Immobilization in nanocellulose matrix reallocates cyanobacterial proteome resources from growth to bioproduction

Solid-state photosynthetic cell factories transform dissolved and atmospheric carbon into chemicals and biomass, offering a platform for the sustainable production of industrially relevant compounds. Yet, how immobilisation affects cell physiology to favour biosynthesis over growth is unclear. Here, we fabricate photosynthetic biohybrids of cellulose nanofiber (CNF) and Synechocystis sp. PCC 6803 by osmotic dehydration. Osmotic dehydration resulted in an anisotropic distribution of the cyanobacterial colonies and provided excellent light distribution during cultivation. In an engineered sucrose-secreting Synechocystis strain, quantitative proteomics showed that immobilization downregulates ribosomal proteins while upregulating sucrose-synthesis and carbon concentrating machinery, as well as a stress signature of enhanced photosystem II repair, photoprotection, and ROS detoxification. These changes are consistent with a reallocation of constrained proteome resources from growth toward product synthesis. This principle may be extendable to photosynthetic production of compounds beyond sucrose.