Lime pretreatment, enzymatic saccharification and fermentation of rice hulls to ethanol

✍ Scribed by Badal C. Saha; Michael A. Cotta

• Book ID: 104004399
• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 514 KB
• Volume: 32
• Category: Article
• ISSN: 0961-9534
• DOI: 10.1016/j.biombioe.2008.01.014

✦ Synopsis

Rice hulls used in this study contained 35.670.1% cellulose and 12.070.7% hemicellulose.

The maximum yield of monomeric sugars from rice hulls (15.0%, w/v) by lime pretreatment (100 mg g À1 hulls, 121 1C, 1 h) and enzymatic saccharification (45 1C, pH 5.0, 72 h) using a cocktail of three commercial enzyme preparations (cellulase, b-glucosidase and hemicellulase) at the dose level of 0.15 ml of each enzyme preparation g À1 hulls was 15471 mg g À1 (32% yield). The lime pretreatment did not generate any detectable furfural and hydroxymethyl furfural in the hydrolyzate. The concentration of ethanol from limepretreated enzyme-saccharified rice hull (138 g) hydrolyzate by recombinant Escherichia coli strain FBR5 at pH 6.5 and 35 1C in 19 h was 9.870.5 g l À1 with a yield of 0.49 g g À1 available sugars. The ethanol concentration was 11.071.0 g l À1 in the case of simultaneous saccharification and fermentation by the E. coli strain at pH 6.0 and 35 1C in 53 h.