"Candidatus

Candidatus

Candidatus is in scientific classification a component of the taxonomic name for a bacterium that cannot be maintained in a Bacteriology Culture Collection. It is an interim taxonomic status for noncultivable organisms. An example would be "Candidatus Phytoplasma allocasuarinae"...

Brocadia anammoxidans" is a bacterial member of the order Planctomycetes

Planctomycetes

Planctomycetes are a phylum of aquatic bacteria and are found in samples of brackish, and marine and fresh water. They reproduce by budding. In structure, the organisms of this group are ovoid and have a holdfast, called the stalk, at the nonreproductive end that helps them to attach to each other...

 and therefore lacks peptidoglycan

Peptidoglycan

Peptidoglycan, also known as murein, is a polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane of bacteria , forming the cell wall. The sugar component consists of alternating residues of β- linked N-acetylglucosamine and N-acetylmuramic acid...

 in its cell wall

Cell wall

The cell wall is the tough, usually flexible but sometimes fairly rigid layer that surrounds some types of cells. It is located outside the cell membrane and provides these cells with structural support and protection, and also acts as a filtering mechanism. A major function of the cell wall is to...

, has a compartmentalized cytoplasm

Cytoplasm

The cytoplasm is a small gel-like substance residing between the cell membrane holding all the cell's internal sub-structures , except for the nucleus. All the contents of the cells of prokaryote organisms are contained within the cytoplasm...

.

"Candidatus Brocadia anammoxidans" is the first discovered organism capable of the anaerobic oxidation of ammonium

Anammox

Anammox, an abbreviation for ANaerobic AMMonium OXidation, is a globally important microbial process of the nitrogen cycle . The bacteria mediating this process were identified in 1991, and at the time were a great surprise for the scientific community...

. This process (dubbed the anammox

Anammox

Anammox, an abbreviation for ANaerobic AMMonium OXidation, is a globally important microbial process of the nitrogen cycle . The bacteria mediating this process were identified in 1991, and at the time were a great surprise for the scientific community...

-process) was discovered in the 1980s by the Gijs Kuenen

Gijs Kuenen

Johannes Gijsbrecht Kuenen is a Dutch microbiologist who is presently professor emeritus at the Delft University of Technology and a visiting scientist at the University of Southern California...

 lab in a waste water treatment plant in Delft

Delft

Delft is a city and municipality in the province of South Holland , the Netherlands. It is located between Rotterdam and The Hague....

, the Netherlands. Ammonium oxidation is coupled to nitrite

Nitrite

The nitrite ion has the chemical formula NO2−. The anion is symmetric with equal N-O bond lengths and a O-N-O bond angle of ca. 120°. On protonation the unstable weak acid nitrous acid is produced. Nitrite can be oxidised or reduced, with product somewhat dependent on the oxidizing/reducing agent...

 reduction to form the harmless dinitrogen gas.

The key enzyme

Enzyme

Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

 involved in this reaction, hydroxylamine oxidoreductase, is located in an organelle

Organelle

In cell biology, an organelle is a specialized subunit within a cell that has a specific function, and is usually separately enclosed within its own lipid bilayer....

-like structure called the anammoxosome. The ability to oxidize ammonium anaerobically makes "Candidatus Brocadia anammoxidans" potentially useful for reducing—or eliminating—ammonium from waste water.

In waste treatment

Because of its ability to eliminate ammonium, a variety of uses have been found for this bacteria, particularly removal of nitrogen

Nitrogen

Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

 from waste streams. The first full scale experiment employing the anammox process in the world was built at the waste water treatment plant Dokhaven/Sluisjesdijk in Rotterdam

Rotterdam

Rotterdam is the second-largest city in the Netherlands and one of the largest ports in the world. Starting as a dam on the Rotte river, Rotterdam has grown into a major international commercial centre...

, the Netherlands.

Existing treatment plants use bacteria that convert ammonium into nitrate

Nitrate

The nitrate ion is a polyatomic ion with the molecular formula NO and a molecular mass of 62.0049 g/mol. It is the conjugate base of nitric acid, consisting of one central nitrogen atom surrounded by three identically-bonded oxygen atoms in a trigonal planar arrangement. The nitrate ion carries a...

. The bacteria that do this need oxygen, which must be supplied by electric pumps. Denitrifying bacteria

Denitrifying bacteria

Denitrifying bacteria form a necessary part of the process known as denitrification as part of the nitrogen cycle, their primary purpose being to metabolise nitrogenous compounds, with the assistance of the nitrase reductase enzyme, to turn oxides back to nitrogen gas or nitrous oxides for energy...

 convert the nitrate into nitrogen gas. These require adding methanol

Methanol

Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with the formula CH3OH . It is the simplest alcohol, and is a light, volatile, colorless, flammable liquid with a distinctive odor very similar to, but slightly sweeter than, ethanol...

. This process consumes an average of 44 watt-hour

Watt-hour

The kilowatt hour, or kilowatt-hour, is a unit of energy equal to 1000 watt hours or 3.6 megajoules.For constant power, energy in watt hours is the product of power in watts and time in hours...

s per day per person served by the sewage

Sewage

Sewage is water-carried waste, in solution or suspension, that is intended to be removed from a community. Also known as wastewater, it is more than 99% water and is characterized by volume or rate of flow, physical condition, chemical constituents and the bacteriological organisms that it contains...

 system.

Researchers estimate that a methanogenic digester coupled to a nitrification

Nitrification

Nitrification is the biological oxidation of ammonia with oxygen into nitrite followed by the oxidation of these nitrites into nitrates. Degradation of ammonia to nitrite is usually the rate limiting step of nitrification. Nitrification is an important step in the nitrogen cycle in soil...

-anammox bioreactor could generate 24 watt-hours per person per day, a net swing of 70 watt-hours.