Effect of growth temperature on lipid fatty acids of four fungi (Aspergillus niger, Neurospora crassa, Penicillium chrysogenum, and Trichoderma reesei)

The effect of growth temperature on the lipid fatty acid composition was studied over a temperature range from 35 to 10 degrees C with 5 degrees C intervals in four exponentially growing fungi: Aspergillus niger, Neurospora crassa, Penicillium chrysogenum, and Trichoderma reesei. Fatty acid unsaturation increased in A. niger, P. chrysogenum, and T. reesei when the temperature was lowered to 20-15, 20, and 20-20 degrees C, respectively. In A. niger and T. reesei, this was due to the increase in linolenic acid content. In P. chrysogenum, the linolenic acid content increased concomitantly with a more pronounced decrease in the less-unsaturated fatty acid, oleic acid, and in palmitic and linoleic acids; consequently, the fatty acid content decreased as the temperature was lowered to 20 degrees C. In T. reesei, when the growth temperature was reduced below 26-20 degrees C, fatty acid unsaturation decreased since the mycelial linolenic acid content decreased. In A. niger and P. chrysogenum, the mycelial fatty acid content increased greatly at temperatures below 20-15 degrees C. In contrast, in N. crassa, fatty acid unsaturation was nearly temperature-independent, although palmitic and linoleic acid contents clearly decreased when the temperature was lowered between 26 and 20 degrees C; concomitantly, the growth rate decreased. Therefore, large differences in the effects of growth temperature on mycelial fatty acids were observed among various fungal species. However, the similarities found may indicate common regulatory mechanisms causing the responses.