Cenarchaeales

Cenarchaeales

Cenarchaeales

The Cenarchaeales is an order of archaea that belongs to the phylum Thaumarchaeota. It is a diverse group of microorganisms that are found in various environments, including marine and freshwater habitats. The order was first described in 2006 and is named after the type genus Cenarchaeum.

Taxonomy

The Cenarchaeales order is classified under the phylum Thaumarchaeota, which is one of the major phyla of archaea. Thaumarchaeota is known for its ability to oxidize ammonia, a process called ammonia oxidation. This metabolic capability is of great ecological significance as it plays a crucial role in the nitrogen cycle.

The order Cenarchaeales currently consists of two families: Cenarchaeaceae and Nitrosopumilaceae. The family Cenarchaeaceae includes the genus Cenarchaeum, which is the type genus of the order. The family Nitrosopumilaceae includes the well-known genus Nitrosopumilus.

Morphology and Physiology

Members of the Cenarchaeales order are typically small, single-celled organisms with a spherical or oval shape. They lack flagella and other motility structures. The cell walls of Cenarchaeales archaea are composed of a unique type of protein called S-layer, which provides structural support and protection.

Cenarchaeales archaea are chemoautotrophs, meaning they obtain energy by oxidizing inorganic compounds and use carbon dioxide as their carbon source. They are known for their ability to oxidize ammonia to nitrite, a process that is important in the global nitrogen cycle. This process is carried out by the enzyme ammonia monooxygenase.

Ecological Significance

Cenarchaeales archaea are found in a wide range of environments, including marine and freshwater habitats. They are particularly abundant in oxygen-deficient zones, such as oxygen minimum zones (OMZs) in the ocean. In these environments, Cenarchaeales play a crucial role in the nitrogen cycle by converting ammonia to nitrite, which is an important step in the process of denitrification.

Furthermore, Cenarchaeales archaea have been found to be involved in the production of greenhouse gases, such as nitrous oxide (N2O). Nitrous oxide is a potent greenhouse gas that contributes to global warming and ozone depletion. Understanding the role of Cenarchaeales in the production of nitrous oxide is important for predicting and mitigating its impact on the environment.

See Also

• Archaea
• Thaumarchaeota
• Ammonia oxidation
• Nitrogen cycle
• Denitrification
• Greenhouse gases
• Oxygen minimum zone