IPTG, Dioxane-Free (isopropyl-β-d-thiogalactopyranoside), is an inducer of β-galactosidase activity in many bacteria. Functioning as alacanalog, IPTG induces β-galactosidase activity by binding to and inhibiting thelacrepressor. This product is used to differentiate recombinants from nonrecombinants in cloning strategies using vectors containing thelacZ orlacZ α-peptide gene.