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Cellulosic ethanol production by combination of cellulase-displaying yeast cells

Paper ID Volume ID Publish Year Pages File Format Full-Text
17191 42650 2012 7 PDF Available
Title
Cellulosic ethanol production by combination of cellulase-displaying yeast cells
Abstract

As an effort to find suitable endoglucanases to generate cellulolytic yeast strains, two fungal endoglucanases, Thermoascus aurantiacus EGI and Trichoderma reesei EGII, and two bacterial endoglucanases, Clostridium thermocellum CelA and CelD, were expressed on the yeast surface, and their surface expression levels, pH- and temperature-dependent enzyme activities, and substrate specificities were analyzed. T. aurantiacus EGI showed similar patterns of pH- and temperature-dependent activities to those of T. reesei EGII which has been widely used due to its high enzyme activity. Although EGII showed higher carboxymethyl cellulose (CMC) degradation activity than EGI, EGI showed better activity toward phosphoric acid swollen cellulose (PASC). For ethanol production from PASC, we combined three types of yeast cells, each displaying T. aurantiacus EGI, T. reesei CBHII (exoglucanase) and Aspergillus aculeatus BGLI (β-glucosidase), instead of co-expressing these enzymes in a single cell. In this system, ethanol production can be easily optimized by adjusting the combination ratio of each cell type. A mixture of cells with the optimized EGI:CBHII:BGLI ratio of 6:2:1 produced 1.3 fold more ethanol (2.1 g/l) than cells composed of an equal amount of each cell type, suggesting the usefulness of this system for cellulosic ethanol production.

► Two fungal and two bacterial endoglucanases were expressed on the yeast surface. ► Enzyme activities of the surface-displayed endoglucanases were analyzed. ► Ethanol was produced from PASC by consortium of cellulase-displaying cells. ► Ethanol production was optimized by adjusting the ratio of each cell type.

Keywords
Cellulase; Cellulosic ethanol; Combination system; Metabolic burden; Yeast surface display
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Publisher
Database: Elsevier - ScienceDirect
Journal: Enzyme and Microbial Technology - Volume 51, Issues 6–7, 10 December 2012, Pages 366–372
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us