Investigating Iodate Reduction By Microbial Communities from the Hanford Site

Ayomikun Olarinoye, Tafadzwa Chigumira, Deondre Glover, Yaolin Fennell, Kimberly Jones, Patrick Ymele-Leki

Chemical Engineering Department, Howard University

This research aims to develop methods for in situ microbial reduction of radioactive Iodate (I¹²⁹) from radioactive waste contaminated groundwater at the Hanford Nuclear Site in Washington State. A microbial community, named “Community 31”, was isolated from the Hanford site. The community has yet to be characterized but was suspected by researchers at the Pacific Northwest National Laboratory (PNNL) to have Iodate reducing potential. Microbial reduction is the use of microorganism to decrease the oxidation number of a chemical species. In this case, Iodate (oxidation state of +5) was targeted to be reduced to Iodide (oxidation state -1). Community 31 was cultivated in a specially designed minimum media (Glover’s M9) that allowed for analysis of Iodate concentration with UV Spectrophotometry. A batch culture of the microbial community was exposed to an initial concentration of 100micromole/Liter of Iodate with constant shaking under anaerobic conditions. The experiment was carried out in the dark to reproduce ground water conditions and was monitored over 24 hours for growth and Iodate reduction. Samples were taken every 4 hours and measured in the UV-Spectrophotometer. Approximately 40% reduction in Iodate was recorded after 24 hours. The data suggests that Community 31 may reduce Iodate. This could have significant environmental implications as it suggests another approach for remediation of contaminated groundwater at the Hanford site.