Actinobacterial Nitrate Reducers and Proteobacterial Denitrifiers Are Abundant in N2O-Metabolizing Palsa Peat
Actinobacterial Nitrate Reducers and Proteobacterial Denitrifiers Are Abundant in N2O-Metabolizing Palsa Peat
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DOI：
10.1128/aem.00810-12
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发表时间：
2012-08-01
影响因子：
4.4
通讯作者：
Horn, Marcus A.
中科院分区：
文献类型：
--
作者：
Palmer, Katharina;Horn, Marcus A.
帕尔萨泥炭的特点是高架的，圆形的霜隆起（泥炭土壤上的永久冻结的冰透镜），是强到中等的温室气体一氧化二氮（N2 O）的来源，甚至是临时的汇。据预测，帕尔萨泥炭对全球变暖的反应很敏感。酸性泥炭Skalluvaara（pH值约4.4）位于芬兰拉普兰西北部的不连续永久冻土带。原位N2 O通量在空间上是可变的，范围从0.01到-0.02 μ mol N2 O m（-2）h（-1）。施肥与硝酸盐刺激原位N2 O排放和N2 O生产缺氧微宇宙没有明显的延迟。N2 O随后在微观世界中被消耗。硝态氮依赖的反硝化作用的最大反应速度（nu（max））约3和1 nmol的N2 O每小时每克（干重[g（DW）]）在土壤中从0到20厘米和低于20厘米的深度，分别。亚硝酸盐依赖的反硝化作用的Nu（max）值比Nu（max）高2- 5倍。硝酸盐依赖的反硝化作用，和N2 O消耗的nu（最大）是1- 6倍高于亚硝酸盐依赖的反硝化作用，突出了高N2 O消耗潜力。检索到narG、nirK、nirS和nosZ等多达12个种级操作分类单位（OTU）。检测到的OTU表明存在各种未培养的土壤微生物和异化硝酸盐还原剂，迄今未检测到的物种，以及放线菌，α-和β-变形菌。nirS的拷贝数总是超过nirK的2个数量级。nirS基因在0 ~ 20 cm土层中的拷贝数高于20 cm以下土层，narG和nosZ基因在0 ~ 20 cm土层中的拷贝数低于20 cm以下土层。集体的数据表明，（一）源和汇功能的泥炭土壤N2 O与反硝化作用，（二）放线菌硝酸盐还原剂和nirS型和nosZ-窝藏proteobacterial fractioners是重要的球员，和（iii）酸性土壤，如泥炭代表水库的不同耐酸fractioners与N2 O通量。
Palsa peats are characterized by elevated, circular frost heaves (peat soil on top of a permanently frozen ice lens) and are strong to moderate sources or even temporary sinks for the greenhouse gas nitrous oxide (N2O). Palsa peats are predicted to react sensitively to global warming. The acidic palsa peat Skalluvaara (approximate pH 4.4) is located in the discontinuous permafrost zone in northwestern Finnish Lapland. In situ N2O fluxes were spatially variable, ranging from 0.01 to -0.02 mu mol of N2O m(-2) h(-1). Fertilization with nitrate stimulated in situ N2O emissions and N2O production in anoxic microcosms without apparent delay. N2O was subsequently consumed in microcosms. Maximal reaction velocities (nu(max)) of nitrate-dependent denitrification approximated 3 and 1 nmol of N2O per h per gram (dry weight [g(DW)]) in soil from 0 to 20 cm and below 20 cm of depth, respectively. nu(max) values of nitrite-dependent denitrification were 2- to 5-fold higher than the nu(max). nitrate-dependent denitrification, and nu(max) of N2O consumption was 1- to 6-fold higher than that of nitrite-dependent denitrification, highlighting a high N2O consumption potential. Up to 12 species-level operational taxonomic units (OTUs) of narG, nirK and nirS, and nosZ were retrieved. Detected OTUs suggested the presence of diverse uncultured soil denitrifiers and dissimilatory nitrate reducers, hitherto undetected species, as well as Actino-, Alpha-, and Betaproteobacteria. Copy numbers of nirS always outnumbered those of nirK by 2 orders of magnitude. Copy numbers of nirS tended to be higher, while copy numbers of narG and nosZ tended to be lower in 0- to 20-cm soil than in soil below 20 cm. The collective data suggest that (i) the source and sink functions of palsa peat soils for N2O are associated with denitrification, (ii) actinobacterial nitrate reducers and nirS-type and nosZ-harboring proteobacterial denitrifiers are important players, and (iii) acidic soils like palsa peats represent reservoirs of diverse acid-tolerant denitrifiers associated with N2O fluxes.