Anaerobic Benzene Degradation in Albertan Sediments

• Author / Creator

  Lee, Korris

• ABSTRACT
  Benzene is a priority contaminant that is commonly coincident with fossil fuel entities, whether
  natural or anthropogenic, and is characterized by high mobility and toxicity. In Alberta, Canada,
  where oil and gas production comprises much of the provincial industrial output, benzene
  contamination presents an omnipresent environmental risk to health and safety, necessitating
  economical methods that can minimize such threats. In this study, bioremediation is
  investigated as a benzene removal option for contaminated sites. Bioremediation can involve
  the use of microorganisms to metabolize benzene, and typically requires either the potentiation
  of available microbes (i.e. biostimulation) or the introduction of external microbes (i.e.
  bioaugmentation) in situ. Remediators can benefit greatly in using indigenous cultures that have
  been developed to maximize degradative capabilities and minimize time burden. This project,
  therefore, is focused on the generation of anaerobic benzene degrading cultures (under
  methanogenic, sulfate-reducing, iron-reducing, and nitrate-reducing conditions) derived from
  indigenous Albertan sediments and analysis of their community properties and primary degrader
  populations, while investigating different strategies to enhance their metabolic performance.
  These include the implementation of iron-dissolution protocols with external chelators such as
  acetohydroxamic acid and oxalic acid to expand ferric iron pools, and the addition of conductive
  magnetite at nano and micrometer scales to enhance the conductivity of microbial morphologies
  that can ease the transfer of electrons for metabolism. Lastly, an attempt was made to produce
  the putative benzene carboxylase AbcDA in vitro and subvert the difficulties of culture creation
  and maintenance entirely.
  The research in this thesis demonstrated robust degradation of benzene in cultures sourced
  from Albertan sediments in a multitude of redox conditions, including nitrate-reducing, ironreducing,
  sulfate-reducing, and methanogenic contexts, with iron and nitrate-reducers exhibiting
  the highest levels of benzene degradation (11-12 uM/d). Primary benzene degraders were
  iii
  identified in nitrate-reducing and iron-reducing cultures, namely Peptococcaceae and
  Geobacter, respectively. Geobacter metallireducens was also identified at a species taxonomic
  level in iron-reducing cultures. While the isolation of Geobacter from iron-reducing cultures was
  unsuccessful, and putative benzene hydroxylases gmet 0231-0232 were not found within these
  consortia, the potential of certain chelator combinations such as acetohydroxamic acid (aHA)
  and oxalic acid in enhancing the benzene degrading performance of iron-reducing cultures was
  demonstrated, although their specific functions within these cultures could not be elucidated.

• Subjects / Keywords

  • Benzene

• Graduation date

  Fall 2022

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-4f16-wn63

• License

  This thesis is made available by the University of Alberta Library with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.