Syntrophic hydrocarbon metabolism under methanogenic conditions
MetadataShow full item record
AbstractMethanogenic metabolism of organic matter is a key process in both natural and engineered systems. Methanogenic hydrocarbon degradation is an important biogeochemical process in the deep subsurface, and subsurface hydrocarbon contamination is frequently remediated by methanogenic processes. Despite the importance of methanogenic processes in hydrocarbon-impacted systems, we currently have an incomplete understanding of the hydrocarbon activation and degradation pathways used by the syntrophic bacteria, the roles of the non-hydrocarbon degrading syntrophs, which are often present in high abundance, and the ways in which syntrophic bacteria and methanogenic archaea establish and maintain relationships that allow them to coordinate their metabolism. By studying methanogenic hydrocarbon degrading enrichment cultures, we remove many complicating features of natural systems and can gain a basic understanding of the primary factors governing hydrocarbon metabolism under methanogenic conditions. In this dissertation, we describe several methanogenic hydrocarbon degrading enrichment cultures with a major focus on a toluene degrading methanogenic enrichment culture. Methanogenic hydrocarbon degrading communities consist of a diverse assemblage of Archaea and Bacteria dominated by members of the Methanomicrobia, Firmicutes, Deltaproteobacteria, Chloroflexi, Spirochaetes and other bacterial phyla in smaller proportions. Using stable isotope probing, key organisms involved in the degradation of toluene were identified, including Desulfosporosinus sp., which is associated with toluene activation as well as Syntrophus- like organisms and Desulfovibrio sp. Metabolite and metagenomic analysis indicate that fumarate addition is involved in toluene activation in this culture and results from this and other cultures suggest that fumarate addition is a key mechanism involved in the activation of alkanes, monoaromatic and polyaromatic hydrocarbons under methanogenic conditions. Comparative metagenomic analysis suggests that key functional features that distinguish methanogenic hydrocarbon degrading cultures include enrichment of archaeal and bacterial hydrogenases, as well as functions related to the regulation of redox conditions, energy conservation and methanogenesis. Hydrogen and/or formate transfer appears to play a major role in metabolite and electron transfer in these cultures. A better understanding of the processes involved in methanogenic hydrocarbon metabolism may provide us with the knowledge to develop new tools to monitor, control and harness these technologies to the benefit of ourselves and our environment.
CitationFowler, S. J. (2014). Syntrophic hydrocarbon metabolism under methanogenic conditions (Unpublished doctoral thesis). University of Calgary, Calgary, AB. doi:10.11575/PRISM/27962
University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.