营养因子对乳酸发酵短杆菌合成赖氨酸的影响

Effects of Nutrition Factors on the Biosynthesis of Lysine in a Lysine Producer Brevibacterium lactofermentum FP094

通过正交试验探讨了碳源、氮源及豆饼水解液对赖氨酸产量的影响 ,确定了最佳工艺条件 .添加醋酸盐、生物素、泛酸盐等对FP0 94菌株中由磷酸烯醇式丙酮酸、丙酮酸和草酰乙酸构成的“三角区”进行扰动 ,定性分析了此扰动对赖氨酸合成所需前体物代谢流量的调节机制 .添加2 .0 %的醋酸钙可使赖氨酸的产量及葡萄糖的转化率均得到显著提高 ,生物素的添加量在 2 0 0～5 0 0 μg/L时可明显提高赖氨酸的产量和转化率 .泛酸钙的限量添加可弱化泛酸缺陷突变株中丙酮酸向乙酰辅酶A的转化 ,并提高天冬氨酸 β 半醛流量向赖氨酸合成分支的分配 .

In this paper, the effects of carbon sources, nitrogen sources and soybean hydrolysates on the overproduction of lysine were studied, and the nutrition composition was optimized at the meantime. Acetic acid, biotin and pantothenate were introduced into the medium as sources of perturbation to redirect the carbon flux of the triangular area consisting of pyruvate, phosphoenolpyruvate and oxaloacetic acid. After the addition of appropriate amount of nutrient cofactors, both the lysine production and the transferring rate of glucose were greatly enhanced due to the increase of flux of aspartic acid, the precursor of lysine. In a pantothenate auxtrophic strain, limited supply of pantothenate delayed the conversion of pyruvate to acetyl CoA, and increased the distribution rate of aspartate β semialdehyde leading to lysine biosynthesis pathway. The possible mechanism of the effects of all those factors on the metabolic regulation was discussed as well.