In the process of growth Streptoverticillium mycoheptinicum, strain 44B/I produced simultaneously a two-component pentaenic antibiotic (mycopenten) and a heptaenic antibiotic (mycoheptin) by the 1st day of cultivation. The ratio of the components remained constant during the whole fermentation process. When grown on the medium with sodium thiosulfate (under conditions of the changed medium potential) the culture produced the heptaen and a mixture of the components with the background absorption of the UV spectrum at 290--360 nm. The ratio of the heptaen and the mixture was also constant during the whole fermentation process.