溶氧振荡对聚β羟基丁酸混合培养过程的调控作用

研究生物可降解塑料PHB(Poly β-hydroxy butyrate)生产的低成本和高产率发酵。采用廉价碳源——废食品糕点作为原料，其中同时具有葡萄糖和乳酸。培养是在同一5L发酵罐中先后接入2种细菌，先由乳酸杆菌Lactobacillus delbrueckii消耗葡萄糖产生乳酸，再由真养产碱菌Ralstonia eutrophus消耗乳酸产生PHB。本文应用混沌控制理论设计溶氧振荡来协调混生菌矛盾的生理需求，同时改变振荡节律激励细胞的代谢能。考虑真养产碱菌在乳酸里的代谢，有异养和真养两种途径，其中两种重要代谢通量，生物氧化能ATP和还原能NADPH，能够反映混生菌细胞的生理状态，二者都与供氧密切有关。实验通过取样进行细胞破碎后，由荧光分析仪监测不同发酵阶段的ATP和NADPH，发现2种代谢能随着溶氧控制的不同节律变化而起伏，溶氧节律振荡能够使混合培养的PHB的浓度比常规供氧方法提高1倍。

Dynamic Variance of Intracellular Metabolic Energies Under Rhythmical Control for Dissolved Oxygen in PHB Mixed Cultivation

The mixed cultivation using cheaper carbon source-wasted food material contained glucose and lactate at the same time was conducted in 5L fermentor, within which glucose was converted to lactate by L. delbrueckii in anaerobic condition and the lactate was converted to PHB by R. eutropha in aerobic condition. Considering dissolved oxygen concentration may affect the level of intracellular ATP and NADPH of the metabolic pathways for R. eutropha in lactate under autotrophy or heterotrophy, rhythmical oscillated control for DO based on chaos control method was consequently presented. This method was employed to satisfy two strains for opposite oxygen preferences, moreover, excite the intracellular metabolic energy simultaneously. The values examined through spectrophotofluorimetry represented that both ATP and NADPH exhibited fluctuations in accordance with the DO rhythm. By means of this control design, the concentration of PHB can be doubled than the usual under stable DO control.