High level of acetaldehyde produced by yeast in beer industry, especially in China, is still an important issue. To obtain a brewing strain with low acetaldehyde, a novel approach, based on domestication by disulfiram–ethanol plates, was developed. A mutant D-A-14 with lower acetaldehyde was obtained with UV mutagenesis. Through longtime domestication, the mutant D-A-14 produced 60.57 % less (2.20 mg/L) than the Wt strain MA12. Besides, the ratio of higher alcohols to esters in beer fermented by the mutant D-A-14 (3.7) was lower than that of MA12 (5.8), which exhibited harmonious flavor. For further study, DNA microarray technique was exploited to analyze the changes in genes involved in metabolism between the Wt and mutant. The data of DNA microarray were consistent with the decrease in acetaldehyde, organic acids, and the ratio of higher alcohols to esters of mutant D-A-14. Therefore, the newly screened strain has the potential to be applied in the brewing industry.

Higher acetaldehyde concentration in beer is one of the main concerns of current beer industry in China. Acetaldehyde is always synthesized during beer brewing by the metabolism of yeast. Here, using ethanol as the sole carbon source and 4-methylpyrazole as the selection marker, we constructed a new mutant strain with lower acetaldehyde production and improved ethanol tolerance via traditional mutagenesis strategy. European Brewery Convention tube fermentation tests comparing the fermentation broths of mutant strain and industrial brewing strain showed that the acetaldehyde concentration of mutant strain was 81.67 % lower, whereas its resistant staling value was 1.0-fold higher. Owing to the mutation, the alcohol dehydrogenase activity of the mutant strain decreased to about 30 % of the wild-type strain. In the meantime, the fermentation performance of the newly screened strain has little difference compared with the wild-type strain, and there are no safety problems regarding the industrial usage of the mutant strain. Therefore, we suggest that the newly screened strain could be directly applied to brewing industry.

Aiming at reduce the acetaldehyde concentration in beer,an industrial brewing yeast strain MI 4 was used as original strain and mutagenized with ultraviolet radiation.After primary screening with disulfiram and domestication with media containing acetaldehyde,a mutant strain D-A-14 was obtained with considerably low yield of acetaldehyde.The concentration of acetaldehyde in the beer brewed with the mutant strain was 2.86 mg / L,which was 76% lower than that of MI 4.In the meantime,the beer brewed with the mutant strain contained less higher alcohols and more esters and showed more harmonious flavor.These results demonstrated that the low-acetaldehyde mutant strain D-A-14 would be suitable for beer industry.