Effect of phosphate ion on mildiomycin production by Streptoverticillium rimofaciens.

Effect of inorganic phosphate and ammonium nitrogen on mildiomycin production by Streptoverticillium rimofaciens was investigated in culture with and without addition of ferrous ion. In the presence of ferrous ion, the suitable supply of inorganic phosphate increased the intracellular ATP, but that was not observed without ferrous ion addition. The intracellular ATP remarkably affected ammonium nitrogen assimilation and mildiomycin production, and its concentration in the ferrous-sufficient culture was about 2 approximately 3 times higher than that in the ferrous-deficient culture. The low concentration of intracellular ATP in the ferrous-deficient culture resulted in the reduction of ammonium nitrogen assimilation and mildiomycin biosynthesis. This phosphate ion effect on the intracellular ATP concentration was demonstrated only when ferrous ion was added into the medium. These suggest that mildiomycin biosynthesis is regulated through the concentration of intracellular ATP related to the ammonium nitrogen assimilation.