Microbial nitrate respiration

Kraft B, Strous M, Tegetmeyer HE. Microbial nitrate respiration - genes, enzymes and environmental distribution. J Biotechnol 2011 155 104—117. 

Figure 4. The general nitrogen model for illuxtrating the microbial role in biogeochemical cycling in Forest ecosystems. Explanations for the fluxes 1. ammonia volatilization 2, forest fertilization 3, 2-fixation 4, denitrification 5, nitrate respiration 6, nitrification 7. immobilization 8, mineralization 9, assimilatory and dissimilatory nitrate reduction to ammonium 10, leaching II, plant uptake 12, deposition N input 13, residue composition, exudation 14, soil erosion 15, ammonium fixation and release by clay minerals 16, biomass combustion 17, forest har esting 18, litteifall (Nihkgard et al, 1994).

Dissimilatory Reduction of Nitrate to Ammonium by Microbial Cultures. We studied nitrate reduction to ammonia by an obligate anaerobe, Clostridium, which cannot gain energy from this reduction by electron transport phosphorylation, and by a number of Enterobacteri-aceae (known to be nitrate respirers) that can gain energy via the nitrate to nitrite step. All these organisms converted NOg" to as the... 

Obuekwe CO, Westlake DWS, Cook FD (1981) Effect of nitrate on reduction of ferric iron by a bacterium isolated from crude oil. CANJMICROBIOL (27) 692-697 Lee AK, Newman DK (2003) Microbial iron respiration impacts on corrosion processes, online, Appl Enviromnental Microbiol, No. 7... 

Recent research has identified some other microbial routes for denitrification that are not heterotrophic. One, called the anammox reaction, involves the oxidation of ammonium to N2 using either nitrite or nitrate as the electron donor. The second has bacteria using Mn " to reduce nitrate to N2. As noted earlier, N2 is generated by the oxidation of ammonium using Mn02 as the electron acceptor. [Denitrification may also be supported by Fe " (aq) oxidation.] These reactions are summarized in Table 12.2. The overall consequence of these reactions is that ammonium does not accumulate in the pore waters where Mn respiration and denitrification are occurring. 

Sorenson, J., 1984. Seasonal variation and control of oxygen, nitrate and sulfate respiration in coastal marine sediments. In M.3. Klug and C.A. Reddy (eds), Current Perspectives in Microbial Ecology. American Society for Microbiology, Washington, D.C., pp. 447-453. 

Depletion of nitrate and the formation of dinitrogen are, however, not exclusively coupled to denitrification, since the microbially mediated reduction utilizing reduced species like or Fe + might occur. Based on field observations, a number of studies invoke the reduction of nitrate by Mn + to form N instead of organic matter respiration (Aller 1990 Schulz et al. 1994 Luther etal. 1997,1998). 

Pathway 4 shows denitrification. This process is linked to microbial respiration where electrons are added to nitrate or nitrite, resulting in the production of nitrous oxide or nitrogen gas. The... 

The metabolic quotient, or specific respiration rate (qCO-, is the ratio of the basal respiration rate (as CO2-C) per unit MBC, and provides an indication of efficiency of microbial in utilization of available substrates (Anderson and Domsch, 1993). Low C02 in detritus of the impacted site suggests poor efficiency of microbes in utilization of available substrates (DeBusk and Reddy, 1998 Wright and Reddy, 2001b). Minimal differences in qC02 were observed for 0-10 cm soil of impacted and reference sites. Consumption of electron acceptors such as oxygen, nitrate, and sulfate during... 

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