The scheme of strategy for improving ethanol stress
tolerance based on metabolomics The scheme of our semirational
method to improve ethanol stress tolerance is shown in
Fig. 1. Ethanol tolerance is defined as the specific growth rate
under ethanol stress condition standardized by the parental
strain in each cultivation batch (Table S1). At first, we cultivated
yeast mutants and measured their specific growth rate and
metabolites using GC/MS. Then, the predictive model of ethanol
tolerance was constructed by means of orthogonal projections to
latent structures (OPLS). According to the variable influence on
projection (VIP, an indicator of important variable in the model
(20)) and regression coefficients (an indicator of contribution to
the predicted variables), we established the important
metabolites related to ethanol tolerance and searched for related
target genes for strain improvement.