Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2007. / Sotira Yiacoumi, Committee Member ; Patricia Sobecky, Committee Member ; Ching-Hua Huang, Committee Member ; Dr. Spyros Pavlostathis, Committee Chair ; Frank Loeffler, Committee Member.

Magister Scientiae - MSc / Wetlands account for approximately 20% of annual global methane emissions. Many wetlands receive inputs of organic matter, nutrients, metals and various toxic compounds from adjacent agricultural and industrial areas. The present study aimed to investigate the microbial composition of a natural methanogenic consortium. A consortium-based molecular approach to study diversity of methanogenic microbial communities in a natural wetland at the primary inflow was used. Key microorganisms of a nethane producing consortium were identified. Extracted high molecular mss DNA ws analysed by PCR combined with denaturing gradient gel electrophoresis and subsequent sequencing of 16S rDNA. This study was also aimed to identify syntrophic microorganisms in the wetland system. The data obtained suggest a well established syntrophic relationship within the wetland. / South Africa

No description available.

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 171-191).

No description available.

Thesis (Ph. D.)--Oregon Graduate Institute of Science and Technology, 1996.

The need to develop a renewable, environmentally friendly source of energy has become a primary focus in modern science, with bio gas showing considerable potential. Interest in the methanogenic Archaea has therefore grown in recent years and extensive studies have been carried out to investigate the population diversity in various habitats. Presently, there are only a few studies that have evaluated the microbial communities inhabiting the gastrointestinal tract of wildlife native to southern Africa. This study aimed to investigate the microbial diversity, in particular the bacterial and methanogen communities involved in fermentative digestion in the gastrointestinal tract of zebra. Assessment of the microbial diversity in zebra faeces included both culture-based techniques and nucleic acid targeting analysis via 16S rRNA gene sequencing. Quantitative analysis using selected solid media revealed high counts for aerobic and anaerobic Bacteria (7.51x108 and 2.45x109/gram of faecal sample respectively). The majority of aerobic colonies that were detected exhibited Bacillus-like morphology. Nucleic acid based analysis of the diversity of both Bacteria and methanogenic Archaea in zebra faecal material was performed. Both manual and kit based extractions were used for DNA isolation in order to compare the efficiency of the two methods. Results show that a vigorous mechanical treatment was best for the release of DNA from the faecal matter. Amplification of target gene regions was carried out using established primer pairs (ARCH69F/ARCH915R and EUB338F/EUB907R) for methanogen and bacterial DNA respectively. Amplified 16S rRNA gene regions were cloned into a high copy number vector and random clones were selected for evaluation. Clones containing the target gene were further analysed by ARDRA and were assigned to a specific phylotype. Two bacterial (105 clones in total) and three methanogen (178 clones in total) clone libraries were constructed, of which 24 phylotypes were established for Bacteria and 25 for methanogenic Archaea. A representative of each phylotype was analysed by sequencing and further phylogenetic analysis was conducted. Six bacterial phylotypes, which represented 56% of all bacterial clones, exhibited 99% sequence similarity to Bacillus species. Six methanogen phylotypes, which exhibited 99% sequence similarity to the hydrogenotrophic species Methanobrevibacter gottschalkii strain PG, were established to be predominant in zebra faeces. These phylotypes represented 71% of all archaeal clones selected for analysis in this study. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.

Thesis (Ph.D.)--University of Alberta, 2009. / Title from PDF file main screen (viewed on Feb. 19, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Geotechnical Engineering, [Department of] Civil and Environmental Engineering, University of Alberta. Includes bibliographical references.

Methanogenesis was studied in soils from two sawgrass wetlands of the Florida Everglades. Marl soils exhibited a significantly higher potential rate of methanogenesis than peat soils. In these wetlands, methanogenesis: (1) decreased rapidly with increasing soil depth, (2) increased at higher temperatures and lower Eh, (3) was stimulated by organic compounds (cellulose, glucose and acetate), and (4) remained unaffected by added ammonium. Lowering the Eh in the peat and marl soils with sulfide or sulfate stimulated methanogenesis. In January 1990, phosphate caused a significant increase in methanogenesis. The potential rates of methanogenesis decreased to undetectable levels when water levels dropped below the surface, and peaked one month after the start of the wet season. Methanogenesis appeared to be a relatively important process in carbon cycling in marl soils and these soils do not accumulate peat. Therefore, one possible explanation for peat accumulation in sawgrass wetlands may be their low rates of methanogenesis.

The cell extract protein content of acetate- and methanol-grown Methanosarcina thermophila was examined by two-dimensional polyacrylamide gel electrophoresis to determine the extent of regulation by the growth substrate. More than 100 mutually-exclusive spots were present in acetate- and methanol-grown cells suggesting a high degree of regulation. Spots corresponding to acetate kinase, phosphotransacetylase, and the five subunits of the nickel-containing carbon monoxide dehydrogenase (CODH) complex were identified in acetate-grown cells. The nickel-containing methyl coenzyme M methylreductase from acetate-grown M. thermophila was purified 16-fold from a cell extract to apparent homogeneity. The enzyme had a native molecular weight of between 132,000 and 141,000 and contained three subunits with a configuration of a1B1y1-. The as-isolated enzyme was inactive, but could be reductively reactivated by either titanium (III) citrate or reduced ferredoxin. Reactivation with ferredoxin was a simplification over previously reported reactivation systems. ATP stimulated, but was not required for reactivation. The CO dehydrogenase enzyme complex from M. thermophila was purified and separated into its respective components: the CO-oxidizing nickel/iron-sulfur (Ni/Fe-S) component and the cobalt-containing corrinoid/iron sulfur (Co/Fe-S) component. EPR spectroscopy and spectroelectrochemical titration of the Fe-S centers of the Ni/Fe-S component indicated the presence of two low-potential [4Fe-4S]2+/1+ centers and third high-potential center whose Fe-S configuration is unknown. When reduced with CO, the NilFe-S component exhibited a previously unobserved Ni-Fe-C EPR signal. The Co/Fe-S component contained one [4Fe-4S]2+/1+ cluster, and the as-isolated corrinoid in the component was in the base-off conformation suggesting that modulation of the electron density of the cobalt ion may result in a modified reactivity of the active site of the corrin. The CODH enzyme complex and isolated Co/Fe-S component reductively dechlorinated trichloroethylene to cis-dichloroethylene, trans-dichloroethylene, 1,1-dichloroethylene, vinyl chloride, and ethylene. Factor III also catalyzed the dechlorination of trichloroethylene when in the presence of titanium (III) citrate. Reconstitution of the Co/Fe-S component with the CO-reduced NilFe-S component also allowed dechlorination demonstrating an electron transfer from the reduced Ni/Fe-S component to the Co/Fe-S component. / Ph. D.