The conversion of biomass, especially organic wastes, to energy is considered an essential part of a sustainable global energy portfolio. Novel microbial electrochemical systems, such as microbial fuel cell for electricity generation and microbial electrolysis cell for hydrogen production, have emerged as potential clean technologies for renewable energy production and waste treatment. The key feature and common process shared by these systems is the microbe-catalyzed electron transfer from organic matter to anodes. Enhancing current output from the anode is critical for the successful application of all these processes, which requires a fundamental understanding of the biofilm that develops on the anode. The applicants aim, through this project, is to advance the emerging area of electromicrobiological engineering by systematically investigating the high current-producing biofilm of a microbial electrochemical system capable of sustainable energy production and waste treatment. This project will build on the recent studies of a mixed bacterial culture in the applicant?s lab that exhibits many of the desirable features for electricity and hydrogen production. The microbial community is simple enough, however, to remain manageable for analysis of complex interactions between the constituent species, thereby providing an ideal case study for investigation of a current-producing anodic community. The main activities of the proposed research program include: (1) isolation and identification of the dominant bacterial strains in the microbial consortium; (2) characterization of the isolated strains in terms of their morphological, physiological, and electrochemical properties; (3) elucidation of the electron transfer mechanisms of the isolated exoelectrogens; and (4) investigation of the interactive relationships between different bacterial species in the anodic consortium.
This is the first systematic investigation of its kind, wherein a mixed culture with high current-generating capability is studied comprehensively to determine the identities of the predominant bacteria, the mechanisms by which the bacteria transfer electrons to the electrode, and the ways in which the bacteria interact in the community. The proposed research, when successfully accomplished, not only will address the unanswered question of why the current generated by mixed cultures is often much greater and more stable than that generated by most pure cultures, but also will result in the discovery of highly efficient new model species for electromicrobiological studies. Furthermore, the conclusions from this research will enrich our understanding of two critical and poorly-understood aspects of microbial electrochemical systems: the mechanisms of extracellular electron transfer, including biogenic mediators, outer membrane cytochromes, and bacterial nanowires and the metabolic interactions within anodic consortia, involving quorum sensing chemicals, mediators, and exchange of electron donors between species. Understanding the fundamental metabolic and electrochemical mechanisms within the anode biofilm not only will enable the design of stable and efficient systems for energy generation, but also will accelerate the development of microbial electrochemical systems for diverse other applications such as bioremediation and biosensing. The applicant has a solid track record of performance and publication in this research field, and has the resources for executing the proposed program successfully.
The broader impacts of this project are educational, environmental, and economic, and range from local to global in scale. The microbial electrochemical systems that relate to both energy and environmental sustainability can serve as a powerful platform for motivating students to study and understand complex concepts of microbial ecology, electrochemistry, and material science and engineering and resolve energy and environmental issues in the future. This project will significantly improve the scientific reasoning skills of graduate, undergraduate, and K-12 students through the development of hands-on microbial fuel cell teaching modules. This project also presents a unique opportunity for blending the educational experience of the local students involved in the project with cutting edge scientific research in an area of national and global concern. Efforts will be made to recruit and mentor underrepresented minority students through OSUs SESEY program. The concomitant treatment of waste during the energy generation process performs a double-duty of sustainability, providing energy from a renewable source while benefiting human health worldwide. Finally, generating energy from agricultural and industrial waste biomass offers a novel source of economic benefit to farmers and industries, especially those in remote areas and in developing countries. The results of this work will be disseminated through publications in refereed journals and conference presentations and also will be made available on the applicants webpage.
