Sankyo Co., Ltd., Tanashi Plant, Tanashi, Tokyo 188, and Sankyo Co., Ltd., Bio-Science Research Laboratories, 1-2-58, Hiromachi, Shinagawa-ku, Tokyo 140, Japan.
Appl Environ Microbiol. 1987 Jul;53(7):1512-4. doi: 10.1128/aem.53.7.1512-1514.1987.
Diploid strains of Torulaspora delbrueckii were tested for industrial application. Because the cell volume of the diploid strain was three times as large as that of the parental haploid strain, collection and subsequent dehydration to make compressed yeast cakes were greatly improved with the diploid YL3. The time required for dehydration of the diploid strain was shortened to 1/2.5 that of the parent strain under conventional conditions. Moreover, for the diploid cells frequent filter changes for dehydration were not required, which was the case with parental cells. Fermentation activity and tolerance to freeze-thawing in dough were succesfully inherited by the diploid strains. The diploid YL3 showed nearly the same activity as the diploid F31 in bread making. However, the endurance period of yeast cakes when stored at 30 degrees C without softening to lead to liquefaction was much longer in YL3 (199 h) than in F31 (132 h). This superiority was ascribed to the fact that YL3 was induced through direct diploidization and had no genetic defect on chromosomes because the wild-type strain was employed as the parent, whereas F31 was obtained through protoplast fusion from two auxotrophic mutants and carried at least two mutagenized genes that were masked by heterolallelism.
对酿酒酵母属德巴利氏毕赤酵母的二倍体菌株进行了工业应用测试。由于二倍体菌株的细胞体积是亲本单倍体菌株的三倍，因此使用二倍体 YL3 大大改善了酵母的收集和随后的脱水，以制成压缩酵母饼。在常规条件下，二倍体菌株的脱水时间缩短至亲本菌株的 1/2.5。此外，与亲本细胞不同，二倍体细胞不需要频繁更换过滤器进行脱水。二倍体菌株成功地继承了发酵活性和耐冷冻-解冻面团的能力。二倍体 YL3 在制作面包方面的活性几乎与二倍体 F31 相同。然而，在 30°C 下储存时，酵母饼的耐久性期没有软化导致液化的时间在 YL3（199 h）中比在 F31（132 h）中长得多。这种优势归因于 YL3 是通过直接二倍化诱导的，并且由于使用了野生型菌株作为亲本，因此在染色体上没有遗传缺陷，而 F31 是通过来自两个营养缺陷型突变体的原生质体融合获得的，并且至少携带两个被异源等位基因掩盖的诱变基因。
