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

近年来，植物、真菌和土壤在有氧条件下和没有产甲烷古生菌的帮助下产生甲烷(CH4)已被证明。但这些科学发现大多是在无菌条件下获得的。在自然条件下(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)下的甲烷产生率可能与无菌培养获得的排放率不同。通过这个项目，我们希望首次在受控的实验室条件下调查包括真菌和微生物在内的充气植物-土壤系统中CH4的产生和同时微生物的消耗。第一个目标是开发一个封闭的模块化结构系统，其中可以研究植物-土壤系统的特定成分及其与CH4产生的相互作用。首先，将探索植物与相关真菌之间的相互作用。土壤中甲烷源的分离将通过使用选择性缓蚀剂来实现。我们解决了植物的存在如何影响土壤内源CH4产生的问题，并将使用稳定的同位素标记来追踪光合作用固定的二氧化碳转化为CH4的过程。此外，我们对系统内的CH4通量很感兴趣。为了测试内源性CH4生产和CH4消费之间是否存在可能的联系，我们将同时量化CH4生产和消费。同位素标记技术和分子方法的结合将被用来追踪甲烷营养细菌中的植物来源的CH4。本研究将测试毛虫取食和害虫侵染后植物来源的CH4排放的响应，温度诱导的CH4排放的变化将与代谢活动有关。本研究的目的是通过量化CH4的产生和消耗来提高我们对植物-土壤系统中CH4通量的理解。此外，我们的结果可能有助于解释陆地生态系统的变异性，并可能改进对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.