Antagonists of Antifungal Substance Polyoxin

Polyoxin inhibited the growth of a number of fungi with Pellicularia sasakii and Rhizoctonia solani being the most sensitive. The growth of P. sasakii in shake culture was inhibited completely at all growth stages by the antibiotic. P. sasakii which had been treated with polyoxin resumed growing when transferred to fresh CZAPEK-Dox medium. The inhibitory action of polyoxin was prevented by the addition of certain nitrogen compounds to the media. Dipeptides were the most effective, while a number of amino acids and bases had no effect. Although the ultraviolet absorption spectrum of polyoxin was modified by the addition of many nitrogen compounds, there was no relationship between the shift in the ultraviolet spectrum and the antagonistic effect.