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Improvement of multiple stress tolerance in yeast strain by sequential mutagenesis for enhanced bioethanol production

Paper ID Volume ID Publish Year Pages File Format Full-Text
21037 43203 2012 8 PDF Available
Title
Improvement of multiple stress tolerance in yeast strain by sequential mutagenesis for enhanced bioethanol production
Abstract

The present work deals with the improvement of multiple stress tolerance in a glucose–xylose co-fermenting hybrid yeast strain RPR39 by sequential mutagenesis using ethyl methane sulfonate, N-methyl-N′-nitro-N-nitrosoguanidine, near and far ultraviolet radiations. The mutants were evaluated for their tolerance to ethanol, temperature and fermentation inhibitors. Among these mutants, mutant RPRT90 exhibited highest tolerance to 10% initial ethanol concentration, 2 g L−1 furfural and 8 g L−1 acetic acid. The mutant also showed good growth at high temperature (39–40°C). A study on the combined effect of multiple stresses during fermentation of glucose–xylose mixture (3:1 ratio) was performed using mutant RPRT90. Under the combined effect of thermal (39°C) and inhibitor stress (0.25 g L−1 vanillin, 0.5 g L−1 furfural and 4 g L−1 acetic acid), the mutant produced ethanol with a yield of 0.379 g g−1, while under combined effect of ethanol (7% v/v) and inhibitor stress the ethanol yield obtained was 0.43 g g−1. Further, under the synergistic effect of sugar (250 g L−1), thermal (39°C), ethanol (7% v/v) and inhibitors stress, the strain produced a maximum of 47.93 g L−1 ethanol by utilizing 162.42 g L−1 of glucose–xylose mixture giving an ethanol yield of 0.295 g g−1 and productivity of 0.57 g L−1 h−1. Under same condition the fusant RPR39 produced a maximum of 30.0 g L−1 ethanol giving a yield and productivity of 0.21 g g−1 and 0.42 g L−1 h−1 respectively. The molecular characterization of mutant showed considerable difference in its genetic profile from hybrid RPR39. Thus, sequential mutagenesis was found to be effective to improve the stress tolerance properties in yeast.

Keywords
Mutagenesis; Stress tolerance; Ethanol fermentation; Mutants; Fermentation inhibitors
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Improvement of multiple stress tolerance in yeast strain by sequential mutagenesis for enhanced bioethanol production
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Bioscience and Bioengineering - Volume 114, Issue 6, December 2012, Pages 622–629
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