Neutral lipids, phospholipids, and a betaine lipid of the snow mold fungus Microdochium nivale

Abstract

The hyphae of the snow mold Microdochium nivale contained lipids in a yield of about 10% w/w of the dry matter of hyphae. The total lipid was fractionated into neutral and polar lipid fractions. In the neutral lipid fraction, triacylglylcerol was the sole major component. As minor components, ergosterol, diacylglycerol, free fatty acid, and fatty acyl ergosterol were identified. The polar lipid fraction contained phospholipids, glycolipids, and a lipid containing neither phosphorus nor sugar. Phosphatidylethanolamine, phosphatidylcholine, phosphatidylglycerol, phosphatidylserine, and phosphatidic acid were identified as phospholipids. The polar lipid fraction included at least four kinds of glycolipids that have not been identified. A very unusual lipid in fungi, a betaine lipid, diacylglyceryltrimethylhomoserine, was identified by chemical and physicochemical analyses. The level of the neutral lipid fraction, which accounted for 60% of the total lipid in hyphae at the exponential phase, was significantly increased compared with that of the polar lipid fraction and constituted 80% of the total at the stationary phase. The neutral and polar lipids of Microdochium nivale contained 18:3 (9,12,15), 18:2 (9,12), 18:1 (9), and 16:0 as principal fatty acids. Among them, 18:2 (9,12) and 18:3 (9,12,15) were the major fatty acids of triacylglycerol, phosphatidylcholine, phosphatidylglycerol, and phosphatidylethanolamine, whereas in diacylglyceryltrimethylhomoserine, the major components were 16:0 and 18:3 (9,12,15).Key words: snow mold, phospholipids, betaine lipid, fatty acid, Microdochium nivale.