(709d) Optimization of Ionic Liquid-Salt Aqueous Two-Phase System for Enzymatic Saccharificaation of Cellulose

Cellulose is an abundant woody biomass gaining attention as a renewable energy source. However, decomposition of cellulose involves multiple steps and large quantities of reagents. The process includes solubilization and decrystallization of cellulose using a solvent (e.g. ionic liquid (IL)), separation of cellulose from the solvent, and digestion of cellulose by cellulase to produce glucose. Aqueous two-phase systems (ATPS), though, can reduce the number of steps because the top and bottom phases can each perform different parts of the overall process. For example, [Bmim]Cl is a solvent effective for pretreatment of cellulose. On the other hand, [Bmim]Cl inhibits the activity of cellulase, an enzyme saccharifies cellulose [1]. Therefore, it is necessary to separate cellulase from [Bmim]Cl and to improve efficiency of saccharification. Aqueous two phase systems (ATPS) can be tailored to have very different properties between the top and bottom phases. Creating an IL-based ATPS can be applied to the integration of cellulose pretreatment and saccharification into "all-in-one" pot. This system will enable us to separate cellulase from [Bmim]Cl and then to carry out an enzymatic saccharification. In this study, an IL-based ATPS was prepared by using [Bmim]Cl and inorganic salts. Phase behaviors of [Bmim]Cl/salt/water systems were investigated. By using Na₂HPO₄ and NaH₂PO₄ as salt, the pH condition in the bottom phase could be controlled. The enzymatic hydrolysis reaction was also carried out. Although the bottom phase still included ILs, it is suggested that IL-based ATPS could improve the productivity of glucose.

Reference

[1] M. Yoshimoto, K. Tanimura et al., Biotechnol. Prog. 29 (2013) 1190–1196.