Microbial production of biodegradable polymers using toxic compounds and CO₂

The integration of harmful-substance biodegradation with the synthesis of value-added biopolymers such as polyhydroxyalkanoates (PHA) offers a promising strategy to reduce production costs and address environmental challenges. As interest grows in CO₂ capture, storage, and utilization, captured CO₂ is increasingly recognized as an economical carbon source for producing biocompatible plastics. In this study, Cupriavidus sp. CY-1 was investigated for its ability to degrade trichloroethene (TCE) and cis-1,2-dichloroethene (cDCE) while simultaneously producing biodegradable polymers. CY-1 showed robust growth when supplied with TCE and co-substrates such as phenol or Tween 80, achieving a maximum cell dry mass of 0.68 g L⁻¹. The highest poly-β-hydroxybutyrate (PHB) accumulation, 350 mg g⁻¹ CDM, was observed with cDCE, phenol, and Tween 80. The strain degraded up to 100 mg L⁻¹ TCE. To further enhance detoxification efficiency, an electrochemical dehalogenation approach is being developed to reduce the toxicity of chlorinated compounds under mild, environmentally benign conditions. To assess PHB production from CO₂, cultures were incubated under various gas mixtures, including H₂/O₂/CO₂ and combinations with N₂ or CO. CY-1 was pre-cultured in nutrient broth, washed, and reinoculated into mineral medium before gas replacement. Under H₂/O₂/CO₂ conditions, the strain achieved a maximum PHB content of 90%, demonstrating effective CO₂ conversion. Although non-combustible gas mixtures yielded lower PHB levels, CY-1 consistently utilized CO₂ as a carbon source. These findings highlight the potential of CY-1 as a dual-function bacterium capable of degrading pollutants and synthesizing CO₂-based bioplastics. Continued development of CO₂-driven PHA production could provide low-cost substrates and contribute meaningfully to global sustainability goals.