Desloover Joachim, Roobroeck Dries, Heylen Kim, Puig Sebastià, Boeckx Pascal, Verstraete Willy, Boon Nico
Laboratory of Microbial Ecology and Technology (LabMET), Ghent University, Ghent, B-9000, Belgium.
Environ Microbiol. 2014 Oct;16(10):3143-52. doi: 10.1111/1462-2920.12404. Epub 2014 Feb 18.
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.
自从发现微生物消耗一氧化二氮（N₂O）这一过程能够减轻N₂O的温室效应以来，该过程就引起了人们的极大兴趣。N₂O的消耗源于其在反硝化过程中被还原为氮气（N₂）。然而，关于另一条途径，即将N₂O还原为NH₄⁺或同化性N₂O消耗，目前仍存在争议。迄今为止，这条途径的研究较少，且缺乏明确的证据。使用无矿物氮培养基对反硝化活性污泥进行富集培养，得到了一种能够在缺氧和好氧条件下消耗N₂O的混合培养物。稀释平板法、分离法和脱氧核糖核酸指纹图谱分析确定，在厌氧和好氧富集培养物中，斯氏假单胞菌菌株是主要的N₂O消耗菌。对一株斯氏假单胞菌分离株进行的详细同位素示踪实验表明，不存在通过同化性还原将N₂O消耗为NH₄⁺的情况。相反，呼吸性N₂O还原与固氮直接相关。
