Drying-resistant, practical baker's yeast

A method for producing a dry diploid baker's yeast of Saccharomyces cerevisiae comprising:

• a. producing a/α-type diploid yeasts by mating an a-type haploid yeast with an α-type haploid yeast to produce an a/α-diploid yeast;
• b. selecting an a/α-type diploid yeast from the a/α-type diploid yeasts produced in step (a) by cultivating each yeast and by making bread using each yeast, and selecting the yeasts with the following characteristics:
• (i) primary points
• ability to grow in a blackstrap molasses medium;
• separability of the cultivated yeast from the medium;
• dehydration efficiency in forming the product of yeast;
• ability to maintain dough-expanding activity during long-term cold storage;
• resistance to softening of the yeast during long-term cold storage;
• ability of the yeast to maintain its color without absorbing the color of blackstrap molasses;
• and
• (ii) secondary point taste of bread produced with the yeast;
• c. disrupting the ATH1 genes of the same a-type and α-type haploid yeasts used to produce the diploid yeast selected in step (b) by inserting a marker'selected from the group consisting of URA3, LYS2 and ADE2 into the respective ATH1 genes, wherein the respective NTH1 genes of the same a-type and α-type haploid yeasts used to produce the diploid yeast selected in step (b) are not disrupted;
• d. mating the ATH1 gene-disrupted a-type haploid yeast obtained in step (c) with the ATH1 gene-disrupted alpha-type haploid yeast obtained in step (c) to produce an ATH1 gene-disrupted diploid yeast;
• e. culturing the ATH1 gene-disrupted a/α-type diploid yeast obtained in step (d);
• f. recovering the cultured yeast;
• g. pressing the recovered yeast;
• and
• h. drying the pressed yeast by fluidized bed drying.