Several novel tiacumicin derivatives containing bromine have been prod
uced by the addition of inorganic bromine to the fermentation broth of
Dactylosporangium aurantiacum subsp. hamdenensis. Structures were elu
cidated employing mass spectrometry and NMR spectroscopy. Antibacteria
l activity of the bromotiacumicins is comparable to that of the parent
compounds.