[Biosynthesis of the polyene antibiotic levorin and the membrane composition of Streptomyces levoris]

Changes in the composition of Streptomyces levoris membranes were studied in the course of the polyene antibiotic levorin biosynthesis when the process was stimulated by Candida tropicalis metabolites and inhibited by inorganic phosphate. In the presence of stimulating compounds, the percentage of membranes increased in S. levoris cells and the membrane composition changed: the protein-to-lipid ratio and the concentration of total phosphorus decreased while the content of carbohydrates increased. Analysis of the lipid component showed that these changes were due to a gradual substitution of non-phosphorus glycolipids for membrane phospholipids and to an enrichment of the membranes with proteolipids. Such changes were not detected in a medium containing the inhibitor. It was for the first time that a considerable amount of the antibiotic produced by the culture was found in the membrane fractions. The data are discussed in relation with a possible role of the actinomycete membrane structures in levorin biosynthesis.