General Survey of Action Site of Altericidins on Metabolism of Alternaria kikuchiana and Ustilago maydis

Abstract

A peptide antibiotic complex, altericidins (altericidin A, B and C), was isolated from the culture broth of Pseudomonas cepacia KB-1. The altericidins inhibit the growth of a wide range of fungi and yeasts, but show no effect on the growth of bacteria species. A general survey of the mode of action of altericidins was done using Alternaria kikuchiana and Ustilago maydis. Growth of both fungi were suppressed within one hour after altericidins treatment, and at 8 ppm altericidins the dry weight of U. maydis sporidia had decreased as compared with the initial dry weight. Endogenous and exogenous respiration of A. kikuchiana mycelia were hardly affected by 5–25 ppm altericidins, but inhibited at 50 ppm. Oxygen uptake of rat-liver mitochondria was not affected at 4 ppm. By altericidins treatment, the incorporation rate of 14C-protein hydrolysate into protein, 14C-uridine into RNA and 14C-thymidine into DNA of both fungi, and of 14C-glucose into cell wall component of A. kikuchiana mycelia were apparently inhibited. However, the results showed that the uptake of these 14C-substrates by the fungi was also inhibited. Altericidins stimulated the incorporation of 14C-acetate into total lipid fraction of fungi. It was supposed that altericidins might act on cytoplasmic membrane of the fungi and disturb the transport of radiolabeled precursors into cells and consequently the biosynthesis of higher molecular substances. © 1984, Pesticide Science Society of Japan. All rights reserved.