A1 Refereed original research article in a scientific journal
Towards high atom economy in whole-cell redox biocatalysis: up-scaling light-driven cyanobacterial ene-reductions in a flat panel photobioreactor
Authors: Grimm, Hanna C.; Erlsbacher, Peter; Medipally, Hitesh; Malihan-Yap, Lenny; Sovic, Lucija; Zöhrer, Johannes; Kosourov, Sergey N.; Allahverdiyeva, Yagut; Paul, Caroline E.; Kourist, Robert
Publisher: ROYAL SOC CHEMISTRY
Publishing place: CAMBRIDGE
Publication year: 2025
Journal: Green Chemistry
Journal name in source: GREEN CHEMISTRY
Journal acronym: GREEN CHEM
Volume: 27
Issue: 11
First page : 2907
Last page: 2920
Number of pages: 14
ISSN: 1463-9262
eISSN: 1463-9270
DOI: https://doi.org/10.1039/d4gc05686h
Web address : https://doi.org/10.1039/D4GC05686H
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/485051172
Light-driven biotransformations in recombinant cyanobacteria benefit from the atom-efficient regeneration of reaction equivalents like NADPH from water and light by oxygenic photosynthesis. The self-shading of photosynthetic cells throughout the reaction volume, along with the need for extended light paths, limits adequate light supply and significantly restricts the potential for upscaling. Here, we present a flat panel photobioreactor (1 cm optical path length) as a scalable system to provide efficient illumination at high cell densities. The genes of five ene-reductases from different classes were expressed in Synechocystis sp. PCC 6803. The strains were characterised in the light-driven reduction of a set of prochiral substrates. With specific activities up to 150 U gCDW-1 under standard conditions in small-scale reactions, the recombinant strains harbouring the ene-reductases TsOYE C25G I67T and OYE3 showed the highest specific activities observed so far in photobiotransformations and were selected for the up-scale in the flat panel photobioreactor in 120 mL-scale. The strain producing OYE3 exhibited a specific activity as high as 56.1 U gCDW-1. The corresponding volumetric productivity of 1 g L-1 h-1 compares favourably to other photosynthesis-driven processes. This setup facilitated the conversion of 50 mM over approximately 8 hours to an isolated yield of 87%. The atom economy of 88% compares favourably to the use of the sacrificial co-substrates glucose and formic acid with 49% and 78%, respectively. Determination of the complete E-Factor of 203 including water reveals that the volumetric yield and water required for cultivation are crucial for the sustainability. In summary, our results point out key factors for the sustainability of light-driven whole-cell biotransformations, and provide a solid basis for future optimisation and up-scale campaigns of photosynthesis-driven bioproduction.
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Funding information in the publication:
This research was funded by the EU FET Open project FuturoLEAF under grant agreement No 899576. R. K. and L. Y. are indebted to the funding by CyanoOxyfunctionalization provided by the Austrian Science Fund (FWF, P 36614-B).
