title: Biomass production from electricity using ammonia as an electron carrier in a reverse microbial fuel cell.
abstract: The storage of renewable electrical energy within chemical bonds of biofuels and other chemicals is a route to decreasing petroleum usage. A critical challenge is the efficient transfer of electrons into a biological host that can covert this energy into high energy organic compounds. In this paper, we describe an approach whereby biomass is grown using energy obtained from a soluble mediator that is regenerated electrochemically. The net result is a separate-stage reverse microbial fuel cell (rMFC) that fixes CO₂ into biomass using electrical energy. We selected ammonia as a low cost, abundant, safe, and soluble redox mediator that facilitated energy transfer to biomass. Nitrosomonas europaea, a chemolithoautotroph, was used as the biocatalyst due to its inherent capability to utilize ammonia as its sole energy source for growth. An electrochemical reactor was designed for the regeneration of ammonia from nitrite, and current efficiencies of 100% were achieved. Calculations indicated that overall bioproduction efficiency could approach 2.7±0.2% under optimal electrolysis conditions. The application of chemolithoautotrophy for industrial bioproduction has been largely unexplored, and results suggest that this and related rMFC platforms may enable biofuel and related biochemical production.
authors.affiliation: Department of Earth and Environmental Engineering, Department of Chemical Engineering, Columbia University-New York, New York, New York, United States of America.
authors.forename: Wendell O
authors.initials: WO
authors.lastname: Khunjar
authors.forename: Asli
authors.initials: A
authors.lastname: Sahin
authors.forename: Alan C
authors.initials: AC
authors.lastname: West
authors.forename: Kartik
authors.initials: K
authors.lastname: Chandran
authors.forename: Scott
authors.initials: S
authors.lastname: Banta
mesh_terms: D000641:Ammonia / Q000378:metabolism*; D001674:Bioelectric Energy Sources / Q000382:microbiology*; D018533:Biomass; D019149:Bioreactors / Q000382:microbiology; D003470:Culture Media / Q000378:metabolism; D004560:Electricity; D004563:Electrochemistry; D004579:Electron Transport; D004734:Energy Metabolism; D005818:Genetic Engineering; D009573:Nitrites / Q000378:metabolism; D043370:Nitrosomonas europaea / Q000235:genetics / Q000378:metabolism; D013997:Time Factors
chemical_list: D003470:Culture Media; D009573:Nitrites; D000641:Ammonia