Fatty acids and sterols of selected hyphochytriomycetes and chytridiomycetes

Abstract

The fatty acids and sterols of eight Chytridiomycetes and two Hyphochytriomycetes, and fatty acids of the Oomycete Pythium gracile, were analyzed by gas-liquid chromatography. In addition to the fatty acids anticipated for fungi, the two Hyphochytriomycetes ( Hyphochytrium catenoides and Rhizidiomyces apophysatus) and four of the Chytridiomycetes ( Catenaria anguillulae, Blastocladiella emersonii, Monoblepharella sp., and Allomyces macrogynus) contained arachidonic acid as a major fatty acid of the polar lipid fraction, and this fatty acid was detected as a minor component of Rhizophlyctis rosea and Spizellomyces punctatum. Eicosapentaenoic acid constituted 4.6% of the polar lipid fatty acids in Monoblepharella sp., and trace amounts were detected in several other species. Both the gamma (ω-6) and alpha (ω-3) isomers of linolenic acid were detected in all of the species analyzed. Cholesterol was the predominant (≥73%) sterol of B. emersonii, R. rosea, A. macrogynus, and Chytridium confervae, and a minor (<12%) component of C. anguillulae, and H. catenoides. The major sterols of the other species included lanosterol ( C. anguillulae, 45%), stigmasta-5,22-dien-3β-ol ( H. catenoides, 51%), 24-ethyl-cholesterol ( S. punctatum, 38%; H. catenoides, 17%; Monoblepharella sp., 70%; and R. apophysatus, 84%), 24-methyl-cholesterol ( H. catenoides, 23%; R. apophysatus, 14%; S. punctatum, 53%), and 24-methylene cholesterol ( Rhizophydium sphaerotheca, 51%). Neither ergosterol nor fucosterol was detected in any of the species studied.