INFLUENCE OF FATTY-ACIDS AND DETERGENTS ON POLYETHER ANTIBIOTIC PRODUCTION BY STREPTOMYCES-HYGROSCOPICUS NRRL B-1865

Addition of pure methyl oleate to a Streptomyces hygroscopicus NRRL B- 1865 culture improved polyether antibiotic production, particularly of the closely related nigericin and abierixin, more than did technical methyl oleate. Among the fatty acid constituents of technical methyl o leate, the methyl esters of stearate and particularly linoleate were d etrimental to growth and antibiotic production, while the methyl ester s of palmitate and palmitoleate had the same effect as technical methy l oleate. The presence of Tween 80 or cyclodextrin in S. hygroscopicus cultures supplemented with methyl oleate increased valine uptake and antibiotic production. Antibiotic production was highest with a mixtur e of 1% methyl oleate, 0.1% Tween 80, and 0.1% cyclodextrin. The resul ts suggested that the stimulatory effect of methyl oleate might be enh anced by a substance increasing the accumulation of branched amino aci ds known to be direct precursors of polyether antibiotics. The rate of abierixin synthesis was more important than that of nigericin at the end of the culture. The nigericin/abierixin ratio decreased from 6 in basal medium supplemented with methyl oleate to 2 in basal medium supp lemented with methyl oleate, Tween 80, and cyclodextrin. A strong decr ease in culture pH seen in the presence of Tween 80 and cyclodextrin m ight lead to a Michael transformation of nigericin to abierixin.