不同碳源对大肠杆菌lpdA突变菌累积丙酮酸的影响

Effect of different carbon sources on pyruvic acid production by using lpdA gene knockout Escherichia coli

摘要:

为了利用大肠杆菌构建模式“细胞工厂”, 必须了解在构建过程中各种因素的影响。本研究选用敲除了lpdA基因的大肠杆菌作为模型细胞, 考察了该突变菌在合成培养基中利用葡萄糖、果糖、木糖和甘露糖累积丙酮酸的能力。结果显示, 在初始糖浓度为10 g/L的情况下, lpdA突变菌可以很好地利用葡萄糖、果糖、木糖和甘露糖转化丙酮酸, 其得率分别达到了0.884 g/g、0.802 g/g、0.817 g/g和0.808 g/g, 且在以葡萄糖、果糖和木糖发酵时, 丙酮酸的积累过程与细胞生长偶联。甘露糖发酵的情况则不同：菌浓度很快达到平台期, 随后丙酮酸积累和甘露糖消耗都表现为线性变化。当在考察了不同的接种量对lpdA突变菌发酵葡萄糖的影响时发现, 大接种量能加快葡萄糖消耗速率、丙酮酸的积累速率和细胞生长速率, 但丙酮酸得率却明显下降。这些结果对构建以大肠杆菌为母体的模式“细胞工厂”有参考价值。

Abstract:

We studied the ability of lpdA gene knockout Escherichia coli to ferment different sugars in mineral salts medium for the production of pyruvate. The sugars studied were glucose, fructose, xylose and mannose at a concentration of 10 g/L. At the same time, effect?of?inoculum?size?on lpdA fermentation with glucose was studied. The strain was able to use all sugars for biomass generation and pyruvate production. The lpdA knockout mutant converted glucose, fructose, xylose and mannose to pyruvate with yields of 0.884 g/g, 0.802 g/g, 0.817 g/g and 0.808 g/L, respectively. The pyruvate accumulation curve coupled with cell growth except for mannose as carbon source. When the inoculation size increased, the rate of glucose consumption, pyruvate accumulation and cell growth increased but lower pyruvate concentration. This study demonstrates that E. coli lpdA mutant has the potential to produce pyruvic acid from xylose and mannose.