Wine yeast fermentation vigor may be improved by elimination of recessive growth-retarding alleles

The presence of recessive growth-retarding alleles can reduce the fitness o f industrial wine yeasts. In nature, these alleles are supposed to be elimi nated through "genome renewal". We emulated this process in the laboratory to increase the fermentation vigor of wine yeasts. The procedure is simply to sporulate the yeast strains and select new homozygous single-spore desce ndants. Most of the yeasts achieve a faster onset of fermentation when rece ssive deleterious genes are eliminated. The increase of the degree of homoz ygosity has no relation, either direct or inverse, with the fermentation vi gor of the yeasts or with the quality of the resulting wine. However, in so me strains in which recessive growth-retarding alleles have been eliminated , the fermentation vigor and the quality of the wine were found to be impro ved simultaneously. (C) 1999 John Wiley & Sons, Inc.