Improvement of fermentative yeasts S. cerevisiae by Non-GMO strategies for the reduction of urethanes in Sherry wines

Abstract

During alcoholic fermentation, the yeasts responsible for the process produce various metabolites, including urea. The reaction of urea with ethanol spontaneously generates ethyl carbamate in wine, a carcinogenic metabolite whose concentration needs to be regulated. Yeasts produce urea during the arginine metabolic pathway. For this purpose, adaptive evolution has been used by using a toxic analogue of l-arginine, l-canavanine, for selective pressure, once increasing the genetic variability of the population by sporulation and subsequent conjugation. Using this strategy, five putative variants of the parental yeast have been obtained and seem to have reduced urea production, thus being able to achieve a lower concentration of ethyl carbamate.