HR: 09:30h
AN: B51D-07 INVITED    [Abstracts]
TI: Tracing The Fate Of Methane-Derived Carbon: Insights Into The Ecological Physiology Of Anaerobic Methanotrophy Via Quantitative Molecular and Geochemical Approaches
AU: * Girguis, P R
EM: pgirguis@oeb.harvard.edu
AF: Harvard University, 16 Divinity Avenue rm 3085, Cambridge, MA 02138, United States
AU: Nyholm, S V
EM: snyholm@oeb.harvard.edu
AF: Harvard University, 16 Divinity Avenue rm 3085, Cambridge, MA 02138, United States
AU: DeLong, E F
AF: Massachusetts Institute of Technology, 15 Vassar Street, Cambridge, MA 02139, United States
AB: The consumption of methane in anoxic marine sediments is a biogeochemical phenomenon mediated by archaea in varying associations with sulfate-reducing bacteria. These anaerobic methanotrophs have yet to be recovered in pure culture and consequently key aspects of their ecology and physiology remain poorly understood. To study the ecological physiology of anaerobic methanotrophy, we developed a high-pressure continuous flow bioreactor to maintain (and when desired, enrich) these communities in conditions that are representative of those in situ. The high pressure bioreactor incorporates a high-pressure membrane inlet mass spectrometer, as well as a porewater and sediment subsampling system, to allow real time isotopic tracer studies, rate measurements as well as frequent subsampling for molecular biological studies. In the experiments presented here, we examined the influence of pressure and key metabolite concentrations on the rates of anaerobic methanotrophy and methanogenesis by anaerobic methanotrophs, and coupled rate measurements to quantitative biological metrics, e.g. growth rates and yields via qPCR and cell sorting. Our data suggest that rates of archaeal methanotrophy and methanogenesis –as well as population growth rate and yield - are strongly influenced by key chemical factors in the geochemical milieu, and this in turn significantly governs the fate of methane-derived carbon in marine ecosystems.
DE: 0330 Geochemical cycles (1030)
DE: 0408 Benthic processes (4804)
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0460 Marine systems (4800)
DE: 0465 Microbiology: ecology, physiology and genomics (4840)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting