Microbial conversion of grisorixin, a monovalent cation ionophorous antibiotic

The isolation and identification of a bioconversion product of grisorixin from a strain of Streptomyces rimosus is reported. The structure of this product was elucidated from physicochemical data, in particular 13C NMR spectra. Its ionophorous and antibiotic properties are markedly different from those of grisorixin.