The effect of growth temperature on the fatty acid composition of Thamnidium elegans Link.

The fatty acid composition of a slightly psychrophilic fungus, Thamnidium elegans, has been determined and compared with other mucoraceous fungi. The growth temperature strongly influences the degree of unsaturation of lipids, as reported for other organisms, but in T. elegans both the quantitative and qualitative profiles of the fatty acids are affected. At low temperature, T. elegans contains both alpha- and gamma-isomers of linolenic acid. The alpha-isomer is reported here for the first time in a mucoraceous fungus. Besides the biosynthesis of alpha-linolenic acid at the low temperature, T. elegans shows an increase in synthesis of a relatively unknown fatty acid in fungi, i.e. octadecatetraenoic acid (18:4delta 6,9,12,15). The significance of the occurrence of both the isomers of linolenic acid as a response to temperature and in relation to fungal phylogeny is discussed.