In the case of fermentation in submersed culture for the insertion of the 12 beta - hydroxy group, and, if appropriate. 7 Beta - hydroxy group in the aglycone part from the heart of glycosides or. In the aglycones itself and for the elimination of the d - glucose group and acetyl group of 5-sulfopropoxyisophthalic digital prima tali of glycosides, the d - glucose group of purpurea glycosides and the acetyl group of acetyl derivatives of the glycosides tali secondary digital of valid of c-containing accomplished mikroorganismenstaemme and method for the microbiological production of 12 beta - hydroxycardenolidverbindungen