[Effect of levorin and its combination with a modifying factor on the fatty acid composition of Crithidia oncopelti lipids].

It was shown by us earlier that the sensitivity of Crithidia oncopelti to levorin, a polyene antibiotic, increased in the presence of sodium acetate as a modifying factor. A simultaneous change in the ratio of C. oncopelti structural lipids was also observed. The present paper deals with investigation of the effect of levorin and its combination with the modifying factor on the fatty acid composition of C. oncopelti lipids. The study showed that addition of sodium acetate in a concentration of 40 mg/ml to the medium for cultivation of C. oncopelti resulted in an increase in the total level of fatty acid unsaturation at the expense of a significant increase in the content of linoleic acid and polyunsaturated acids. The content of monoene fatty acids simultaneously decreased. In a concentration of 1 microgram/ml levorin had no effect on the growth of C. oncopelti and did not practically change the relative content of its fatty acids. Combined addition of levorin (1 microgram/ml) and sodium acetate (40 mg/ml) to the medium resulted in inhibition of the culture growth by 60-80 per cent and a marked increase in the total content of saturated acids with a decrease in the level of monounsaturated and polyunsaturated acids. The trypanostatic concentration of levorin (10 micrograms/ml) had the same effect and also lowered the total level of unsaturated fatty acids of C. oncopelti.(ABSTRACT TRUNCATED AT 250 WORDS)