Lee Y L, Chang H N
Department of Chemical Engineering, Korea Advanced Institute of Science and Technology, Cheongryang, Seoul 130-650, Korea.
Biotechnol Bioeng. 1990 Aug 5;36(4):330-7. doi: 10.1002/bit.260360403.
A recombinant Escherichia coli HB101(pPAKS2) producing penicillin acylase was cultured in a membrane cell recycle fermentor. The strain was very stable throughout the whole experiment. The main inhibitory by-product was acetic acid, and cell growth ceased when its concentration was above 14 g/L Cell density could be increased up to 145 g/L dry weight without experiencing by-product inhibition by regulating glucose concentration in the fermentor and by using total membrane recycle. Acetic acid formation was negligible not only when cells were cultured in medium containing no glucose but also when glucose was limited. Dissolved oxygen control as well as glucose limitation was an indispensable condition for minimizing acetic acid formation when the medium contained glucose. Low concentrations of accumulated acetic acid were reused when glucose was limited. Use of highly concentrated medium reduced the membrane surface area required for cell recycle greatly. The recycle fermentor could be operated in various operational modes including partial bleed and repeated recycle culture to give high productivity. Productivity of a repeated recycle system was over 10 times higher than that of a simple batch system.
一株产青霉素酰化酶的重组大肠杆菌HB101(pPAKS2)在膜细胞循环发酵罐中进行培养。在整个实验过程中该菌株非常稳定。主要的抑制性副产物是乙酸，当其浓度高于14 g/L时细胞生长停止。通过调节发酵罐中的葡萄糖浓度并采用全膜循环，细胞密度可提高至145 g/L干重而不受副产物抑制。不仅在无葡萄糖培养基中培养细胞时乙酸生成可忽略不计，而且在葡萄糖受限的情况下也是如此。当培养基含有葡萄糖时，控制溶解氧以及限制葡萄糖是将乙酸生成降至最低的必要条件。当葡萄糖受限时，低浓度积累的乙酸可被再利用。使用高浓度培养基可大大减少细胞循环所需的膜表面积。该循环发酵罐可在包括部分排放和重复循环培养等多种操作模式下运行，以实现高生产率。重复循环系统的生产率比简单分批系统高出10倍以上。
