Breeding high-efficiency Chinese rice wine yeast by a new drug resistance strategy

Abstract:

[Objective] High fermentation efficiency is desirable for Saccharomyces cerevisiae used in the Chinese rice wine brewing. In this study, we developed a drug resistance screening protocol to obtain a Chinese rice wine yeast strain with higher fermentation efficiency. [Methods] Clotrimazole (CTZ)-resistant strains of S. cerevisiae were isolated from the parent Chinese rice wine yeast strain. Then fermentation power, fermentation rate, and brewing property were used to screen mutants with higher fermentation efficiency compared with the parent. [Results] A total of 18 stable CTZ-resistant mutants were obtained through UV mutagenesis from Chinese rice wine yeast strain XY. In these 18 CTZ-resistant mutants, strain XY-3 gave a 5.21% higher max-fermentation rate than that of the strain XY by flask fermentation tests. In lab-scale Chinese rice wine brewing, strain XY-3 (15.30 g/d) also showed a higher maximum fermentation rate than that of strain XY (14.77 g/d), leading to shorter fermentation period of Chinese rice wine brewing by 1–2 days. [Conclusion] Combining traditional mutation with CTZ-resistant screening protocol was an efficient approach to screen Chinese rice wine yeasts with higher fermentation efficiency.