To convert plant matter to fuel and other sustainable bioproducts, it must first be broken into digestible sugars for microbes. Gamma-valerolactone (GVL) is a promising chemical solvent for biomass degradation. However, it is toxic to fermentative microbes. Scientists discovered the mechanisms of GVL toxicity to fermentative microbes. They identified gene deletions that created sensitivity or tolerance to the solvent. They used this knowledge to engineer a fermenting yeast strain with improved tolerance to GVL and enhanced conversion of sugars to biofuel.