Abstract The fungal microorganism Cunninghamella echinulata was utilized to para- hydroxylate the synthetic substrate (±)-1-isopropylamino-3-phenoxy-propan-2-ol (1). The resulting product,(±)-1-(4-hydroxyphenoxy)-3-isopropylamino-propan-2-ol, or (±)- prenalterol,(2) was formed in> 85% yield. Extracts from incubates were derivatized with trifluoroacetic anhydride and the concentrations of 1 and 2 were determined by GC on a ...