Shewanella woodyi cultures were used to correlate bioluminescence intensity with changes in the electrochemical potential of a saltwater medium using soluble electron acceptors. A relationship between the concentration of NaNO 3 or CoCl 2 to bioluminescence intensity was confirmed using aerobic cultures of S. woodyi at 20 C with glucose as the sole carbon source. In general, increasing the concentration of nitrate or Co(II) reduced the bioluminescence per cell, with complete luminescence being repressed at ≥5 mM nitrate and ≥0.5 mM Co(II). Results from cell viability fluorescent staining concluded that increasing the concentration of Co(II) or nitrate did not affect the overall viability of the cells when compared with cultures lacking Co(II) or nitrate.These data show that potentials of <0.2 V vs Normal Hydrogen Electrode (NHE) repress the luminescence from the cells, but the exact mechanism is unclear. Our results indicated that the luminescence intensity from S. woodyi could be systematically reduced using these two soluble electron acceptors, making S. woodyi a potential model bacterium for whole-cell luminescence bioelectrochemical sensor applications. K E Y W O R D Sbioluminescence, extracellular electron transfer, redox potential, Shewanella

We will present bioluminescence data from Shewanella woodyi cultures in order to correlate bioluminescence intensity with changes in the electrochemical potential in a saltwater medium using soluble electron acceptors. A relationship between the concentration of NaNO3, CoCl2, or ZnCl2 to bioluminescence intensity was confirmed using aerobic cultures of S. woodyi at 20°C with glucose as the sole carbon source. In general, increasing the concentration of nitrate, Co(II), or Zn(II) reduced the bioluminescence per cell, with complete luminescence being repressed at ≥5 mM nitrate and ≥0.5 mM Co(II). Results from cell viability fluorescent staining concluded that increasing the concentration of Co(II) or nitrate did not affect the overall viability of the cells when compared to cultures lacking Co(II) or nitrate. Our presentation will show that electrochemical potentials of < 0.2 V vs NHE repress the luminescence from the cells, but the exact mechanism is unclear. Our results indicate that the luminescence intensity from S. woodyi could be systematically reduced using these three soluble electron acceptors making S. woodyi a potential model bacterium for whole‐cell luminescence bioelectrochemical sensor applications. Support or Funding Information University of Dayton Graduate Student Summer Fellowship and Dean's Summer Fellowship programs

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