Ancient Microorganisms

Milijardu godina nakon formiranja zemlje planet je bio vruć, okružen oblacima koji su sadržavali velike količine vodika, ugljikova dioksida i ostalih plinova, ali ne i slobodnog kisika. Smatra se da su tada nastali metanogeni - prve arhebakterije. Prabakterije ili arhebakterije nastanjuju ekstremna staništa: močvare, slana jezera i vruće izvore. Zbog specifičnosti staništa na kojima obitavaju (uvjeti slični onima na primitivnoj Zemlji u dalekoj prošlosti) i osobina ovih bakterija znanstvenici ih smatraju najstarijim organizmima na Zemlji. Arhebakterije u staničnoj stjenci nemaju peptidoglikan, a imaju aminokiseline koje nemaju ostale bakterije. Genetičkom analizom ustanovilo se kako postoji više skupina prabakterija: metanogene, halofilne i termoacidofilne bakterije. Metanogene su bakterije dobile ime prema svojoj jedinstvenoj sposobnosti dobivanja energije sintezom metana iz ugljikova dioksida i vodika. Kisik štetno djeluje na njih, stoga žive u uvijetima bez prisustva kisika (anaerobnim uvjetima), primjerice u močvarnom mulju, kanalizaciji i slično. Halofilne prabakterije žive u uvjetima visoke koncentracije soli, poput vode Mrtvog mora dok termoacidofilne bakterije žive u izrazito kiselim okruženjima.For billions of years after the formation of the earth, the planet was hot, surrounded by clouds that contained large amounts of hydrogen, carbon dioxide and other gases but not free oxygen. Methanogens — the first archebacteria — were then thought to have arisen. Prabacteria or archebacteria inhabit extreme habitats: wetlands, salt lakes and hot springs. Due to the specific habitat they inhabit (conditions similar to those on primitive Earth in the distant past) and the characteristics of these bacteria, scientists consider them to be the oldest organisms on Earth. Archebacteria in the cell wall do not have peptidoglycan, and they have amino acids that do not have other bacteria. Genetic analysis revealed that there are several groups of prabacteria: methanogenic, halophilic, and thermocacidophilic bacteria. Methanogenic bacteria are named after their unique ability to produce energy by synthesizing methane from carbon dioxide and hydrogen. Oxygen has a detrimental effect on them, so they live in oxygen-free conditions (anaerobic conditions), for example in marsh sludge, sewage and the like. Halophilic prabacteria live in conditions of high salt concentration, such as the Dead Sea water, whereas thermacidophilic bacteria live in highly acidic environments