Structural and Functional Links between Denitrifiers, Fermenters and Methanogens: Impact on Greenhouse Gases

沼气排放温室气体甲烷(CH4)和一氧化二氮(N20)。在上一次资助期评估的生态系统中，经过2006年的实验干燥和再湿后，孔隙水甲烷浓度和产甲烷潜力较低，而厌氧CCV生产潜力、近地表硝酸盐浓度和一氧化二氮排放量较高。因此，干燥和再湿会影响产甲烷食物链和反硝化作用。下一个供资阶段的新目标是确定强化干燥和再湿以及洪水对(I)发酵菌、(Ii)产甲烷菌和(Iii)反硝化菌的结构和活性的影响。反硝化菌的多样性将通过功能基因分析(Narg和nosZ)和培养方法进行鉴定。新的生物将被生态生理学特征和分类学验证。基于功能基因的比较信使核糖核酸和DNA的T-RFLP分析、定量聚合酶链式反应和基于16S rRNA的微阵列分析将被用于检测活跃生物群落结构的变化。发酵菌、产甲烷菌和反硝化菌的米氏动力学将被用来识别群落结构相关的活动变化，从而阐明沼气中温室气体产生菌的结构-功能关系。

Fens emit the greenhouse gases methane (CH4) and nitrous oxide (N20). In the fen evaluated in the previous funding period, pore-water methane concentrations and methanogenic potentials were lower after experimental drying and rewetting in 2006, whereas anaerobic CCVproduction potentials, surface-near nitrate concentrations, and nitrous oxide emissions were higher. Thus, the methanogenic food chain and denitrtfication were affected by drying and rewetting. The new objectives of the next funding period are to identify the effect of intensified drying and rewetting, as well as flooding on the structure and activity of (i) fermenters, (ii) methanogens, and (iii) denitrifiers. Denitrifier diversity will be identified by functional gene analysis (narG and nosZ) and cultivation methods. Novel organisms will be ecophysiologically characterized and taxonomically validated. Comparative mRNA and DNA based T-RFLP analyses of functional genes, qPCR, and 16S rRNA-based microarray analyses will be used to detect changes in community structure of active organisms. Michaelis-Menten-kinetics of fermenters, methanogens, and denitrifiers will be applied to identify community structure-related activity changes and thus elucidate structurefunction relationship of greenhouse-gas producing organisms in fens.