Age and evolution of bacteria

Summary Age and evolution of bacteria can be estimated, including facts and hypotheses belonging to morphology, biochemistry, paleontology, ecology and pathogenicity. The corresponding dates are summarized in the following.About 3.5×10⁹ years: Origin of heterotrophic eobiontes.—About 3.0×10⁹ years: The increasing lack of prebiogenic substances is due to the evolution of the respiratory pathway, that is due to the evolution of the photoautotrophy and now released O₂ is due to the evolution of strictly aerobic cells. There is, simultaneously, a transition of spheres to long forms, development of an amoebalike motility, the evolution of spirochetes and the substitution of cholesterol for cardiolipin in the more evolved cells (i.e. strictly aerobic cells etc.).—About 2.0×1.0×10⁹ years: Evolution of the eucyte by symbiosis of a great, primitive, anaerobic, cholesterol-containing cell with a little, strictly aerobic, cardiolipin-containing cell, with a spirochete and in some extent also with photoautotrophic cell.—About 1.0×10⁹ years (maximum: 1.8–1.5×10⁹ years, minimum: 7×10⁸ years): Evolution of metazoa and begin of cell differentiation.—About 2.0–1.0×10⁹ years: Evolution of the bacterial murein sacculus and then development of flagella mediated motility.—About 6×10⁸ years (maximum:1.0×10⁹ years, minimum: 4.5×10⁸ years): Evolution of the gram-negative cell wall.—About 4.0×10⁸ years: Evolution of the gram-positive cell wall.—About 5.0×10⁸ years: Gram-negative, strictly anaerobic bacteria become the first enteric bacteria in coelenterates. About 4.0×10⁸ years: gram-negative, microaerophilic bacteria become Enterobacteriaceae in vertebrates in addition to the strictly anaerobic organisms.—About 3.0–2.0×10⁸ years: Consolidation of the Salmonella in reptiles.—About 2.0–1.5×10⁸ years: Consolidation of Escherichia and other coliform species in mammals.—About 10⁶ years: Evolution of typically human pathogenic organisms, transmitted in homogeneous-homonomous infection ways, i.e. N. gonorrhoeae, S. typhi, T. pallidum, etc.Dedicated to Prof. H. Habs, Bonn, to his 75th anniversary on 11 September 1977.Acknowledgment. I thank Prof. F. Müller, Hamburg, and Prof. P. Sitte, Freiburg i. Br., for stimulating discussions.