Anaerobic Benzene Degradation in Albertan Sediments

  • Author / Creator
    Lee, Korris
    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
    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
  • Graduation date
    Fall 2022
  • Type of Item
  • Degree
    Doctor of Philosophy
  • DOI
  • 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.