Abstract
Antimycin A is a complex of four major components designated as A1, A2, A3 and A4, which were isolated, A4 for the first time, in pure crystalline form. All components exhibited the same fungicidal activity, using Saccharomyces cerevisiae Y-30 as the test organism ; the higher activity of A3 reported before was found to be only apparent, and could be attributed to its higher diffusion coefficient in agar. The teleocidal activity was also the same for all components. Mutations to increased production of antimycin A do not necessarily lead to a change of composition; but, in the various mutants examined, when a change in composition was observed, it was in favor of A1. Three new minor components, designated as A0, A5 and A6, have been detected which represent not more than 1 % of the complex.
