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

点击翻译按钮获取中文摘要

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.