What type of organisms are represented by E. coli?

E. coli, or Escherichia coli, is a type of bacterium that is commonly found in the intestines of humans and other animals. It belongs to the domain Bacteria, which comprises single-celled microorganisms that lack a nucleus and membrane-bound organelles. Bacteria are characterized by their prokaryotic cell structure and can be found in a wide variety of environments, often playing essential roles in processes such as digestion and nutrient cycling.

As a representative organism of this group, E. coli is extensively studied in microbiology for its metabolic processes and its role as an indicator organism in water safety and food quality. The other choices refer to completely different categories: Archaea are another group of prokaryotic organisms but are distinct from bacteria; Eukarya includes organisms with eukaryotic cells, such as plants, animals, and fungi; and viruses are acellular entities that require a host cell to replicate. This distinguishes E. coli firmly within the bacterial classification.