 °C in 48 h was 18.9 ± 0.9 g with a yield of 0.46 g per g of available sugars (0.29 g/g straw). The ethanol concentration (per L) was 15.1 ± 0.1 g with a yield of 0.23 g/g of straw in the case of simultaneous saccharification and fermentation by the E. coli strain at pH 6.0 and 37 °C in 48 h.

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