Allison L Theberge



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The internal transfer of electrons through proteins from high to low electrochemical potentials is a fundamental aspect of life. Some microbes possess the unique ability to transfer internally derived electrons to external insoluble electron acceptors such as electrodes, redox proteins, and other cells in a process known as extracellular electron transfer (EET). Currently, this microbial process is applied in creation of microbial electrochemical systems (MESs). These systems are used in renewable energy and wastewater treatment research and applications. Shewanella woodyi is a cold tolerant, marine microbe that is an understudied candidate for its metal reduction capabilities, although it is closely related to other well-characterized strains in the Shewanella genus. Additionally, S. woodyi has bioluminescent properties and previous research indicated a relationship between bioluminescent intensity and EET existed. The bioluminescence enzyme luciferase relies on reduced flavins to generate light, therefore changes in flavin redox state can have an impact on bioluminescence. Throughout this research, the general growth of S.woodyi under a variety of conditions was characterized. Additionally, the relationship between EET and bioluminescence was confirmed utilizing the soluble electron acceptors of cobalt(II) and nitrate as the substrate for EET. Through high throughput luminescence assays and open circuit potential experiments, it was determined that increasing concentrations of the electron acceptors resulted in decreased bioluminescence output from the cells. Cell viability staining concluded that the increased concentrations of acceptors were not decreasing cell density and thus luminescence output, indicating a valid relationship between EET and bioluminescence.

Publication Date


Project Designation

Graduate Research

Primary Advisor

Justin C. Biffinger

Primary Advisor's Department



Stander Symposium project

An Investigation Correlating Bioluminescence and Metal Reduction Utilizing Shewanella woodyi