Document Detail


A novel strategy to construct yeast Saccharomyces cerevisiae strains for very high gravity fermentation.
MedLine Citation:
PMID:  22363590     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Very high gravity (VHG) fermentation is aimed to considerably increase both the fermentation rate and the ethanol concentration, thereby reducing capital costs and the risk of bacterial contamination. This process results in critical issues, such as adverse stress factors (ie., osmotic pressure and ethanol inhibition) and high concentrations of metabolic byproducts which are difficult to overcome by a single breeding method. In the present paper, a novel strategy that combines metabolic engineering and genome shuffling to circumvent these limitations and improve the bioethanol production performance of Saccharomyces cerevisiae strains under VHG conditions was developed. First, in strain Z5, which performed better than other widely used industrial strains, the gene GPD2 encoding glycerol 3-phosphate dehydrogenase was deleted, resulting in a mutant (Z5ΔGPD2) with a lower glycerol yield and poor ethanol productivity. Second, strain Z5ΔGPD2 was subjected to three rounds of genome shuffling to improve its VHG fermentation performance, and the best performing strain SZ3-1 was obtained. Results showed that strain SZ3-1 not only produced less glycerol, but also increased the ethanol yield by up to 8% compared with the parent strain Z5. Further analysis suggested that the improved ethanol yield in strain SZ3-1 was mainly contributed by the enhanced ethanol tolerance of the strain. The differences in ethanol tolerance between strains Z5 and SZ3-1 were closely associated with the cell membrane fatty acid compositions and intracellular trehalose concentrations. Finally, genome rearrangements in the optimized strain were confirmed by karyotype analysis. Hence, a combination of genome shuffling and metabolic engineering is an efficient approach for the rapid improvement of yeast strains for desirable industrial phenotypes.
Authors:
Xianglin Tao; Daoqiong Zheng; Tianzhe Liu; Pinmei Wang; Wenpeng Zhao; Muyuan Zhu; Xinhang Jiang; Yuhua Zhao; Xuechang Wu
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2012-02-17
Journal Detail:
Title:  PloS one     Volume:  7     ISSN:  1932-6203     ISO Abbreviation:  PLoS ONE     Publication Date:  2012  
Date Detail:
Created Date:  2012-02-24     Completed Date:  2012-06-29     Revised Date:  2013-06-26    
Medline Journal Info:
Nlm Unique ID:  101285081     Medline TA:  PLoS One     Country:  United States    
Other Details:
Languages:  eng     Pagination:  e31235     Citation Subset:  IM    
Affiliation:
Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang Province, People's Republic of China.
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MeSH Terms
Descriptor/Qualifier:
Adaptation, Physiological / drug effects
Cell Membrane / drug effects,  metabolism
Chromosomes, Fungal / genetics
DNA Shuffling / methods*
Electrophoresis, Gel, Pulsed-Field
Ergosterol / metabolism
Ethanol / pharmacology
Fatty Acids / metabolism
Fermentation / drug effects,  physiology*
Gene Expression Regulation, Fungal / drug effects
Gene Rearrangement / drug effects
Genes, Fungal / genetics
Genetic Testing
Genomic Instability
Hypergravity*
Industrial Microbiology
Karyotyping
Metabolic Engineering / methods*
Mutation / genetics
Saccharomyces cerevisiae / cytology,  enzymology,  genetics,  physiology*
Stress, Physiological / drug effects
Trehalose / metabolism
Chemical
Reg. No./Substance:
0/Fatty Acids; 57-87-4/Ergosterol; 64-17-5/Ethanol; 99-20-7/Trehalose
Comments/Corrections

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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