Characterizing Outer Membrane Vesicles in the Methanotroph Methylomicrobium album BG8

  • Author / Creator
    Hermary, Mariah K.
  • Outer membrane vesicles (OMVs) are extracellular vesicles released from the outer leaflet of the membrane of Gram-negative bacteria. These membrane-derived vesicles are found in numerous different phyla of Gram-negative bacteria. OMV functions are as diverse as the bacteria that produce them, from exporting cellular debris to nutrient acquisition to interspecies and intraspecies communication and more. Although OMVs are incredibly common, there has yet to be a universal mechanism described for OMV production in Gram-negative bacteria.
    Methanotrophs are a specialized group of microorganisms that derive their biomass and bioenergetics from single carbon sources, such as methane and methanol. Methanotrophs are major global methane cycle regulators as the only biological methane sink. In addition, methanotrophs have significant potential for converting the greenhouse gas methane into value-added industrial products.
    In this study, Methylomicrobium album BG8 is the first methanotrophic bacterium documented to produce OMVs. Of the screened methanotrophs, M. album BG8 is the only bacterium to produce these extracellular structures. OMV presence has been maintained under various growth conditions. These vesicles were harvested and purified away from the bacterial biomass. The purified OMVs were sequenced to determine the protein cargo content. From the proteome, OMVs have a putative function for calcium and iron acquisition response for M. album BG8. The Type I secretion system is also predicted to be partially responsible for protein cargo selection in M. album BG8.
    In addition, a mutant strain of M. album BG8 that does not produce OMVs regardless of the media conditions is documented. A list of potential gene candidates is generated based on the
    differences in genome and transcriptome between the wild-type parental and mutant strains.
    These genes are hypothesized to be associated with OMV generation.
    Together, the results of this research will provide necessary insight into the physiology of
    these unknown subcellular structures in M. album BG8. Future research has the potential for
    researchers to genetically modify other industrial methanotrophs strains to allow for OMV
    biogenesis. This data will improve the industrialization of this strain as OMVs can be utilized as
    an extraction mechanism for value-added products, advancing efforts in the carbon capture and
    biomass conversion field.

  • Subjects / Keywords
  • Graduation date
    Fall 2022
  • Type of Item
  • Degree
    Master of Science
  • 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.