Abstract

The lipids of Bacteroides melaninogenicus were readily extractable with chloroform-methanol. Three per cent of the fatty acids were not extractable. The neutral lipids contained 4% of the extractable fatty acids, the stench characteristic of these organisms, and 0.5 μmole of vitamin K₂ isoprenologues K₂-35, K₂-40, and K₂-45 per g (dry weight). This is one-fifth to one-tenth of the vitamin K₂ level found in other bacteria. Ninety-six per cent of the extractable fatty acids were associated with the phospholipids (60 μmoles of lipid phosphate/g, dry weight), which consisted of the diacyl lipids phosphatidic acid, phosphatidyl serine, and phosphatidyl ethanolamine (with phosphatidyl glycerol and cardiolipin in one strain). The unusual phosphosphingolipids ceramide phosphorylethanolamine, ceramide phosphorylglycerol, and ceramide phosphorylglycerol phosphate accounted for 50 to 70% of the lipid phosphate. In protoheme-requiring strains, the protoheme concentration in the growth medium regulated the growth rate and the amount of enzymatically reducible cytochrome c. There were no gross changes in the lipid composition in cells containing different levels of enzymatically reducible cytochrome c.

Images in this article

Image
on p.87

Image
on p.88

Image
on p.89

Click on the image to see a larger version.

Selected References