Introduction of the tac‐promoter by lactose under fermentation conditions

Abstract

Abstract The use of the expensive IPTG for induction of the tac‐promoter is not practicable at the industrial scale because of the large amounts necessary for induction. We developed a system in which IPTG as inducer was replaced by lactose which induces the tac‐promoter with the same efficiency. In E. coli CW3011 (pOF1.0) lactose is utilized as inducer and carbon source even in the presence of glucose, presumably as a consequence of the overproduction of lac‐permease.