葡萄糖酸钠发酵中底物-产物作用对氧传递的影响及发酵过程优化

目的]探讨葡萄糖酸钠发酵中底物-产物作用对氧传递的影响,以期为黑曲霉发酵生产葡萄糖酸钠的生物工艺优化提供理论依据。方法]通过小型反应器试验,分别确定了葡萄糖酸钠和葡萄糖两种物质对溶液体积传氧系数的影响,进而又考察了两种物质交互作用的影响,在该基础上对发酵工艺进行改进,将原先的代放工艺改成葡萄糖流加工艺,通过流加葡萄糖维持较低的糖浓度,利用OUR为参照指标,在维持相同OUR水平下,比较了两种发酵工艺。结果]研究中发现葡萄糖酸钠浓度的升高会显著降低kLa,而葡萄糖对其影响则较小;在葡萄糖酸钠溶液中逐渐升高葡萄糖的浓度,会造成kLa的下降,低浓度的葡萄糖有利于体系的氧传递。葡萄糖的消耗及葡萄糖酸钠的积累对体积氧传质速率有明显的影响,在实现相同菌体的氧气摄取速率情况下,优化后新工艺所需的搅伴转速和通气流量等设备供氧条件明显优于原工艺,新工艺在降低发酵能耗的同时,还避免了原工艺中代放操作造成的未利用底物的浪费。结论]该研究探明了葡萄糖酸钠发酵中底物-产物作用对氧传递的影响,优化了黑曲霉发酵生产葡萄糖酸钠的生物工艺。

Influence of Interaction between Substrate and Product on Oxygen Transfer in Sodium Gluconate Fermentation and Bioprocess Optimization

Objective] To discuss the influence of interaction between substrate and product on oxygen transfer in sodium gluconate fermentation,so as to provide theoretical basis for sodium gluconate production by Aspergillus niger fermentation.Method] Based on small reactor test,the influence of glucose consumption and sodium gluconate accumulation on volumetric oxygen transfer coefficient was found,and the interaction between glucose and sodium gluconate was investigated.Based on this finding,the previous intermittent process was replaced by fed-glucose process.The two fermentation processes were then prepared at the same OUR level.Result] The increasing concentration of sodium gluconate significantly reduced kLa,while had little influence on glucose;the increasing glucose concentration also decreased kLa,thus it can be concluded that low concentration of glucose is beneficial to oxygen transfer.The volumetric oxygen mass transfer rate was greatly influenced by the consumption of glucose and the accumulation of sodium gluconate.Under the same oxygen intake rate,the optimized technology was better than the original technology in its agitation speed and air flow rate,it not only reduced the energy consumption of fermentation,but also avoid the wastes of unused substrate.Conclusion] The study explored the influence of interaction between substrate and product on oxygen transfer in sodium gluconate and optimized the biological production of sodium gluconate by Aspergillus niger fermentation.