Light-Driven Hydrogen Production in Genetically Engineered Cadmium Sulfide/ <i>Escherichia coli</i> Biohybrids

Whole-cell-based biohybrids, which integrate the light-harvesting capabilities of semiconductor nanomaterials with the highly efficient biocatalytic conversion of microorganisms, have garnered significant attention for the development of efficient solar energy storage systems. Notably, the use of bioprecipitation of nanomaterials for constructing biohybrid systems is an emerging trend due to its relative ease of preparation. This study presents a biohybrid system for light-driven hydrogen production by combining the improved bioprecipitation of cadmium sulfide (CdS) nanoparticles with the heterologous mass production of hydrogenase in Escherichia coli (CdS/E. coli). Specifically, the bioprecipitation capability was enhanced through heterologous expression of the gene encoding l-cysteine desulfhydrase (CysDSH). Enhanced sulfide formation in E. coli reduced the CdS bioprecipitation time and resulted in smaller CdS nanoparticles with a larger surface area, thereby improving the light-to-chemical energy conversion properties. The CdS/E. coli biohybrid constructed with CysDSH-gene-expressing cells exhibited approximately a 2-fold increase in light-driven hydrogen production, with an apparent quantum yield of 0.45% at 460 nm. This study demonstrates that genetic engineering can modify both semiconductor nanoparticle formation and material conversion in whole-cell-based biohybrids. These findings expand the current knowledge and offer guidelines for constructing biohybrids, providing strategies for enhancing solar-to-chemical energy conversion systems.