Characterization of commercial cellulases and their use in the saccharification of a sugarcane bagasse sample pretreated with dilute sulfuric acid

Abstract

This study aimed to correlate the efficiency of enzymatic hydrolysis of the cellulose contained in a sugarcane bagasse sample pretreated with dilute H(2)SO(4) 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 2(3) 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.

Evaluation and Selection of Potential Biomass Sources of North-East India towards Sustainable Bioethanol Production

“…Similarly, cellulose conversion range between 27.5 and 47.7% and 15.9 and 48.8% was obtained by employing two enzyme preparations cellulase I and cellulase II, respectively, during 24 h hydrolysis (Santos et al, 2011). Although the hydrolytic efficiency of the biomasses of our study appears to be lower than those reported earlier, it is difficult to make direct comparisons as appropriate enzyme loading and hydrolytic conditions also affect sugars recovery from the substrates (Zhu et al, 2008;Rezende et al, 2011).…”

Variedades híbridas de bagaço de cana-de-açúcar: caracterização química e hidrólise enzimática em condições de pré-tratamento difrenciadas

“…Apresenta grande importância na sacarificação da biomassa, uma vez que a presença de celobiose pode inibir a ação enzimática das endo e exoglucanase (DHILLON et al, 2011;SANTOS et al, 2011). …”

Efeito da lignina de bagaços de cana-de-açúcar pré-tratados na hidrólise enzimática da celulose

“…O teor desses componentes varia bastante entre diferentes amostras de bagaço, como consequência das características genotípicas da cana-de-açúcar, das condições de cultivo, dos métodos de colheita e estocagem do bagaço (HAMES et al, 2003 ESTEVES, 2011;MENDES et al, 2011;SANTOS et al, 2011;SIQUEIRA et al, 2013). Além desses componentes, o bagaço de cana pode conter cinzas, que podem chegar 4,0% da massa total do bagaço, e extrativos, compostos não estruturais, cujos teores podem variar de 4,0 % a 9,0%, dependendo, inclusive, do método analítico utilizado (CANILHA et al, 2011;MILNE et al, 1992;SEABRA et al, 2010;TEMPLETON et al, 2010 WEGENER, 1983a;SAHA, 2003).…”

“…Além desses substituintes, grupos acetila e ácidos hidroxicinâmicos (ferúlico e cumárico) também são encontrados (WENDE; FRY, 1997). (LEE et al, 2009;SIQUEIRA et al, 2011SIQUEIRA et al, , 2013 (KANG et al, 2013;SANTOS et al, 2011;TOQUERO;BOLADO, 2014).…”

“…O pré-tratamento com ácido sulfúrico diluído tem sido amplamente utilizado, principalmente no processamento de gramíneas, com relativo sucesso (CANILHA et al, 2011;CASTRO;HSU et al, 2010;ISHIZAWA et al, 2007;SANTOS et al, 2011;WYMAN, 2004 essas gotículas são forçadas para fora da parede celular, alterando a sua distribuição topoquímica na biomassa pré-tratada (DONOHOE et al, 2008;CHENG, 2002). A figura 9 ilustra o comportamento da lignina nessas condições.…”