In Vivo Emission of Dinitrogen by Earthworms via Denitrifying Bacteria in the Gut
In Vivo Emission of Dinitrogen by Earthworms via Denitrifying Bacteria in the Gut
复制标题
蚯蚓通过肠道反硝化细菌体内排放二氮
DOI：
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发表时间：
2006
影响因子：
4.4
通讯作者：
H. Drake
中科院分区：
文献类型：
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作者：
M. Horn;R. Mertel;M. Gehre;M. Kästner;H. Drake
摘要蚯蚓排放温室气体一氧化二氮（N2O），而肠道中摄入的分解剂似乎是N2O的主要来源。本研究的主要目的是确定蚯蚓是否也释放二氮（N2），完全反硝化的最终产物。当[15 N]硝酸盐注入肠道，蚯蚓Aporrectodea caliginosa和蚯蚓发射标记的N2（也标记N2O）在体内条件下，这两个蚯蚓的N2排放是相对线性的，每小时每克（鲜重）分别约1.2和6.6 nmol N2。孤立的肠道内容物也产生[15 N]硝酸盐衍生的N2和N2O缺氧条件下。N2是由N2O还原酶形成的，乙炔是这种酶的抑制剂，抑制了活蚯蚓释放[15 N]硝酸盐衍生的N2。标准的气相色谱分析表明，N2O排放量是相对线性的，在最初的孵化期，增加乙炔。N2的天然排放的计算速率（即，不添加硝酸盐）。caliginosa和L. terrestris分别为1.1和1.5纳摩尔N2每小时每克（鲜重），这些排放率近似N2O。这些集体观察表明，（i）蚯蚓排放N2伴随着排放N2O通过在肠道中的分解细菌的原位活性和（ii）N2O是定量的一个重要的分解衍生的最终产品在原位条件下。
ABSTRACT Earthworms emit the greenhouse gas nitrous oxide (N2O), and ingested denitrifiers in the gut appear to be the main source of this N2O. The primary goal of this study was to determine if earthworms also emit dinitrogen (N2), the end product of complete denitrification. When [15N]nitrate was injected into the gut, the earthworms Aporrectodea caliginosa and Lumbricus terrestris emitted labeled N2 (and also labeled N2O) under in vivo conditions; emission of N2 by these two earthworms was relatively linear and approximated 1.2 and 6.6 nmol N2 per h per g (fresh weight), respectively. Isolated gut contents also produced [15N]nitrate-derived N2 and N2O under anoxic conditions. N2 is formed by N2O reductase, and acetylene, an inhibitor of this enzyme, inhibited the emission of [15N]nitrate-derived N2 by living earthworms. Standard gas chromatographic analysis demonstrated that the amount of N2O emitted was relatively linear during initial incubation periods and increased in response to acetylene. The calculated rates for the native emissions of N2 (i.e., without added nitrate) by A. caliginosa and L. terrestris were 1.1 and 1.5 nmol N2 per h per g (fresh weight), respectively; these emission rates approximated that of N2O. These collective observations indicate that (i) earthworms emit N2 concomitant with the emission of N2O via the in situ activity of denitrifying bacteria in the gut and (ii) N2O is quantitatively an important denitrification-derived end product under in situ conditions.