Emily Cervenka MSc Candidate, diCenzo Lab Electrifying the Green Economy: Microbial Manufacture of PHB Bioplastic from CO2-derived Formate Reducing global carbon expenditure requires a dedication to innovation and problem-solving at every level, including a rapid divestment from fossil-based fuels and materials. Fossil carbon-based chemical feedstocks, whose production accounts for 14% of all oil and 8% of all gas demand worldwide, can thus be replaced by carbon-sequestering alternatives that are microbially converted into value-added products. In this work, we aimed to develop such an electro-biohybrid system for the conversion of CO2 to the fully compostable bioplastic, polyhydroxybutyrate (PHB). This system involves the electrochemical reduction of CO2 to formate, which would serve as a feedstock for a PHB-producing microbe. For the microbe, we chose Sinorhizobium meliloti due to its natural ability to grow on a wide range of carbon substrates including formate, its genetic tractability, and its ability to naturally synthesize valuable bioproducts such as PHB. Initial tests revealed that although S. meliloti can use formate as a carbon source, formate concentrations above 20 mM are toxic and inhibit the growth of S. meliloti. There was no significant difference in the growth of S. meliloti when provided 20 mM of commercially available formate compared to electrochemically generated formate, confirming that the electrochemical process did not generate toxic byproducts that would inhibit growth. In ongoing work, we are testing whether S. meliloti accumulates PHB during growth with formate as the sole carbon source. In an effort to increase PHB yield, we are using a S. meliloti mutant lacking the PHB depolymerase gene, which was observed to accumulate more PHB than the wild type in both nitrogen-limiting and nitrogen-excess conditions. Overall, this work contributes to the development of a CO2-to-bioproduct pipeline that might one day displace fossil carbon and transform the petrochemical industry from a carbon-intensive to a carbon neutral operation.
Comments are closed.
|
Categories
All
Archives
April 2024
|