Production of 17-<i>O</i>-demethyl-geldanamycin, a cytotoxic ansamycin polyketide, by <i>Streptomyces hygroscopicus</i> DEM20745

<p>The actinomycete DEM20745, collected from non-rhizosphere soil adjacent to <i>Paraserianthes falactaria</i> trees (Cangkringan, Indonesia), is an efficient producer of the anticancer ansamycin polyketide 17-<i>O</i>-demethyl-geldanamycin (17-<i>O</i>-DMG), a biosynthetic precursor of the Hsp90 inhibitor geldanamycin (GDM). In DEM20745, 17-<i>O</i>-DMG is the major ansamycin product observed reaching a maximum titre of 17 mg/L in the fermentation broth. 17-<i>O</i>-DMG has the potential to be a key starting material for the semi-synthesis of GDM analogues for use in anticancer therapy. Thus, this preferential biosynthesis of 17-<i>O</i>-DMG facilitates easy access to this important molecule and provides further insight in the biosynthesis of the geldanamycins.</p>