ALTERATIONS IN THE PERMEABILITY OF NEUROSPORA CRASSA DUE TO POLYENE ANTIBIOTICS

Abstract

Thirty-three antibiotics and synthetic fungicides were examined for their effect on the growth and morphology of Neurospora crassa. Only the polyene antibiotics (nystatin, amphotericin B, and filipin) caused a decrease in the dry weight of mycelial mats, which was accompanied by the appearance of cytoplasmic constituents in the medium. The influence of polyene concentration, incubation time, mycelial age, various metabolic inhibitors, pH, and medium composition on this phenomenon are described. The present evidence indicates that the polyenes exert their primarily fungicidal effect by an alteration of permeability, probably as a result due to direct action on the membrane of sensitive organisms.