Skip to main content

Chad Nielsen

Chad Nielsen

Major Advisor: Charles Miller

Master's Student


Polyhydroxyalkanoates (PHAs) are a type of biodegradable plastics that are produced by a number of microorganisms as a carbon and energy storage molecule when the cells are under stress. They are a promising alternative to synthetic plastics but are currently too expensive for widespread use. The two largest hurdles to economic production are the cost of carbon feedstock and the cost of isolating and purifying PHAs. Using methananotrophic bacteria that can utilize methane gas as their sole carbon source may reduce the cost of carbon feedstock. Indirectly secreting PHAs using phasin proteins that bind to PHAs and HlyA signal peptides to initiate translocation of PHAs across cell membrane may reduce the cost of downstream processing. In this study, the phasin-HlyA secretion approach is applied to the methanotrophic bacteria Methylosinus trichosporium OB3b. Currently, only the preliminary work of culturing Ms. trichosporium OB3b and creating genetic circuits for two phasin proteins (Pha4 and PhaP1) for use in testing the secretion system have been successfully achieved. As such, there is insufficient data to determine whether the system will function at this time.