nitrifying bacteria

Small group of oxygen-requiring bacteria that use nitrogen as an energy source. These microorganisms are important in the nitrogen cycle as converters of soil ammonia to nitrates, compounds usable by plants. The nitrification process requires two distinct groups: bacteria that convert ammonia to nitrites, and bacteria that convert nitrites to nitrates. In agriculture, irrigation with dilute solutions of ammonia results in an increase in soil nitrates through the action of nitrifying bacteria. Seealso denitrifying bacteria.

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Nitrifying bacteria are chemoautotrophic bacteria that grow at the expense of inorganic nitrogen compounds. Many species of nitrifying bacteria have complex internal membrane systems that are the location for key enzymes in nitrification: ammonia monooxygenase which oxidizes ammonia to hydroxylamine, and nitrite oxidoreductase, which oxidizes nitrite to nitrate.

Ecology

Nitrifying bacteria are widespread in soil and water, and are found in highest numbers where considerable amounts of ammonia are present (areas with extensive protein decomposition, and sewage treatment plants). Nitrifying bacteria thrive in lakes and streams with high inputs of sewage and wastewater because of the high ammonia content.

Oxidation of ammonia to nitrate

Nitrification in nature is the result of actions of two groups of organisms, the nitrosifyers (ammonia-oxidizing bacteria) and nitrifying bacteria (nitrite-oxidizing, nitrate producing bacteria)

Nitrosifying bacteria
1. NH₃ + O₂ + 2e^- + 2H⁺ → NH₂OH + H₂O
2. NH₂OH + H₂O + 1/2 O₂ → NO₂^- +2 H₂O + H⁺
Nitrifying bacteria
NO₂^- + 1/2 O₂ → NO₃^-

Nitrifying bacteria that oxidize ammonia (nitrosifyers)	Characteristics	Genus	Phylogenetic group	DNA (mol% GC)	Habitats
Gram-negative short to long rods, motile (polar flagella)or nonmotile; peripheral membrane systems	Nitrosomonas	Beta	45-53	Soil, Sewage, freshwater, Marine
Large cocci, motile, vesicular or peripheral membranes	Nitrosococcus	Gamma	49-50	Freshwater, Marine
Spirals, motile (peritrichous flagella); no obvious membrane system	Nitrosospira	Beta	54	Soil
Pleomorphic, lobular, compartmented cells; motile (peritrichous flagella)	Nitrosolobus	Beta	54	Soil

See also

• Denitrification
• Nitrification
• Nitrogen cycle
• Nitrogen deficiency
• Nitrogen fixation

References

Nitrifying bacteria that oxidize nitrite	Characteristics	Genus	Phylogenetic group	DNA (mol% GC)	Habitats
Short rods, reproduce by budding, occasionally motile (single subterminal flagella) or non-motile; membrane system arranged as a polar cap	Nitrobacter	Alpha	59-62	Soil, Freshwater, Marine
Long, slender rods, nonmotile, no obvious membrane system	Nitrospina	Delta	58	Marine
Large Cocci, motile (one or two subterminal flagellum) membrane system randomly arranged in tubes	Nitrococcus	Gamma	61	Marine
Helical to vibroid-shaped cells; nonmotile; no internal membranes	Nitrospira	Nitrospirae	50	Marine, Soil

The variation of nitrifying bacterial population sizes in a sequencing batch reactor (SBR) treating low, mid, high concentrated synthetic wastewater.(Report) Nov 01, 2007; Abstract: The purpose of this study was to correlate the population size of ammonia-oxidizing bacteria (AOB) and nitrite... Read more with a free trial on HighBeam.com »

Scientists at School of Municipal & Environmental Engineering Detail Research in Science.(nitrifying sequencing batch biofilm reactor)(Report) Jan 13, 2012; Researchers detail in "Characterization of the microbial community in a partial nitrifying sequencing batch biofilm... Read more with a free trial on HighBeam.com »

Nitrifying filter problems. (excerpt from The Effects of Fluctuations in Biodegradable Organic Matter on Nitrification Filters) (Waterworks Digest) Jul 01, 1992; Biological treatment is becoming necessary in drinking water preparation, whether designed as a biological process or as an... Read more with a free trial on HighBeam.com »

Nitrifying bioformula. (Bioremediation). Mar 01, 2003; New case studies indicate the effectiveness of bioaugmentation to improve nitrification. One study, at a typical activated sludge... Read more with a free trial on HighBeam.com »

US Patent Issued to Hynix Semiconductor on Jan. 18 for "Method for Manufacturing Semiconductor Device Using a Free Radical Assisted Chemical Vapor Deposition Nitrifying Process" (South Korean Inventors) Jan 21, 2011; ALEXANDRIA, Va., Jan. 21 -- United States Patent no. 7,871,939, issued on Jan. 18, was assigned to Hynix Semiconductor Inc.... Read more with a free trial on HighBeam.com »