The composition of biological membrane lipids has been assumed to be much the same and rather simple. But, in October 17 Nature, Jaap Damste and colleagues at the Royal Netherlands Institute for Sea Research, Den Burg, The Netherlands, show that some microbial membrane lipid structures have a previously unidentified lipid composition, probably .to meet the need for the containment of highly toxic metabolic intermediates (Nature, 419: 708-712, October 17, 2002).

Damste et al. examined the anaerobic ammonium-oxidizing (anammox) bacteria Candidatus 'Brocadia anammoxidans', which derive their energy from the anaerobic combination of ammonia and nitrite into dinitrogen gas. In the membrane lipids of these bacteria, they observed cyclobutane rings that give rise to an exceptionally dense membrane. These lipids contain up to five linearly fused cyclobutane moieties with cis ring junctions that are unprecedented in nature but have been identified from other sources as promising building blocks...