Engineering a chemoenzymatic cascade for sustainable photobiological hydrogen production with green algae

Abstract

Photobiological hydrogen generation is among the most promising routes for the mass production of hydrogen energy. However, the cost and sustainability of photobiological methods largely hamper their large-scale commercial production. Here, we design an anaerobic environment with a constant near-neutral pH for the sustainable induction of green algae flocculation by engineering a robust chemoenzymatic cascade system consisting of glucose, glucose oxidase, catalase, and magnesium hydroxide. We found that Chlamydomonas reinhardtii could stably produce hydrogen in this engineered photobiological system for nearly a month, with an average rate of 0.44 μmol H₂ h⁻¹ (mg chlorophyll)⁻¹. This study thus opens a new avenue to photobiological hydrogen production at industrial scales for promising “liquid sunshine” applications.