Age and evolution of bacteria
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.