Influence of α- dl-tocopherol on fungal lipid composition

Abstract

The addition of α- dl-tocopherol to growing cultures of the fungus Glomerella cingulata increased triacylglycerol content 50% or more but decreased the synthesis of triacylglycerols approximately 16-fold; moreover, α-tocopherol treated cultures had 10% to 85% less malonaldehyde than control cultures. These results suggest that α-tocopherol caused increased triacylglycerol content by decreasing triacylglycerol breakdown. In contrast, phosphoglyceride content and synthesis remained virtually unchanged by the addition of α-tocopherol. In both classes of glycerolipid, treatment with α-tocopherol led to increased ratios of unsaturated to saturated fatty acids; but, α-tocopherol treatment led to an increase in the number of double bonds per mole of fatty acid in the triacylglycerols and to a decrease in the number of double bonds per mole of fatty acid in the phosphoglycerides. We infer that, through deacylation-reacylation reactions, the triacylglycerols of treated cultures supplied the phosphoglycerides with relatively saturated fatty acids and that the triacylglycerols also were used for storage of relatively unsaturated fatty acids derived from the phosphoglycerides. Our results suggest that α-tocopherol can be used to produce predictable shifts in the fatty acid composition of fungal phosphoglycerides. Such shifts can be useful tools in attempting to understand how changes in the fatty acid composition of phospholipids influence the physical properties and functions of cellular membranes.