Novel polar lipids of halophilic eubacterium Planococcus H8 and archaeon Haloferax volcanii

Abstract

As part of a study to identify novel lipids with immune adjuvant activity, a structural comparison was made between the polar lipids from two halophiles, an archaeon Haloferax volcanii T and a eubacterium Planococcus H8. H. volcanii polar lipid extracts consisted of 44% archaetidylglycerol methylphosphate, 35% archaetidylglycerol, 4.7% of archaeal cardiolipin, 2.5% archaetidic acid, and 14% sulfated glycolipids 1 and 2. Nuclear magnetic resonance (NMR) and Fast atom bombardment mass spectrometry (FAB MS) data determined the glycolipids to be 6-HSO 3- d-Man p-α1-2- d-Glc p-α1,1-[ sn-2,3-di- O-phytanylglycerol] and a novel glycocardiolipin 6′-HSO 3- d-Man p-α1-2- d-Glc p-α1,1-[ sn-2,3-di- O-phytanylglycerol]-6-[phospho- sn-2,3-di- O-phytanylglycerol]. The polar lipids of Planococcus H8 consisted of 49% saturated phosphatidylglycerol and cardiolipin (9:1, w/w), and surprisingly 51% of the photosynthetic membrane lipid sulfoquinovosyldiacylglycerol (SQDG). This study documents archaeal cardiolipin and a novel glycocardiolipin in H. volcanii (lacking purple membrane), and is the first report of SQDG in a non-photosynthetic, halophilic bacterium.