Examining Protein Cargo and the Potential Physiological Mechanisms of Outer Membrane Vesicles (OMVs) in Methanotrophic Bacteria

The potent Greenhouse Gas methane is emitted by various anthropogenic processes, such as agriculture and fossil fuel use. Although methane has a global warming potential ~30 times greater than carbon dioxide, the presence of methane is beneficial to a subset of microorganisms. Methane-oxidizing bacteria, or methanotrophs, utilize methane as a carbon and energy source yet can be exploited for their ability to synthesize value-added products, such as biofuels and bioplastics. For the first time documented, Outer Membrane Vesicles (OMVs) production has been identified in the methanotroph Methylomicrobium album BG8. These membrane-enclosed structures can transport biological cargo outside of the bacterium. Manipulating this export mechanism has the potential to forward the industrialization of value-added products as a natural alternative to harsh chemical extractions. In addition, OMVs provide insights for specific physiology requirement for the bacterium. The research question proposed consists of three parts; purifying OMVs from the bacterial host, defining the biological contents of the OMVs, and determining the genetic mechanism behind OMV production for future bioproduct extraction. Purified OMVs were isolated from host cells and underwent mass spectrometry to determine the protein cargo content. Protein hits were referenced to genomics and transcriptomics data sets to elucidate the physiological mechanism in producing OMVs and the cargo selection mechanism. Candidate genes will be cloned into an M. album BG8 mutant containing an OMV-absent phenotype in an attempt to recover OMV production.