Impact of Alternative Substrates on Methane, Methanol, and Chloromethane Metabolism of Methylotrophs in Forest Soils

森林土壤中的甲基营养微生物在很大程度上控制着陆地生态系统与大气的甲烷、甲醇和氯甲烷的全球交换。甲烷是一种温室气体。甲醇和氯甲烷会影响臭氧的形成。森林土壤中的甲基营养物质利用这些化合物作为能源和碳源。然而，环境中甲烷、甲醇和氯甲烷的浓度如此之低，以至于它们的利用不太可能充分节约甲基营养物质的能量。因此，森林土壤中的甲基营养物质可能利用森林土壤中丰富的替代底物，如纤维素和半纤维素的水解产物，有机物的厌氧降解产物，植物蜡中烷烃和木质素的可溶代谢物。拟议的项目将解决利用一碳大气气体的甲基营养生物的营养战略，并在森林土壤中茁壮成长。将对两个温带山毛榉林(施泰格瓦尔德、索林)的土壤样本进行调查。拟议的实验将允许使用最先进的稳定同位素探测技术、培养、代谢组学和蛋白质组学以及底物消耗动力学来鉴定活性甲基营养菌及其在原位相关底物浓度下的代谢途径。此外，实验将揭示土壤微生物群落对尚未得到充分解决的全球甲醇和氯甲烷循环的影响。

Methylotrophic microbes in forest soils govern to a substantial degree the global exchange of methane, methanol, and chloromethane of terrestrial ecosystems with the atmosphere. Methane is a greenhouse gas. Methanol and chloromethane affect ozone formation. Forest soil methylotrophs utilise these compounds as energy and carbon sources. However, ambient concentrations of methane, methanol, and chloromethane are such low that it is unlikely that their utilisation allows for sufficient energy conservation of methylotrophs. Thus, forest soil methylotrophs likely utilise alternative substrates that are abundant in forest soil, such as hydrolysis products of cellulose and hemicellulose, anaerobic degradation products of organic matter, nalkanes from plant waxes, and soluble metabolites of lignin. The proposed project will resolve trophic strategies of methylotrophs that utilise one-carbon atmospheric gases, and thrive in forest soils. Soil samples of two temperate beech stands will be investigated (Steigerwald, Solling). The proposed experiments will allow for identification of active methylotrophs and their metabolic pathways at in situ-relevant substrate concentrations using state of the art stable isotope probing techniques, cultivation, metatranscriptomics and –proteomics, and substrate consumption kinetics. Furthermore, experiments will reveal insights into the impact of soil microbial communities on the yet insufficiently resolved global cycles of methanol and chloromethane.