Engineering Microbe-Material Interface to produce Solar Chemicals and Fuels from CO2

In light of the global energy crisis and rapidly increasing carbon footprint in the atmosphere, there’s a high call for solar powered energy solutions, particularly through carbon capture and utilization (CCU) technologies. Photosynthetic biohybrid systems combining light harvesting materials with microbial biocatalysts is a promising approach for sustainable synthesis of chemicals from CO2.1 We demonstrate this through integrating CO2 reducing microbes with earth earth-abundant, non-toxic elements derived semiconductors performing CO2 reduction into chemicals powered by sunlight. In this talk, I’ll be presenting two projects exploring semiconductor-microbe biohybrids for solar chemical technologies.

The first project focuses on developing a photosynthetic biohybrid chassis coupled with fermentation for fatty acid production from carbon dioxide. We developed a biohybrid system Integrating a metal chalcogenide semiconductor Cu2ZnSnS4 (CZTS) with the CO2-fixing electrotrophic bacterium Sporomusa ovata. This photocatalytic biohybrid system efficiently produced acetate and ethanol over five days of stable light-driven operation. The acetate and ethanol produced were subjected for a fermentative chain elongation by a Clostridum species, forming C4 (butyrate) and C6 (caproate) fatty acids. The second project is about bioinspired solar methanogenesis coupled with alcohol upgrading. Here we develop a dual-function semi artificial biohybrid system made of organic semiconductor Integrated with methanogenic archaea (Methanosarcina species). This photocatalytic biohybrid efficiently converts CO2 into CH4, paired with a hole induced alcohol oxidation reaction on solar illumination. Additionally, to further elucidate the extracellular electron transfer mechanisms in the two Methanosarcina species employed, we performed complementary cellular characterization using Raman spectroscopy, ICP-OES, and UV-vis analysis on the cells – which results in corroborating findings in line with genomic/transcriptomic evidence of the organisms.