Bacteria denitrifying

Denitrifying bacteria are frequently encountered as anaerobic degraders of diverse xenobiotics. They are facultatively anaerobic and frequently also degrade xenobiotics aerobically. However, the pathways as well as the specific patterns are different under aerobic and denitrifying conditions. Nitrate is reduced to N2 via nitrate, NO, and N2O. Iron (III) or manganese (IV) reduction is a geochemically important alternative pathway of anaerobic respiration and has been shown repeatedly to be linked 

Energetics of Benzoate Oxidation Using Different Electron Acceptors 

Thiobacillus denitrificans is well known as a lithoautotrophic denitrifier it oxidizes anaerobically thiosulfate (S2032 ) with nitrate (N03 ) to biosynthesize ATP although it also aerobically oxidizes thiosulfate (Aminuddin and Nicholas, 1973, 1974a) (Fig. 1.9). The anaerobic oxidation system of thiosulfate is similar to those of other thiobacilli (though these are aerobic bacteria), and the denitrifying processes in the bacterium are similar to those in the heterotrophic denitrifiers. The complete genome of the bacterium has recently been sequenced (Beller et al., 2006). 

Recently, other lithoautotrophic denitrifiers have been found that oxidize ferrous compounds with nitrate Ferro globus placidus (Hafenbradl et al., 1996) and Dechlo-rosoma suillum (Chaudhuri et al., 2001) (Fig. 1.10). 

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Heme d,6 another isobacteriochlorin, occurs as one of two cofactors in the reductase cytochrome cdj which mediates the nitrite reduction to nitrogen monoxide (NO) and from there to dinitrogen oxide (N20) in denitrifying bacteria.7... 

Gallus C, B Schink (1994) Anaerobic degradation of pimelate by newly isolated denitrifying bacteria. Microbiology (UK) 140 409-416. 

Kniemeyer O, C Probian, R Rossello-Mora, J Harder (1999) Anaerobic mineralization of quaternary carbon atoms isolation of denitrifying bacteria on dimethylmalonate. Appl Environ Microbiol 65 3319-3324. 

Rudolph A, A Tschech, G Euchs G (1991) Anaerobic degradation of cresols by denitrifying bacteria. Arch Microbiol 155 238-248. 

Song B, NJ Palleroni, MM Haggblom (2000) Isolation and characterization of diverse halobenzoate-degrad-ing denitrifying bacteria from soils and sediments. Appl Environ Microbiol 66 3446-3453. 

The metabolism of phenols under anaerobic conditions has been examined under denitrifying, sulfate-reducing, Fe (lll)-reducing, and anaerobic nonmethanogenic conditions. It is plausible to suggest a common pathway that has been elucidated for denitrifying bacteria. This comprises (a) activation of phenol by the formation of phenylphosphate, (b) carboxylation at a position para to... 

Schennen U, K Braun, H-J Knackmuss (1985) Anaerobic degradation of 2-fluorobenzoate by benzoatedegrading, denitrifying bacteria. J Bacterial 161 321-325. 

Seyfried B, G Glod, R Schocher, A Tschech, J Zeyer (1994) Initial reactions in the anaerobic oxidation of toluene and m-xylene by denitrifying bacteria. Appl Environ Microbiol 60 4047-4052. 

Rabus R, F Widdel (1996) Utilization of alkylbenzenes during anaerobic growth of pure cultures of denitrifying bacteria on crude oil. Appl Environ Microbiol 62 1238-1241. 

Bae H-S, ImW-T, Suwa Y, Lee JM, Lee S-T, Chang Y-K (2009) Characterization of diverse heterocyclic amine-degrading denitrifying bacteria from various environments. Arch Microbiol 191 329-340... 

The anthranilate intermediate is believed to be metabolized to denitrogenated products. The list of proposed metabolites is also included in Fig. 25. A consortium of anaerobic and denitrifying bacteria was found to degrade indole via oxindole [341], but further details were not given to ensure if pathway 1 was followed. 

It is thought that bicarbonate excretions by oral tissues and the neutral pH of the saliva maintain a neutral pH in the areas inhabited by nitrite-producing bacteria, thus preventing nitrite becoming toxic to the resident bacterial flora in the oral cavity. As with denitrifying bacteria isolated from other environments... 

Sigman et al. [134] have described a bacterial method for measuring the isotopic composition of seawater nitrate at the natural-abundance level. The method is based on the analysis of nitrous oxide gas (N2O) produced quantitatively from nitrate by denitrifying bacteria. The classical denitrification pathway consists of the stepwise reduction of nitrate (NOp to nitrite (N02), nitric oxide (NO), nitrous oxide (N2O), and dinitrogen (N2) ... 

As illustrated in Figure 35, the same redox behaviour is exhibited by the positively charged blue protein pseudoazurin (FW=13 400 p/ = 8.9), a class of proteins devoted to reduction of NCV to NO in denitrifying bacteria. 

Not all chemical reactions proceed at rates fast enough to create significant deviations from NAECs. For example, although N2 gas is consumed by nitrogen-fixing plankton and produced by denitrifying bacteria, these processes are too slow to affect the relatively high seawater concentrations established by equilibration with the atmosphere. 

Denitrifying bacteria Mn- or Fe-reducing bacteria Sulfate reducing bacteria Sulfate reducing bacteria Fermenting bacteria... 

Denitrification occurs only in the presence of oxidized nitrogen and in an environment with limited (whieh prevails in the subsurfaee). Beeause denitrifieation is an enzyme-mediated reaetion, the substrate concentration funetions as a rate-determining factor. The dominant denitrifying bacteria are heterotrophie. The favored environmental conditions for the growth of denitrifying baeteria include a neutral pH (6-8), a favorable water-air (oxygen) ratio, and a subsurface temperature between 20 and 30°C. 

Nitrite reductases (NiRs)—enzymes found in several strains of denitrifying bacteria— catalyze the one-electron reduction of nitrite anion to nitric oxide (Equation 1). - In addition to the importance of this process in the global nitrogen cycle (Figure 1), further incentive for the study of the denitrification process is provided by its environmental impact, ranging from the production of NO as a pollutant and NjO as a potent greenhouse gas, to lake eutrophication due to farm runoff that contains high concentrations of nitrates and nitrites. 

Nitrite reductase Denitrification Denitrifying bacteria Liu etal. (1986)... 

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