Living Hydrogel Bioreactors With Liquid Cavities Stabilize Microbial Consortia for Sustainable Algal Lipid Biomanufacturing

Compartmentalized microbes and microbial consortia enable sustainable biomanufacturing, but the stability of these systems is frequently compromised by growth-rate mismatches and inhibitory metabolites. Here, we present living hydrogel bioreactors with liquid cavities that confine bacteria while permitting metabolite exchange with algae, thereby mitigating deleterious interactions and supporting lipid biosynthesis. A carbonate-bicarbonate buffer further stabilizes the culture environment. In a co-culture of Lactiplantibacillus plantarum and Chlorella vulgaris, hydrogel confinement alone improves algal viability and lipid yield, while further regulation with buffering increases lipid accumulation by over threefold relative to free co-culture. Integration into a continuous-flow photobioreactor sustains long-term symbiosis, maintains near-neutral pH, and achieves robust lipid productivity over extended operation. These results establish living hydrogel bioreactors as a platform for engineering stable, programmable microbial consortia in sustainable algal lipid biomanufacturing.