Improved fermentation kinetics by wine yeast strains evolved under ethanol stress

Abstract

Adaptive laboratory evolution works on the principle that populations of cells adapt to their environment over time by natural selection. In this work, we assess adaptive laboratory evolution as a tool to improve the performance of winemaking yeast strains, in order to cope with the challenges of global climate change. Specifically we addressed ethanol tolerance as a way to ensure good fermentation kinetics despite increasing sugar content in musts.Two industrial wine yeast strains were subjected to adaptive laboratory evolution in continuous culture in the presence of 6–8% ethanol. Evolved strains showed improved fermentation kinetics and reduced residual sugar in synthetic must. Some of these strains also showed improved fermentation kinetics in pilot scale fermentation of natural white and rosé grape must. Levels of acetic acid, glycerol, and some volatile compounds were also different between the original and evolved strains.This work proves that adaptive laboratory evolution is a promising method for the improvement of industrial wine yeast strains. However, both the genotype of the original strains and the particular conditions in which selective pressure is applied can have great influence on the usefulness of the final outcome.