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Aerobic denitrification, or co-respiration, the simultaneous use of both oxygen (O 2) and nitrate (NO − 3) as oxidizing agents, performed by various genera of microorganisms. [1] This process differs from anaerobic denitrification not only in its insensitivity to the presence of oxygen, but also in its higher potential to form nitrous oxide ...
Aerobic denitrifiers can conduct an aerobic respiratory process in which nitrate is converted gradually to N 2 (NO 3 − → NO 2 − → NO → N 2 O → N 2), using nitrate reductase (Nar or Nap), nitrite reductase (Nir), nitric oxide reductase (Nor), and nitrous oxide reductase (Nos).
Aerobic denitrifiers are mainly Gram-negative bacteria in the phylum Proteobacteria. Enzymes NapAB, NirS, NirK and NosZ are located in the periplasm, a wide space bordered by the cytoplasmic and the outer membrane in Gram-negative bacteria. [16] A variety of environmental factors can influence the rate of denitrification on an ecosystem-wide scale.
Dissimilatory nitrate reduction to ammonium is a two step process, reducing NO 3 − to NO 2 − then NO 2 − to NH 4 +, though the reaction may begin with NO 2 − directly. [1] Each step is mediated by a different enzyme, the first step of dissimilatory nitrate reduction to ammonium is usually mediated by a periplasmic nitrate reductase.
Anaerobic respiration is used by microorganisms, either bacteria or archaea, in which neither oxygen (aerobic respiration) nor pyruvate derivatives (fermentation) is the final electron acceptor. Rather, an inorganic acceptor such as sulfate ( SO 2− 4 ), nitrate ( NO − 3 ), or sulfur (S) is used. [ 16 ]
Some strains are capable of 'aerobic denitrification', the complete dissimilation of nitrate to dinitrogen (or nitrous oxide) under aerobic growth conditions. The microbe also can oxidize ammonia to nitrite while growth on organic energy sources, a process known as 'heterotrophic nitrification'. Coupled to denitrification, heterotrophic ...
The FNR (defective in fumarate and nitrate reduction) protein of E. coli is an oxygen – responsive transcriptional regulator required for the switch from aerobic to anaerobic metabolism [1]. "Type III mutants, originally frdB , were designated fnr because they were defective in fumarate and nitrate reduction and impaired in their ability to ...
The terms aerobic respiration, anaerobic respiration and fermentation (substrate-level phosphorylation) do not refer to primary nutritional groups, but simply reflect the different use of possible electron acceptors in particular organisms, such as O 2 in aerobic respiration, or nitrate (NO − 3), sulfate (SO 2−