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.