Prototrophic hybrids of bakers yeast. I. Selection of haploids and diploids of prototrophic yeast

Abstract

Abstract153 haploids, including 8 prototrophs, 12 biotin prototrophs and 4 biotin auxotrophs were isolated from Y, F and FB strains of the baker's yeast Saccharomyces cerevisiae. Remaining haploids were dependent on vitamins of B group other than biotin.Obtained haploids were characterized by large cell sizes, a or α mating type, the ability to fermentation of sugars and the assimilation of non‐fermented carbon sources.Haploids obtained from the yeast of Y and FB strains a good growth in the synthetic medium.Prototrophic haploids, prototrophic haploids with biotin auxotrophs and biotin prototrophs with biotin auxotrophs were crossed. 89 prototrophic hybrids capable of growth in synthetic medium without vitamins were selected out of 178 hybrids obtained.Hybrids are characterized by features typical for baker's yeast; however, not all of them are capable of sporulation.As result of selection, prototrophic hybrids and 16 hybrids characterized by a good increase of biomass in molasses medium were chosen.The efficiency of the biomass of hybrids designated as YY 3040/2, YY 3040/3 and FFB 1910/2 is considerably higher than one obtained from the cultivation of the industrial strain French Mautner (Mf).All hybrids possess adequate enzymatic activity in anaerobic metabolism of saccharose and maltose.Selected prototrophic hybrids were sent out to two yeast factories in the country for experimental propagation.