Eine oder zwei Membranen bei Prokaryoten: Was war zuerst da?

From a classical perspective, the bacterial cell wall is divided into Gram-positive and Gram-negative. It was shown recently that several Grampositive bacterial groups (monoderm) might have developed from diderm bacteria by losing the outer membrane. Within the archaea, recent studies also describe diderm cell walls via high-resolution electron microscopy. A rising number of structural information on uncultivated microorganisms sheds new light on potential cell wall architectures of the first living cells.