Binding-Enhanced Organic Semiconductor-Bacteria Hybrids for Efficient Visible Light-Driven CO2 Conversion to Bioplastics.

Abstract

Photosynthetic semiconductor-biohybrids, which integrate excellent light-harvesting capabilities of semiconductors and high activity and selectivity of biocatalysts, have proven a promising strategy to enable solar-driven CO2 conversion to chemicals. However, broadening the light-harvesting scope and strengthening interfacial contact, which facilitates enhancing solar-to-chemical conversion efficiencies, remain challenging. Herein, we report a series of organic semiconductors (OSCs) to hybridize with nonphotosynthetic bacteria, Ralstonia eutropha, realizing efficient CO2 photoreduction to poly-β-hydroxybutyrate (PHB). The OSCs with extended conjugated backbones absorb light from the entire visible region, while their side chains containing zwitterionic choline phosphate form quadrupoles with phosphatidyl choline on the cell membrane, fortifying interfacial interactions between OSCs and bacteria. Both aspects facilitate the utilization of more photon energy and improve the transmembrane transfer of photogenerated electrons into the cells, strengthening the metabolic pathways in bacteria. Accordingly, an optimal OSC-biohybrid driven by visible light offers continuous production of PHB from CO2 for several days, with a maximum yield of 107.3 mg L-1 OD600-1 and a CO2-to-PHB quantum efficiency of 1.14%. Our strategy not only endows nonphotosynthetic bacteria with photosynthetic capacity but also achieves matchable photoautotrophic PHB output with that from heterotrophic fermentation.