bacteria
Bacteria (lat. Bacteria; see below for other Slovak and Latin names) are, in the current understanding, a domain from the cell taxon (= cellular organisms; lat. Cellulata). Together with archaeons, they form an informal group of prokaryotes. On closer inspection, the term bacteria is understood differently in the literature (see below); the subject of this article (with the exception of a partial chapter on systematics) is bacteria in the narrowest sense, the so-called eubacteria (Eubacteria).
A bacterial cell normally consists of a peptidoglycan cell wall, a nuclear region (nucleoid), DNA without introns, plasmids, and prokaryotic-type ribosomes. Bacteria do not reproduce sexually, instead they most commonly divide binary. Bacteria are the most widespread group of organisms in the world.
Bacteria are of great importance in the planetary cycle of nutrients and often enter into mutually beneficial relationships with other organisms. On the other hand, many pathogenic bacteria are also known, i.e. species that cause infections.
Systematická klasifikácia
Escherichia coli bacteria under the electron microscope.
Scope of the concept and inclusion in the system
The scope of the term bacterium changed depending on the time and the author. The term "bacteria" can therefore, depending on the system used, refer to:
in the past:
prokaryotes
prokaryotes in addition to cyanobacteria, rickettsia in the broad sense (= rickettsia in the narrow sense, bartonella and chlamydia) and possibly mycoplasmas, sometimes also in addition to spirochetes and occasionally also in addition to actinomycetes (Rickettsia, bartonella, chlamydia and mycoplasma were considered viruses or organisms in such systems transition between bacteria and viruses; spirochetes were considered animals or organisms at the transition between bacteria and animals; actinomycetes were considered fungi or organisms at the transition between bacteria and fungi.[31][32][33][34][35] [36])
prokaryotes (possibly excluding cyanobacteria), including non-cellular organisms, especially viruses
prokaryotes except cyanobacteria
prokaryotes except archaeons and cyanobacteria (This variant is quite rare. Synonym: Eubacteriophyta)
today:
prokaryotes except archaeons (Synonym: Eubacteria)
Explanation: The term prokaryotes here includes classical bacteria (including rickettsiae, bartonella, chlamydiae, mycoplasmas, spirochetes, actinomycetes), archaeons and cyanobacteria (including cyanobacteria).
For variants of classification of bacteria in the system of living organisms, see System of living organisms.