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Light-driven Enzymatic Decarboxylation
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Light-Driven Photobiocatalytic Oxyfunctionalization in a Continuous Reactor System without External Oxygen Supply
Lenny Malihan-Yap1, Qian Liang1, Alessia Valotta2
1Institute of Molecular Biotechnology, Graz University of Technology, Petersgasse 14, 8010 Graz, Austria.
ACS Sustainable Chemistry & Engineering
|March 21, 2025
Summary
Cyanobacteria engineered with a Baeyer-Villiger Monooxygenase produce oxygen internally, overcoming limitations in continuous chemical oxidation. This photosynthetic oxygen generation enables efficient production of ε-caprolactone, a polymer precursor, under mild conditions.
Area of Science:
- Biocatalysis and metabolic engineering
- Sustainable chemical synthesis
- Photosynthetic oxygen production
Background:
- Oxygenases are valuable biocatalysts for C-H oxyfunctionalization but face challenges with oxygen supply in continuous systems.
- Transporting oxygen across gas-liquid interfaces requires high pressure or specialized materials, hindering scalability.
- Existing methods often suffer from oxygen-limitation, impacting volumetric productivity and efficiency.
Purpose of the Study:
- To develop a novel method for oxygen supply in biocatalytic oxidations using photosynthetic oxygen production.
- To engineer cyanobacteria to express a Baeyer-Villiger Monooxygenase for the synthesis of ε-caprolactone.
- To evaluate the efficiency of this system in both batch and continuous flow reactors.
Main Methods:
- Engineered the cyanobacterium *Synechocystis* sp. PCC 6803 to express a Baeyer-Villiger Monooxygenase from *Burkholderia xenovorans*.
- Utilized whole-cell cyanobacterial biocatalysts for the oxidation of cyclohexanone to ε-caprolactone.
- Performed reactions in batch and continuous coil reactors with controlled oxygen supply.
Main Results:
- Engineered cyanobacteria successfully produced ε-caprolactone using internally generated photosynthetic oxygen.
- Continuous flow systems with cyanobacterial biocatalysts achieved high volumetric productivity (3 mmol L-1 h-1) even under oxygen limitation.
- A 7-fold improvement in space-time yield was observed in the continuous coil reactor compared to batch mode.
Conclusions:
- Photoautotrophic production systems using engineered cyanobacteria overcome oxygen supply limitations for biocatalytic oxyfunctionalization.
- This combined approach of flow catalysis and photosynthetic oxygen production enables more sustainable chemical synthesis.
- The cyanobacterial whole-cell system demonstrates improved waste-to-product ratios and atom economy compared to traditional methods.
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