Shaanxi Key Laboratory of Degradable Biomedical Materials, Northwest University, Xi'an 710069, China.
J Biosci Bioeng. 2010 Mar;109(3):257-61. doi: 10.1016/j.jbiosc.2009.08.008. Epub 2009 Sep 16.
The primary processing problem in recombinant Escherichia coli fermentation is the production of acetic acid, which can inhibit both cell growth and recombinant protein production. The ability of E. coli to assimilate acetate permits it to solve this problem in a rather creative manner. In this study, the effects of acetic acid assimilation through a glucose starvation period at different cell growth phases were investigated in fed-batch cultures of recombinant E. coli. Experimental results showed that the human-like collagen (HLC) production could be improved by introducing glucose starvation at the end of batch culture and pre-induction phase, while the glucose starvation at the induction phase resulted in a poor HLC productivity. The acetic acid assimilation was observed during all the glucose starvation periods. In addition, a systematic study for evaluating the effects of acetic acid was carried out by adding acetate into culture media at different cell growth phases and then employing a glucose starvation after several hours. It was found that obvious acetate inhibition on cell growth occurred in the batch culture phases while its inhibitory effect on HLC expression occurred only in the post-induction phase. The longer the elevated acetic acid concentration maintained, the stronger the inhibitory effects were. These results are of significance for optimizing and scaling-up fermentation processes.
在重组大肠杆菌发酵中，主要的加工问题是产生乙酸，它会抑制细胞生长和重组蛋白的生产。大肠杆菌同化乙酸的能力使其能够以一种相当有创意的方式解决这个问题。在这项研究中，通过在不同细胞生长阶段的葡萄糖饥饿期来研究重组大肠杆菌分批补料培养中的乙酸同化作用。实验结果表明，通过在分批培养和预诱导阶段结束时引入葡萄糖饥饿，可以提高类似人胶原蛋白（HLC）的生产，而在诱导阶段的葡萄糖饥饿会导致 HLC 生产力下降。在所有的葡萄糖饥饿期都观察到了乙酸的同化。此外，通过在不同的细胞生长阶段向培养基中添加乙酸，并在数小时后进行葡萄糖饥饿，进行了一项系统的评估乙酸影响的研究。结果发现，在分批培养阶段，乙酸对细胞生长有明显的抑制作用，而对 HLC 表达的抑制作用仅发生在诱导后阶段。维持升高的乙酸浓度的时间越长，抑制作用就越强。这些结果对于优化和放大发酵过程具有重要意义。
