Methane (CH4) is a critical greenhouse gas with ~ 25 times greater global warming potential than carbon dioxide. As the largest natural source of CH4, wetlands have faced a setback in the global warming scenario. Manipulation of wetland hydrology can be a potential management strategy to enhance CH4 consumption (by microbial oxidation) from constructed and managed wetlands. Although work in pure cultures have shown the importance of methane oxidizing bacteria (methanotrophs) in regulating net CH4 flux, few field based studies have been done on the microbial ecology of these CH4 oxidizing communities and how they respond to differing land management systems. For example, there is considerable interest in enabling current wetlands and creating wetlands that have hydrologic pulsing that is driven by seasonal rainfall and watershed dynamics. However, little is known about the ecology of methanotrophs in the “pulsing fringe”—the oxic sediment-water interface of wetlands. The objective of this study was to characterize the functionally active methanotroph communities and link them to potential methane oxidation rates in response to pulsing wetland hydrology and seasonally induced changes in redox conditions. 13C-CH 4 stable isotope probing of biomarker Phospholipid Fatty Acids (PLFAs) was successfully used to track the 13C flow into the methanotroph community. Identification and quantification of methanotrophs was effectively achieved to link bacterial structure and function.
The results show that, in addition to methanotrophy being controlled by environmental factors such as soil water content, oxygen and methane availability, the physiology of the microorganisms themselves can be uniquely adapted to extant conditions and potentially influence process rates. Results from this study demonstrate that seasonally pulsed wetlands have greater diversity of methanotrophs under elevated methane concentrations. In comparison, methane oxidation in the permanently flooded site was solely driven by a specialized group of methanotrophs. This study provides fundamental information for developing pulsing wetlands system that facilitates greater taxonomic diversity of methanotrophs and methanotrophy.
|Advisor:||Dick, Richard P.|
|Commitee:||Dick, Richard P., Dick, Warren A., Lower, Brian H., Mitsch, William J.|
|School:||The Ohio State University|
|School Location:||United States -- Ohio|
|Source:||DAI-B 78/11(E), Dissertation Abstracts International|
|Subjects:||Ecology, Microbiology, Biogeochemistry, Soil sciences, Biochemistry, Environmental science, Geochemistry|
|Keywords:||Methane, Methane oxidation, Methanotrophs, Phospholipid fatty acids, Soil, Wetland hydrology|
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