Quantification of methane sources and sinks in a plant-soil system

近年来，在没有产甲烷古菌的帮助下，植物、真菌和土壤在氧气条件下产生甲烷（CH4）。但这些科学发现大多是在无菌条件下获得的。自然条件下（包括动物饲养、氧气和湿度条件的变化、与其他生物的相互作用）的CH4产率可能与无菌培养获得的排放率不同。在这个项目中，我们希望首次研究在受控的实验室条件下，在一个通风的植物-土壤系统中包括真菌和微生物的CH4生产和同时的微生物消耗。第一个目标是开发一个封闭室模块化结构系统，其中植物-土壤系统的特定组成部分及其相互作用可以研究CH4的产生。首先，植物和相关真菌的相互作用将被探索。选择性抑制剂可实现土壤中CH4源的分离。我们解决了植物的存在如何影响土壤内源CH4产生的问题，并将使用稳定同位素标记来追踪光合作用固定CO2到CH4的转化。此外，我们对系统内CH4的通量也很感兴趣。为了检验内源性CH4产生和CH4消耗之间是否存在可能的联系，我们将同时量化CH4的产生和消耗。同位素标记技术与分子方法的结合将用于追踪甲烷营养细菌中植物来源的CH4。我们将测试毛毛虫取食和害虫侵害后植物来源的CH4排放的响应，温度引起的CH4排放变化将与代谢活性有关。本研究项目的目的是通过对CH4产生和消耗的量化来提高我们对植物-土壤系统中CH4通量的认识。此外，我们的研究结果可能有助于解释陆地生态系统的变异性，并可能改善气候引起的生态系统CH4通量变化的预测。

In recent years methane (CH4) production under oxic conditions and without the help of methanogenic Archaea has been shown for plants, fungi, and soil. But the scientific findings were largely obtained under sterile conditions. Likely, CH4 production rates under natural conditions (including e.g. animal feeding, changing oxygen and moisture conditions, interaction with other organisms) will differ from the emission rates obtained from sterile cultures. With this project we want to investigate for the first time the CH4 production and simultaneous microbial consumption in an aerated plant-soil system including fungi and microbes under controlled laboratory conditions.The first goal is to develop a closed-chamber modular construction system where specific components of the plant-soil system and their interaction can be investigated with regard to CH4 production. Primarily, the interaction of plants and associated fungi will be explored. Separation of CH4 sources in soil will be achieved by using selective inhibitors. We address the questions how the presence of plants affects soil endogenic CH4 production and will use stable isotope labeling to trace the conversion of photosynthetically fixed CO2 to CH4. Moreover, we are interested in CH4 fluxes within the system. To test the existence of a possible connection between endogenic CH4 production and CH4 consumption we will simultaneously quantify CH4 production and consumption. A combination of isotope labelling techniques with molecular methods will be used to trace plant-derived CH4 within methanotrophic bacteria. The response of plant-derived CH4 emissions after caterpillar feeding and vermin infestation will be tested and temperature-induced changes in CH4 emissions will be related to metabolic activity.The aim of this research project is to improve our understanding of CH4 fluxes in the plant-soil system via the quantification of CH4 production and consumption. Furthermore, our results might contribute to explain the variability of terrestrial ecosystems and may improve predictions of climate induced changes of ecosystem CH4 fluxes.