Validamycin was found to cause an abnormal branching at the tips of the hyphae of Pellicularia sasakii under specific conditions. By application of this phenomenon, an agar dilution method, "dendroid-test method", was established. In another method called the "reversed layer method", agar plates inoculated with P. sasakii are incubated for 40 to 45 hours, then covered with more agar medium and paper disks dipped in the sample solution are applied on the surface. After overnight incubation the diameters of the inhibition zones are measured.
Japan Antibiotics Research Association