Nitrous oxide metabolism in nitrate-reducing bacteria: Physiology and regulatory mechanisms

Maria Torres, Jorg Simon, Gary Rowley, Eulogio Bedmar, David Richardson, Andrew Gates, Maria Delgado

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32 Citations (Scopus)
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Abstract

Nitrous oxide (N2O) is an important greenhouse gas (GHG) with substantial global warming potential and also contributes to ozone depletion through photochemical nit- ric oxide (NO) production in the stratosphere. The negative effects of N2O on climate and stratospheric ozone make N2O mitigation an international challenge. More than 60% of global N2O emissions are emitted from agricultural soils mainly due to the appli- cation of synthetic nitrogen-containing fertilizers. Thus, mitigation strategies must be developed which increase (or at least do not negatively impact) on agricultural effi- ciency whilst decrease the levels of N2O released. This aim is particularly important in the context of the ever expanding population and subsequent increased burden on the food chain. More than two-thirds of N2O emissions from soils can be attributed to bacterial and fungal denitrification and nitrification processes. In ammonia-oxidizing bacteria, N2O is formed through the oxidation of hydroxylamine to nitrite. In denitrifiers, nitrate is reduced to N2 via nitrite, NO and N2O production. In addition to denitrification, respiratory nitrate ammonification (also termed dissimilatory nitrate reduction to ammonium) is another important nitrate-reducing mechanism in soil, responsible for the loss of nitrate and production of N2O from reduction of NO that is formed as a by-product of the reduction process. This review will synthesize our current understand- ing of the environmental, regulatory and biochemical control of N2O emissions by nitrate-reducing bacteria and point to new solutions for agricultural GHG mitigation.
Original languageEnglish
Pages (from-to)353-432
Number of pages80
JournalAdvances in Microbial Physiology
Volume68
Early online date29 Mar 2016
DOIs
Publication statusPublished - 2016

Keywords

  • Denitrification
  • Nitrate-ammonifying bacteria
  • Nitrate reduction
  • Nitrite reduction
  • Nitric oxide reductase
  • Nitrous oxide reductase

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