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首页> 外文期刊>Applied Microbiology >Actinobacterial Nitrate Reducers and Proteobacterial Denitrifiers Are Abundant in N2O-Metabolizing Palsa Peat
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Actinobacterial Nitrate Reducers and Proteobacterial Denitrifiers Are Abundant in N2O-Metabolizing Palsa Peat

机译：N2O代谢性帕尔萨泥炭中富含放线菌的硝酸盐还原剂和蛋白细菌的反硝化剂

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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 (N_(2)O). 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 N_(2)O fluxes were spatially variable, ranging from 0.01 to ?0.02 μmol of N_(2)O m~(?2) h~(?1). Fertilization with nitrate stimulated in situ N_(2)O emissions and N_(2)O production in anoxic microcosms without apparent delay. N_(2)O was subsequently consumed in microcosms. Maximal reaction velocities ( v _(max)) of nitrate-dependent denitrification approximated 3 and 1 nmol of N_(2)O per h per gram (dry weight [g_(DW)]) in soil from 0 to 20 cm and below 20 cm of depth, respectively. v _(max) values of nitrite-dependent denitrification were 2- to 5-fold higher than the v _(max) nitrate-dependent denitrification, and v _(max) of N_(2)O consumption was 1- to 6-fold higher than that of nitrite-dependent denitrification, highlighting a high N_(2)O 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 N_(2)O 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 N_(2)O fluxes.
机译：帕尔萨泥炭的特征是高高的圆形霜冻（永久冻结的冰晶状体顶部的豆土），是温室气体一氧化二氮（N_（2）O）的强至中等来源，甚至是临时汇。据预测，帕尔萨泥炭对全球变暖敏感。酸性的木炭泥炭Skalluvaara（pH值约为4.4）位于芬兰拉普兰西北部的不连续多年冻土带中。原位N_（2）O通量在空间上是可变的，N_（2）O m〜（？2）h〜（？1）的范围从0.01到？0.02μmol。硝酸盐的施肥在缺氧的微观世界中刺激了原位N_（2）O的排放和N_（2）O的产生，而没有明显的延迟。 N_（2）O随后在微观世界中被消耗。在0到20 cm及以下的土壤中，硝酸盐依赖性反硝化的最大反应速度（v _（max））大约为每克每小时3和1 nmol N_（2）O每克（干重[g_（DW）]）。分别为cm的深度。亚硝酸盐依赖性反硝化的v _（max）值比硝酸盐依赖性v _（max）的v _（max）高2至5倍，N_（2）O消耗的v _（max）为1-6。比依赖于亚硝酸盐的反硝化高出三倍，这突出了高的N_（2）O消耗潜力。最多可检索narG，nirK和nirS以及nosZ的12种物种级操作生物分类单位（OTU）。检测到的OTU提示存在多种未培养的土壤反硝化剂和异化硝酸盐还原剂，迄今未发现的物种以及放线菌，阿尔法和贝塔蛋白菌。 nirS的拷贝数总是比nirK的拷贝数高2个数量级。 nirS的拷贝数倾向于更高，而narG和nosZ的拷贝数倾向于在0至20 cm的土壤中低于20 cm以下的土壤。集体数据表明，（i）泥炭土壤N_（2）O的源和汇功能与反硝化作用有关，（ii）放线菌硝酸盐还原剂和nirS型和携带nosZ的蛋白细菌反硝化剂是重要的参与者。 iii）像泥炭泥炭这样的酸性土壤代表了与N_（2）O通量相关的各种耐酸反硝化剂的储集层。

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