Rational engineering of Saccharomyces cerevisiae towards improved tolerance to multiple inhibitors in lignocellulose fermentations

Abstract Background The fermentation of lignocellulose hydrolysates to ethanol requires robust xylose-capable Saccharomyces cerevisiae strains able operate in the presence microbial inhibitory stresses. This study aimed at developing industrial S. with enhanced tolerance towards pretreatment-derived inhibitors, by identifying novel gene combinations that confer resistance multiple inhibitors (thus cumulative inhibitor phenotype) minimum impact on xylose ability. strategy consisted sequential delta-integrations double-gene cassettes containing one conferring broad ( ARI1 , PAD1 or TAL1 ) coupled an inhibitor-specific ADH6 FDH1 ICT1 ). performances transformants were compared parental strain terms biomass growth, yields and productivity, as well detoxification capacities a synthetic cocktail, sugarcane bagasse hydrolysate hardwood spent sulphite liquor. Results first second round delta-integrated exhibited trade-off between yield. Transformants showed increased phenotypes relative controls specifically fermentations concentrated liquors 40% 80% v/v concentrations 2% SC media. Unexpectedly, capacity was reduced control, but certain genes had minor (e.g. + combination negatively impacted both growth yield, which could be linked protein increasing transformant susceptibility weak acids temperature due cell membrane changes. Conclusions integration selected proven increase pretreatment hydrolysates, they limited glucose. However, some sequences conversion.