Name: Sharath Srinivasiah

Email: srinivas@dbi.udel.edu

Author: Sharath Srinivasiah1*, Dhritiman Ghosh2, Jackie Lovett1, Krishnakali Roy2, Megan Furman1, Mark Radosevich2, and K. Eric Wommack1

Author affiliation: 1) University of Delaware, Newark, DE, USA 2) Biosystems Engineering and Soil Science Department, University of Tennessee, Knoxville, TN, USA * Presenting Author

Abstract title: Viral and bacterial interactions in a Uranium contaminated aquifer

Absstract:

Uranium contaminated environments are still prevalent in sites that were once used in mining and processing of radioactive materials during the development of nuclear technology. Rifle, Colorado has one such environment, where the ground water is contaminated with U(VI). As part of an experimental-strategy for bioremediation, wells in the contaminated subsurface aquifer were point-source injected with aceatate as an electron donor for dissimilatory metal-reducing bacteria like Geobacter that reduce highly mobile and soluble hexavalent Uranium U(VI) to insoluble Ur (IV). During microbial reduction tetravalent U(IV) precipitates from solution and is effectively prevented from spreading through the aquifer. As acetate diffuses across the ground water, population dynamics of metal reducing bacteria, and probably viruses are influenced along with U(VI) reduction. Preliminary investigations demonstrate a noticeable impact of acetate addition on the abundance and activity of groundwater viral assemblages. Well D-04, closest to the site of acetate-injection, showed an increase in bacterial and viral abundance over 24 hours of incubation and net positive levels of viral production. A more distant down-gradient well (D-11) and an up gradient well (U-01) showed little to no viral production as viral and bacterial abundances were stable over the 24 h incubation period. Ironically, higher viral abundances and viral to bacterial ratios (VBRs) were consistently observed in the up-gradient sample. In contrast, VBRs were nearly 10 fold lower (i.e., 1 versus 10) in the down-gradient wells as compared to the U-01 well. Ongoing work seeks to further clarify the relationship between acetate biostimulation and viral production and changess in the composition of viral assemblages.