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Fed-batch cultivation ofEscherichia coli YK537 (pAET-8) for production ofphoA promoter-controlled human epidermal growth factor
Authors:Yonggang Wang  Peng Du  Renbao Gan  Zhimin Li  Qin Ye
Affiliation:(1) State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 200237 Shanghai, China;(2) Institute of Biochemistry and Cell Biology, Shanghai Institute of Biological Science, The Chinese Academy of Science, 200031 Shanghai, China
Abstract:Secretion of the expressed heterologous proteins can reduce the stress to the host cells and is beneficial to their recovery and purification. In this study, fed-batch cultures ofEscherichia coliYK537 (pAET-8) were conducted in a 5-L fermentor for the secretory production of human epidermal growth factor (hEGF) whose expression, was under the control of alkaline phosphatase promoter. The effects of feeding of glucose and complex nitrogen sources on hEGF production were investigated. When the fed-batch culture was conducted in a chemically defined medium, the cell density was 9.68 g/L and the secreted hEGF was 44.7 mg/L in a period of 60 h. When a complex medium was used and glucose was added in pH-stat mode, the secreted hEGF was improved to 345 mg/L. When the culture was fed with glucose at a constant specific rate of 0.25 gg−1h−1, hEGF reached 514 mg/L. The effects of adding a solution containing yeast extract and tryptone were further studied. Different rate of the nitrogen source feeding resulted in different levels of phosphate and acetic acid formation, thus affected hEGF expression. At the optimal feeding rate, hEGF production achieved 686 mg/L.
Keywords:human epidermal growth factor   phoA promoter  fed-batch culture   Escherichia coli   phosphate  secretion
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