Bacteria ammonification

Ammonification (organic nitrogen NH3) Many microbes, especially bacteria... 

Besides nitrogen fixation, the only other major source of reduced nitrogen is the decomposition of soil or aquatic organic matter. This process is called ammonification. Heterotrophic bacteria are principally responsible for this. These organisms utilize organic compounds from dead plant or animal matter as a carbon source, and leave behind NH3 and NHJ, which can then be recycled by the biosphere. In some instances heterotrophic bacteria may incorporate a complete organic molecule into their own biomass. The majority of the NH3 produced in this way stays within the biosphere however, a small portion of it will be volatilized. In addition to this source, the breakdown of animal excreta also contributes to atmospheric... 

Beek and Frissel (1973) Growth of nitrifier and ammonifer bacteria by Michaelis-Menten kinetics NH4 oxidation by first-order kinetics with environmental variables mineralization of proteins, sugars, cellulose, lignin, and living biomass by first-order kinetics immobilization by first-order kinetics including considerations for microbial biomass and C/N ratio NH3 volatilization by diffusion NH4 clay fixation by equilibrium model. 

Bacteria play an important role in the redox chemistry of nitrogen species in seawater. Starting with PON, the first step is remineralisation in which PON is converted to DON. The breakdown of some of the DON to DIN follows with the first product being NH3 the process is relatively rapid and known as ammonification. NH3 is protonated to a limited extent in seawater, giving rise to NH4 ions. Nitrification is the stepwise oxidation of NH4 to N02 and eventually to N03. Denitrification, the reduction of nitrogen species to N2, can occur under conditions of hypoxia or anoxia. In such cases, bacteria respire organic material using N03 and NO2 as electron acceptors. 

Ammonification Bacteria/zo oplankton Aerob/anaerob Heterotrophic Release ofN 8... 

Ammonification is another process that can result in N release. The simplest definition of the process is the release ofNH4 from organic matter (e.g., Herbert, 1999). It can occur by a number of different processes including remineralization by bacteria in the water column and sediments. Photochemical ammonification occurs abiotically when NH4+ is released from organic matter as a result of exposure to UV radiation (reviewed in Bronk, 2002 and Chapter 10 by Gryz-bowski and Tranvik, this volume). Ammonium efflux from cells has also been observed following urea uptake in a number of culture experiments (e.g., Price and Harrison, 1988 Rees and Bekheet, 1982 Uchida, 1976). The release may be due to passive diffusion through the cell membrane and is likely unavoidable because NH3 is lipid soluble. 

Many organisms, especially bacteria, decompose organic material with the release of ammonia, a process referred to as ammonification. 

Fig. 3.17 Summary of the nitrogen cycle (oxidation states of nitrogen shown in parentheses). Ammonium assimilation and ammonification can occur in oxic and anoxic environments, as can nitrogen fixation (although the most prolific bacteria are aerobes).

Bacteria 100-170 °F. Different species of bacteria are active throughout this range so an optimum can not be given. At temperatures above 130 F. bacteria dominate and are responsible for the ammonification that occurs at these temperatures. The most common bacteria found by researchers are Pseudomonas species. 

Such biochemical process of removing nitrogen from the bio-geo-chemical cycle is called ammonification. In the presence of ammonium is repidly oxidized with the participation of microorganisms to nitrate NO. This biochemical process of oxidizing ammonia is called nitrification. Autotrophic nitrification has 2 stages. First, bacteria of genera Nitrosomonas, Nitrosospira, Nitrosococcus, Nitrosolobus form nitrite ... 

Ammonification bacteria, ftmgi convert the residues to NH3 this dissolves to form NH4. ... 

The reduction of nitrite to ammonia was described for bacteria with a fermentative rather than a respiratory metabolism [125]. However, growth of various bacteria by oxidation of non-fermentable substrates such as formate linked to the reduction of nitrite to ammonia, demonstrated that nitrite ammonification may also function as respiratory energy conserving process [126]. The enzymol-ogy and bioenergetics of respiratory nitrite ammonification have been recently reviewed [17]. In respiratory nitrite ammonification, nitrite is reduced to ammonia without the release of intermediate products, such as NO or N2O, in a six-electron step by a cytochrome c nitrite reductase, the so-caUed NrfA protein [Eq. (10)] [127-131]. 

A first model for the organization of respiratory nitrite ammonification and direction of proton exchange associated with electron transfer from formate to nitrate in E. coli had been described earlier [126]. The reduction of nitrate to nitrite by the oxidation of formate is linked to the generation of a proton electrochemical potential (Section 3.1.1., discussion on nitrate reductase). Whether the overall architecture of the nitrate reductase complex from E. coli also holds for other nitrite-ammonifying bacteria, has to be investigated. S. deleyianum and... 

Ammonification This process converts organic nitrogen to ammonium, which can then be converted to other forms of nitrogen that can be assimilated by plants or organisms. The process of ammonification is facilitated by bacteria or fungi. 

I. AMMONIFICATION IN THE SOIL The dead bodies and excreta of living beings are attacked in the ground by the exoenzymes of many bacteria. For example, the exoenz3rmes of many Clostridia attack this dead matter and the proteins are converted to amino acids. Many bacteria release ammonia from these amino acids. The most active ammonifying oi anisms are Bacillus mycoidesy Proteus vulgaris and various actinomycetes. Quantitatively the most important process is oxidative deamination (p. 210). 

It is possible that at least lichens producing usnic acid can adversely affect soil fertility. Malicki (1965) found that some usnic acid is leached out of usnic-producing Cladinae and can be found in the soil beneath them. He also found that ammonification bacteria and those decomposing cellulose are affected by the antibiotic properties of usnic acid (although there is no effect on Azotobacter) (Malicki, 1967). 

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