Fermemtation process for the high level production of bovine growth hormone

摘要

A high density fermentation process for high yield production of bovine growth hormone by transformant E. coli is described. The process employs transformant strains of E. coli containing an expression vector coding for bovine growth hormone under the control of a bacteriophage lambda promoter-operator and a plasmid containing the lambda cI857 gene which codes for the temperature-sensitive repressor protein. In the initial growth period, the level of dissolved oxygen in the fermentation medium is maintained at about 20% to 60% saturation and the temperature of the medium is kept at 26 DEG -30 DEG C. Production of bovine growth hormone is then induced by raising the temperature of the medium to at least about 42 DEG C. The temperature is then reduced to about 38 DEG C. to 41 DEG C. to optimize cell growth for the remainder of the induction period, during which the level of dissolved oxygen in the medium is maintained at about 10% to 40% saturation.