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Title: Leveraging Genetic-Background Effects in Saccharomyces cerevisiae To Improve Lignocellulosic Hydrolysate Tolerance

We report a major obstacle to sustainable lignocellulosic biofuel production is microbe inhibition by the combinatorial stresses in pretreated plant hydrolysate. Chemical biomass pretreatment releases a suite of toxins that interact with other stressors, including high osmolarity and temperature, which together can have poorly understood synergistic effects on cells. Improving tolerance in industrial strains has been hindered, in part because the mechanisms of tolerance reported in the literature often fail to recapitulate in other strain backgrounds. Here, we explored and then exploited variations in stress tolerance, toxin-induced transcriptomic responses, and fitness effects of gene overexpression in different Saccharomyces cerevisiae (yeast) strains to identify genes and processes linked to tolerance of hydrolysate stressors. Using six different S. cerevisiae strains that together maximized phenotypic and genetic diversity, first we explored transcriptomic differences between resistant and sensitive strains to identify common and strain-specific responses. This comparative analysis implicated primary cellular targets of hydrolysate toxins, secondary effects of defective defense strategies, and mechanisms of tolerance. Dissecting the responses to individual hydrolysate components across strains pointed to synergistic interactions between osmolarity, pH, hydrolysate toxins, and nutrient composition. By characterizing the effects of high-copy gene overexpression in three different strains, we revealed the breadth of themore » background-specific effects of gene fitness contributions in synthetic hydrolysate. Lastly, our approach identified new genes for engineering improved stress tolerance in diverse strains while illuminating the effects of genetic background on molecular mechanisms.« less
Authors:
 [1] ;  [2] ;  [2] ;  [3]
  1. Univ. of Wisconsin, Madison, WI (United States). Great Lakes Bioenergy Research Center and Microbiology Training Program
  2. Univ. of Wisconsin, Madison, WI (United States). Great Lakes Bioenergy Research Center
  3. Univ. of Wisconsin, Madison, WI (United States). Great Lakes Bioenergy Research Center and Laboratory of Genetics
Publication Date:
Grant/Contract Number:
FC02-07ER64494
Type:
Accepted Manuscript
Journal Name:
Applied and Environmental Microbiology
Additional Journal Information:
Journal Volume: 82; Journal Issue: 19; Journal ID: ISSN 0099-2240
Publisher:
American Society for Microbiology
Research Org:
Univ. of Wisconsin, Madison, WI (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; 59 BASIC BIOLOGICAL SCIENCES
OSTI Identifier:
1427694