Shanghai United Cell Biotechnology Co. Ltd.

The periplasmic release of human growth hormone was improved by osmotic shock from Escherichia coli.The osmotic shock was optimized through pretreatment of the cells with 1-20 mmol·L^-1 Ca²⁺ for 10 min.The recovery of human growth hormone increased by 17.8% after optimization.Pretreatment with Ca²⁺ can effectively improve the recovery of human growth hormone extracted by osmotic shock.

Feasibility of expression of recombinant human parathyroid hormone induced by lactose instead of IPTG was investigated.The influences of inducer concentration, induction time and culture method of fermentation were investigated to determine the optimal induction conditions.The target protein was about 56.8% of total cellular proteins with 0.6% lactose at 4 h, and the expression level reached about 42.6% in 5 L fermentor with fed-batch culture.Lactose could be used as inducer in the expression of rhPTH(1-34) in Escherichia coli.