[Effect of inorganic phosphate on levorin biosynthesis and on the mycelial makeup of Streptomyces levoris].

The effect of inorganic phosphate on biosynthesis of the polyenic antibiotic levorin by Streptomyces levoris and composition of the culture mycelium was studied. It was found that the synthetic medium with 0.4 mM of phosphate was optimal for growth of Str. levoris. When the concentration of phosphate was higher, the biomass increased, while the synthesis of levorin appeared to be inhibited and morphological changes in the culture were observed. Phosphate had a significant effect on the mycelium composition. When its concentration was increased 10 times as compared to the optimal one, the amounts of protein, RNA, total phosphorus and polyphosphates increased 1.3--1.4, 1.6--1.7, 2--3 and 10 times respectively, while the synthesis of levorin decreased 5 times. Changes in the lipid component of the mycelium were also observed. In the absence of inorganic phosphate in the medium the acetone precipitating fraction of the lipids contained 20--40 per cent of the phosphoruless compounds. During cultivation their portion increased up to 70--77 per cent. However, in the presence of its excess the polar lipids were represented only by phospholipids during the whole life cycle. The fatty acid spectrum of the lipids did not depend on the phosphate concentration and was represented mainly by saturated fatty acids with a branched chain of a series of iso- and anteiso-structures containing 14--18 carbon atoms.