MEMBRANE LIPID-COMPOSITION AND INVERTASE SECRETION OF NEUROSPORA-CRASSA AND ITS WALL-LESS MUTANT SLIME - EFFECTS OF TEMPERATURE AND THE SURFACTANT TWEEN-80

The effects of temperature and the surfactant Tween 80 on the secretio n of invertase by the ascomycete fungus Neurospora crassa and its wall -less strain slime were investigated. Temperature acclimation dramatic ally affects the phospholipid fatty acid pattern in both strains. The levels of polyunsaturated fatty acids in membrane lipids of wild-type Neurospora crassa and slime increased as growth temperature decreased. Chromatogram analysis from cultures acclimated to 15-degrees-C showed high levels of linolenic acid (18:3), and low levels of oleic acid (1 8:1), suggesting desaturation. Reducing the temperature during growth to 15-degrees-C affected phospholipid fatty acid composition in both s trains, which resulted in a higher level of invertase secretion. The w ild-type Neurospora crassa showed no difference in invertase secretion in the presence of Tween 80. However, the addition of the surfactant to slime cultures caused a 60% increase in invertase secretion, which was more evident after 48 h incubation.