Biotechnology and Bioengineering, Vol.115, No.12, 2859-2868, 2018
Direct conversion of cellulose into ethanol and ethyl-beta-d-glucoside via engineered Saccharomyces cerevisiae
Simultaneous saccharification and fermentation (SSF) of cellulose via engineered Saccharomyces cerevisiae is a sustainable solution to valorize cellulose into fuels and chemicals. In this study, we demonstrate the feasibility of direct conversion of cellulose into ethanol and a biodegradable surfactant, ethyl-beta-d-glucoside, via an engineered yeast strain (i.e., strain EJ2) expressing heterologous cellodextrin transporter (CDT-1) and intracellular beta-glucosidase (GH1-1) originating from Neurospora crassa. We identified the formation of ethyl-beta-d-glucoside in SSF of cellulose by the EJ2 strain owing to transglycosylation activity of GH1-1. The EJ2 strain coproduced 0.34 +/- 0.03 g ethanol/g cellulose and 0.06 +/- 0.00 g ethyl-beta-d-glucoside/g cellulose at a rate of 0.30 +/- 0.02 g.L-1.h(-1) and 0.09 +/- 01 g.L-1.h(-1), respectively, during the SSF of Avicel PH-101 cellulose, supplemented only with Celluclast 1.5 L. Herein, we report a possible coproduction of a value-added chemical (alkyl-glucosides) during SSF of cellulose exploiting the transglycosylation activity of GH1-1 in engineered S. cerevisiae. This coproduction could have a substantial effect on the overall technoeconomic feasibility of theSSF of cellulose.