Development of Supercritical Fluid Bioreactor

本文是以超临界流体，特别是超临界二氧化碳(SCCO_2)为反应介质的生物反应器开发研究的摘要。(1)在超临界CO_2中的Possidle酶反应：考察了两个有用的反应：一个是三酰甘油与毛霉脂肪酶的酯交换反应，另一个是三酰甘油与热溶蛋白芽孢杆菌的热裂解酶合成N-(Benzyloxycarbonly)-L-aspartyl-L-Phenyalanine甲酯(Z-APM)。在第一个例子中，当底物的浓度低到它们在SCCO_2中的溶解度时，在SCCO_2中的水解和直接酯交换的速度大约是在正己烷中的三倍，而在第二个例子中，改变了底物的最佳比例，以产生比在有机溶剂中更高的碱性pH。(2)反应动力学分析：假设反应方案模拟了酯交换反应的时间过程，并确定了每个反应步骤的速度常数，使模拟结果与实验结果相一致。(3)超临界流体生物反应器：从反应器中分离并排除部分产物中的游离脂肪酸，在发生酯化反应的情况下可以实现高效反应。为实现高效的反应体系，研制了连续反应反应器。在高压反应器中进料固体底物并在常压下回收产品进行了几次努力。连续反应稳定进行，考察了平均停留时间和水浓度对转化率和产物组成的影响。

This is the abstract of the study on the development of a bioreactor where thne supercritical fluid, particularly supercritical cardon dioxide (SCCO_2), is used as reaction medium.(1) Possidle enzymatic reactions in SCCO_2 :Two examples of the useful reactions were investigated ; one was the interesterification of triacylglycerol with lipase of Mucor miehei origin, and the other was the synthesis of N-(Benzyloxycarbonly)-L-aspartyl-L-Phenyalanine methyl ester(Z-APM) with thermolysin of Bacillus thermoproteolyticus origin. In the first example the rates of hydrolysis and direct interesterification were in SCCO_2 about three times as much as in n-hexane, when the concentrations of substrates were as low as their solubility in SCCO_2 and in the secoud example the optimum ratio of substrates was shifted to produce more alkaline pH than the one reported in the organic solvent.(2) Analysis of reaction kinetics : The reaction scheme was assumed to simulate the time course of interesterification, and the rate constantes of each reaction step were determined to make the simulation agree with the experimental results. It was found that the effect of water on the rate constants differed between hydrolysis and direct intersterification.(3) Supercritical fluid bioreactor : The efficient reaction can be expected in case of interestrification reaction of a part of the products, liberated fatty acids, is separated and excluded from the reactor. The reactor of continuous reaction was developed for future realization of the efficient reaction system. Several effors were made to feed the solid substrate in the high pressure reactor and to recover the product under atmospheric pressure. The continuous reaction could be conducted stably, and the effect of average residence time and water concentration on the conversion as well as the product constituent could be measured.