Photosynthetic engineered living materials incorporating recombinant Chlamydomonas reinhardtii enable long-term semi-continuous photobiotransformation

Photosynthetic engineered living materials (ELMs) present an attractive platform for producing valuable compounds and fuels using solar energy. Compared to traditional suspension cultures, ELMs enable long-term biocatalytic activity, more efficient light utilization, and facilitate downstream processing. In this study, we developed photosynthetic ELMs by entrapping Chlamydomonasreinhardtii in either alginate or TEMPO-oxidized cellulose nanofibers (TCNF). The strain utilized was converting cyclohexanone to ε-caprolactone via photobiotransformation. The cell loading and matrix material were evaluated in short-term reactions and during repeated batch cultures. We showed that the entrapped cells remain photosynthetically active and catalytically competent over extended periods. By replenishing the substrate and collecting the product every 24 hours we achieved semi-continuous photobiotransformation for over two weeks, reaching an average productivity of 2.31 ± 0.26 g m-2 d-1 and accumulating 0.31 ± 0.03 mol m-2 of ε-caprolactone. These findings establish photosynthetic ELMs as a viable approach for long-term whole-cell photobiotransformation.