Optimal Operating Conditions for Cultivation of Plant Cells in an External Loop Airlift Bubble Colum

本研究采用胡萝卜愈伤组织生产β -胡萝卜素的培养作为植物细胞培养的模式系统，在更低、更均匀的水动力剪切应力条件下，采用外环气升式气泡塔作为适合大规模培养的生物反应器。本研究的目的是：(a)考察不同操作条件对细胞生长和β -胡萝卜素产量的影响；(b)以β -胡萝卜素含量、产量和生产率为目标函数，确定各操作变量的最佳选择；(c)建立动力学模型，预测时间过程，寻找最佳操作条件。各研究课题的研究结果总结如下：1。生物反应器几何形状和操作条件对悬浮胡萝卜细胞生长和β -胡萝卜素产量的影响。虽然气升式生物反应器和摇瓶的各操作变量的最佳值几乎相同，但摇瓶的β -胡萝卜素含量和产量大于摇瓶。组合最优操作条件下的产量比对照条件下的产量高出数倍。较高的温度有利于栽培前期的生长和生产，而较低的温度有利于栽培后期的生长和生产。这表明了两阶段的培养，温度由高到低。研究了气升式生物反应器的特性。生物反应器结构和操作条件对固定化胡萝卜细胞β -胡萝卜素产量的影响3种不同海藻酸钙凝胶珠中固定化胡萝卜细胞的生长和β -胡萝卜素含量分别比相应悬浮细胞低1/2 ~ 1/3和1/5 ~ 1/10。较高分子量的海藻酸盐在较大程度上抑制了藻酸盐的生长，提高了藻酸盐的含量。这证实了β -胡萝卜素含量与细胞生长呈负相关。利用一种新型糖脂对β -卡拉丁烯的排泄进行进一步的研究。各种培养方法的比较和最佳操作条件的寻找假设细胞生长受到抑制和β -胡萝卜素产量对生长的非线性依赖的动力学模型很好地再现了所观察到的时间过程。模型中的动力学参数以无量纲形式与操作条件相关，基于各自的变量和控制培养的参数。具有相关性的模型较好地预测了时间过程和最佳运行条件。在结冷胶培养基上的固体培养中，四种不同细胞系的含量均不大于相应悬浮细胞的1/10。结果表明，固体培养对细胞生长没有显著的抑制作用，但其含量显著增加，即使在固体培养中，含量也与生长呈负相关。少

The present research employed the cultivation of carrot calluses for production of beta-carotene as a model system of plant cell culture and the external loop airlift bubble column as a bioreactor suitable to large scale culture under lower and more uniform hydodynamic shear stress. The purpose of this work is (a) to examine the effects of the various operating conditions on cell growth and beta-carotene production, (b) to determine the optimum of each operating variable taking the content, yield and productivity of beta-carotene as the objective functions, and (c) to establish kinetic model to predict the time courses and to search for an optimal operating condition. The results obtained for each research subject are summarized as follows.1. Effects of bioreactor geometry and operating conditions on cell growth and beta-carotene production of suspended carrot cellsAlthough the optimum values of each operating variable were almost the same for both airlift bioreactor and shaking flask, … More the beta-carotene content and productivity in the former was grater than those in the latter. The production under the combined optimal operating conditions was several times higher than that under the control conditions. The higher temperature favored both growth and production in the earlier stage of cultivation, while the lower ne favored those in the later stage. This suggested a two-phase cultivation shifting the temperature from higher to lower one. The characteristics of airlift bioreactor was also investigated.2. Effects of bioreactor geometry and operating conditions on beta-carotene production of immobilized carrot cellsThe carrot cells immobilized in the three different calcium alginate gel beads gave the lower growth and beta-carotene content than the corresponding suspended cells by factors of 1/2 to 1/3 and 1/5 to 1/10, respectively. The higher molecular weight of the alginates used reduced the growth and enhanced the content to a greater extent. This verified the negative correlation of beta-carotene content with cell growth. A further study on excretion of beta-caratene will be continued by using a novel glycolipid.3. Comparison of various culture methods and search for optimal operating conditionsThe kinetic model assuming an inhibited cell growth and a nonlinear dependence of beta-carotene production on growth well reproduced the observed time courses. The kinetic parameters in the model were correlated with the operating conditions in the dimensionless form based on the respective variables and parameters for the control cultures. The model with the correlations fairly predicted the time courses and the optimal operating conditions. In the solid cultivation on the gellan gum medium, the four different cell lines gave the content of no greater than 1/10 of that for the corresponding suspended cells. This revealed that no great decrease in cell growth due to solid cultivation resulted in a remarkable increase in the content although the negative correlation of content with growth was observed even in the solid cultivation. Less