Membrane lipids of mesophilic anaerobic bacteria thriving in peats have typical archaeal traits.
The 16S ribosomal DNA based distinction between the bacterial and archaeal domains of life is strongly supported by the membrane lipid composition of the two domains; Bacteria generally contain dialkyl glycerol diester lipids, whereas Archaea produce isoprenoid dialkyl glycerol diether and membrane-spanning glycerol dialkyl glycerol tetraether (GDGT) lipids. Here we show that a new group of ecologically abundant membrane-spanning GDGT lipids, containing branched instead of isoprenoid carbon skeletons, are of a bacterial origin. This was revealed by examining the stereochemistry of the glycerol moieties of those branched tetraether membrane lipids, which was found to be the bacterial 1,2-di-O-alkyl-sn-glycerol stereoconfiguration and not the 2,3-di-O-alkyl-sn-glycerol stereoconfiguration as in archaeal membrane lipids. In addition, unequivocal evidence for the presence of cyclopentyl moieties in these bacterial membrane lipids was obtained by NMR. The biochemical traits of biosynthesis of tetraether membrane lipids and the formation of cyclopentyl moieties through internal cyclization, which were thought to be specific for the archaeal lineage of descent, thus also occur in the bacterial domain of life.
Royal Netherlands Institute for Sea Research (NIOZ), Department of Marine Biogeochemistry and Toxicology, PO Box 59, 1790 AB Den Burg-Texel, the Netherlands. jweijers@nioz.nl
Johan W H
JW
Weijers
Stefan
S
Schouten
Ellen C
EC
Hopmans
Jan A J
JA
Geenevasen
Olivier R P
OR
David
Joanna M
JM
Coleman
Rich D
RD
Pancost
Jaap S
JS
Sinninghe Damsté
D001105:Archaea / Q000737:chemistry* / Q000254:growth & development; D001421:Bacteria, Anaerobic / Q000737:chemistry / Q000254:growth & development; D002851:Chromatography, High Pressure Liquid; D005995:Glyceryl Ethers / Q000032:analysis*; D013058:Mass Spectrometry; D008563:Membrane Lipids / Q000032:analysis*; D015394:Molecular Structure; D010802:Phylogeny; D044003:Sphagnopsida / Q000382:microbiology*; D013237:Stereoisomerism
D005995:Glyceryl Ethers; D008563:Membrane Lipids