Why is the T7 polymerase gene in E coli strain BL21DE3 under

Why is the T7 polymerase gene in E. coli strain BL21(DE3) under the control of an inducible promoter?

Solution

The T7 polymerase gene in E. coli strain BL21(DE3) under the control of an inducible promoter because many expression plasmids often use these \"inducible expression system\" when adding inducible promoters such as \"IPTG\" to the medium. These inducible promoters are going to prevent formation of dead cells by promoting synthesis or protein expression of T7 RNA polymerase in E coli cells finally growth phase of cells will be health to reach appropriate \"cell density\". Therefore, these inducible promoters are going to activate expression of plasmid systems using medium finally these inducible promoters control problems produced via toxic protein products formation