Direct fermentation of amorphous cellulose to ethanol by engineered Saccharomyces cerevisiae coexpressing Trichoderma viride EG3 and BGL1

Abstract

Direct ethanol fermentation from amorphous cellulose was achieved using an engineered industrial Saccharomyces cerevisiae strain. Two cellulase genes endoglucanase (eg3) and β-glucosidase (bgl1) were obtained from Trichoderma viride and integrated into the genome of S. cerevisiae. These two cellulases could be constitutively coexpressed and secreted by the recombinant strain S. cerevisiae-eb. The enzyme activities were analyzed in the culture supernatants, with the highest endoglucanase activity of 2.34 units/ml and β-glucosidase activity of 0.95 units/ml. The effects of pH, temperature and metal ions on enzyme activities were analyzed. The coexpression strain S. cerevisiae-eb could grow in carboxymethyl cellulose (CMC) and utilize it as the single carbon source. The 20 g/L CMC as a model substrate of amorphous cellulose was used in fermentation. The ethanol production reached 4.63 g/L in 24 h, with the conversion ratio of 64.2% compared with the theoretical concentration. This study demonstrated that the engineered industrial strain S. cerevisiae-eb could convert amorphous cellulose to ethanol simultaneously and achieve consolidated bioprocessing (CBP) directly.

CRISPR-Cas9 Approach Constructing Cellulase sestc-Engineered Saccharomyces cerevisiae for the Production of Orange Peel Ethanol

“…The current study indicated that the final ethanol concentration reached 7.53 g/L, and the conversion rates of ethanol were 0.377 g/g glucose and 0.151 g/g dry orange peel. These indices approached or exceeded those previously reported ( Yamada et al, 2013 ; Gong et al, 2014 ; Yu and Li, 2015 ; Wu et al, 2018 ).…”

“…The construction of cellulase gene-engineered S. cerevisiae was an effective approach to achieve in situ saccharification and ethanol production. S. cerevisiae coexpressing cellulase/cellodextrin and Trichoderma viride EG3/BGL1 produced ethanol contents of 4.3 g/L ( Yamada et al, 2013 ) and 4.63 g/L ( Gong et al, 2014 ). S. cerevisiae expressing Aspergillus aculeatus β-glucosidase achieved an ethanol content of 15 g/L ( Treebupachatsakul et al, 2016 ).…”

Two New Native β-Glucosidases from Clavispora NRRL Y-50464 Confer Its Dual Function as Cellobiose Fermenting Ethanologenic Yeast

“…For example, cellulolytic enzyme yield was significantly improved for a non-fermentation fungus Neurospora crassa by genetic engineering [ 17 , 18 ]. Saccharomyces cerevisiae was enabled to utilize cellulose by integration of endoglucanase and β-glucosidase genes from Tichoderma viride [ 19 ]. S .…”

Current Methodologies and Advances in Bio-ethanol Production

“…A similar work published before by Voorend et al [53] suggested that the overexpression of GA20-OXIDASE1 in maize increased the saccharification of modified biomass after NaOH pretreatment [53]. Therefore, apart from developing pretreatment technologies and composing enzyme consortiums, lignocellulose feedstock improvement also seems to be a feasible strategy to enhance bioethanol yields [54][55][56][57][58].…”