Browsing by Author "Taylor, Nicole"

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    Biodegradation of Aromatic Hydrocarbons by Methanogenic Consortia and Groundwater-Associated Microbial Communities
    (2021-01-08) Taylor, Nicole; Gieg, Lisa Marie; Hubert, Casey R. J.; Dunfield, Peter F.
    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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    Comparative Evaluation of Coated and Non-Coated Carbon Electrodes in a Microbial Fuel Cell for Treatment of Municipal Sludge
    (MDPI AG, 2019-03-16) Nandy, Arpita; Sharma, Mohita; Venkatesan, Senthil Velan; Taylor, Nicole; Gieg, Lisa; Thangadurai, Venkataraman
    This study aims to provide insight into the cost-effective catalyst on power generation in a microbial fuel cell (MFC) for treatment of municipal sludge. Power production from MFCs with carbon, Fe2O3, and Pt electrodes were compared. The MFC with no coating on carbon generated the least power density (6.72 mW·m?2) while the MFC with Fe2O3-coating on carbon anodes and carbon cathodes generated a 78% higher power output (30.18 mW·m?2). The third MFC with Fe2O3-coated carbon anodes and Pt on carbon as the cathode catalyst generated the highest power density (73.16 mW·m?2) at room temperature. Although the power generated with a conventional Pt catalyst was more than two-fold higher than Fe2O3, this study suggests that Fe2O3 can be investigated further as an efficient, low-cost, and alternative catalyst of Pt, which can be optimized for improving performance of MFCs. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) results demonstrated reduced resistance of MFCs and better charge transfer between biofilm and electrodes containing coated anodes compared to non-coated anodes. Scanning electron microscopy (SEM) was used to analyze biofilm morphology and microbial community analysis was performed using 16S rRNA gene sequencing, which revealed the presence of known anaerobic fermenters and methanogens that may play a key role in energy generation in the MFCs.