RUI: Linking Microbial Diversity to Carbon Metabolism in Peatlands of Canada and Siberia

寒带和亚北极泥炭地生态系统仅覆盖地球陆地面积的3- 4% (346-500 Mha)，但它们以不完全腐烂的有机质或泥炭的形式储存了世界上约1/3的土壤碳。大部分泥炭地（约3.84亿公顷）分布在俄罗斯、波罗的海共和国、芬诺斯坎迪亚、阿拉斯加和加拿大。就全球碳循环而言，泥炭地是一个主要的碳库，但目前尚不清楚它们是大气碳的源还是汇，尽管Gorham（1991,1994,1995）估计北部泥炭地是大气CO2的净汇（76tg C /年-1）和大气CH4的净源（46tg C /年-1）仍被广泛引用。尽管泥炭微生物群落作为好氧和厌氧分解介质（包括CO2和CH4的产生）的核心重要性早已被认识到，但对泥炭中微生物群落结构与碳循环之间的联系知之甚少。分子生态学技术的最新发展现在允许定量表征泥炭中的微生物（古细菌，真细菌和真菌）群落结构，因此我们可以开始将微生物群落结构与生态系统功能联系起来，这是本提案的总体目标。在这项提案中，维拉诺瓦大学的研究人员试图将定量生物地球化学方法、定量分子生态学方法以及对学生的教育和培训结合起来，努力了解泥炭地的微生物群落结构与碳循环在过程水平上的关系，泥炭地似乎在响应两个不同大陆的全球变化。他们将从加拿大西部大陆和西伯利亚中部的不连续永久冻土区收集完整的1米长的泥炭岩心，后者在西伯利亚泥炭研究所的同事的技术和后勤援助下。在每个岩心10厘米的深度，他们将定量评估生态系统功能的各个方面，包括CO2和CH4生产潜力，特定过程的土壤酶（苯酚氧化酶，几丁质酶，酸性磷酸酶，芳香硫酸酯酶）的活性，低分子量溶解有机阴离子（醋酸盐，乳酸盐，固有酸盐，甲酸盐，丙酮酸盐，草酸盐和酒石酸盐）的浓度，以及细菌和真菌生物量（使用草酸和麦角甾醇测定）。此外，他们将利用泥炭总基因组DNA提取、PCR扩增、质粒克隆和序列分析来鉴定每个泥炭样品中的特定古细菌、真细菌和真菌“物种”。利用这种方法，研究人员希望能够将永久冻土正在积极融化的泥炭地地区的微生物群落结构与泥炭地生态系统功能联系起来，这可能是气候变化的前兆。

ABSTRACTOCE-0120610Boreal and subarctic peatland ecosystems cover only about 3-4 % of the earth's land surface (346-500 Mha) yet they store about 1/3 of the world's soil carbon as incompletely decayed organic matter, or peat. Most of these peatlands ( ca. 384 million ha) are found in Russia, the Baltic Republics, Fennoscandia, Alaska and Canada. In terms of the global C cycle, peatlands represent a major C pool, yet it is unclear whether they function as sources or sinks of atmospheric C, although Gorham's (1991, 1994, 1995) estimates that northern peatlands represent a net sink of atmospheric CO2 (76 Tg C yr -1 ) an a net source of atmospheric CH4 (46 Tg C yr -1 ) remain widely cited. Although the central importance of peat microbial populations as mediators of both aerobic and anaerobic decomposition, including the production of both CO2 and CH4, has long been recognized, little is known about the linkages between microbial community structure and C cycling in peat. Recent developments in molecular ecological techniques now permit quantitative characterization of microbial (Archaeal, eubacterial, and fungal) community structure in peat, so that we can begin to link microbial community structure to ecosystem function, the overall goal of this proposal. In this proposal, researchers at Villanova University seek to integrate quantitative biogeochemical approaches, quantitative molecular ecological approaches, and education and training of students in striving to understand how microbial community structure related to carbon cycling at the process level in peatlands that appear to be responding to global change on two separate continents. They will collect intact 1-m long peat cores from the discontinuous permafrost areas of both continental western Canada and central Siberia, the latter with the technical and logistical assistance of colleagues at the Siberian Research Institute of Peat. At 10-cm depth intervals in each core, they will quantitatively evaluate various aspects of ecosystem function including CO2 and CH4 production potentials, activities of process-specific soil enzymes (phenol oxidase, chitinase, acid phosphatase, arylsulfatase), concentrations of low molecular weight dissolved organic anions (acetate, lactate, proprionate, formate, pyruvate, oxalate and tartrate), and bacterial and fungal biomass (using muramic acid and ergosterol assays). In addition, they will use total peat genomic DNA extractions, PCR amplification, plasmid cloning and sequence analysis to identify specific Archaeal, eubacterial and fungal "species" in each peat sample. Using this approach, the investigators expect to be able to link microbial community structure to peatland ecosystem function in peatland regions where permafrost is actively melting, possibly representing a harbinger of climate change.