How do coal degrading methanogens make biogas? Unravelling central metabolism of Methermicoccus shengliensis

甲烷是地球上第二大温室气体。甲烷排放到大气的主要来源是产甲烷古生菌，强调了这些生物对全球碳循环和环境的重要性。尽管对产甲烷菌的研究已有40多年的历史，但最近发现了一种新的产甲烷途径：嗜热产甲烷菌Methermicoccus(M.)胜利菌能够利用多种甲氧基化芳香族化合物作为甲烷产生的底物，称为甲氧基营养产甲烷。一种甲氧基营养甲烷菌的发现，再加上地球上丰富的甲氧基化化合物，如木质素，表明甲氧基营养古菌在甲烷形成和全球碳循环中的作用迄今可能被低估。此外，胜利木霉是第一个具有煤组分产甲烷潜力的微生物，这是微生物煤层气生产优化的一个重要发现。尽管这一杰出的考古学家具有重要意义和新颖性，但对其新陈代谢的详细分析仍然缺乏。我打算通过研究转录和蛋白质组学对甲氧基化芳香族化合物生长的反应以及相关酶的酶学特征来填补这一空白。此外，我还将分析在实验室规模的生物反应器中，需要一个以上的微生物来降解甲氧基化化合物和形成甲烷的合养微生物联合体和胜利氏微囊藻之间对甲氧基化化合物的竞争。通过这种方法，我的目标是初步了解胜利木霉在将甲氧基化合物转化为甲烷方面的生态重要性，以及在煤层气生产或石油生物降解中的可能应用。

Methane is the second most important greenhouse gas on earth. The main source of methane emission into the atmosphere are methanogenic archaea emphasizing the importance of those organisms for the global carbon cycle and the environment. Although methanogens have been studied for more than 40 years, a novel methanogenic pathway has recently been discovered: the thermophilic methanogen Methermicoccus (M.) shengliensis is able to use a large variety of methoxylated aromatic compounds as substrates for methane generation termed methoxydotrophic methanogenesis. Discovery of a methoxydotrophic methanogen in combination with the abundance of methoxylated compounds such as lignin on earth indicate that methoxydotrophic archaea might play a so far underestimated role in methane formation and the global carbon cycle. Moreover, M. shengliensis represents the first microorganism with the potential for methane generation from coal components which is an important finding with regard to the optimization of microbial coalbed methane generation. Despite the significance and novelty of this outstanding archaeon a detailed analysis of its metabolism is still missing. I intend to fill this gap by studying transcriptomic and proteomic responses to growth on methoxylated aromatics along with enzymological characterization of relevant enzymes. Furthermore, I will analyze the competition for methoxylated compounds between M. shengliensis and syntrophic microbial consortia that require more than one microorganism for the degradation of methoxylated compounds and formation of methane by use of laboratory scale bioreactors. With this approach I aim to get first insights into the ecological importance of M. shengliensis for conversion of methoxylated compounds to methane with regard to a possible application of M. shengliensis in coal bed methane production or biodegradation of oil.