溶氧对L-天冬酰胺酶发酵的影响及其控制

目的 探索溶氧对L-天冬酰胺酶发酵过程的影响及其控制方法。方法 通过装液量试验、接种量试验、葡萄糖试验和氧载体试验,考察摇瓶发酵过程中溶氧对L-天冬酰胺酶合成的影响,采用通纯氧自控pH的发酵工艺进行溶氧控制和pH控制。结果 采用通纯氧自控pH的发酵工艺,可延长发酵周期,有效防止菌体过早自溶,大大促进L-天冬酰胺酶的合成,较分批发酵提高产酶83％,达到110u/ml。发酵动力学特性分析表明,该发酵方式L-天冬酰胺酶的合成与菌体生长不相关,控制比生长速率μ为0.15～0.301/h,均有利于L-天冬酰胺酶的合成,可使Qp_(max)达到3922mmol/g.h。结论 溶氧对大肠杆菌L-天冬酰胺酶的合成有严重影响,已建立了控制溶氧的发酵工艺。

Influence of Dissolved Oxygen on Fermentation of L-asparaginase and Control

Objective To explore the influence of dissolved oxygen on the fermentation of L-asparagi-nase and the method for controlling dissolved oxygen. Methods The influence of dissolved oxygen on the synthesis of L-asparaginase during fermentation was studied under various medium volumes, inoculum amounts, glucose concentrations and oxygen-vectors. The dissolved oxygen during fermentation was controlled by automatical control of pH value through supplying pure oxygen. Results The automatical control of pH value by supplying pure oxygen prolonged the fermentation period, effectively prevented the premature autolysis of cells and significantly accelerated the synthesis of L-asparaginase. The yield of L-asparaginase (110 u/ml) increased by 83 % compared with that by batch fermentation. Fermentation kinetics indicated that the synthesis of L-asparaginase is not related to the growth of bacteria. When the specific growth rate of bacteria was controlled at 0.15-0.30 l/h, the Qpmax reached 3 922 mmol/g.h. Conclusion Dissolved oxygen influenced the synthesis of L-asparaginase significantly. A fermentation process for controlling dissolved oxygen was developed.