Khatmiamycin, a motility inhibitor and zoosporicide against the grapevine downy mildew pathogen Plasmopara viticola from Streptomyces sp. ANK313

In the course of our screening for anti-peronosporomycetal agents, we isolated a new compound khatmiamycin ( 1 ), together with five known metabolites, GTRI-02 ( 3 ), 4-ethyl-5-methyl-heptanamide ( 4 ), aloesaponarin II ( 5 ), LL-C10037 α ( 6 ) and LL-C10037 β ( 7 ) from the culture broth of a terrestrial Streptomyces sp. ANK313. The structures of these metabolites were assigned on the basis of their spectroscopic data. Khatmiamycin ( 1 ) exhibited potent motility inhibitory (100%) and lytic (83±7%) activities against zoospores of the grapevine downy mildew pathogen Plasmopara viticola at 10 μg ml −1 , followed by compounds 5 (MIC 25 μg ml −1 ), 7, 6, 3 in the order of decreasing activity. Khatmiamycin ( 1 ) also showed potent antibacterial activity against Staphylococcus aureus and Streptomyces viridochromogenes (Tü57) by causing inhibition zones of 11 and 14 mm diameter, respectively, at the dose of 40 μ g per disk. This is the first report on motility inhibitory and lytic activities of metabolites from a terrestrial Streptomyces species against the zoospores of downy mildew pathogen P. viticola .