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Mixotrophy for carbon-conserving waste upcycling
Michael Weldon1, Christian Euler1
1Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, Canada.
Plos Computational Biology
|August 26, 2025
Summary
Cupriavidus necator can convert waste streams into valuable chemicals. This study shows hydrogen and ethylene glycol can power this process, enabling carbon-neutral or carbon-negative waste upcycling.
Area of Science:
- Biotechnology
- Chemical Engineering
- Environmental Science
Background:
- Modern chemical manufacturing is unsustainable, necessitating alternative production routes.
- Electrochemical and biological processes show promise for upgrading waste streams like CO2 and plastic waste.
- Upcycling waste faces challenges due to heterogeneity and high energy demands.
Purpose of the Study:
- To uncover constraints on carbon-conservative chemical transformation using Cupriavidus necator.
- To systematically examine carbon yield and thermodynamic feasibility of mixotrophic scenarios.
- To evaluate carbon-carbon mixotrophic scenarios for waste upcycling.
Main Methods:
- Systematic examination of carbon yield and thermodynamic feasibility.
- Evaluation of mixotrophic scenarios combining waste-derived carbon sources with hydrogen oxidation.
- Assessment of carbon-carbon mixotrophic scenarios using alternative carbon sources for electron supply.
Main Results:
- Hydrogen and ethylene glycol are feasible electron sources for carbon-neutral or carbon-negative mixotrophic upgrading of acetate or butyrate.
- Carbon conservation is likely infeasible for most other waste-derived carbon sources.
- Identified constraints and feasible pathways for waste upcycling using C. necator.
Conclusions:
- Cupriavidus necator offers a flexible platform for waste valorization.
- Specific electron donors like hydrogen and ethylene glycol enable carbon-efficient waste upcycling.
- This research provides a roadmap for developing C. necator strains for sustainable chemical production.
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