Isopropyl-β-D-thiogalactoside, often used in combination with X-Gal or Bluo-Gal, is used for blue and white screening of
recombinant l colonies. IPTG is not metabolized by and is a lactose analogue. Once it enters the cell, it will produce a
long-lasting induction effect. Therefore, the induction efficiency of IPTG is high, and often only a small amount (1 mmol/L) is
needed to achieve the ideal induction effect. Since IPTG is not metabolized, it specifically induces the expression of foreign
proteins in the cell. Unaffected by cell metabolism, the induction effect remains stable.