Novel lipid components of the Azotobacter vinelandii cyst membrane

Phospholipids are ubiquitous components of biological membranes. In the vegetative cells of Azotobacter vinelandii , a Gram-negative free-living aerobic soil bacterium, the membrane lipids are phospholipids with polar head group and fatty acyl compositions similar to those of Escherichia coli 1 . We report here that when A. vinelandii differentiates to form metabolically dormant cysts, the phospholipids in the membranes are replaced by a family of 5- n -alkylresorcinols and 6- n -alkylpyrones. These novel amphiphilic lipids form a unique membrane matrix which may contribute to the physiology and desiccation resistance of the cyst.