Browsing by Author "Berdugo-Clavijo, Carolina"

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    High temperature utilization of PAM and HPAM by microbial communities enriched from oilfield produced water and activated sludge
    (2019-04-09) Berdugo-Clavijo, Carolina; Sen, Arindom; Seyyedi, Mojtaba; Quintero, Harvey; O’Neil, Bill; Gieg, Lisa M
    Abstract Non-hydrolyzed polyacrylamide (PAM) and partially hydrolyzed polyacrylamide (HPAM) are commonly used polymers in various industrial applications, including in oil and gas production operations. Understanding the microbial utilization of such polymers can contribute to improved recovery processes and help to develop technologies for polymer remediation. Microbial communities enriched from oilfield produced water (PW) and activated sludge from Alberta, Canada were assessed for their ability to utilize PAM and HPAM as nitrogen and carbon sources at 50 °C. Microbial growth was determined by measuring CO2 production, and viscosity changes and amide concentrations were used to determine microbial utilization of the polymers. The highest CO2 production was observed in incubations wherein HPAM was added as a nitrogen source for sludge-derived enrichments. Our results showed that partial deamination of PAM and HPAM occurred in both PW and sludge microbial cultures after 34 days of incubation. Whereas viscosity changes were not observed in cultures when HPAM or PAM was provided as the only carbon source, sludge enrichment cultures amended with HPAM and glucose showed significant decreases in viscosity. 16S rRNA gene sequencing analysis indicated that microbial members from the family Xanthomonadaceae were enriched in both PW and sludge cultures amended with HPAM or PAM as a nitrogen source, suggesting the importance of this microbial taxon in the bio-utilization of these polymers. Overall, our results demonstrate that PAM and HPAM can serve as nitrogen sources for microbial communities under the thermophilic conditions commonly found in environments such as oil and gas reservoirs.
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    Methanogenic biodegradation of crude oil and polycyclic aromatic hydrocarbons
    (2015-01-29) Berdugo-Clavijo, Carolina; Gieg, Lisa
    The methanogenic biodegradation of crude oil is an important process occurring in many subsurface hydrocarbon-associated environments, but little is known about this metabolism in such environments. In this thesis work, the methanogenic biodegradation of crude oil and polycyclic aromatic hydrocarbons (PAH) was investigated. Methanogenic cultures able to metabolize light and heavy crude oil components were enriched from oilfield produced waters. Metabolites (e.g., alkylsuccinates) and genes (e.g. assA and bssA) associated with a fumarate addition mechanism were detected in the light oil-amended culture. A Smithella sp. dominated the community, suggesting this organism was involved in the degradation of the hydrocarbon components. In experiments conducted in sandstone-packed column systems simulating marginal oil fields, the light oil-amended culture was shown to bioconvert alkanes and aromatic hydrocarbons to CH4. Other oil-associated microbial inocula also enhanced CH4 production from oil in the column systems. Shifts in the microbial communities were observed after the inocula were incubated in the columns. Methanogenic hydrocarbon metabolism was also investigated using new enrichment cultures that biodegraded 2-ringed PAHs under methanogenic conditions. Metabolite and marker gene analyses were conducted on these cultures to investigate the mechanism(s) involved in PAH metabolism. The PAH-utilizing enrichments were dominated by methanogens closely affiliating with Methanosaeta and Methanoculleus, and bacterial members most closely related to the Clostridiaceae family. Further qPCR analysis with a 2-methylnaphthalene-amended culture suggested that Clostridium was the main hydrocarbon degrader in the enrichment. The results of these studies have added new knowledge to the field of methanogenic hydrocarbon biodegradation that may find application in bioremediation or microbial enhanced energy recovery.