Title: Microbes in extreme environments - Encyclopedia of the Environment
Headings: Microbes in extreme environments
Microbes in extreme environments
1. Biodiversity of extremophilic microbes
2. The discovery of the Archaea: a revolution
3. Extremophilic organisms and the limits of life
4. How do extremophiles preserve their biological functions?
5. Usefulness of “extremozymes” for biotechnologies
References and notes

Content: Even more surprisingly, some archaea are capable of symbioses with complex organisms such as sponges. Archaea are found in the gut microbiota, which plays an important role in human health (see Human microbiotes: allies for our health ). No pathogens have yet been identified in archaea, but their link to certain diseases or metabolic disorders such as obesity has been proven. The evolution and expansion of archaea and bacteria are equally complex. Archaea have an astonishing evolutionary proximity to eukaryotes. Some hypotheses suggest that archaea are at the origin of the emergence of eukaryotes [5] (see Symbiosis & evolution). Figure 3. Electron microscopic image of an abyssal hyperthermophilic archaea: Thermococcus fumicolans [Microphotography © Ifremer].