title: Deconstructing the genetic basis of spent sulphite liquor tolerance using deep sequencing of genome-shuffled yeast.
abstract: BACKGROUND
  Identifying the genetic basis of complex microbial phenotypes is currently a major barrier to our understanding of multigenic traits and our ability to rationally design biocatalysts with highly specific attributes for the biotechnology industry. Here, we demonstrate that strain evolution by meiotic recombination-based genome shuffling coupled with deep sequencing can be used to deconstruct complex phenotypes and explore the nature of multigenic traits, while providing concrete targets for strain development.
  
  
  RESULTS
  We determined genomic variations found within Saccharomyces cerevisiae previously evolved in our laboratory by genome shuffling for tolerance to spent sulphite liquor. The representation of these variations was backtracked through parental mutant pools and cross-referenced with RNA-seq gene expression analysis to elucidate the importance of single mutations and key biological processes that play a role in our trait of interest. Our findings pinpoint novel genes and biological determinants of lignocellulosic hydrolysate inhibitor tolerance in yeast. These include the following: protein homeostasis constituents, including Ubp7p and Art5p, related to ubiquitin-mediated proteolysis; stress response transcriptional repressor, Nrg1p; and NADPH-dependent glutamate dehydrogenase, Gdh1p. Reverse engineering a prominent mutation in ubiquitin-specific protease gene UBP7 in a laboratory S. cerevisiae strain effectively increased spent sulphite liquor tolerance.
  
  
  CONCLUSIONS
  This study advances understanding of yeast tolerance mechanisms to inhibitory substrates and biocatalyst design for a biomass-to-biofuel/biochemical industry, while providing insights into the process of mutation accumulation that occurs during genome shuffling.
authors: Department of Biology, Centre for Structural and Functional Genomics, Concordia University, 7141 Sherbrooke Street West, Montréal, Québec H4B 1R6 Canada ; Current address: Energy Biosciences Institute, University of California, Berkeley, Berkeley, CA 94704 USA.
authors: Dominic
authors: D
authors: Pinel
authors: Department of Biology, Centre for Structural and Functional Genomics, Concordia University, 7141 Sherbrooke Street West, Montréal, Québec H4B 1R6 Canada.
authors: David
authors: D
authors: Colatriano
authors: Department of Biology, Centre for Structural and Functional Genomics, Concordia University, 7141 Sherbrooke Street West, Montréal, Québec H4B 1R6 Canada ; Current address: Crabtree Nutrition Laboratories, McGill University Health Center, Montreal, Quebec H3A 1A1 Canada.
authors: Heng
authors: H
authors: Jiang
authors: School of Environmental Sciences, University of Guelph, Guelph, Ontario N1G 2 W1 Canada.
authors: Hung
authors: H
authors: Lee
authors: Department of Biology, Centre for Structural and Functional Genomics, Concordia University, 7141 Sherbrooke Street West, Montréal, Québec H4B 1R6 Canada.
authors: Vincent Jj
authors: VJ
authors: Martin
keywords: Complex trait; Evolutionary engineering; Genome shuffling; Reverse engineering; Tolerance; Yeast