EFFECT OF BENZOIC-ACID ON METABOLIC FLUXES IN YEASTS - A CONTINUOUS-CULTURE STUDY ON THE REGULATION OF RESPIRATION AND ALCOHOLIC FERMENTATION
EFFECT OF BENZOIC-ACID ON METABOLIC FLUXES IN YEASTS - A CONTINUOUS-CULTURE STUDY ON THE REGULATION OF RESPIRATION AND ALCOHOLIC FERMENTATION
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DOI：
10.1002/yea.320080703
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发表时间：
1992-07-01
期刊：
影响因子：
2.6
通讯作者：
VANDIJKEN, JP
中科院分区：
文献类型：
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作者：
VERDUYN, C;POSTMA, E;VANDIJKEN, JP
在以0.10 h-1的稀释率（D）生长的酿酒酵母CBS 8066的葡萄糖限制恒化培养物的培养基储库中添加苯甲酸盐导致生物质产量降低，并且比氧摄取速率（qO 2）从2.5增加到高达19.5 mmol g-1h-1。在临界浓度以上，苯甲酸的存在导致酒精发酵和减少qO 2至13 mmol g-1 h-1。苯甲酸盐对呼吸的刺激作用依赖于稀释率：在高稀释率下，苯甲酸盐不会增强呼吸。细胞只能逐渐适应苯甲酸盐存在下的生长：直接给予培养物苯甲酸盐脉冲导致洗脱。由于在低稀释率下生长的培养物中苯甲酸盐的存在导致分解代谢葡萄糖通量的巨大变化，因此研究苯甲酸盐对发酵罐中残留葡萄糖浓度以及某些选定酶水平的影响是有意义的。在D=0.10 h-1时，残留葡萄糖浓度随着苯甲酸盐浓度的增加而成比例增加。这表明葡萄糖通量的调节主要通过细胞外葡萄糖浓度的变化而不是通过合成额外量的载体来发生。此外，各种细胞内酶水平与呼吸速率不呈正相关。一个显著的例外是柠檬酸合成酶：它的水平随着呼吸速率的增加而增加。在苯甲酸存在下，在乙醇限制的培养物中的酿酒酵母也导致非常高的qO 2水平为19-21 mmol g-1 h-1。在葡萄糖和乙醇的生长过程中，苯甲酸的存在下，正好增加了线粒体体积的四分之一的总cellularvolume.Also与克拉布特里阴性酵母产朊假丝酵母，马克思克鲁维酵母和多形汉逊酵母，苯甲酸的存在下的增长导致qO 2的增加，在高浓度的苯甲酸，在有氧发酵。与S.酿酒酵母中，当在苯甲酸盐存在下以D=0.10 h-1生长时，这些酵母的最高qO 2等于或低于在没有苯甲酸盐的情况下在mu（max）下可获得的qO 2。葡萄糖抑制了S.酿酒酵母K. Crabtree阴性酵母在高浓度苯甲酸盐下的最大好氧发酵速率（D=0.10 h-1）明显低于S. marxianus。啤酒。这可能是由于在有氧条件下，这些酵母不能提高低的基础丙酮酸脱羧酶水平：在限氧条件下不含苯甲酸盐的培养导致酒精发酵速率和丙酮酸脱羧酶水平与S.啤酒。
Addition of benzoate to the medium reservoir of glucose-limited chemostat cultures of Saccharomyces cerevisiae CBS 8066 growing at a dilution rate (D) of 0.10 h-1 resulted in a decrease in the biomass yield, and an increase in the specific oxygen uptake rate (qO2) from 2.5 to as high as 19.5 mmol g-1h-1. Above a critical concentration, the presence of benzoate led to alcoholic fermentation and a reduction in qO2 to 13 mmol g-1 h-1. The stimulatory effect of benzoate on respiration was dependent on the dilution rate: at high dilution rates respiration was not enhanced by benzoate. Cells could only gradually adapt to growth in the presence of benzoate: a pulse of benzoate given directly to the culture resulted in wash-out.As the presence of benzoate in cultures growing at low dilution rates resulted in large changes in the catabolic glucose flux, it was of interest to study the effect of benzoate on the residual glucose concentration in the fermenter as well as on the level of some selected enzymes. At D=0.10 h-1, the residual glucose concentration increased proportionally with increasing benzoate concentration. This suggests that modulation of the glucose flux mainly occurs via a change in the extracellular glucose concentration rather than by synthesis of an additional amount of carriers. Also various intracellular enzyme levels were not positively correlated with the rate of respiration. A notable exception was citrate synthase: its level increased with increasing respiration rate.Growth of S. cerevisiae in ethanol-limited cultures in the presence of benzoate also led to very high qO2 levels of 19-21 mmol g-1 h-1. During growth on glucose as well as on ethanol, the presence of benzoate coincided with an increase in the mitochondrial volume up to one quarter of the total cellular volume.Also with the Crabtree-negative yeasts Candida utilis, Kluyveromyces marxianus and Hansenula polymorpha, growth in the presence of benzoate resulted in an increase in qO2 and, at high concentrations of benzoate, in aerobic fermentation. In contrast to S. cerevisiae, the highest qO2 of these yeasts when growing at D=0.10 h-1 in the presence of benzoate was equal to, or lower than the qO2 attainable at mu(max) without benzoate. Enzyme activities that were repressed by glucose in S. cerevisiae also declined in K. marxianus when the glucose flux was increased by the presence of benzoate.The maximal aerobic fermentation rate at D=0.10 h-1 of the Crabtree-negative yeasts at high benzoate concentrations was considerably lower than for S. cerevisiae. This is probably due to the fact that under aerobic conditions these yeasts are unable to raise the low basal pyruvate decarboxylase level: cultivation without benzoate under oxygen-limited conditions resulted in rates of alcoholic fermentation and levels of pyruvate decarboxylase comparable to those of S. cerevisiae.