Production of oceanic nitrous oxide by ammonia-oxidizing archaea
Production of oceanic nitrous oxide by ammonia-oxidizing archaea
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DOI：
10.5194/bg-9-2419-2012
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发表时间：
2012-01-01
期刊：
影响因子：
4.9
通讯作者：
Schmitz, R. A.
中科院分区：
文献类型：
--
作者：
Loescher, C. R.;Kock, A.;Schmitz, R. A.
最近发现，海洋中微生物氨氧化在很大程度上是由古细菌而不是细菌进行的，这极大地改变了对海洋硝化作用的看法。在海洋的大部分地区，古生菌氨氧化菌（AOA）的数量优势超过了它们的细菌对应物（AOB），这导致了一种假设，即AOA而不是AOB可能是海洋产生强烈温室气体一氧化二氮（N2O）的关键生物，这是硝化作用的副产品。在热带北大西洋东部（埃特纳）和热带南太平洋东部（ETSP）的水体中均能检测到古菌氨单加氧酶基因（amoA）。特别是在埃特纳中，古细菌amoA基因和N2O的丰度和表达的可比模式共同发生在氧最低，而细菌amoA基因的丰度可以忽略不计。此外，从埃特纳的海水培养古细菌的选择性抑制减少N2O的产生显着。在与唯一的培养海洋古菌氨氧化剂Nitrosopumilus maritimus SCM 1的研究中，我们提供了第一个直接的证据，N2O生产的纯培养AOA，不包括参与其他微生物可能存在于富集。N. maritimus在低氧浓度下表现出与埃特纳的oxycline中存在的浓度相当的高N2O产生速率，而来自两种AOB培养物的N2O产生在类似条件下非常低。根据我们的研究结果，我们假设，在热带海洋地区的N2O的生产结果主要来自古细菌硝化作用，并将受到预测的海洋中溶解氧的减少。
The recent finding that microbial ammonia oxidation in the ocean is performed by archaea to a greater extent than by bacteria has drastically changed the view on oceanic nitrification. The numerical dominance of archaeal ammonia-oxidizers (AOA) over their bacterial counterparts (AOB) in large parts of the ocean leads to the hypothesis that AOA rather than AOB could be the key organisms for the oceanic production of the strong greenhouse gas nitrous oxide (N2O) that occurs as a by-product of nitrification. Very recently, enrichment cultures of marine ammonia-oxidizing archaea have been reported to produce N2O.Here, we demonstrate that archaeal ammonia monooxygenase genes (amoA) were detectable throughout the water column of the eastern tropical North Atlantic (ETNA) and eastern tropical South Pacific (ETSP) Oceans. Particularly in the ETNA, comparable patterns of abundance and expression of archaeal amoA genes and N2O co-occurred in the oxygen minimum, whereas the abundances of bacterial amoA genes were negligible. Moreover, selective inhibition of archaea in seawater incubations from the ETNA decreased the N2O production significantly. In studies with the only cultivated marine archaeal ammonia-oxidizer Nitrosopumilus maritimus SCM1, we provide the first direct evidence for N2O production in a pure culture of AOA, excluding the involvement of other microorganisms as possibly present in enrichments. N. maritimus showed high N2O production rates under low oxygen concentrations comparable to concentrations existing in the oxycline of the ETNA, whereas the N2O production from two AOB cultures was comparably low under similar conditions. Based on our findings, we hypothesize that the production of N2O in tropical ocean areas results mainly from archaeal nitrification and will be affected by the predicted decrease in dissolved oxygen in the ocean.