Photosynthetic microorganisms, such as cyanobacteria and microalgae play a key role in the ecosystem while also holding great economic potential for a sustainable future. These organisms offer diverse applications, ranging from human and animal consumption to wastewater treatment, and serving as platforms for photosynthetic production of fuels and chemicals. By combining synthetic biology, and metabolic engineering, a wide array of chemicals can be synthesised by these microorganisms, taking advantage of photosynthesis. Through photosynthesis, these microbes convert sunlight and atmospheric carbon dioxide into biomass and/or various chemicals. Immobilising photosynthetic microorganisms in environmentally friendly and biodegradable polymer matrices can transfer the production into a solid-state (hydrogel) system. Immobilised systems emerge as an effective strategy for enhancing production, simplifying operation, and facilitating upscaling.
Key findings include the enhanced production yields of sucrose and ethylene by engineered cyanobacterial Synechocystis sp. PCC 6803 strains. Furthermore, Synechocystis produced sucrose drives the biotransformation of cyclohexanone to ε-caprolactone in an engineered Escherichia coli. The expression of a Baeyer-Villiger monooxygenase in the eukaryotic green alga Chlamydomonas reinhardtii is explored as an alternative with photosynthetic co-factor regeneration and O2 production. The biotransformation is further optimised by the improvement of the strain and coupled with photosynthetic hydrogen production in a stepwise manner. By employing 3D-printing and a photocurable bioink composed of cells, alginate, galactoglucomannan-methacrylate and a photoinitiator, I demonstrate its compatibility with both prokaryotic and eukaryotic photosynthetic microorganisms and ethylene production and biotransformation. The 3D-printed films demonstrate improved stability and present the possibility of creating complex architectures.
The outcomes of this research underscore the versatility of photosynthetic microorganisms for applications in different solid-state chemical production systems. These findings open novel avenues for the utilisation engineered photosynthetic living materials, contributing to the advancement of a more sustainable chemical industry.