Inhibition of oleandomycin synthesis by glucoses added during fermentation

Oleandomycin biosynthesis by Streptomyces antibioticus is repressed by glucose added to the growth medium in the process of fermentation. Phosphotransferase involved in the synthesis of acetyl CoA and propionyl CoA (the precursors of the antibiotic macrolactone ring) is neither inhibited nor repressed, and the substrate specificity of the enzyme does not change. The content of cAMP in the mycelium of S. antibioticus does not change significantly when either glucose or sucrose is added to the medium 24 h after the inoculation whereas the content of exogenous cAMP rises abruptly 24 h after glucose addition. At the same time, the medium becomes much more acidic and the content of protein in the mycelium rises noticeably. Consequently, cAMP may be involved in the regulation of the culture growth.