Mutation breeding of Saccharomyces cerevisiae with lower methanol content and the effects of pectinase, cellulase and glycine in sugar cane spirits.

To decrease the methanol content of the sugar cane sprits, mutagenesis of ultraviolet (UV) coupled with diethyl sulfate (DES) was used to generate a mutant of Saccharomyces cerevisiae with lower methanol content. Meanwhile, the effects of the additions of pectinase, cellulase and glycine on the production of methanol in sugar cane spirits were evaluated. After mutagenesis of UV coupled with DES, a mutant S. cerevisiae DU9 with low production of methanol (97.3 ± 1.7 mg/L) was selected, with a 12.3% decrease of that of S. cerevisiae D4 only with DES treatment, and with a 27.8% reduction of that of the strain without any treatment. Pectinase and cellulase significantly increased the methanol levels of the sugar cane spirits. The results showed that there was linear relationship between glycine (concentration within 0∼0.9 g/L) and methanol in sugar cane sprits and the linear equation was y = 104.7 × -4.79 with the conversion rate of glycine conversion to methanol as 24.56%. Mutagenesis of UV coupled with DES is an efficient way to generate a mutant of S. cerevisiae with lower methanol content. Also, it is necessary to control the additions of pectinase, cellulase and glycine in the fermentation medium, and other unknown ways to generate methanol metabolic pathway in yeasts may need further study.