''Nitrospira moscoviensis'' was the second bacterium classified under the most diverse nitrite-oxidizing bacteria phylum, ''Nitrospirae''. It is a

gram-negative Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall ...

, non-motile,

facultative {{wiktionary, facultative Facultative means "optional" or "discretionary" (antonym '' obligate''), used mainly in biology in phrases such as: * Facultative (FAC), facultative wetland (FACW), or facultative upland (FACU): wetland indicator statuses ...

lithoauthotropic bacterium that was discovered in

Moscow Moscow ( , US chiefly ; rus, links=no, Москва, r=Moskva, p=mɐskˈva, a=Москва.ogg) is the capital and largest city of Russia. The city stands on the Moskva River in Central Russia, with a population estimated at 13.0 million ...

, Russia in 1995. The genus name, ''

Nitrospira ''Nitrospira'' (from Latin: nitro, meaning "nitrate" and Greek: spira, meaning "spiral") translate into “a nitrate spiral” is a genus of bacteria within the monophyletic clade of the Nitrospirota phylum. The first member of this genus was d ...

'', originates from the prefix “nitro” derived from nitrite, the microbe’s

electron donor In chemistry, an electron donor is a chemical entity that donates electrons to another compound. It is a reducing agent that, by virtue of its donating electrons, is itself oxidized in the process. Typical reducing agents undergo permanent chem ...

and “spira” meaning coil or

spiral In mathematics, a spiral is a curve which emanates from a point, moving farther away as it revolves around the point. Helices Two major definitions of "spiral" in the American Heritage Dictionary are: The species name, ''moscoviensis'', is derived from Moscow, where the species was first discovered. ''N. moscoviensis'' could potentially be used in the production of bio-degradable polymers.

History

In 1995, Silke Ehrich discovered ''Nitrospira moscoviensis'' in a sample taken from an eroded iron pipe. The pipe was a part of a heating system in Moscow, Russia. The rust was transferred to a culture where cells could be isolated. For optimum growth, Ehrich and his team cultivated the cells on a mineral salt medium at a temperature of 39 °C and at a pH of 7.6-8.0.

Morphology

''Nitrospira moscoviensis'' is classified as being

, non-motile, and having a curved rod shape. The curved rods are approximately 0.9-2.2 µm long x 0.2-0.4 µm wide. ''N. moscoviensis'' can exist in both aquatic and terrestrial habitats and reproduces using

binary fission Binary may refer to: Science and technology Mathematics * Binary number, a representation of numbers using only two digits (0 and 1) * Binary function, a function that takes two arguments * Binary operation, a mathematical operation that t ...

. Defining features of ''N. moscoviensis'' is the absence of intra-

cytoplasmic membrane The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment ( ...

s and carboxysomes possession of a flatulent

periplasmic space The periplasm is a concentrated gel-like matrix in the space between the inner cytoplasmic membrane and the bacterial outer membrane called the ''periplasmic space'' in gram-negative bacteria. Using cryo-electron microscopy it has been found tha ...

Metabolism

''Nitrospira moscoviensis'' is a facultative

lithoautotroph A lithoautotroph is an organism which derives energy from reactions of reduced compounds of mineral (inorganic) origin. Two types of lithoautotrophs are distinguished by their energy source; photolithoautotrophs derive their energy from light while ...

commonly referred to as a

chemolithoautotroph A lithoautotroph is an organism which derives energy from reactions of reduced compounds of mineral (inorganic) origin. Two types of lithoautotrophs are distinguished by their energy source; photolithoautotrophs derive their energy from light while ...

. In

aerobic Aerobic means "requiring air," in which "air" usually means oxygen. Aerobic may also refer to * Aerobic exercise, prolonged exercise of moderate intensity * Aerobics, a form of aerobic exercise * Aerobic respiration, the aerobic process of cellu ...

environments, ''N. moscoviensis'' obtains energy by

oxidizing Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a d ...

nitrite to nitrate. Without the element

molybdenum Molybdenum is a chemical element with the symbol Mo and atomic number 42 which is located in period 5 and group 6. The name is from Neo-Latin ''molybdaenum'', which is based on Ancient Greek ', meaning lead, since its ores were confused with lea ...

, the nitrite-oxidizing system will not function. When ''N. moscoviensis'' is in nitrite free environments it can use aerobic hydrogen oxidation. When ''N. moscoviensis'' reduces nitrite using hydrogen as an electron donor growth is blocked. A key difference in ''N. moscoviensis’'' nitrite-oxidizing system is location; unlike most nitrate oxidizing systems, it is not located in the

. Kirstein and Bock (1993) implied that the location of the nitrite-oxidizing system corresponds directly to ''N. moscoviensis'' having an enlarged

. By oxidizing nitrate outside of the cytoplasmic membrane, a permease nitrite system is not needed for the

proton gradient An electrochemical gradient is a gradient of electrochemical potential, usually for an ion that can move across a membrane. The gradient consists of two parts, the chemical gradient, or difference in solute concentration across a membrane, and th ...

. The exocytoplasmic oxidation of nitrite also prevents build-up of toxic nitrite within the cytoplasm. Another important metabolism ability for ''N. moscoviensis'' is its ability to cleave

urea Urea, also known as carbamide, is an organic compound with chemical formula . This amide has two amino groups (–) joined by a carbonyl functional group (–C(=O)–). It is thus the simplest amide of carbamic acid. Urea serves an important r ...

ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous was ...

and CO₂. The ability to use urea comes directly from the presence of urease encoding genes which is interesting because most nitrite-oxidizing bacteria are unable to use ammonia as an energy source.

Urease Ureases (), functionally, belong to the superfamily of amidohydrolases and phosphotriesterases. Ureases are found in numerous bacteria, fungi, algae, plants, and some invertebrates, as well as in soils, as a soil enzyme. They are nickel-containin ...

encoding genes function by catalyzing urea hydrolysis to form ammonia and

carbamate In organic chemistry, a carbamate is a category of organic compounds with the general formula and structure , which are formally derived from carbamic acid (). The term includes organic compounds (e.g., the ester ethyl carbamate), formally o ...

Ecology

''Nitrospira moscoviensis'' grows in temperatures from 33 to 40 °C and pH 7.6-8.0 with an optimal nitrite concentration of 0.35 nM. ''Nitrospira moscoviensis'' plays a key role in the two-step

Nitrogen Cycle The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among atmospheric, terrestrial, and marine ecosystems. The conversion of nitrogen can be carried out through both biologi ...

process. The first step of

Nitrification ''Nitrification'' is the biological oxidation of ammonia to nitrite followed by the oxidation of the nitrite to nitrate occurring through separate organisms or direct ammonia oxidation to nitrate in comammox bacteria. The transformation of amm ...

requires an ammonia-oxidizing bacterium (AOB) or ammonia-oxidizing archaeon (AOA) followed by a nitrite-oxidizing bacterium (NOB). The unique capability of ''N. moscoviensis'' to cleave

into

and

carbon dioxide Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...

allows for a

symbiotic relationship Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasit ...

with ammonia-oxidizing microorganisms (AOM) that lack this urease-production ability also known as negative AOM. A correlation in environment preferences between ''Nitrospira'' species with ''nxrB'' gene encoding the β-subunit of nitro-oxidoreductase and AOM species with ''amoA'' gene further confirmed this relationship. ''N. moscoviensis'' provides ammonia via

hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution reaction, substitution, elimination reaction, elimination, and solvation reactions in which water ...

of urea to these ammonia-oxidizing microorganisms which in turn produce nitrite, the primary energy source of ''N. moscoviensis''. The relationship between ureolytic nitrite-oxidizing bacteria and negative AOM is called reciprocal feeding. Thus far, ''Nitrospira'' species have been recognized in natural environments as the primary vehicle for nitrite oxidation including soils, activated-sludge, ocean and fresh water,

hot spring A hot spring, hydrothermal spring, or geothermal spring is a spring produced by the emergence of geothermally heated groundwater onto the surface of the Earth. The groundwater is heated either by shallow bodies of magma (molten rock) or by circ ...

s, and

water treatment plants Water treatment is any process that improves the quality of water to make it appropriate for a specific end-use. The end use may be drinking, industrial water supply, irrigation, river flow maintenance, water recreation or many other uses, inclu ...

Genomics

Following its isolation, ''N. moscoviensis''’s genome was sequenced by Dr. Ehrich et al. Its 4.59 Mb

genome In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding ge ...

has a GC content of 56.9+/-0.4 mol% with a predicted 4,863 coding sequences. ''N. moscoviensis'''s 16S rRNA gene sequences were found to be 88.9% similar to ''N. marina''’s. Despite its relatively low similarity to ''N. marina'', ''N. moscoviensis'' was classified within the ''Nitrospirae'' phylum primarily due to shared morphological features including the presence of an enlarged

periplasm The periplasm is a concentrated gel-like matrix in the space between the inner cytoplasmic membrane and the bacterial outer membrane called the ''periplasmic space'' in gram-negative bacteria. Using cryo-electron microscopy it has been found that ...

ic space. ''Nitrospira moscoviensis''’s fully sequenced genome has provided useful

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

insights beyond the scope of 16S rRNA sequence studies. The discovery of the gene encoding the β-subunit of nitrite-

oxidoreductase In biochemistry, an oxidoreductase is an enzyme that catalyzes the transfer of electrons from one molecule, the reductant, also called the electron donor, to another, the oxidant, also called the electron acceptor. This group of enzymes usually ut ...

, ''nxrB'', from ''N. moscoviensis'' as a functional genetic marker of ''Nitrospira'', not only confirmed previous 16S rRNA phylogenetic classifications within the phylum, but revealed a new understanding of ''Nitrospira''’s richness in terrestrial environments. The phylum has expanded from two bacteria, ''N. marina'' and ''N. moscoviensis'', to a 6-branched genera composed of a characteristically diverse group of nitrite-oxidizing bacteria with ''N. moscoviensis'' positioned in lineage II.

Biotechnology

The cytoplasm of ''Nitrospira moscoviensis'' contains

polyhydroxybutyrate Polyhydroxybutyrate (PHB) is a polyhydroxyalkanoate (PHA), a polymer belonging to the polyesters class that are of interest as bio-derived and biodegradable plastics. The poly-3-hydroxybutyrate (P3HB) form of PHB is probably the most common type ...

(PHB) granules.

References

External links

MicrobeWiki – Nitrospira
*
LPSN
{{Taxonbar, from=Q16986573 Nitrospirota Bacteria described in 2001