Some examples of organisms within the domain eubacteria are algae, E. coli and salmonella. Also known as true bacteria, these are microscopic, prokaryotic, single-celled organisms without nuclei that produce their food by photosynthesis.
Although some eubacteria are harmful to humans, and all known bacterial pathogens are eubacteria, they can also be useful. Eubacteria are used in the production of wines, cheeses and yogurts and are also part of the process used at wastewater treatment plants. These organisms have been around for over 3 billion years and, as result of the oxygen produced from their photosynthesis process, made it possible for air-breathing animals to survive.