An Outer Membrane Photosensitized Geobacter Sulfurreducens-Cds Biohybrid for Redox Transformation of Cr(Vi) and Tetracycline

Microbe-photocatalyst biohybrids, integrating the high light-harvesting efficiency of photocatalyst with the high catalytic activity of microorganism, have emerged as a promising strategy for the energy and environmental applications. However, few such biohybrids have been tested for complex pollution system. Herein, an outer membrane photosensitized Geobacter sulfurreducens-CdS biohybrid was constructed. Cr(VI) and tetracycline were regarded as target contaminants in combined wastewater to evaluate the redox performance of G. sulfurreducens-CdS biohybrid. Our results revealed that the interface interaction between G. sulfurreducens and CdS under illumination achieved an significantly promotion for simultaneous removal of Cr(VI) and tetracycline compared with bare G. sulfurreducens or CdS. The outer membrane was found to play a significant role in photoelectron transfer. DPV curves demonstrated that CdS enhanced the catalytic activity of C-type cytochromes on outer membrane under irradiation. C-type cytochromes with light-enhanced catalytic activity was responsible for the increase of the photoelectron-hole pairs separation efficiency. The possible degradation pathway of tetracycline was proposed based on determined intermediates, whose toxicities were well evaluated. Importantly, the toxicity of the detected final intermediates was decreased. Overall, this work is devoted to mechanistic study of G. sulfurreducens-CdS biohybrid and provides a reference for purification of combined wastewater by microbe-photocatalyst biohybrids