RELATIONSHIP BETWEEN VALINE, FATTY-ACIDS, AND SPIRAMYCIN BIOSYNTHESISIN STREPTOMYCES-AMBOFACIENS

Spiramycin biosynthesis in Streptomyces ambofaciens was stimulated in the presence of valine or by sequential addition of some short-chain f atty acids to a culture medium containing an ammonium salt as source o f nitrogen. Acetate kinase and acetyl-CoA carboxylase, enzymes that ca talysed the formation of precursors of spiramycin biosynthesis (acetyl -CoA and malonyl-CoA), were detected during the active growth and anti biotic production phases. In this latter phase a higher level of acety l-CoA carboxylase activity was observed with valine (1.02 mu mol.min(- 1) mg protein(-1)) than with ammonium (0.05 mu mol.min(-1).mg protein( -1)) as nitrogen source, while the evolution and the level of acetate kinase activity were the same in both media. Successive addition of ac etate and isobutyrate stimulated highly and weakly the acetyl-CoA carb oxylase and acetate kinase activity, respectively.