Inverse regulation of spore germination and growth by cyclic AMP in Streptomyces hygroscopicus.

The cyclic AMP level in germinating spores of Streptomyces hygroscopicus rises to a miximum ag outgrowth of germ tubes. Exogenous cyclic AMP results in an inverse effect on germination speed and growth.

Phosphate inhibition of secondary metabolism in Streptomyces hygroscopicus and its reversal by cyclic AMP.

Inorganic phosphate inhibited the biosynthesis of the macrolide antibiotic turimycin in different strains of Streptomyces hygroscopicus. In the wild type strain a depression was observed with increasing phosphate concentrations. A total inhibition was found at 0.1 M phosphate. In a high producing mutant a minimum of turimycin production occured when the phosphate concentration was between 5 mM and 10 mM. Above this concentration the antibiotic synthesis increased again but the production period shifted to a later period of cultivation. Addition of inorganic phosphate resulted in an initial increase of intracellular cyclic AMP content. But a second elevation characterizing the normal level of cyclic AMP throughout the growth phase was prevented by phosphate. Exogenous cyclic AMP as well as positive effectors of the adenylyl cyclase system were able to overcome the phosphate suppression. Cyclic AMP abolished the reduction of protein synthesis following phosphate addition and caused the reappearance of a protein band which may be responsible for the turimycin biosynthesis.

Biosynthetic studies on the macrolide antibiotic turimycin using 14C-labeled precursors.

Using a strain of Streptomyces hygroscopicus JA 6599 several 14C-compounds were investigates as potential precursors of the macrolide antibiotic turimycin followed by partial degradation to localize the radioactivity. L-Methionine-14C-methyl and n-butyrate-1-14C were incorporated exclusively and in a specific manner. The incorporation ratios were dependent on the addition time of the precursors. Studies of the incorporation of acylmycaroses and demycarosyl turimycin into the antibiotic are also reported.