RESUMEN
Lactose was shown to no less competent than Isopropyl-?-D-thiogalactoside (IPTG) in inducing the expression of the ENHANCIN coding gene from Helicoverpa armigera granulosis virus in Eswcherichia coli BL21 (DE3) regulated by a T7 promoter, since the lactose induction could lead to an ENHANCIN band no smaller than the one in IPTG induction on the SDS-PAGE gel. This would decrease the cost of the large-scale ENHANCIN production. The lactose concentration was optimized at 2.2% - 2.5% (w/v) . Different treatments on the lactose sterilization showed that lactose steam- sterilized in 116. 5℃ for 15min could lead to the ENHANCIN production. The convenience and the relatively low cost in its" operation could further decrease the cost of the ENHANCIN production.