A novel glycosphingolipid from Gram-negative aquatic bacteria

The chloroform–methanol extractable lipids of the Gram-negative fresh-water bacteria Arcocella aquatica NO-502 and Flectobacillus major FM were found to contain an unusual ninhydrin-positive glycolipid. It was purified by two-stage silica gel-column chromatography. By the use of IR and 1H-NMR spectroscopy, mass spectrometry and chemical-degradation experiment, the lipid was established to be 1-O-monoglycosyl ceramide, the carbohydrate moiety of which was the α-pyranose-ring form of 7-desoxy-7-amino- -manno-heptulosonic acid, or 1-hydroxycarbonyl-6-deoxy-6-amino-α- -mannopyranose. The ceramide portion consisted mainly (by 95% in the A. aquatica glycolipid and 80% in the F. major glycolipid) of 2-N-(2′- -hydroxy-13′-methyltetradecanoyl)-15-methyl-4(E)-hexadecasphingenine. The minor molecular species differed from the major one only in fatty acid structure. The glycolipid accounted for 8 and 11% of the total lipids extracted from A. aquatica NO-502 and F. major FM cells, respectively.