[Ergosterol synthesis by hybrids and strains of yeasts of the genus saccharomyces with different ploidies].

Numerous hybrid and polyploid strains of the Saccharomyces genus were obtained by hybridization. The activity of ergosterol synthesis was assayed in hybrids, several industrial races, and in haploid and diploid cultures produced from the spores of these races. The content of ergosterol was determined in 160 strains and hybrids. Ergosterol synthesis is controlled by recessive genes, and accumulation of ergosterol in the cell depends on the interaction between genes. During growth in semiindustrial conditions, triploid hybrids accumulated more biomass than diploid, and particularly haploid, strains. Polyploid hybrids valuable for food industry have been selected, according to several characteristics, from active hybrid strains. One of them, the triploid 262, is characterized by a high rate of ergosterol synthesis, good baking quality, and resistance to dehydration.