Biochemical characteristics of non-streptomycin-producing mutants of Streptomyces griseus. II. Lipids and fatty acid composition of vegetative mycelia.

Five non-streptomycin-producing non-aerial-mycelium-forming mutants (Str-Amy-) of Streptomyces griseus obtained either by spontaneous degeneration or during continuous cultivation of the high-producing aerial-mycelium-forming parent strain HP (Str+Amy+) were checked with regard to the composition of mycelial lipid material. All the Str-Amy- derivatives differed from their ancestor strain HP by an increased ration of 12-methyltetradecanoic acid (aC15:0) to isopalmitic acid (iC16:0) during growth on a chemically defined medium lacking branched-chain amino acids. This finding attests alterations in the availability of precursors for the biosynthesis of methyl-branched fatty acids. The qualitative composition of phospholipids and other polar lipids in one mutant group was found to be similar to the progenitor strain but, additionally, both a yellow pigment and a neutral lipid component were produced in excess. A second type of mutant differed by its incapability to form ornithinolipids even under phosphate limitation. Changes of phospholipid composition were demonstrated in the course of fermentation. Formation of ornithinolipid was suppressed by an excess of inorganic phosphate in the medium, while the portions of phosphatidylethanolamine and cardiolipin increased strongly. Furthermore, the formation of ornithinolipids was influenced by nitrogen sources. these results suggest that the composition of membrane of S. griseus varies in dependence upon the composition of the medium and the age of the mycelium.