Optimize The Human-like Collagen Ii Genetically Engineered Bacteria Medium And Fed-batch Operation

Recombinant Escherichia coli BL21 is used to produce human-like collagen. To improve human-like collagen production by optimizing its culture medium. The key constituents of media were optimized using Response Surface Methodology (RSM) and metabolic flux analysis (MFA). Meanwhile, two feeding way (autocontrol and manual operation) were optimized.The optimization results are as follows:The key constituents of media were optimized using response surface methodology (RSM). Before thermal induction, among all the tested samples, the highest biomass production and the lowest production of some hazardous by-products, especially acetic acid, were obtained in media containing 0.085 mol/L glucose and 0.019 mol/L nitrogen (Carbon-Nitrogen ratio,4.47:1). After thermal induction, when the concentrations of glucose and nitrogen in media were 0.065 mol/L and 0.017 mol/L, respectively (Carbon-Nitrogen ratio,3.82:1), the productivity of human-like collagen per cell was the highest while that of acetic acid was the lowest. Additionally, the extended analysis showed that the production of lactic acid and propionic acid increases while that of some of the intermediate acids of the tricarboxylic acid cycle decreases if the dose of only glucose is increased.By performing metabolic flux analysis (MFA), the carbon-nitrogen ratio in both the batch and feeding media were optimized for the high-level production of human-like collagenⅡ. Three carbon-nitrogen ratio, in both the batch and feeding media, were used in this study, and the MFA results showed that the optimal carbon-nitrogen ratio for the batch and feeding media were 2.36:1 and 5.12:1(mol:mol), respectively, thus, resulting in the highest dry cell density (67.2 g/L dry cell weight) and human-like collagen production (10.8 g/L), and the autocontrol feeding way prove to be very useful in fed-batch culture.