Exploring improved endoglucanase expression in Saccharomyces cerevisiae strains
Date
2010
Authors
Du Plessis L.
Rose S.H.
Van Zyl W.H.
Journal Title
Journal ISSN
Volume Title
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Abstract
The endoglucanase I and II genes (egI or Cel7B and egII or Cel5A) of Trichoderma reesei QM6a were successfully cloned and expressed in Saccharomyces cerevisiae under the transcriptional control of the yeast ENO1 promoter and terminator sequences. Random mutagenesis of the egI-bearing plasmid resulted in a twofold increase in extracellular EGI activity. Both endoglucanase genes were co-expressed with the synthetic, codon-optimised cellobiohydrolase gene (s-cbhI) from T. reesei as well as the β-glucosidase gene (bgl1) from Saccharomycopsis fibuligera in S. cerevisiae. Extracellular endoglucanase activity was lower when co-expressed with s-cbhI or bgl1. Recombinant strains were able to hydrolyse phosphoric acid swollen cellulose, generating mainly cellotriose, cellobiose and glucose. Cellobiose accumulated, suggesting the β-glucosidase activity to be the rate-limiting factor. As a consequence, the recombinant strains were unable to produce enough glucose for growth on amorphous cellulose. The results of this study provide insight into further optimisation of recombinantly expressed cellulase combinations for saccharification and fermentation of cellulose to ethanol. © 2009 Springer-Verlag.
Description
Keywords
Amorphous cellulose, Cellobiohydrolases, Cellobiose, Cellulose degradation, Endoglucanase gene, Endoglucanase I, Endoglucanases, Extracellular, Glucosidase, Glucosidase activity, Optimisations, Phosphoric-acid swollen cellulose, Random mutagenesis, Rate limiting factors, Recombinant strains, S.cerevisiae, Saccharomyces cerevisiae, Saccharomyces cerevisiae strains, Saccharomycopsis, T. reesei, Terminator sequences, Transcriptional control, Trichoderma reesei, Bioethanol, Degradation, Ethanol, Genes, Glucose, Phosphoric acid, Saccharification, Yeast, Cellulose, alcohol, beta glucosidase, cellulose, cellulose 1,4 beta cellobiosidase, glucan synthase, glucose, phosphoric acid, cellulose, enzyme activity, ethanol, fermentation, gene expression, hydrolysis, mutation, plasmid, recombination, yeast, article, controlled study, enzyme activity, Escherichia coli, fermentation, fungal strain, high performance liquid chromatography, hydrolysis, Hypocrea jecorina, mutagenesis, nonhuman, nucleotide sequence, plasmid, protein expression, saccharification, Saccharomyces cerevisiae, Saccharomycetales, Amino Acid Sequence, Cellulase, Cellulases, Cellulose, Chromatography, High Pressure Liquid, Cloning, Molecular, Escherichia coli, Ethanol, Gene Dosage, Glucose, Molecular Sequence Data, Mutagenesis, Plasmids, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Saccharomycopsis, Trichoderma, Biodegradation, Cellulose, Cellulose Degradation, Endo Enzymes, Ethanol, Genes, Glucanase, Glucose, Phosphoric Acid, Saccharification, Saccharomyces Cerevisiae, Strains, Hypocrea jecorina, Saccharomyces cerevisiae, Saccharomycopsis fibuligera
Citation
Applied Microbiology and Biotechnology
86
5
86
5