Engineered microbial hydrogels with confined architecture and binary microbes for efficient hydrogen production.

Renewable energy sources, particularly hydrogen, offer a promising solution to address global energy crisis and carbon emissions. Microalgae-driven hydrogen production has attracted immense interest in both scientific and industrial fields. However, challenges such as high oxygen sensitivity, substantial water demand, and low hydrogen production efficiency limit their potential. Here, we develop a core-shell symbiotic hydrogel system for enhanced hydrogen production via leveraging coaxial 3D bioprinting to spatially separate microalgae (i.e., core component) and bacteria (i.e., shell component). These networks optimize light and nutrient utilization while providing a localized anaerobic microenvironment to facilitate hydrogen production from microalgal photosynthesis. The symbiotic system enables a high hydrogen yield (1763 ± 98 mL L-1). The system not only provides a highly efficient, liquid-free strategy for biohydrogen generation, but also advances the understanding of symbiotic relationships and microorganism-material interactions for creating advanced living material systems.