碳源对重组大肠杆菌发酵生产GLP-1融合蛋白的影响

以一株表达人胰高血糖素样肽-1融合蛋白的重组大肠杆菌为研究对象,首先通过摇瓶实验对碳源种类进行了初步选择,发现葡萄糖和甘油对菌体生长以及GLP-1融合蛋白表达较为适宜。进一步在5 L反应器上对初始葡萄糖及甘油浓度进行了考察,发现高浓度碳源有利于菌体生长却抑制GLP-1融合蛋白表达,但能提高GLP-1融合蛋白的体积得率。在0.25%初始葡萄糖或甘油存在的条件下,在培养过程中流加葡萄糖或甘油维持其在发酵液中的浓度,比较了两者对菌体生长以及GLP-1融合蛋白表达的影响,结果发现,以甘油为碳源时,菌体生长以及GLP-1融合蛋白的表达量均高于以葡萄糖为碳源的结果,最终发酵液的菌浓(OD_(600))可达到25.4,较葡萄糖为碳源时19.1提高了33.0%,GLP-1融合蛋白表达水平和体积得率分别可达到22.4%和1.051 g/L,较葡萄糖为碳源的15.8%和0.504 g/L分别提高41.8%和108.5%。该结果对GLP-1融合蛋白表达菌株发酵条件的进一步优化提供了依据。

Effects of carbon sources on GLP-1 fusion protein production by fermentation of recombinant Escherichia coli

A recombinant Escherichia coli strain expressed GLP-1 fusion protein was studied. Firstly, the effects of carbon sources on the recombinant E. coli were investigated in shake flasks and the results showed that the glucose and glycerol were the proper carbon sources for the expression of GLP-1. Then, the initial concentration of carbon sources （glucose and glycerol） on the cell growth and GLP-1 fusion protein production were investigated in a 5 L fermentor. It indicated that the higher concentration of the carbon source was beneficial to cell density, and the volume yield of GLP-1 fusion protein could be improved. On basic of this, the 0.25 % glucose or glycerol was considered as the initial carbon concentration, and the carbon concentration of culture medium were maintained by feeding glucose or glycerol. By feeding of glycerol, the cell concentration （ OD600 ）, the expression level of GLP-1 and the volume yield of GLP-1 reached 25.4, 22.4 % and 1. 051 g/L, respectively. Compared with that of glucose as carbon source it increased by 33.0 %, 41.8 % and 108.5 %, respectively. The results could provide guidelines for further optimization of GLP-1 fermentation process.