It has been previously discovered that gram-negative, metal-reducing bacterium, Shewanella oneidensis (Shewanella), is able to sustain growth in the presence of Cd, Se, and Te. Under these conditions, Shewanella reduces metal cations through unique mechanisms of extracellular electron transfer (EET). Shewanella’s ability to reduce metals to an insoluble form can be applied to areas of ‘green’ chemistry as well as the biosynthesis of semiconductor nanoparticles such as quantum dots. The major candidates responsible for this process are heme bonded proteins found within the membrane. As Shewanella repopulates, the bacterium radiates electrons to electron acceptors in solution. Within these experiments, we used various electron acceptors including Cd, Se, Te, Ag quantum dots, and Zn quantum dots. Upon exploring the affects of nanomaterial metals on the growth rate of Shewanella, we quantified the expression of charge transfer species in Shewanella such as cytochromes. This investigation determines the correlation between charge transfer species expression in the presence of such materials. Quantifications were determined using SDS-PAGE electrophoresis with HEME stain. Color changes of media were also observed during this experiment demonstrating the reduction of added metals to solution. The results presented here demonstrate the physical alterations within Shewanella in order to sustain growth in the presence of nanomaterial electron acceptors.

Expression of charged transfer species in Sewanella oneidensis in the presence of nanomaterial metals

255th National Meeting (2018)

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