Anammox

Definition

Anammox, or anaerobic ammonium oxidation, is a microbial process in which ammonium is oxidized to nitrogen gas under anaerobic conditions. This process is carried out by a specialized group of bacteria known as Planctomycetes, which are Gram-negative, non-proteobacteria.

5 Must Know Facts For Your Next Test

1. Anammox bacteria are chemolithoautotrophs, meaning they obtain energy from inorganic chemical reactions and carbon from carbon dioxide.
2. The anammox process is a key step in the global nitrogen cycle, contributing to the removal of fixed nitrogen from aquatic and terrestrial environments.
3. Anammox bacteria have a unique cell structure, with a membrane-bound organelle called the 'anammoxosome' where the anammox reaction takes place.
4. Anammox bacteria are slow-growing, with doubling times ranging from 10 to 20 days, making them challenging to cultivate in the laboratory.
5. Anammox bacteria play a significant role in the removal of nitrogen from wastewater treatment plants, where they can contribute up to 50% of the total nitrogen removal.

Review Questions

• Describe the role of anammox bacteria in the nitrogen cycle and their significance in the environment.
  • Anammox bacteria play a crucial role in the global nitrogen cycle by converting ammonium and nitrite directly to nitrogen gas under anaerobic conditions, a process known as anaerobic ammonium oxidation or anammox. This process is an important pathway for the removal of fixed nitrogen from aquatic and terrestrial environments, helping to maintain a balance in the nitrogen cycle. Anammox bacteria are found in diverse environments, including marine sediments, freshwater lakes, and wastewater treatment plants, where they can contribute significantly to nitrogen removal, making them important players in the biogeochemical cycling of nitrogen.
• Explain the unique cell structure and metabolism of anammox bacteria and how these adaptations enable their specialized role in the nitrogen cycle.
  • Anammox bacteria possess a unique cell structure, with a specialized membrane-bound organelle called the 'anammoxosome' where the anammox reaction takes place. This compartmentalization allows for the efficient conversion of ammonium and nitrite to nitrogen gas under anaerobic conditions. Anammox bacteria are chemolithoautotrophs, meaning they obtain energy from inorganic chemical reactions and use carbon dioxide as their carbon source. This specialized metabolism, along with their slow growth rate, makes them well-suited for their role in the nitrogen cycle, where they can outcompete other microorganisms in anoxic environments and contribute significantly to the removal of fixed nitrogen from the environment.
• Discuss the importance of anammox bacteria in wastewater treatment and the challenges associated with their cultivation and study.
  • Anammox bacteria play a significant role in the removal of nitrogen from wastewater treatment plants, where they can contribute up to 50% of the total nitrogen removal. Their ability to convert ammonium and nitrite directly to nitrogen gas under anaerobic conditions makes them a valuable component of wastewater treatment processes. However, the cultivation and study of anammox bacteria present unique challenges due to their slow growth rate, with doubling times ranging from 10 to 20 days. This slow growth makes them difficult to isolate and maintain in laboratory settings, limiting our understanding of their physiology and ecology. Despite these challenges, ongoing research on anammox bacteria continues to provide valuable insights into their role in the nitrogen cycle and their potential applications in sustainable wastewater treatment.

Related terms

Planctomycetes:

A phylum of bacteria that are known for their complex cell structure, including a compartmentalized cell plan and lack of peptidoglycan in their cell walls.

Denitrification:

The process by which nitrate is reduced to nitrogen gas, often carried out by bacteria under anaerobic conditions.

Nitrogen Cycle:

The biogeochemical cycle that describes the transformation and movement of nitrogen through the environment, involving processes such as nitrogen fixation, nitrification, and denitrification.