Mating type and ploidy effect on the β-glucosidase activity and ethanol-producing performance of Saccharomyces cerevisiae with multiple δ-integrated bgl1 gene

作者：Wang, Jianjun^*; Ma, Yuanyuan; Zhang, Kun; Yang, Huajun; Liu, Cheng; Zou, Shaolan; Hong, Jiefang; Zhang, Minhua

来源：Journal of Biotechnology, 2016, 231: 24-31.

DOI：10.1016/j.jbiotec.2016.05.028

• beta-Glucosidase
• delta-Integration
• Ploidy
• Mating-type
• Ethanol

In order to investigate the effect of mating type and ploidy on enzymatic activity and fermentation performance in yeast with multiple delta-integrated foreign genes, eight ploidy series strains were constructed. The initial haploid strain BGL-alpha was shown to contain about 19 copies of the bgl1 gene. In rich media containing 2% (w/v) sugar the specific activities of BGL-a alpha. were lower than those of BGL-aa or BGL-alpha alpha, which indicates the existence of mating type effects. While the maximum OD660 decreased with rising ploidy, the biomass yield showed no significant difference between the eight strains and the specific activities (expressed as U/mL or U/mg DCW) showed little to no variation. When cellobiose was used as the carbon source and beta-glucosidase substrate, beta-glucosidase was expressed more quickly and at higher levels than in glucose-containing media. The maximum specific activitiy values obtained were 19.07 U/mL and 19.39 U/mL for BGL-alpha alpha and BGL-aa, repsectively. The anaerobic biomass and ethanol-producing performance in rich media containing 10% cellobiose showed no significant difference among the eight strains. Their maximal ethanol concentrations and corresponding yields ranged from 40.27 to 43.46 g/L and 77.56 to 83.71%, respectively. When the acid- and alkali-pretreated corncob (10% solids content) was used, the diploid BGL-a alpha fermented the best. When urea was used as the only supplemented nutrient, the ethanol titer and yield were 35.65 g/L and 83.69%, respectively, while a control experiment using industrial Angel yeast with exogenous beta-glucosidase addition gave values of 37.93 g/L and 89.04%. The combined effects of delta-integration of bgl1, ploidy and mating type result in BGL-aa or BGL-alpha alpha being the optimal choice for enzyme production and BGL-a alpha being more suitable for cellulosic ethanol fermentation. These results provide valuable information for future yeast breeding and utilization efforts.

• 出版日期2016-8-10
• 单位天津大学