EFFECT OF VALIDAMYCIN ON THE GROWTH AND MORPHOLOGY OF PELLICULARIA SASAKII

Abstract

The effect of validamycin on the growth of Pellicularia sasakii was studied biochemically and morphologically. Validamycin significantly inhibited the rate of colony extension on water-agar, and smaller and denser colony appeared. On the other hand, its growth was not inhibited significantly when determined by the increase in the amount of protein or ribonucleic acid. Although the increase in the total length of hyphae was suppressed to some extent, the increase in the total volume of hyphae as estimated from the length and width of hyphae was not suppressed significantly. Validamycin suppressed the elongation of the primary hypha and first secondary hyphae, while the elongation of the rest of secondary hyphae was even stimulated in the presence of validamycin. Although branching of hyphae at the periphery of colony was apparently much accelerated by validamycin, there was no difference in the total number of branching points between cultures with and without validamycin. There was no difference in the cell wall components of the fungus of both cultures. It was concluded that validamycin does not inhibit the fungal growth in mass but alters the morphology of the fungus. Among other fungi tested, all belonging to Basidiomycetes were affected by this antibiotic in the same manner, while its effect on fungi belonging to other classes was diverse.