Ayar-Kayali Hulya, Tarhan Leman
Faculty of Education, Department of Chemistry, University of Dokuz Eylül, Buca, Izmir, Turkey.
Prep Biochem Biotechnol. 2007;37(3):247-63. doi: 10.1080/10826060701386737.
The effect of glucose concentration as a carbon source in the range of 5-20 g/L on the fermentative productions of intra-and extra-cellular ethanol, acetate, formate, oxalate, lactate, and pyruvate, as well as pyruvate decarboxylase in A. orientalis were investigated, depending on the incubation period. Intra-and extra-cellular pyruvate levels increased with rising glucose concentrations up to 15 and 20 g/L of glucose, respectively. In addition, intra-cellular pyruvate levels reached their maximum on the 48th hour in the range of 12.5-20 g/L of glucose, except for 5 and 10 g/L while extra-cellular pyruvate were at the 48th and 60th hours. As a fermentative end product, intra-and extra-cellular ethanol levels increased with increasing glucose concentrations of the growth medium and with incubation period. Activity of pyruvate decarboxylase, one of the key enzymes of the alcoholic fermentation, increased significantly with increasing glucose concentrations up to the 48th hour. Intra-and extra-cellular acetate levels increased significantly with increasing glucose concentrations of the growth medium and reached their maximums on the 48th hour, as was the case also for pyruvate. Intra-cellular formate levels increased up to 15 g/L, while extra-cellular levels increased with increasing glucose concentration. The maximum intra-and extra-cellular lactate levels were determined at 12.5 g/L and 20 g/L of glucose on the 48th hour, respectively. The results suggest that elevated ethanol production suppressed lactate and formate production, supported via possibly formed CO(2). In addition, pyruvate, as well as acetate, were used as carbon sources due to the depletion of glucose contents in the growth medium.
研究了5-20 g/L范围内葡萄糖浓度作为碳源对东方醋酸杆菌细胞内和细胞外乙醇、乙酸、甲酸、草酸、乳酸和丙酮酸发酵产物以及丙酮酸脱羧酶的影响，具体取决于培养时间。细胞内和细胞外丙酮酸水平分别随着葡萄糖浓度升高至15 g/L和20 g/L而增加。此外，除了5 g/L和10 g/L的葡萄糖浓度外，在12.5-20 g/L葡萄糖浓度范围内，细胞内丙酮酸水平在第48小时达到最大值，而细胞外丙酮酸水平在第48小时和第60小时达到最大值。作为发酵终产物，细胞内和细胞外乙醇水平随着生长培养基中葡萄糖浓度的增加以及培养时间的延长而增加。酒精发酵关键酶之一丙酮酸脱羧酶的活性在第48小时前随着葡萄糖浓度的增加而显著增加。细胞内和细胞外乙酸水平随着生长培养基中葡萄糖浓度的增加而显著增加，并在第48小时达到最大值，丙酮酸也是如此。细胞内甲酸水平在葡萄糖浓度达到15 g/L时升高，而细胞外甲酸水平随着葡萄糖浓度的增加而升高。细胞内和细胞外乳酸水平的最大值分别在第48小时的12.5 g/L和20 g/L葡萄糖浓度下测定。结果表明，乙醇产量的提高抑制了乳酸和甲酸的产生，这可能是通过可能形成的CO₂来支持的。此外，由于生长培养基中葡萄糖含量的耗尽，丙酮酸以及乙酸被用作碳源。
