微量元素对大肠杆菌生长和乙酸生成的影响研究

Effects of Trace Elements on Growth and Acetate Production of Escherichia coli

大肠杆菌DA19的代谢特性与培养基中添加微量元素有较大的关系。在基本培养基中 ,当氮源限制时 ,添加微量元素可以在一定程度上改善DA19菌体的生长 ,提高菌体得率YX G,大大减少乙酸的生成 ;当氮源充分时 ,与不添加微量元素相比 ,DA19在添加微量元素后 ,菌体浓度大大增加 ,虽然葡萄糖消耗速率加快 ,但产乙酸仍然很少 ,只有不添加时的 13% ,YX G 提高至少 6 0 %。基本培养基中添加 0 .1～ 1mL L的微量元素混合溶液对DA19菌体生长、乙酸生成及葡萄糖消耗没有显著影响。在单独添加不同种类的微量元素时 ,BO33- 、Zn2 + 、MoO42 + 、Cu2 + 没有特别明显的影响 ,Al3+ 会抑制菌体生长和葡萄糖利用 ,而Co2 + 、Mn2 + 、Fe2 + 可以改善细胞生长 ,特别是添加Fe2 + 时 ,细胞生长及乙酸生成等培养结果与添加微量元素混合溶液几乎相同。

The metabolic characteristics of Escherichia coli DA19 were affected by the trace elements added in the minimal medium. When cultured in the minimal medium with an initial NH 4 + concentration of 17.4 mmol/L, both growth and cell yield based on consumed glucose were improved and less acetate was produced as a mixture of trace elements was added, and NH 4 + became a limiting nutrient at glucose concentration higher than 5.45g/L. When cultured in the minimal medium with sufficient nitrogen source (57.5 mmol/L of NH 4 +), addition of trace elements resulted in a great increase in cell growth and glucose consumption. The cell yield based on consumed glucose increased by at least 60% while produced acetate was only 13% of those obtained in medium without the addition of trace elements. The amount of added trace elements mixture, ranging from 0.1 to 1 mL/L, had almost the same effects on cell growth, acetate production and glucose consumption. Al 3+ had negative effects on the growth and glucose utilization while Co 2+ , Mn 2+ or Fe 2+ respectively improved growth and reduced acetate production. On the other hand, BO 3 3- , Zn 2+ , MoO 4 2+ , or Cu 2+ almost had no significant effects on the metabolic activities of DA19. In the medium supplemented with Fe 2+ , the behavior of the culture of DA19 was almost the same as that in medium supplemented with the trace element mixture.