Pathway of nitrous oxide consumption in isolated Pseudomonas stutzeri strains under anoxic and oxic conditions

Abstract

The microbial consumption of nitrous oxide (N2O) has gained great interest since it was revealed that this process could mitigate the greenhouse effect of N2O. The consumption of N2O results from its reduction to dinitrogen gas (N2) as part of the denitrification process. However, there is ongoing debate regarding an alternative pathway, namely reduction of N2O to NH4(+), or assimilatory N2O consumption. To date, this pathway is poorly investigated and lacks unambiguous evidence. Enrichment of denitrifying activated sludge using a mineral nitrogen-free medium rendered a mixed culture capable of anoxic and oxic N2O consumption. Dilution plating, isolation and deoxyribonucleic acid fingerprinting identified a collection of Pseudomonas stutzeri strains as dominant N2O consumers in both anaerobic and aerobic enrichments. A detailed isotope tracing experiment with a Pseudomonas stutzeri isolate showed that consumption of N2O via assimilatory reduction to NH4(+) was absent. Conversely, respiratory N2O reduction was directly coupled to N2 fixation.

Nitrous Oxide Metabolism in Nitrate-Reducing Bacteria

“…However, it has been recently demonstrated the capacity of Ps. stutzeri species to consume N 2 O under oxic conditions (Desloover et al, 2014), supporting previous observations showing that the nosZ gene can also be expressed at high O 2 concentrations (Miyahara et al, 2010). Supporting these findings, it has been recently reported in Pa. denitrificans the reduction of N 2 O at high O 2 partial pressure (Qu, Bakken, Molstad, Frostegard, & Bergaust, 2016).…”

“…Recent isotope tracing experiments by using Ps. stutzeri showed that consumption of N 2 O via assimilatory reduction to ammonium did not occur (Desloover et al, 2014). However, the latter studies showed that respiratory N 2 O reduction can be coupled to N 2 fixation as N 2 O is first reduced to N 2 before is further reduced to ammonium and incorporated into cellular biomass.…”

Decaying Cyanobacteria decrease N2O emissions related to diversity of intestinal denitrifiers of Chironomus plumosus

“…This result was consistent with a previous report (Poulsen et al, 2014). The genera Pseudomonas and Stenotrophomonas belonging to Gamma-proteobacteria were ubiquitous in sediment and waste plants, while not detected in the gut due to primer partial (Cutruzzola et al, 2003;Bartacek et al, 2010;Bellini et al, 2013;Desloover et al, 2014;Zheng et al, 2014). The community composition of nitrite-and nitrous-oxide-reducing bacteria in the gut was indeed affected by the presence of cyanobacteria.…”

The soil N cycle: new insights and key challenges

“…55 % was achieved with such inoculation. Desloover et al (2014) identified a Pseudomonas stutzeri strain that was able to grow on N 2 O as the only source of N and electron acceptor. Pseudomonas stutzeri is known to possess both nitrogenase and nitrous oxide reductase (nosZ I) (Pomowski et al, 2011).…”

“…Pseudomonas stutzeri is known to possess both nitrogenase and nitrous oxide reductase (nosZ I) (Pomowski et al, 2011). A 15 N labelling study showed that N 2 O is immobilized into microbial biomass via N 2 O reduction to N 2 followed by reuptake of the released N 2 and subsequent fixation into NH + 4 via nitrogenase (Desloover et al, 2014). …”