The growth of gram-negative, dissimilatory, metal-reducing bacterium Shewanella oneidensis (Shewanella) was studied in the presence of the Cd, Se, and Te cations anaerobically and under limited oxygen conditions. Under these conditions, Shewanella reduced metal cations through its unique mechanisms of extracellular electron transfer (EET). We show the effects of high concentrations of Cd, Se and Te using bacterium growth rates and expression of charge transfer species such as outer membrane cytochromes directly involved in EET. Our results demonstrate that Shewanella readily sustains growth in the presence of high concentrations of Na2SeO3 and Na2TeO3, but requires a longer adaptation period to concentrations of Cd cations higher than 0.1 mM. The hindered growth of Shewanella under these conditions can perhaps be caused by the high affinity for adsorption of Cd cations to bacterial cell walls. The utilization of toxic materials from the environment can be applied toward the biosynthesis of sought after semiconductor nanoparticles such as quantum dots. Despite its naturally high resistivity to toxic metals, Shewanella has not yet been utilized for biosynthesis of highly popular cadmium nopaticles (CdS, CdSe or CdTe). The research presented here demonstrates the first step of adaptation of Shewanella growth in the presence of the high concentrations of metals relevant for nanomaterial biosynthesis.

Growth of Shewanella oneidensis in the presence of toxic metals: A basis for sustainable semiconducting nanoparticle biosynthesis

253rd National Meeting (2017)

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