Direct conversion of cellulose into ethanol and ethyl‐β‐d‐glucoside via engineered Saccharomyces cerevisiae

Abstract

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-β-d-glucoside, via an engineered yeast strain (i.e., strain EJ2) expressing heterologous cellodextrin transporter (CDT-1) and intracellular β-glucosidase (GH1-1) originating from Neurospora crassa. We identified the formation of ethyl-β-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-β-d-glucoside/g cellulose at a rate of 0.30 ± 0.02 g·L ·h and 0.09 ± 01 g·L ·h , 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.

Toward Sustainable Production of Sugar-Based Alkyl Polyglycoside Surfactant─A Comprehensive Review on Synthesis Route and Downstream Processing

“…Nevertheless, water activity should be regulated in a way that avoids secondary hydrolysis, which results in the reduction of yield, but sufficient to maintain enzyme activity for optimal reaction and allow substrate solubilization. − In general, reverse hydrolysis is considered as a simpler and cost-efficient process if compared to transglycosylation. This is because the feedstock used in this process, i.e., glucose or any monosaccharide, is naturally available and considerably cheaper than a glycosyl donor (e.g., 4-nitrophenyl β- d -glycopyranoside, disaccharide) that is used in transglycosylation as in Figure . − ,, Nevertheless, Jayakody et al have demonstrated that microcrystalline cellulose could be exploited as a substrate for the transglycosylation process, which reveals the potential of using natural cellulose. Similarly, Jocquel et al reported the use of wheat bran as a substrate with the presence of pentanol and enzyme cocktails and were able to transglycosylate xylan into pentyl β- d -xyloside with a different degree of polymerization, together with the byproduct’s xylose and glucose.…”

“…It allows enzymatic reactions to perform in a natural cellular environment, which protects the enzyme from degradation. In a study of Jayakody et al, 75 cellulose was fermented by Saccharomyces cerevisiae EJ2 with the supplementation of cellulase to coproduce bioethanol and ethyl β-Dglucoside. This strain produced β-glucosidase GH1-1 and cyclodextrin transporter CDT-1 intracellularly.…”

“…This is because the feedstock used in this process, i.e., glucose or any monosaccharide, is naturally available and considerably cheaper than a glycosyl donor (e.g., 4-nitrophenyl β-Dglycopyranoside, disaccharide) that is used in transglycosylation as in Figure 10. [78][79][80]85,86 Nevertheless, Jayakody et al 75 have demonstrated that microcrystalline cellulose could be exploited as a substrate for the transglycosylation process, which reveals the potential of using natural cellulose. Similarly, Jocquel et al 87 reported the use of wheat bran as a substrate with the presence of pentanol and enzyme cocktails and were able to transglycosylate xylan into pentyl β-D-xyloside with a different degree of polymerization, together with the byproduct's xylose and glucose.…”

Renewable Energy Products through Bioremediation of Wastewater

“…The small yields of ethanol obtained in fermentation (typically 10% (v/v)) currently need subsequent energy intensive distillation. Conventional ethanol plants will expend more than 30 per cent of bioethanol fuel's heat energy during the distillation process [49,85,86].…”

Neither 1G nor 2G fuel ethanol: setting the ground for a sugarcane-based biorefinery using an iSUCCELL yeast platform

“…Although fuel ethanol has been the main product of interest in most of the studies discussed above, the formation of other biotechnological compounds has also been reported using the iCELL approach, e.g. 2,3-butanediol (Nan et al 2014), lactic acid (Turner et al 2016), and biosurfactants (Jayakody et al 2018).…”