Formation of methylated and phosphorylated metabolites during the fermentation process of verdamicin.

In an attempt to understand the biosynthetic processes leading to the formation of verdamicin (end product), we have examined the patterns of the formation of methylated and phosphorylated metabolites, which resulted from either the addition of l-[methyl-(14)C]methionine or [(32)P]KH(2)PO(4) to the fermentation. Incorporation of label from l-[methyl-(14)C]methionine into the bioactive sisomicin, verdamicin, and the chromatographically polar components increased with the progression of time. Two methylated bioinactive metabolites were found in the culture broth after removal of the methylated bioactive metabolites. In contrast to the bioactive metabolites, incorporation of the methyl-(14)C label into the two methylated bioinactive metabolites decreased with the progression of time. A phosphorylated bioinactive metabolite (nonmethylated) was also found in the culture broth, fermented in the presence of [(32)P]KH(2)PO(4). The role of the phosphorylated metabolite in the biosynthesis of the bioactive metabolites cannot yet be explained.