Fujii T, Miyawaki O, Yano T
Department of Agricultural Chemistry, The University of Tokyo, Bunkyou-ku, Tokyo 113, Japan.
Biotechnol Bioeng. 1991 Dec 5;38(10):1166-72. doi: 10.1002/bit.260381008.
Continuous production of L-alanine with conjugated enzyme systems of alanine dehydrogenase (AlaDH) and lactate dehydrogenase (LDH) or alcohol dehydrogenase (ADH) was carried out with NAD regeneration in an ultrafiltration hollow-fiber capillary reactor (HFCR) which was proposed as a test bioreactor with very small scale. In the AlaDH/LDH system, pyruvate is the intermediate product for L-alanine so that an optimal point existed in pyruvate concentration for the production rate of L-alanine. NAD cycling number of 4850 and L-alanine productivity of 61.7 mmol/L h were obtained at the best condition. In the AlaDH/ADH system, however, the substrate inhibition in the AlaDH reaction by pyruvate should be considered and the best results of NAD cycling number and (L)-alanine productivity were 2700 and 13.5 mmol/L h, respectively. In consideration of concentration distribution and mixing in the axial direction on an HFCR, performance of the reactor was theoretically analyzed with a multistage stirred tank reactor model combined with the kinetic model based on all the elementary reactions involved. Although quantitative discrepancy existed in some cases, the present theoretical model could explain experimental results and is expected to be generally applicable to standard hollow fiber reactors.
利用丙氨酸脱氢酶（AlaDH）与乳酸脱氢酶（LDH）或乙醇脱氢酶（ADH）的共轭酶系统，在超滤中空纤维毛细管反应器（HFCR）中进行L-丙氨酸的连续生产，并伴有NAD再生。该反应器被提议作为一种超小规模的测试生物反应器。在AlaDH/LDH系统中，丙酮酸是L-丙氨酸的中间产物，因此在丙酮酸浓度方面存在一个L-丙氨酸生产率的最佳点。在最佳条件下，NAD循环数为4850，L-丙氨酸生产率为61.7 mmol/L·h。然而，在AlaDH/ADH系统中，应考虑丙酮酸对AlaDH反应的底物抑制作用，NAD循环数和（L）-丙氨酸生产率的最佳结果分别为2700和13.5 mmol/L·h。考虑到HFCR中轴向的浓度分布和混合情况，结合基于所有基本反应的动力学模型，用多级搅拌釜反应器模型对反应器性能进行了理论分析。尽管在某些情况下存在定量差异，但目前的理论模型能够解释实验结果，并有望普遍适用于标准中空纤维反应器。
