Mitsumasu Kanako, Liu Ze-Shen, Tang Yue-Qin, Akamatsu Takashi, Taguchi Hisataka, Kida Kenji
Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto 860-0862, Japan.
College of Engineering, Peking University, No. 5 Yiheyuan Road, Haidian District, Beijing 100871, China.
J Biosci Bioeng. 2014 Dec;118(6):689-95. doi: 10.1016/j.jbiosc.2014.05.012. Epub 2014 Jun 20.
Continuous fermentation using the industrial Saccharomyces cerevisiae diploid strain WW was carried out under acidic or high-temperature conditions to achieve acid- or thermo-tolerant mutants. Mutants isolated at pH 2.5 and 41°C showed improved growth and fermentation ability under acidic and elevated temperature conditions. Haploid strains WW17A1 and WW17A4 obtained from the mutated diploid strain WW17A showed better growth and 4.5-6.5% higher ethanol yields at pH 2.7 than the original strains. Haploid strain WW12T4 obtained from mutated diploid strain WW12T showed 1.25-1.50 times and 2.8-4.7 times higher total cell number and cell viability, respectively, than the original strains at 42°C. Strain AT, which had significantly improved acid- and thermo-tolerance, was developed by mating strain WW17A1 with WW12T4. Batch fermentation at 41°C and pH 3.5 showed that the ethanol concentration and yield achieved during fermentation by strain AT were 55.4 g/L and 72.5%, respectively, which were 10 g/L and 13.4% higher than that of the original strain WW. The present study demonstrates that continuous cultivation followed by haploidization and mating is a powerful approach for enhancing the tolerance of industrial strains.
使用工业酿酒酵母二倍体菌株WW进行连续发酵，在酸性或高温条件下培养以获得耐酸或耐热突变体。在pH 2.5和41°C条件下分离得到的突变体在酸性和高温条件下表现出更好的生长和发酵能力。从突变二倍体菌株WW17A获得的单倍体菌株WW17A1和WW17A4在pH 2.7时比原始菌株生长更好，乙醇产量高出4.5 - 6.5%。从突变二倍体菌株WW12T获得的单倍体菌株WW12T4在42°C时总细胞数和细胞活力分别比原始菌株高1.25 - 1.50倍和2.8 - 4.7倍。通过将菌株WW17A1与WW12T4杂交培育出了耐酸性和耐热性显著提高的菌株AT。在41°C和pH 3.5条件下进行分批发酵，结果表明菌株AT发酵过程中的乙醇浓度和产量分别为55.4 g/L和72.5%，比原始菌株WW分别高出10 g/L和13.4%。本研究表明，连续培养后进行单倍体化和杂交是提高工业菌株耐受性的有效方法。
