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Title: Fuel ethanol production from microwave pretreated wheat straw

Author
item Saha, Badal
item Biswas, Atanu
item Cotta, Michael

Submitted to: UJNR Food & Agricultural Panel Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 8/24/2008
Publication Date: 8/24/2008
Citation: Saha, B.C., Biswas, A., Cotta, M.A. 2008. Fuel ethanol production from microwave pretreated wheat straw. Proceedings of the United States-Japan Cooperative Program in Natural Resources Food and Agriculture Panel 37th Annual Meeting, August 24-28, 2008, Chicago, Illinois. p. 46-47.

Interpretive Summary:

Technical Abstract: The effects of temperature (160-240 deg C, 5 min) and duration (5-20 min at 200 deg C) of microwave pretreatment of wheat straw (8.6%, w/v, in water) on its enzymatic saccharification to fermentable sugars were evaluated. The yield of monomeric sugars from microwave (200 deg C, 10 min) pretreated wheat straw (8.6%, w/v, in water) after enzymatic saccharification (45 deg C, pH 5.0, 120 h) using a cocktail of 3 commercial enzyme preparations (cellulase, beta-glucosidase, and hemicellulase) at the dose level of 0.15 ml of each enzyme preparation per g wheat straw was 544±7 mg/g straw (glucose, 320±14 mg; xylose, 189±7 mg; arabinose, 21±1 mg; galactose, 10±0 mg; 70% yield). In addition, the hydrolyzate contained 2.9±1.6 mg furfural, 0.3±0 mg hydroxymethyl furfural, and 60±8 mg acetic acid per g of straw. The maximum release of sugars (651±7 mg/g straw, 84% yield) from wheat straw after enzymatic hydrolysis was obtained by microwave pretreatment in dilute acid (0.5% H2SO4, w/v,) at 160 deg C for 10 min. Microwave pretreatment of wheat straw with lime (0.1 g/g straw) at 160 deg C for 10 min released 604±30 mg total sugars/g straw (78% yield) after enzymatic hydrolysis. The concentration of ethanol from microwave pretreated (200 deg C, 10 min, in water) and enzyme saccharified (45 deg C, pH 5.0, 120 h) wheat straw (78 g/L) hydrolyzate after overliming by recombinant Escherichia coli strain FBR5 at pH 6.5 and 35 deg C in 40 h was 16.8±0.1 g/L with a yield of 0.49 g/g available sugars (0.22 g/g straw). The ethanol concentration was 16.7±1.5 g/L with a yield of 0.21 g/g straw in the case of simultaneous saccharification and fermentation of microwave pretreated (200 deg C, 10 min, in water) wheat straw (78 g/L) after overliming by the E. coli strain at pH 6.0 and 35 deg C in 69 h.