fulltext.study @t Gmail

Ethanol-tolerant Saccharomyces cerevisiae strains isolated under selective conditions by over-expression of a proofreading-deficient DNA polymerase δ

Paper ID Volume ID Publish Year Pages File Format Full-Text
21985 43247 2009 6 PDF Available
Title
Ethanol-tolerant Saccharomyces cerevisiae strains isolated under selective conditions by over-expression of a proofreading-deficient DNA polymerase δ
Abstract

Ethanol damages the cell membrane and functional proteins, gradually reducing cell viability, and leading to cell death during fermentation which impairs effective bioethanol production by budding yeast Saccharomyces cerevisiae. To obtain more suitable strains for bioethanol production and to gain a better understanding of ethanol tolerance, ethanol-tolerant mutants were isolated using the novel mutagenesis technique based on the disparity theory of evolution. According to this theory evolution can be accelerated by affecting the lagging-strand synthesis in which DNA polymerase δ is involved. Expression of the pol3-01 gene, a proofreading-deficient of DNA polymerase δ, in S. cerevisiae W303-1A grown under conditions of increasing ethanol concentration resulted in three ethanol-tolerant mutants (YFY1, YFY2 and YFY3), which could grow in medium containing 13% ethanol. Ethanol productivity also increased in YFY strains compared to the wild-type strain in medium containing 25% glucose. Cell morphology of YFY strain cells was normal even in the presence of 8% ethanol, whereas W303-1A cells were expanded by a big vacuole. Furthermore, two of these mutants were also resistant to high-temperature, Calcofluor white and NaCl. Expression levels of TPS1 and TSL1, which are responsible for trehalose biosynthesis, were higher in YFY strains relative to W303-1A, resulting in high levels of intracellular trehalose in YFY strains. This contributed to the multiple-stress tolerance that makes YFY strains suitable for the production of bioethanol.

Keywords
Ethanol tolerance; Yeast; Bioethanol; Error-prone DNA polymerase; Disparity theory of evolution
First Page Preview
Ethanol-tolerant Saccharomyces cerevisiae strains isolated under selective conditions by over-expression of a proofreading-deficient DNA polymerase δ
Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Bioscience and Bioengineering - Volume 108, Issue 3, September 2009, Pages 199–204
Authors
, , , , , , ,
Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering