Production of Potential Substitutes for Conventional Plastics Using Metabolically Engineered Acetobacterium woodii

Increasing greenhouse gas emissions and decreasing fossil fuel supplies necessitate the development of alternative methods for producing petroleum-based commodities. Plastics are also primarily petroleum-based goods with rising demand, thus there is growing interest in plastic substitutes. Polyhydroxyalkanoates (PHAs) are naturally produced biopolymers that are utilized by microorganisms as a source of energy and carbon storage. Poly-3-hydroxybutyrate (PHB) is a member of the PHA family and is considered the most promising candidate to replace polyethylene (PE). PHB is naturally produced by Cupriavidus necator, but recombinant production has also been recently established. This study is the first to investigate the heterologous production of PHB with recombinant Acetobacterium woodii using CO2 + H2 as a carbon and energy source. The introduction of a synthetic PHB production pathway resulted in the production of 1.23 g/L CDW and 1.9% PHB/cell dry weight (CDW), which corresponds to a production of 23.5 mg/L PHB. PHB quantification was simplified using LipidGreen2 fluorescence measurements.