Identification of carbon and nitrogen assimilating microbial populations in anaerobically methane-oxidising mats by stable isotope probing

甲烷厌氧氧化（AOM）是海洋系统甲烷排放调控的一个重要过程。有强有力的证据表明，AOM是由一种与产甲烷古菌相关的新古菌群（ANME）进行的，这种古菌群通常与硫酸盐还原原核生物（SRP）有着密切的物理联系。然而，目前仍然没有厌氧甲烷营养微生物的纯培养物。因此，该过程的基本方面，如其机制，可能的中间体，以及所有涉及的微生物群的身份仍然未知。最近，我们小组成功地在黑海的微生物AOM-mats上完成了第一个稳定同位素标记实验，表明13c -甲烷被吸收到脂质生物标志物中。显然，理解不同垫生态系统中代谢相互作用和相互依赖关系的关键是更好地理解吸收性碳和氮通量。因此，我们的项目将利用一套稳定的碳和氮同位素探测方法阐明厌氧甲烷氧化微生物群落的同化能力。我们将采用核酸和脂质生物标志物分析来揭示碳汇和来源，以及不同n -化合物作为氮源或在垫中呼吸过程中的作用。这将有助于揭示同化途径，同时使我们能够识别所涉及的主要活性微生物群。最终，我们的目标是了解单个微生物在甲烷依赖的化学合成垫生态系统中的作用，并将微生物垫中单个微生物的碳同化模式与厌氧甲烷氧化的可能机制联系起来。

The anaerobic oxidation of methane (AOM) is a major process in the regulation of methane emissions from marine systems. There is strong evidence that AOM is carried out by a novel group of Archaea (ANME) related to methanogenic Archaea, which often occurs in close physical associations with sulphate-reducing prokaryotes (SRP). However, there are still no pure cultures of anaerobic methanotrophic microorganisms available. Consequently, fundamental aspects of the process, like its mechanism, possible intermediates, and the identity of all microbial groups involved remain unknown. Recently, a first stable isotope labelling experiment was successfully accomplished with microbial AOM-mats from the Black Sea by our group, which showed the uptake of the 13C-methane into lipid biomarkers.Clearly, a key to the understanding of the metabolic interactions and interdependencies in the different mat ecosystems necessitates a better understanding of assimilatory carbon and nitrogen fluxes. Therefore, our project will elucidate assimilative capabilities within anaerobically methaneoxidizing microbial mat communities using a suite of stable carbon and nitrogen isotope probing approaches. We will employ nucleic acid and lipid biomarker analysis to unveil carbon sinks and sources and the role of different N-compounds as nitrogen sources or for respiratory processes in the mat. This will allow to reveal assimilatory pathways, and simultaneously will enable us to identify the dominant active microbial groups involved. Ultimately, the goals are to understand the role of individual microorganisms for the methane-dependent chemosynthetic mat ecosystem and to relate patterns of carbon assimilation of individual microorganisms in the microbial mat to possible mechanisms of anaerobic methane oxidation.