1 M IPTG Solution is a sterile aqueous reagent used to induce transcription from lac-derived promoters in bacteria such as E. coli. It functions as a non-metabolizable analog of allolactose, enabling controlled activation of lac, tac, and T7-lac expression systems in liquid cultures and on agar plates, including blue-white screening when used with X-gal.

Typical working concentrations range from 0.05 to 1 mM in culture. For plates, add to cooled sterile media prior to pouring; for cultures, add at the desired cell density and mix to ensure uniform distribution. Compatibility includes ampicillin-, kanamycin-, and chloramphenicol-based selection when used with appropriate vectors.

Store at −20 °C. Thaw, mix thoroughly, and keep on ice during use. Avoid repeated freeze–thaw cycles by preparing aliquots. Use aseptic technique to maintain sterility.