INHIBITION OF AMMONIA OXIDATION IN NITROSOMONAS-EUROPAEA BY SULFUR-COMPOUNDS - THIOETHERS ARE OXIDIZED TO SULFOXIDES BY AMMONIA MONOOXYGENASE
INHIBITION OF AMMONIA OXIDATION IN NITROSOMONAS-EUROPAEA BY SULFUR-COMPOUNDS - THIOETHERS ARE OXIDIZED TO SULFOXIDES BY AMMONIA MONOOXYGENASE
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DOI：
10.1128/aem.59.11.3718-3727.1993
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发表时间：
1993-11-01
影响因子：
4.4
通讯作者：
ARP, DJ
中科院分区：
文献类型：
--
作者：
JULIETTE, LY;HYMAN, MR;ARP, DJ
有机硫化合物是众所周知的硝化抑制剂。研究了二甲基硫醚、二甲基二硫醚和乙烯利对亚硝化单胞菌氨氧化的抑制作用。二甲基硫醚和二甲基二硫醚都是氨氧化的弱抑制剂，并表现出氨单加氧酶（AMO）底物的典型抑制特性。甲硫醚的消耗需要氧气，并防止与乙炔或烯丙基硫脲，两个AMO抑制剂。详细考察了二甲硫醚对氨氧化的抑制作用。在氨存在下孵育的细胞悬液将二甲硫醚氧化为二甲亚砜。耗尽的其他六个硫醚也防止通过处理细胞悬浮液与烯丙基硫脲或乙炔。三种硫醚的氧化产物被鉴定为相应的亚砜。形成的亚砜的量占硫化物贫化量的大部分。利用气相色谱-质谱联用技术，研究了N。europaea，其中将衍生自O-18（2）的单个O-18原子并入硫化物中。这一结果支持了我们的结论，单加氧酶参与氧化烯丙基甲基硫醚。硫醚类化合物是一类新的AMO底物。这是首次报道AMO在N.欧洲。N.氧化二甲硫醚的Europaea在氨氧化细菌中不是唯一的。海洋亚硝化球菌（Nitrosococcus oceanus）也被证明可以将二甲基硫醚氧化为二甲基亚砜。
Organic sulfur compounds are well-known nitrification inhibitors. The inhibitory effects of dimethylsulfide, dimethyldisulfide, and ethanethiol on ammonia oxidation by Nitrosomonas europaea were examined. Both dimethylsulfide and dimethyldisulfide were weak inhibitors of ammonia oxidation and exhibited inhibitory characteristics typical of substrates for ammonia monooxygenase (AMO). Depletion of dimethylsulfide required O2 and was prevented with either acetylene or allylthiourea, two inhibitors of AMO. The inhibition of ammonia oxidation by dimethylsulfide was examined in detail. Cell suspensions incubated in the presence of ammonia oxidized dimethylsulfide to dimethyl sulfoxide. Depletion of six other thioethers was also prevented by treating cell suspensions with either allylthiourea or acetylene. The oxidative products of three thioethers were identified as the corresponding sulfoxides. The amount of sulfoxide formed accounted for a majority of the amount of sulfide depleted. By using gas chromatography coupled with mass spectrometry, allylmethylsulfide was shown to be oxidized to allylmethylsulfoxide by N. europaea with the incorporation of a single atom of O-18 derived from O-18(2) into the sulfide. This result supported our conclusion that a monooxygenase was involved in the oxidation of allylmethylsulfide. The thioethers are concluded to be a new class of substrates for AMO. This is the first report of the oxidation of the sulfur atom by AMO in whole cells of N. europaea. The ability of N. europaea to oxidize dimethylsulfide is not unique among the ammonia-oxidizing bacteria. Nitrosococcus oceanus, a marine nitrifier, was also demonstrated to oxidize dimethylsulfide to dimethyl sulfoxide.