Archaebacteria

Abstract

Experimental work published elsewhere has shown that the Archaebacteria encompass several distinct subgroups including methanogens, extreme halophiles, and various thermoacidophiles. The common chacteristics of Archaebacteria known to date are these: (1) the presence of characteristic tRNAs and ribosomal RNAs; (2) the absence of peptidogly can cell walls, with in many cases, replacement by a largely proteinaceous coat; (3) the occurrence of ether linked lipids built from phytanyl chains and (4) in all cases known so far, their occurrence only in unusual habitats. These organisms contain a number of ‘eucaryotic features’ in addition to their many bacterial attributes. This is interpreted as a strong indication that the Archaebacteria, while not actually eucaryotic, do indeed represent a third separate, line of descent as originally proposed.