Modelagem da reação de hidrólise enzimática de substrato celulósico

Abstract

Several studies were developed in this work to produce alternative kinetic models of enzymatic hydrolysis with respect to the characteristics of the substrate. First, the most appropriate methodology for calculating the crystallinity index of a mixture of crystalline and amorphous celluloses was determined, in addition to generating materials with specific characteristics of amorphous and crystalline content from cellulose pretreatments. The pretreatment with planetary ball mill for 2:30 h at 400 rpm and ionic liquid ([EMIM][OAc]) at 120°C/120 min generated different materials with unique properties of particle size, crystallinity, morphology, and surface area that significantly influenced its hydrolysis by enzymatic extracts Celluclast 1.5L and Novozymes N188. Additionally, the adsorption isotherm of Celluclast 1.5L was obtained, but not for the laboratory extract of Aspergillus awamori. Two kinetic models admitted different characteristics of the reaction system for the enzymes and the substrate, whose parameters were estimated using experimental data from the literature. In the cellulose model in one phase, it was described the system containing cellulase and cellobiase, adsorbable and inhibitable, and conversion to glucose strictly hydrolyzing cellobiose. In the two-phase cellulose model, a higher hydrolytic rate was found in the degradation of amorphous cellulose on crystalline, as well as higher adsorption and stronger inhibition of cellulases catalyzing amorphous cellulose. By the developed models and experimental data on modified cellulose, the influence of pure cellulose structural characteristics on its kinetic was expanded.