Evaluation of Nanoparticle-Immobilized Cellulase for Improved Ethanol Yield in Simultaneous Saccharification and Fermentation Reactions

TitleEvaluation of Nanoparticle-Immobilized Cellulase for Improved Ethanol Yield in Simultaneous Saccharification and Fermentation Reactions
Publication TypeJournal Article
Year of Publication2011
AuthorsLupoi JS, Smith EA
Journal TitleBiotechnology and Bioengineering
Volume108
Pages2835-2843
Date Published12
Type of ArticleArticle
ISBN Number0006-3592
Accession NumberWOS:000296703300006
Keywordsadsorption, beta-glucosidase, biofuels, biomass, cellulase, cellulose, endoglucanase, enzymatic hydrolysis, enzymatic-hydrolysis, enzyme immobilization, polystyrene, reesei cbhi cellulase, silanized silica, simultaneous saccharification and fermentation, stability, thermomonospora-fusca e-5
Abstract

Ethanol yields were 2.1 (P = 0.06) to 2.3 (P = 0.01) times higher in simultaneous saccharification and fermentation (SSF) reactions of microcrystalline cellulose when cellulase was physisorbed on silica nanoparticles compared to enzyme in solution. In SSF reactions, cellulose is hydrolyzed to glucose by cellulase while yeast simultaneously ferments glucose to ethanol. The 35 degrees C temperature and the presence of ethanol in SSF reactions are not optimal conditions for cellulase. Immobilization onto solid supports can stabilize the enzyme and promote activity at non-optimum reaction conditions. Mock SSF reactions that did not contain yeast were used to measure saccharification products and identify the mechanism for the improved ethanol yield using immobilized cellulase. Cellulase adsorbed to 40 nm silica nanoparticles produced 1.6 times (P = 0.01) more glucose than cellulase in solution in 96 h at pH 4.8 and 35 degrees C. There was no significant accumulation (<250 mu g) of soluble cellooligomers in either the solution or immobilized enzyme reactions. This suggests that the mechanism for the immobilized enzyme's improved glucose yield compared to solution enzyme is the increased conversion of insoluble cellulose hydrolysis products to soluble cellooligomers at 35 degrees C and in the presence of ethanol. The results show that silica-immobilized cellulase can be used to produce increased ethanol yields in the conversion of lignocellulosic materials by SSF. Biotechnol. Bioeng. 2011; 108: 2835-2843. (C) 2011 Wiley Periodicals, Inc.

DOI10.1002/bit.23246
Alternate JournalBiotechnol. Bioeng.