STIMULATION OF SPORE FORMATION, MYCELIAL GROWTH AND THIOSTREPTON PRODUCTION BY SEVERAL THIOL COMPOUNDS AND BETA-NAD IN STREPTOMYCES-AZUREUS ATCC 14921 AND ITS DERIVATIVES

Sporulation-stimulating compounds were screened by using mutant PK100a of Streptomyces azureus ATCC 14921 (wild type strain PK0), in which spore formation was inhibited by a pock forming plasmid pSA1.1. On agar media, L- and D-cysteines, bacitracin, glutathione, and beta-NAD induced the formation of colored spores or spore mass of the strain PK100a. These compounds also stimulated the spore formation of strain PK0 and its good spore-forming (plasmid free) strain PK100C, and the growth of aerial and submerged mycelia of these three strains. L- and D-cysteines allowed 1.3 to 1.4-fold increase in the production of antibiotic thiostrepton in strains PK0 and PK100C. The thiostrepton production of strain PK100a, which hardly produced it, was also increased by L and D cysteines by as much as 20% of that of strain PK0.