Browsing by Author "Barnhart, Elliott Paul"

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Analysis of methane producing communities within underground coal beds
(Montana State University - Bozeman, College of Letters & Science, 2011) Barnhart, Elliott Paul; Chairperson, Graduate Committee: Matthew Fields
The Powder River Basin in southeastern Montana and northeast Wyoming is the largest source of coal mined in the United States but most of the coal contained in the basin is buried too deeply to be economically accessible. These remote coal beds are dynamic zones where biogeochemical processes work to sustain a microbial ecosystem. Previous work has shown that a direct byproduct of these microbial processes is biogenic methane that can be harvested and utilized as an energy source. Methane is the principle component of natural gas and this can be used as an energy source for electricity generation, heat and transportation fuel producing only carbon dioxide and water when burned in the presence of oxygen. The only known organisms on the planet able to produce methane are classified as Archaea, microorganisms termed methanogens. However, little is known about the responsible methanogens, the conditions conducive to coal-associated methane production, nor the microbial community interactions that promote methane production. Advances in subsurface sampling and molecular techniques have provided a route to capture active microbial consortia from coal beds, but methods need to be refined in order to deal with the unique attributes of coal. Microorganisms involved in coal bed methane (CBM) formation were investigated by applying molecular methods in combination with cultivation techniques with and without nutrient supplementation to maximize methane production in batch, bench-scale incubations. Our research suggests that Clostridium species are involved with the breakdown of coal and Acetobacterium species are able to utilize substrates produced by the coal degradation. Coal and yeast extract each appear to contribute important nutrients that stimulate coal degrading communities. A better understanding of this microbial system and the biotic and abiotic parameters that control activity may permit microbially enhanced CBM production in situ to become an industrially sustainable process through the application of suitable methane stimulation strategies.
In situ and enhanced coal-bed methane production from the Powder River Basin
(Montana State University - Bozeman, College of Letters & Science, 2014) Barnhart, Elliott Paul; Chairperson, Graduate Committee: Matthew Fields; Kara Bowen De León, Bradley D. Ramsay, Alfred B. Cunningham, and Matthew W. Fields were co-authors of the article, 'Investigation of coal-associated bacterial and archaeal populations from a diffusive microbial sampler (DMS)' in the journal 'International journal of coal geology' which is contained within this thesis.; Bradley D. Ramsay, Kara Bowen De León, Kristen A. Brileya, Denise M. Akob, Richard E. Macur, Alfred B. Cunningham, Matthew W. Fields were co-authors of the article, 'Stimulation of coal-dependent methanogenesis with native microbial consortia from the Powder River Basin' submitted to the journal 'Applied and environmental microbiology' which is contained within this thesis.; Kiki Johnson, Kristopher A. Hunt, Sean Cleveland, Marcella A. McClure, Matthew W. Fields were co-authors of the article, 'Genomic insight into the evolution of the acetate switch in archaea' submitted to the journal 'Nature' which is contained within this thesis.
The majority of the coal in the Powder River Basin (PRB) is located in formations too deep to be economically mined but microorganisms within some of these deep coal seams generate coal-bed methane (CBM) which can be harvested and utilized as an energy source. However, little is known about the in situ microbial community, the environmental conditions conducive to CBM production, or the microbial community interactions that promote CBM production. Several sampling locations within the PRB were identified as methane-producing sites based on geochemical analysis of groundwater. A diffusive microbial sampler (DMS) was utilized for microbial sampling which was loaded with coal and only opened at the bottom of the wells where the coal seam was exposed. Pyrotag analysis of DMS coal identified the predominant in situ bacterial and archaeal populations, providing insight into microbes generating CBM within the PRB. Changes in the composition and structure of microbial communities that occur under stimulated conditions were investigated by applying molecular methods in combination with cultivation techniques (with and without nutrient supplementation) to identify conditions which maximize methane production in batch, bench-scale incubations. Results from these studies indicated the addition of yeast extract resulted in an increase in methane production as well as a shift to a microbial population capable of acetate production and/or acetate utilization. Isolation methods targeting coal utilizing Bacteria and methanogenic Archaea were applied in addition to DNA based methods to infer microbial community members present within coalbeds. The acetoclastic methanogen Methanosarcina was isolated which is the only identified methanogen with the high-efficiency acetate kinase (Ack) / phosphotransacetylase (Pta) methane production pathway. This pathway provides increased growth and methane production when acetate concentrations are high which can result from microbial stimulation with nutrients. Genomic analysis revealed Ack evolved through gene duplication and divergence of acetyl CoA synthetase within the methanogenic genome. This research provided novel insight into the evolution of the high-efficiency Ack/Pta pathway. Collectively, this dissertation presents a novel link between the Ack/Pta pathway, stimulated CBM production and genomic insight into the development of this pathway.