ULTRAMICROBACTERIA IN URANIUM-CONTAMINATED Y-12 GROUNDWATER

This research project is prompted by the limited understanding of the occurrence and function of Ultramicrobacteria (UMB) in contaminated groundwater systems. Investigations focused on sampling and characterizing UMB in contaminated groundwater withdrawn from wells in a shallow uranium-contaminated aquifer over a period of four months at the Y-12 Superfund site in Oak Ridge, TN. UMB are active and abundant environmental bacteria with a relatively small average cell volume of 0.009µm³. Increased knowledge of the community responses and biological components of radioactive uranium-contaminated sites is vital to controlling and mitigating the impact of uranium, and radiological contamination within aquifers. Both the 0.2 µm size fraction and the UMB (0.1 µm) community were extracted following an in-field well-injection of an organic electron-donor, emulsified vegetable oil. Utilizing an Illumina MiSeq, 16s rRNA amplicon sequencing and shotgun metagenomics of DNA extracted from 0.1 µm filters yielded UMB community data. The suspended planktonic organisms of the surrounding size fractions were further enumerated and characterized via cell counts and microscopy imagery. This ongoing research furthers our understanding into the role and response of the UMB community in chronic uranium-contaminated environments, and the UMB community’s response following a groundwater perturbation. Moreover, this research has the potential to further our understanding of how the UMB community may respond to bioremediation efforts.