Construction of Heterogeneous Thermal Biocatalytic System for High-Performance Cellulosic Ethanol Production

Abstract

As a renewable energy source, cellulosic ethanol has excellent prospects which can help to break our dependence on fossil fuels. Simultaneous saccharification and fermentation (SSF)is the most appealing strategy for producing cellulosic ethanol. However, for the SSF process, the disparity between the optimal temperatures for cellulases (50°C) and yeasts (30°C) hinders the efficacy of SSF. Herein, the composite material of 2D titanium carbon nanosheets (Ti3C2Tx) and graphene oxide (GO), having excellent photothermal conversion efficiency, was used as the carrier for cellulase immobilization. This composite material served as the central component of the heterogeneous thermal SSF system. Under light irradiation, the SSF reaction between cellulases and yeasts at the optimal temperature was accomplished by controlling the temperature differential between the microenvironment around the immobilized enzyme and overall system temperature such that the immobilized cellulase can always demonstrate the highest activity between 30 and 50°C. Furthermore, compared to the typical SSF system, the ethanol yield of the heterogeneous thermal SSF system was largely increased by 18.5%. Thus, for promoting the industrial use of cellulosic ethanol, this strategy is extremely beneficial.

Keywords: Cellulosic ethanol, simultaneous saccharification and fermentation, Ti3C2Tx, photothermal conversion