Toward Sustainability: Intensification of Light-Driven Whole Cell Biocatalysis

Photobiocatalysis with photoautotrophic whole cells has demonstrated strong potential for producing chiral molecules and platform chemicals using sustainable inputs such as light, water and CO₂ under mild reaction conditions. Coupling enzymatic transformations directly to natural photosynthesis enables higher atom efficiency compared with heterotrophic systems. However, large-scale application remains challenging, particularly due to light attenuation in photobioreactors. In this review, we summarize recent advances in whole-cell photobiotransformations with emphasis on process conditions. We also discuss strategies for intensifying photobiocatalysis through improved reactor design and new immobilization materials, along with developments in fast-growing photoautotrophic strains. Sustainability analyses indicate that organic electron donors represent only one factor influencing environmental performance, and simply replacing them with photosynthetic water splitting does not inherently yield a carbon-negative process. Nonetheless, our calculations show that when high substrate loadings are combined with wastewater use and optimized downstream processing, photosynthesis-driven biotechnology can offer substantial reductions in CO₂ emissions.