目前利用基因重組大腸桿菌生產外來蛋白質之醱酵方法分成兩階段，首先以批次培養提高菌體濃度，其次以饋料批次饋入新鮮培養基與誘導劑，以誘導外來基因表現。由於以往的文獻發現在批次培養中大腸桿菌比生長速率是影響異種蛋白質產量的重要參數，因此本研究之目的在於探討誘導後細胞比生長速率對於重組蛋白白細胞介素20號(IL-20)生產之影響。研究發現，本研究所使用之宿主載體系統Escherichia coli BL21 (DE3)/pET-43a產生的醋酸僅在2 g/L以下，所以醱酵系統並無醋酸累積之問題。其次內涵體的累積亦不明顯，IL-20主要是以可溶性狀態存在於細胞內。其次，以平均比生長速率0.103 h-1進行饋料可得到最高的比產量(109 mg/g cell)，此結果顯示誘導後比生長速率對比IL-20產量之影響存在一最適值。將實驗數據進一步分析，若以蛋白質比生產速率之觀點，將平均比生長速率控制在0.23 h-1可得到IL-20最高比生產速率16.4 mg/(g cell)•h。

The method for producing recombinant proteins by Escherichia coli consists of two stages. The first was to increase cell density at the batch-cultured stage; and the second was to feed fresh medium with inducer using fed-batch operation for inducing the expression of foreign gene. The literatures had documented that the cell growth rate is a major factor affecting the yield of recombinant proteins. Therefore, the objective of this study was to investigate the effect of cell growth rate of post-induction on the production of the recombinant protein interleukin-20 (IL-20). The results indicated that the host-vector system E. coli BL21(DE3) produced little acetic acid (below 2 g/L), thus the fermentation system was not influenced by the accumulation of acetate. The formation of inclusion bodies were not obvious, most of the IL-20 existed as soluble form inside the cells. In addition, the highest specific IL-20 yield (109 mg/g cell) was obtained when the average growth rate was 0.103 h-1. From the experimental data, the highest specific production rate of IL-20 was estimated as 16.4 mg/(g cell)•h if the average cell growth rate could be controlled at 0.23 h-1.

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