The extremely halophilic Archaebacteria.

Chemotaxonomic techniques have been used to determine relationships within a wide range of extremely halophilic archaebacteria including a newly isolated group of alkaliphilic strains. DNA-16SrRNA hybridization has revealed that these organisms form a distinct order comprising ten genera within two families. DNA-DNA reassociation studies indicate seventeen species within these genera. Polar lipid compositions of strains have been shown to be a useful diagnostic tool for the elucidation of groups at the generic level. Analysis of lipids also revealed the presence of a novel archaebacterial C20C25 diether core lipid within certain genera. Satellite DNA was present in many strains and its presence is correlated with the presence of large plasmids in the cells. Conventional biochemical tests have been applied to a number of strains in parallel with the chemotaxonomic analyses. A proposed revision of the taxonomy of the extreme halophiles is included in an attached appendix.