Characterization of commercial cellulases and their use in the saccharification of a sugarcane bagasse sample pretreated with dilute sulfuric acid |
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Authors: | Santos Victor T O Esteves Paula J Milagres Adriane M F Carvalho Walter |
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Institution: | 1.Department of Biotechnology, School of Engineering of Lorena, University of São Paulo (USP), Estrada Municipal do Campinho, s/n°, P.O. Box 116, 12602-810, Lorena, SP, Brazil ; |
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Abstract: | This study aimed to correlate the efficiency of enzymatic hydrolysis of the cellulose contained in a sugarcane bagasse sample
pretreated with dilute H2SO4 with the levels of independent variables such as initial content of solids and loadings of enzymes and surfactant (Tween
20), for two cellulolytic commercial preparations. The preparations, designated cellulase I and cellulase II, were characterized
regarding the activities of total cellulases, endoglucanase, cellobiohydrolase, cellobiase, β-glucosidase, xylanase, and phenoloxidases
(laccase, manganese and lignin peroxidases), as well as protein contents. Both extracts showed complete cellulolytic complexes
and considerable activities of xylanases, without activities of phenoloxidases. For the enzymatic hydrolyses, two 23 central composite full factorial designs were employed to evaluate the effects caused by the initial content of solids (1.19–4.81%,
w/w) and loadings of enzymes (1.9–38.1 FPU/g bagasse) and Tween 20 (0.0–0.1 g/g bagasse) on the cellulose digestibility. Within
24 h of enzymatic hydrolysis, all three independent variables influenced the conversion of cellulose by cellulase I. Using
cellulase II, only enzyme and surfactant loadings showed significant effects on cellulose conversion. An additional experiment
demonstrated the possibility of increasing the initial content of solids to values much higher than 4.81% (w/w) without compromising
the efficiency of cellulose conversion, consequently improving the glucose concentration in the hydrolysate. |
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