(754g) Effects of Ionic Liquids and Liposomes on Enzymatic Cellulose Hydrolysis Process

The heterogeneous system of cellulose reaction suffers from irreversible adsorption of the enzyme molecules to solid substrate, which is recognized as one of the mechanisms responsible for the enzyme deactivation and decreasing accessible surface area of the substrate. Ionic liquids (ILs) decrease the crystallinity of cellulose, whereas IL treatment usually decrease the enzymatic activity of cellulose. Here, the effect of liposome membranes on cellulase from Trichoderma viride was studied in the presence or absence of ILs. The liposomal cellulase and free enzyme were examined in their hydrolytic activities to insoluble cellulose powder CC31 in the acetate buffer solution (pH 4.8) of 15 w/w% [Bmim][Cl] (1-butyl-3-methylimidazolium chloride). The mean diameter and size distribution of cellulase-containing liposome were practically unchanged under the above condition. In the saccharification reaction of insoluble cellulose, the localization of cellulase and liposome was found to be important, because the cellulase dispersed in liposome suspensions resulted higher activity than that conjugated into liposomes. The activities of liposomal and free cellulase to cellobiose as soluble substrate were less susceptible to [Bmim][Cl] than their cellulolytic activities to CC31, meaning that β-glucosidase is relatively stable among the three enzyme components of cellulase. The rate of glucose production could be appreciably improved by the pretreatment of CC31 with [Bmim][Cl] alone at 120°C for 30 min followed by the liposomal cellulase-catalyzed hydrolysis of the substrate at 45°C at the [Bmim][Cl] concentration of 15 w/w% [1]. In addition, the coexistence of liposomes prevented deactivations of enzymes in the presence of [Bmim][Cl].

[1] K. Tanimura et al., Hydrolysis of insoluble cellulose to glucose catalyzed by cellulase-containing liposomes in an aqueous solution of 1-butyl-3-methylimidazolium chloride. Biotechnol. Prog. 2013, 29, 1190–1196.