(514k) Investigation of Shewanella Oneidensis MR-1 As a Bioremediation Agent for Iodate

Radioiodine-129 (I¹²⁹) from leaking nuclear waste storage tanks is one of the major contaminants of groundwater at the Hanford Site in Washington State. Speciation of I¹²⁹ in the contaminated groundwater is predominantly as iodate, organo-iodide and iodide.

Shewanella oneidensis MR-1 is a strain of bacteria known to reduce silver and uranium and has been validated for its potential to serve as an ex situ bioremediation agent against iodate. A proposed bioremediation solution is to use microbial dissimilatory reduction of iodate to iodide. This study hypothesizes that planktonic and biofilm cultures of S. oneidensis can effectively reduce iodate to chemical species that are more readily remediated through chemical or biological approaches. For the purpose of this study, S. oneidensis was grown in minimal media (GM9) in the presence and absence of iodate under both, aerobic and anaerobic conditions. Iodate concentrations were monitored by colorimetric assays with UV Spectrophotometry. Data suggests that S. oneidensis can reduce iodate by 28% under aerobic conditions, and no reduction occurs under anaerobic conditions. Further assays are underway to investigate the impact of S. oneidensis biofilm formation on iodate reduction as well as elucidate its microbial mechanisms for iodate reduction. These assays will determine whether iodate reduction and contamination cleanup are possible through bacterial biofilms.

Success of this project will result in the validation of using S. oneidensis for possible contamination cleanup of nuclear waste. This may lead to the development and design of novel microbial bioreactors for the bioremediation of groundwater, soils and sediments.

Funder Acknowledgement(s): This study was supported by an NSF DEB Award#1832140 to Dr. Patrick Ymele-Leki.