溶氧控制对黄色短杆菌YILW合成L-异亮氨酸的影响

摘要

The condition of dissolved oxygen of L-isoleucine synthesis in Brevibacterium flavum YILW was explored,and the metabolic networks and metabolic flux balance model were constructed. The fermentation processes were studied on the condition of different dissolved oxygen in 30 L fermenter. The results show that high dissolved oxygen leads to bacterium growth. Higher production ratio of L-isoleucine maintains a long time under the condition of 15％ dissolved oxygen. Thus the grading-controlling mode of dissolved oxygen was proposed: 25％ dissolved oxygen concentration in the cell growth phase and 15％ dissolved oxygen concentration in the phase of acid stable. Under this strategy,the yield of L-isoleucine is 31.8 g/L in 30 L fermenter in 60 h,and the conversion of sugar to acid is up to 18.3％. The vice acid is reduced significantly such as lactic, alanine. The results was demonstrated by using the method of metabolic flux analysis ,providing a theoretical basis for the in-depth understanding from the perspective of the amount of dissolved oxygen on L-isoleucine fermentation , and providing a theoretical guidance for further optimization of L-isoleucine fermentation condition of dissolved oxygen.%对黄色短杆菌YILW合成L-异亮氨酸的发酵溶氧条件进行了探索,构建了该菌合成上L-异亮氨酸的代谢网络和代谢流平衡模型.在30 L发酵罐中考察了不同溶氧浓度下L-异亮氨酸发酵过程.研究结果表明:高溶氧浓度有利于菌体生长,15%溶氧浓度下产酸速率高且维持的时间长,有利于L-异亮氨酸的积累.为此提出了分段控氧模式:在菌体生长期,溶氧浓度控制为25%;在产酸稳定期,溶氧浓度控制为15%.在此溶氧控制模式下,在30 L发酵罐上补料分批发酵60 h.L-异亮氨酸产量可达31.8 g/L,糖酸转化率可达18.3%,且乳酸、丙氨酸等副酸明显减少.对此结果运用代谢流分析的方法进行论证,旨在从量的角度理解溶氧对L-异亮氨酸合成的影响提供理论基础,对进一步优化L-异亮氨酸发酵溶氧条件提供理论指导.