近日，中科院南京土壤研究所贾仲君课题组与国际同行合作，针对北欧冰岛火山灰草地土壤，发现古菌主导了氨氧化过程并抑制了甲烷氧化菌生长，而氨氧化细菌则未参与这一过程，研究结果在线发表于《国际微生物生态学会会刊》(The ISME Journal）。

指甲盖面积大小的土壤中，微生物数量最高可达上百亿，种类最多可达上百万。这些难以计数的土壤微生物如何相互作用，并在复杂环境中发挥功能，一直是土壤微生物学的技术难点和研究前沿。贾仲君等利用稳定性同位素示踪氨氧化微生物DNA，开发出高通量测序微生物群落技术，将低丰度微生物检测限提高至少上百倍。

此后，贾仲君课题组以稻田土壤甲烷和氨氧化相互作用过程为模式体系，进一步开发了高通量测序13C-功能基因技术，定量刻画了稻田甲烷氧化与氨氧化的微生物相互作用，发现尿素显著刺激了类型Ia甲烷氧化菌生长，甲烷抑制了一种氨氧化细菌的生长，其主要原因可能是研究体系中C/N比高于9.0，氮素成为该类型甲烷氧化菌的生长限制因子。研究人员还发现古菌主导了氨氧化过程并抑制了甲烷氧化菌生长，而氨氧化细菌则未参与这一过程。（来源：中国科学报 柯讯）

Interactions between Thaumarchaea, Nitrospira and methanotrophs modulate autotrophic nitrification in volcanic grassland soil

Abstract  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 (13)CO2 and (13)CH4, 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.

原文链接：http://europepmc.org/abstract/MED/24858784