| Abstract: | The effects of L-valine and L-isoleucine on the composition of mycelial fatty acids were investigated during growth of differentiating parent strains of Streptomyces hygroscopicus and Streptomyces griseus as well as their non-differentiating derivatives (Amy-strains) on a synthetic medium. Both in the Amy+ and Amy- strains, in the presence of L-valine, the portion of the isopalmitic acid (iC16:0) increased, but the addition of L-isoleucine led to an elevated level of the 12-methyltetradecanoic acid (aC15:0). The results suggest that the genetically determined alterations in the ratio of both fatty acids in the non-differentiating derivatives may be due to specific changes in the biosynthetic pathways of both amino acid precursors rather than due to changes of their catabolism. |
