Alterations in the permeability of Neurospora crassa due to polyene antibiotics.

Kinsky, Stephen C. (Washington University, St. Louis, Mo.). Alterations in the permeability of Neurospora crassa due to polyene antibiotics. J. Bacteriol. 82:889-897. 1961.-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 media composition on this phenomenon are described. The present evidence indicates that the polyenes exert their primarily fungicidal effect by an alteration of permeability, probably due to direct action on the membrane of sensitive organisms.