IPTG, Isopropyl beta-D-1-thiogalactopyranoside, binds the lac repressor and induces expression of beta-galactosidase in E. coli. IPTG is widely used to induce the expression of cloned genes under the control of the lac operon and to screen blue/white colony in X-gal plate. Note: IPTG is often prepared in distilled water in 1 M stock solution (238 mg/ml). Sterile the solution using 0.2 um filter. Aliquot the stock and store under -20C.
