热带假丝酵母的二元酸分泌现象及其动力学

Kinetics of secretion and acid production by Candida tropicalis cells in dicarbonxylic acid fermentation system

在热带假丝酵母（Ｃａｎｄｉｄａ ｔｒｏｐｉｃａｌｉｓ）发酵生产十三碳二元酸体系中，细胞内有二元酸和烷烃的积累，其酸分泌相对于胞内烷烃的转化是快过程。为了解释细胞的生物转化和分泌现象，并为对进一步生产过程的优化作理论准备，该文以静息细胞为实验对象，利用磷酸盐缓冲溶液的ｐＨ 变化精确计算酸分泌量，研究了胞内二元酸的分泌和烷烃转化过程的动力学，基于酸分泌机理，提出了产酸化学结构模型。模型对二元酸分泌量的模拟值与试验值吻合得较好，相对误差小于５％ 。

The resting cell of Candida tropicalis have the features of accumulating alkane and dicarbonxylic acid as its intermediate products. The mechanics of the influence on the secretion of dicarbonxylic acid by the extracellular pH and the concentration of dicarboxylic acid anion in the broth were studied by measuring the change of pH in the phosphate buffer in which the resting cells were secreting acid. The amount of acid secreted was calculated promptly and accuratedly. A kinetic model based on the mechanics of acid secretion was proposed and model parameters were kitted by the random search method. The simulated results fit the experimental data well. The maxium error is less than 5%. The conclusion is that the effect on acid production of pH and dicarboxylic acid concentration can be explained properly.