Bioremediation of Petroleum-Based Contaminants by Alkane-Degrading Bacterium Alcanivorax borkumensis

The world’s dependence on petroleum hydrocarbons has led to significant environmental implications. For example, oil spills cause lasting environmental damage, and the increase of plastics in the marine environment has been growing, specifically, microplastics that can be difficult to detect due to their small size. Petroleum hydrocarbons occur naturally in nearly all marine environments, which has allowed hundreds of microorganisms to evolve to utilize these hydrocarbons as their primary energy source. These microbes are classified as hydrocarbonoclastic and are utilized to remove spilled oil biodegradation. Over the last ten years, progress has been made in the biodegradation of oil spills by introducing nanoparticles to facilitate the proliferation of these hydrocarbonoclastic species near the oil-water interface. There is an immediate need to understand the interaction between hydrocarbonoclastic bacteria and nanomaterials. Understanding how nanoparticles may enhance the bioremediation of oil spills is vital. We call this new field nano-enhanced bioremediation. Increasing the understanding of how nanoparticles enhance bioremediation will lead to major advancements in nano-enhanced bioremediation as a sustainable alternative to traditional oil spill cleanup methods. Furthermore, the interaction of nanomaterials and bacteria lays the groundwork for understanding the interaction of micro-and nanoplastics and bacteria, where research is currently lacking. During this course of study, we used the model hydrocarbonoclastic bacterium Alcanivorax borkumensis grown in the presence of nanoparticles from multiple precursors. The nanoparticles were coated with a cationic polymer to increase the electrostatic attraction between the bacteria and the nanoparticles. A. borkumensis was also grown with microplastics to understand the interaction between hydrocarbon-degrading bacteria and microplastics. Polyethylene microspheres' physical and thermal properties were used to provide evidence of microplastic biodegradation. Lastly, this project aimed to increase understanding of how biofilm formation influences the fate of microplastics. We developed a method to monitor the formation of biofilms on microplastics on the surface. This method provided evidence that biofilm formation may not influence the transport of microplastics as current literature suggests. The findings in this dissertation are vital to the future of the bioremediation of petroleum-based hydrocarbons in the aquatic environment.