Anomalies in the growth kinetics of Saccharomyces cerevisiae strains in aerobic chemostat cultures
作者:S H de Kock、J C du Preez、S G Kilian
DOI:10.1038/sj.jim.2900813
日期:2000.4.1
Aerobic glucose-limited chemostat cultivations were conducted with Saccharomyces cerevisiae strains NRRL Y132, ATCC 4126 and CBS 8066, using a complex medium. At low dilution rates all three strains utilised glucose oxidatively with high biomass yield coefficients, no ethanol production and very low steady-state residual glucose concentrations in the culture. Above a threshold dilution rate, respiro-fermentative (oxido-reductive) metabolism commenced, with simultaneous respiration and fermentation occurring, which is typical of Crabtree-positive yeasts. However, at high dilution rates the three strains responded differently. At high dilution rates S. cerevisiae CBS 8066 produced 7–8 g ethanol L−1 from 20 g glucose L−1 with concomitant low levels of residual glucose, which increased markedly only close to the wash-out dilution rate. By contrast, in the respiro-fermentative region both S. cerevisiae ATCC 4126 and NRRL Y132 produced much lower levels of ethanol (3–4 g L−1) than S. cerevisiae CBS 8066, concomitant with very high residual sugar concentrations, which was a significant deviation from Monod kinetics and appeared to be associated either with high growth rates or with a fermentative (or respiro-fermentative) metabolism. Supplementation of the cultures with inorganic or organic nutrients failed to improve ethanol production or glucose assimilation. Journal of Industrial Microbiology & Biotechnology (2000) 24, 231–236.
使用复合培养基对 NRRL Y132、ATCC 4126 和 CBS 8066 三株酿酒酵母进行了有氧葡萄糖限制恒温培养。在低稀释率条件下,所有三种菌株都氧化利用葡萄糖,生物量产量系数高,不产生乙醇,培养物中的稳态残留葡萄糖浓度非常低。当稀释率超过临界值时,呼吸发酵(氧化还原)新陈代谢开始,呼吸和发酵同时进行,这是典型的克拉布氏阳性酵母菌。然而,在高稀释率下,三种菌株的反应不同。在高稀释率下,S. cerevisiae CBS 8066 从 20 克葡萄糖(L-1)产生 7-8 克乙醇(L-1),同时残留葡萄糖水平较低,只有在接近冲淡稀释率时才会明显增加。相比之下,在呼吸发酵区,S. cerevisiae ATCC 4126 和 NRRL Y132 产生的乙醇水平(3-4 克/升)都比 S. cerevisiae CBS 8066 低得多,同时残留糖浓度非常高,这与莫诺动力学有明显偏差,似乎与高生长速率或发酵(或呼吸发酵)新陈代谢有关。给培养物补充无机或有机营养物质都不能提高乙醇产量或葡萄糖同化。工业微生物学与生物技术杂志》(2000 年)24 期,231-236 页。