Kinetic modeling of rapid enzymatic hydrolysis of crystalline cellulose after pretreatment by NMMO

Abstract

Pretreatment of cellulose with an industrial cellulosic solvent, N-methylmorpholine-N-oxide, showed promising results in increasing the rate of subsequent enzymatic hydrolysis. Cotton linter was used as high crystalline cellulose. After the pretreatment, the cellulose was almost completely hydrolyzed in less than 12 h, using low enzyme loading (15 FPU/g cellulose). The pretreatment significantly decreased the total crystallinity of cellulose from 7.1 to 3.3, and drastically increased the enzyme adsorption capacity of cellulose by approximately 42 times. A semi-mechanistic model was used to describe the relationship between the cellulose concentration and the enzyme loading. In this model, two reactions for heterogeneous reaction of cellulose to glucose and cellobiose, and a homogenous reaction for cellobiose conversion to glucose was incorporated. The Langmuir model was applied to model the adsorption of cellulase onto the treated cellulose. The competitive inhibition was also considered for the effects of sugar inhibition on the rate of enzymatic hydrolysis. The kinetic parameters of the model were estimated by experimental results and evaluated.

Product inhibition of cellulases studied with 14C-labeled cellulose substrates

“…In some studies, the experimental setup enabling the continuous elimination of end-products has been used [6]. The numerical values of inhibition constants have been obtained by the fitting of hydrolysis data to the complex equations derived for the full time-course [14-20]. The validity of these figures depends on the validity of the model [21].…”

Estudo Da Adsorção De Celulase Em Bagaço De Cana-De-Açúcar Pré-Tratado Durante Hidrólise Enzimática

“…Área temática: Processos Biotecnológicosconduzidos à temperatura de 4° C, pois nessa temperatura é possível estudar o fenômeno de adsorção sem a presença da hidrólise da celulose (Kumar e Wyman, 2009;Wang et al, 2011;Khodaverdi et al, 2012;Zheng et al 2013), porém a temperatura é um dos fatores que afeta o processo de adsorção (Site, 2001), assim isotermas de adsorção determinadas em temperaturas diferentes de 50° C não são adequadas para representar a hidrólise enzimática da celulose.…”

“…Muitos modelos matemáticos de hidrólise enzimática de substratos celulósicos e lignocelulósicos descrevem a etapa de adsorção por meio de isotermas como as de Langmuir e utilizam as mesmas isotermas em todos os momentos da reação (Kadam et al, 2004;Khodaverdi et al, 2012). Esta abordagem assume que as características da adsorção do sistema substrato-enzima não se alteram durante o tempo de hidrólise.…”

New lignocellulose pretreatments using cellulose solvents: a review

“…102 In it, NMMO dissolves cellulose fibers due to its high polarity N-O bond, which breaks the hydrogen bond network of the cellulose and forms new hydrogen bonds with the solute. Recent studies have shown the potential of NMMO for pretreating pure cellulose, 105 sugarcane bagasse, 106 spruce, 107 oak, 107 rice straw, 108 and poplar. 103,104 Since lignin has been shown to be a radial scavenger and antioxidant, lignocellulose can be pretreated in NMMO directly.…”