In a groundbreaking advance that bridges synthetic biology and solar-powered chemistry, researchers at Queen Mary University of London, led by Dr. Lin Su, have engineered a revolutionary solar reactor that cultivates autotrophic Escherichia coli directly within a photoelectrochemical system. Published in the Journal of the American Chemical Society, this innovative device integrates an organic photovoltaic cell, semiconductor electrodes, enzyme catalysts, and genetically modified bacteria to replicate photosynthesis in a completely synthetic and highly controllable environment. Remarkably, the reactor converts carbon dioxide (CO₂) and water into living bacterial biomass fueled solely by sunlight, bypassing traditional photosynthetic organisms such as plants, algae, and photosynthetic microbes.
This pioneering study offers a glimpse into a future where clean chemistry and biotechnology converge to provide sustainable routes for producing chemicals, plastics, and even microbial protein without reliance on fossil fuels. By harnessing the power of sunlight, the system first performs water splitting on a bismuth vanadate (BiVO4) photoanode, releasing oxygen—a critical electron acceptor that supports aerobic bacterial respiration. Simultaneously, an organic photovoltaic-based photocathode coupled with enzymes captures and reduces dissolved CO₂ into formate, a key one-carbon compound. This formate acts as an intermediary energy vector, shuttling solar energy into the bacterial cells where it fuels growth and biomass production.
Unlike earlier biohybrid platforms that combined abiotic light absorbers and microbes, this device achieves integration with fully tunable components. The organic solar cell’s architecture can be adjusted to optimize light harvesting; the enzyme responsible for CO₂ reduction, formate dehydrogenase (FDH), can be genetically and chemically engineered to enhance catalytic efficiency; and the E. coli chassis can be reprogrammed to synthesize a diverse array of target molecules instead of simple biomass. This modularity marks a critical evolution toward flexible, scalable solar refineries that efficiently couple chemical energy capture with microbial bioproduction.
The challenge of co-locating solar chemical reactions with living bacteria in one reactor stemmed from toxicity issues, as metal ion catalysts often poison biological systems. Dr. Su’s group addressed this by employing a semi-biological approach incorporating biocompatible materials and isolated enzymes instead of heterogeneous inorganic catalysts. This enabled a symbiotic environment where E. coli safely consumes the photogenerated formate using the oxygen co-produced by water splitting, thereby closing the carbon and energy loops. The reactor’s operation does not require an external electrical bias, relying purely on sunlight to drive sequential photoelectrochemical and biological reactions.
Technically, the device architecture features a BiVO4|TiCo photoanode that efficiently oxidizes water, paired against an organic photovoltaic (OPV) module layered with an indium oxide-titania (IO-TiO2) electron transport layer and encapsulated with graphite epoxy for stability. The cathode hosts FDH and carbonic anhydrase (CA) enzymes which facilitate rapid CO₂ uptake and reduction to formate. This engineering feat demonstrates that non-photosynthetic microbes can be powered by synthetic light absorbers, effectively mimicking the core steps of natural photosynthesis but allowing greater control over the biochemical outputs.
The implications of this research are vast. By generating biomass from CO₂ and sunlight in an integrated reactor, the platform lays the groundwork for sustainable microbial manufacturing of complex chemicals, bioplastics, and nutritional proteins—all vital for addressing climate change and resource scarcity. More importantly, the demonstration confirms that the intricate coordination between inorganic photoelectrodes, enzyme catalysis, and bacterial metabolism can be achieved in a single reactor vessel, removing the need for costly and inefficient two-step processing.
Dr. Su emphasizes the significance of modular design in this system: the organic solar cell’s performance can be finely tuned to maximize photon capture; enzymes can be evolved to improve turnover numbers; and metabolic pathways within E. coli can be rewired to convert formate into specialty compounds. This flexible integration offers a powerful platform for synthetic biology innovations, capable of rapid adaptation to produce a new generation of solar-powered cell factories for green chemistry.
The team’s collaboration extends across disciplines, merging breakthroughs in organic photovoltaics capable of functioning at elevated temperatures with advances in enzyme purification and synthetic biology. Dr. Celine Wing See Yeung of the University of Cambridge highlights the collective effort that “brought together materials chemistry and synthetic biology to build solar-powered chemical refineries,” harnessing the best of both fields to forge new technologies for sustainable manufacturing.
Furthermore, accomplished synthetic biologist Professor Erwin Reisner points out that this research charts a path toward semi-biological systems capable of producing high-value chemicals from CO₂ feedstocks. By replacing fossil fuel inputs with solar-powered biochemical synthesis, such hybrid reactors could transform industrial processes and contribute significantly to reducing greenhouse gas emissions on a global scale.
The journey is nascent, and current yields remain modest, with the reactor operating for hours rather than continuous weeks. Nevertheless, the proof of concept signals a paradigm shift in autotrophic microbial growth, demonstrating that synthetic light harvesters can seamlessly complement non-photosynthetic microbes. Future iterations integrating optimized solar cells, engineered enzymes with greater durability, and metabolically enhanced E. coli strains promise to unlock the full potential of this technology.
Professor Ron Milo from the Weizmann Institute underscores the broader impact: “Scaling bacterial growth using CO₂ as a feedstock represents a crucial advance toward sustainable food production with dramatically reduced land and water footprints.” As humanity grapples with environmental crises, technologies built on renewable energy and carbon recycling are indispensable. This integrated solar reactor exemplifies the innovative approaches necessary to meet these global challenges.
Overall, this multidisciplinary achievement heralds the emergence of next-generation solar biorefineries. By seamlessly combining materials science, enzymology, and microbial engineering, the team has created a versatile platform that transforms sunlight and CO₂ into living systems capable of producing sustainable materials and chemicals. As research progresses, this biohybrid system holds immense promise for revolutionizing the chemical industry and fostering a greener, more resilient future.
Subject of Research:
Not applicable
Article Title:
Toward Solar-Powered Growth of Autotrophic Escherichia coli Using Photoelectrochemistry
News Publication Date:
19-May-2026
Web References:
http://dx.doi.org/10.1021/jacs.6c03677
Image Credits:
Lin Su, Queen Mary University of London
Keywords
Chemistry; Synthetic biology; Green chemistry; Chemical engineering
