Biodegradation of Aromatic Hydrocarbons by Methanogenic Consortia and Groundwater-Associated Microbial Communities
Date
2021-01-08
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Abstract
The biodegradation of hydrocarbons is an important environmental process responsible for in situ remediation of crude oil and gas components. Microorganisms of many lineages and redox conditions have been characterized to degrade numerous types of petroleum hydrocarbons, including those with aromatic structures. Alkyl-substituted mono- and polycyclic aromatic hydrocarbons are more chemically reactive than their unsubstituted counterparts, and as such their anaerobic degradation pathways have been studied to varying degrees. Aromatic hydrocarbons require enzymatic functionalization before biodegradation can occur; these activation enzymes and products are often unique to anaerobic reactions, therefore identifying the metabolites produced or the enzymes carrying out these reactions lends evidence to identifying in situ bioremediation of aromatic hydrocarbon contamination. Hydrocarbon biodegradation in the deep subsurface is often associated with methanogenesis. Anaerobic toluene degradation has been extensively studied and has been shown in multiple studies to involve an activation process known as fumarate addition, however methanogenic biodegradation of other alkylbenzenes and polycyclic aromatic hydrocarbons is comparatively poorly understood. In this work, the biodegradation of ethylbenzene and p-xylene was examined in the presence of toluene; p-toluic acid was found as a metabolite of p-xylene biotransformation, but no evidence of fumarate addition to either p-xylene or ethylbenzene were observed. A second methanogenic biodegradation study of naphthalene, 2-methylnaphthalene, and phenanthrene revealed 2-naphthoic acid as the primary metabolite produced by microbial cultures. A third study involved evaluating the use of a trapping device for passively sampling microorganisms from groundwater contaminated with aromatic hydrocarbons; this study showed that the chosen sorptive material did not influence the biodiversity of microbial communities, did not influence the rate of hydrocarbon biodegradation, and the presence of hydrocarbons was correlated to higher biomass recovery.
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Keywords
environmental microbiology, petroleum microbiology, aromatic hydrocarbons, methanogenesis, hydrocarbon biodegradation
Citation
Taylor, N. (2021). Biodegradation of Aromatic Hydrocarbons by Methanogenic Consortia and Groundwater-Associated Microbial Communities (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.