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

北极和亚北极泥炭地生态系统仅覆盖地球陆地表面的3- 4%（346-500 Mha），但它们以不完全腐烂的有机物或泥炭的形式储存了世界土壤碳的约1/3。大部分的这些泥炭地（CA。3.84亿公顷）分布在俄罗斯、波罗的海共和国、芬兰斯堪的纳维亚、阿拉斯加和加拿大。 在全球碳循环方面，泥炭地代表了一个主要的碳库，但目前还不清楚它们是作为大气碳的源还是汇，尽管戈勒姆（1991，1994，1995）估计北方泥炭地代表了大气CO2的净汇（76 Tg C yr-1）和大气CH 4的净源（46 Tg C yr-1）仍然被广泛引用。尽管泥炭微生物种群作为好氧和厌氧分解介质（包括CO2和CH 4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和C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（微生物、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整合定量生物地球化学方法，定量分子生态学方法以及学生的教育和培训，以努力了解微生物群落结构如何与泥炭地过程水平的碳循环相关，这些泥炭地似乎正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米长的泥炭芯，后者在西伯利亚泥炭研究所同事的技术和后勤援助下进行。在每个核心的10厘米深的间隔，他们将定量评估生态系统功能的各个方面，包括CO2和CH 4的生产潜力，特定过程的土壤酶的活性（酚氧化酶、几丁质酶、酸性磷酸酶、芳基硫酸酯酶）、低分子量溶解有机阴离子的浓度（乙酸盐、乳酸盐、丙酸盐、甲酸盐、丙酮酸盐、草酸盐和酒石酸盐）以及细菌和真菌生物质（使用胞壁酸和麦角固醇测定）。此外，他们将使用总泥炭基因组DNA提取，PCR扩增，质粒克隆和序列分析，以确定特定的微生物，真细菌和真菌“物种”在每个泥炭样本。使用这种方法，研究人员希望能够将微生物群落结构与泥炭地生态系统功能联系起来，在泥炭地地区，永久冻土正在积极融化，这可能是气候变化的预兆。

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.