Method for controlling foreign gene expression by controlling sugar concentration of medium and method for producing foreign gene product

摘要

Escherichia coli carrying a hybrid plasmid constructed by inserting a desired foreign gene into an expression vector, was cultured in a medium containing a sugar component utilizable by the E. coli as a carbon source at a concentration of 0.3% or more so that the expression of said desired foreign gene was suppressed. This E. coli was cultured in the medium in which the sugar concentration was maintained at 0.3% or more in a first process to suppress the foreign gene and to support sufficient cell growth and thereafter at less than 0.3% in a second process to release the suppression to permit effective production of the foreign gene product, which resulted in high concentration of the foreign gene product in the final culture.