[Festival lecture. The position of microorganisms in the global phylogenetic system of three domains]

New insights into genealogic relations among organisms due to similarities of 16S rRNA sequences of more than 1000 representatives of the various groups led to a classification of the presently known living beings into three domains: Bacteria, Archaea (Archaebacteria) and Eucarya. All medical relevant prokaryotes belong to the domain Bacteria. The systematics of the eukaryote microorganisms (protista and fungi) and their numerous medically relevant representatives will be widely changed in the near future due to latest scientific findings on phylogenetic relations. The retrospective analysis of the 16S rRNA phylogenetic tree led to assuming a chemolithoautotrophic origin of life and an early splitting into three domains in an early precellular phase of evolution.