Effects of sulfur dioxide on lichen lipids and fatty acids.

Lipids and fatty acids were studied in some lichen species after exposure to 1 ppm of aqueous sulfur dioxide. The changes in lipid composition are specific to the lichen species tested. The exposure of lichens to SO2 resulted in a slight reduction of the total phospholipid content. The amount of betaine lipid diacylglyceryltrimethylhomoserine was increased in Stereocaulon paschale, but the level of this lipid was not changed in Peltigera aphthosa. An increase in fatty acid unsaturation in lichens in response to the effect of SO2 probably has adaptive significance.