Microbial Consumption of Methanol in a Grassland

甲醇是一种在对流层中含量丰富的活性挥发性有机化合物（VOC），草原是全球甲醇的重要来源。然而，土壤微生物对陆地生态系统中甲醇通量影响的环境生理学研究在很大程度上尚未得到研究。申请人以前的工作表明，迄今未知的土壤细菌参与了曝气土壤的环境甲醇氧化。拟议的项目将研究温带草原上的好氧和厌氧甲醇利用菌（包括革兰氏阳性细菌和真菌）。采用稳定同位素探测（SIP）方法，对四种丰富的草地植物物种与不同土壤和层际甲醇利用菌群落的关系进行了测试。在一个植被周期内，对所调查草原的甲醇通量和活性甲醇利用者的转录基因标记进行评估，并通过确证性的实验室实验解决地下和地上甲醇通量的比例问题。14C示踪实验将用于定位土壤和植物中的活动。将解决活性厌氧甲醇利用器的特性，并通过实验确定其对异常微量营养物质（稀土元素）的依赖。与J. Williams （MPI美因茨）和A. Held（拜罗伊特大学）合作，将通过质子传递质谱（PTR MS）测量甲醇的原位通量，旨在将通量数据与原位活性微生物相关联。所提出的工作将为草原单物种生理学和分布到生态系统水平的甲醇通量的升级奠定基础。

Grasslands are substantial global sources of methanol, which is a highly abundant and reactive volatile organic compound (VOC) in the troposphere. However, environmental physiology of soil microorganisms that impact on methanol flux in terrestrial ecosystems has largely not been investigated. Previous work of the applicant suggests that hitherto unknown soil bacteria are involved in ambient methanol oxidation of aerated soil. The proposed project will address aerobic and anaerobic methanol-utilizers (incl. Gram-positive bacteria and fungi) in temperate grassland. It will be tested with four abundant grassland plant species if those are associated with distinct soil and phyllosphere methanol utilizer communities employing stable isotope probing (SIP). Over a vegetation period, methanol flux and transcribed gene markers of active methanol utilizers will be assessed at the investigated grassland, and in a corroborative laboratory experiment the ratio of below-ground and above-ground methanol flux will be resolved. 14C tracer experiments will be used to localize activities in soil and plants. The identities of active anaerobic methanol utilizers will be resolved and their dependence on unusual trace nutrients (rare earth elements) will be experimentally determined. In collaboration with J. Williams (MPI Mainz) and A. Held (University Bayreuth) in situ fluxes of methanol will be measured by proton transfer mass spectrometry (PTR MS) aiming at correlation of flux data with in situ active microorganisms. The proposed work will set the stage for an upscaling of single-species physiology and distribution to ecosystem-level methanol flux in grassland.