Interactions between Thaumarchaea, Nitrospira and methanotrophs modulate autotrophic nitrification in volcanic grassland soil
Interactions between Thaumarchaea, Nitrospira and methanotrophs modulate autotrophic nitrification in volcanic grassland soil
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DOI：
10.1038/ismej.2014.81
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发表时间：
2014-12-01
期刊：
影响因子：
11
通讯作者：
Laanbroek, Hendrikus J.
中科院分区：
文献类型：
--
作者：
Daebeler, Anne;Bodelier, Paul L. E.;Laanbroek, Hendrikus J.
铵/氨是氨氧化剂的唯一能量底物，也是其他微生物必需的氮源。因此，当铵浓度受到限制时，氨氧化剂必须与陆地生态系统中的其他土壤微生物（例如甲烷氧化细菌（MOB））竞争。在这里，我们报告了以氨氧化古菌（AOA）和类硝化螺菌亚硝酸盐氧化细菌（NOB）为主的硝化群落之间的相互作用，以及在具有两种水平的铵和甲烷可用性的受控微观实验中的 MOB 群落之间的相互作用。我们观察到铵浓度升高对硝化和甲烷氧化过程以及自养生长硝化菌的丰度具有强烈的刺激作用。然而，通过使用 (CO2)-C-13 和 (CH4)-C-13 进行稳定同位素标记来鉴定，硝化和甲烷氧化中的关键参与者在两种铵水平下是相同的，即分别为 1.1a 型 AOA、亚系 I 和 II 类 Nitrospira NOB 和甲基微生物/甲基八叠球菌样 MOB。氨氧化细菌几乎不存在，氨氧化几乎完全归因于 AOA。有趣的是，尽管AOA功能基因丰度在孵化过程中增加了10倍，但自养生长的证据非常有限，表明部分混合营养的生活方式。此外，AOA 和 NOB 的自养生长在两种铵水平下均受到活性 MOB 的抑制。我们的研究结果表明，土壤中硝化菌和甲烷氧化剂之间存在以前被忽视的氮竞争，从而将自然界中两个最重要的生物地球化学循环联系起来。
Ammonium/ammonia is the sole energy substrate of ammonia oxidizers, and is also an essential nitrogen source for other microorganisms. Ammonia oxidizers therefore must compete with other soil microorganisms such as methane-oxidizing bacteria (MOB) in terrestrial ecosystems when ammonium concentrations are limiting. Here we report on the interactions between nitrifying communities dominated by ammonia-oxidizing archaea (AOA) and Nitrospira-like nitrite-oxidizing bacteria (NOB), and communities of MOB in controlled microcosm experiments with two levels of ammonium and methane availability. We observed strong stimulatory effects of elevated ammonium concentration on the processes of nitrification and methane oxidation as well as on the abundances of autotrophically growing nitrifiers. However, the key players in nitrification and methane oxidation, identified by stable-isotope labeling using (CO2)-C-13 and (CH4)-C-13, were the same under both ammonium levels, namely type 1.1a AOA, sublineage I and II Nitrospira-like NOB and Methylomicrobium-/Methylosarcina-like MOB, respectively. Ammonia-oxidizing bacteria were nearly absent, and ammonia oxidation could almost exclusively be attributed to AOA. Interestingly, although AOA functional gene abundance increased 10-fold during incubation, there was very limited evidence of autotrophic growth, suggesting a partly mixotrophic lifestyle. Furthermore, autotrophic growth of AOA and NOB was inhibited by active MOB at both ammonium levels. Our results suggest the existence of a previously overlooked competition for nitrogen between nitrifiers and methane oxidizers in soil, thus linking two of the most important biogeochemical cycles in nature.