8.14D: Nonthermophilic Crenarchaeota
- Discuss the characteristics of nonthermophilic crenarchaeota, specifically Halococcus, that allow it to survive in extreme environments
Crenarchaeota can be extreme halophiles, and include organisms living in highly salty environments (for example, halococcus).
Halococcus is a genus of extremely halophilic archaea, meaning that they require high salt levels, sometimes as high as 32% NaCl, for optimal growth. Halophiles are found mainly in inland bodies of water with high salinity, where their pigments (from a protein called rhodopsinprotein) tint the sediment bright colors. Rhodopsin protein and other proteins serve to protect Halococcus from the extreme salinities of the environment. Some Halococcus may be located in highly salted soil or foods. Because they can function under such high-salt conditions, Halococcus and similar halophilic organisms have been utilized economically in the food industry and even in skin-care production. Halococcus’ genome has not been sequenced yet, although studies of its 16s rDNA have demonstrated its placement on the phylogenetic tree. Due to the organisms’ potential longevity, Halococcus may be a good candidate for exploring taxonomic similarities to life found in outer space.
Halococcus is able to survive in its high-saline habitat by preventing the dehydration of its cytoplasm. To do this they use a solute, which is either found in their cell structure or is drawn from the external environment. Special chlorine pumps allow the organisms to retain chloride to maintain osmotic balance with the salinity of their habitat. The cells are cocci, 0.6-1.5 micrometres long, with sulfated polysaccharide walls. The cells are organtrophic, using amino acids, organic acids, or carbohydrates for energy. In some cases they are also able to photosynthesize.
Key Points
- Halococcus is a genus of extreme halophilic archaea.
- Halophiles are found mainly in inland bodies of water with high salinity, where their pigments (from a protein called rhodopsinprotein) tint the sediment bright colors.
- Halococcus and similar halophilic organisms have been utilized economically in the food industry and even in skin-care production.
- Halococcus is able to survive in its high-saline habitat by preventing the dehydration of its cytoplasm using a solute which is either found in their cell structure or is drawn from the external environment.
Key Terms
- halophile : An organism that lives and thrives in an environment of high salinity, often requiring such an environment; a form of extremophile.