Ammonium ion suppresses the biosynthesis of tylosin aglycone by interference with valine catabolism in Streptomyces fraciae

• Published in: Journal of antibiotics Vol. 36; no. 12; pp. 1792 - 1794
• Main Authors: Omura, S, Tanaka, Y, Mamada, H, Masuma, R
• Format: Journal Article
• Language: English
• Published: 01.01.1983
• Subjects: ammonium; Streptomyces fradiae; tylosin
• ISSN: 0021-8820

The authors have reported that tylosin production by Streptomyces fradiae is inhibited by ammonium ion. The inhibition appears to occur at a step before the formation of the aglycone moiety, protylonolide. Protylonolide biosynthesis by a mutant of S. fradiae was enhanced under ammonium ion-depressed conditions produced in the presence of an ammonium ion-trapping agent such as natural zeolite. A recent paper from this laboratory revealed that protylonolide biosynthesis involved valine metabolism. The amino acid is deaminated and decarboxylated to give iso-butyrate, which is then isomerized to n-butyrate, a direct precursor for protylonolide biosynthesis. This finding prompted the authors to examine if there is a correlation between the inhibitory effect of ammonium ion on tylosin production and valine catabolism, since amino acid degradation is under the general control by ammonium ion in enteric bacteria. This communication presents evidence that ammonium ion suppresses protylonolide production by inhibition and repression of valine dehydrogenase in S. fradiae .