Collaborative Research: EAGER: CET: Exploiting Endogenous Cellular Hydrogen Peroxide as a Source of Electrons for Reductive Photosynthetic Biosynthesis

Nontechnical Abstract This EArly-concept Grants for Exploratory Research (EAGER) award is made in response to Dear Colleague Letter 23-109, as part of the NSF-wide Clean Energy Technology initiative. Engineering of microbes for biofuel and biochemical production is an essential pathway as society continues to move away from fossil carbon-based feedstocks. Certain bacteria can oxidize organic carbon molecules like carbon dioxide, but these reactions also generate toxic hydrogen peroxide. With this project, researchers at Columbia University and CUNY City College investigate if the hydrogen peroxide, which is created inside the microbes and actively consumed to protect cells, is an untapped source of energy that can be exploited for the development of highly efficient hybrid photosynthetic bioproduction platforms. They synthesize a new protein that uses this toxic waste product and visible light to drive the carbon-negative biosynthesis of biofuels and other high-value chemicals. The transformative concept could lead to a broad range of future biochemical engineering applications. Additionally, the project provides training opportunities for the next generation of scientists and engineers at one of the nation’s largest university systems (CUNY), which has a large population of students with underrepresented minorities backgrounds. Technical Abstract With funding from an EArly-concept Grants for Exploratory Research (EAGER) award through the NSF-wide Clean Energy Technology initiative, the researchers investigate if light can be used by newly designed proteins to upgrade the electrons in the unwanted cellular waste material, hydrogen peroxide, to provide electrons for reductive reactions in engineered bacteria, thereby dramatically boosting the efficiency of biofuel and biochemical production from carbohydrates in photobioreactors. Specific tasks of the project are to 1) develop an E. coli strain platform to control and monitor hydrogen peroxide production in the cells; 2) create and validate a synthetic photoprotein capable of producing L-lactate from pyruvate using electrons from hydrogen peroxide oxidation; and 3) demonstrate that hydrogen peroxide is an untapped source of electrons by utilizing the synthetic photoprotein to upgrade the electrons with photons, and use them to regenerate NADH, a co-enzyme, in living cells that lack hydrogen peroxide scavenging capabilities. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.