Inactivation of putative PKS genes can double geldanamycin yield in Streptomyces hygroscopicus 17997.

The putative polyketide biosynthesis (PKS) genes cos10 and pg10 were inactivated by insertion of a kanamycin-resistance gene into the genome of the geldanamycin-producing strain, Streptomyces hygroscopicus 17997. The resultant inactivation were confirmed by PCR analysis. The abilities of the PKS gene inactivation strains to produce geldanamycin were compared with the natural geldanamycin- producing strain, S. hygroscopicus 17997. The cos10-inactivated strain exhibited an unchanged ability to produce geldanamycin, but the pg10- inactivated strain can produce twice the yield of the natural strain when grown under the same conditions. We propose that there is a sub-PKS pathway in the geldanamycin-producing strain, S. hygroscopicus 17997.