title: The effect of bicarbonate on the microbial dissolution of autunite mineral in the presence of gram-positive bacteria.
abstract: Bacteria are key players in the processes that govern fate and transport of contaminants. The uranium release from Na and Ca-autunite by Arthrobacter oxydans strain G968 was evaluated in the presence of bicarbonate ions. This bacterium was previously isolated from Hanford Site soil and in earlier prescreening tests demonstrated low tolerance to U(VI) toxicity compared to other A. oxydans isolates. Experiments were conducted using glass serum bottles as mixed bioreactors and sterile 6-well cell culture plates with inserts separating bacteria cells from mineral solids. Reactors containing phosphorus-limiting media were amended with bicarbonate ranging between 0 and 10 mM and meta-autunite solids to provide a U(VI) concentration of 4.4 mmol/L. Results showed that in the presence of bicarbonate, A. oxydans G968 was able to enhance the release of U(VI) from Na and Ca autunite at the same capacity as other A. oxydans isolates with relatively high tolerance to U(VI). The effect of bacterial strains on autunite dissolution decreases as the concentration of bicarbonate increases. The results illustrate that direct interaction between the bacteria and the mineral is not necessary to result in U(VI) biorelease from autunite. The formation of secondary calcium-phosphate mineral phases on the surface of the mineral during the dissolution can ultimately reduce the natural autunite mineral contact area, which bacterial cells can access. This thereby reduces the concentration of uranium released into the solution. This study provides a better understanding of the interactions between meta-autunite and microbes in conditions mimicking arid and semiarid subsurface environments of western U.S.
authors.affiliation: Applied Research Center, Florida International University, 10555 W. Flagler Street, Miami, FL 33174, USA; Department of Biomedical Engineering, Florida International University, 10555 W. Flagler Street, Miami, FL 33174, USA.
authors.forename: Paola M
authors.initials: PM
authors.lastname: Sepulveda-Medina
authors.affiliation: Applied Research Center, Florida International University, 10555 W. Flagler Street, Miami, FL 33174, USA. Electronic address: katsenov@fiu.edu.
authors.forename: Yelena P
authors.initials: YP
authors.lastname: Katsenovich
authors.affiliation: Pacific Northwest National Laboratory, PO Box 999, K3-62, Richland, WA 99352, USA.
authors.forename: Dawn M
authors.initials: DM
authors.lastname: Wellman
authors.affiliation: Applied Research Center, Florida International University, 10555 W. Flagler Street, Miami, FL 33174, USA.
authors.forename: Leonel E
authors.initials: LE
authors.lastname: Lagos
mesh_terms: D001173:Arthrobacter / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D001639:Bicarbonates / Q000737:chemistry* / Q000378:metabolism; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D010710:Phosphates / Q000737:chemistry / Q000378:metabolism*; D011848:Radioactive Pollutants / Q000737:chemistry / Q000378:metabolism*; D012964:Sodium / Q000737:chemistry / Q000378:metabolism; D017974:Uranium Compounds / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001639:Bicarbonates; D010710:Phosphates; D011848:Radioactive Pollutants; D017974:Uranium Compounds; C075963:hydrogen uranyl phosphate; D012964:Sodium; D002118:Calcium
keywords: Aqueous bicarbonate; Arthrobacter sp; Autunite mineral; Microscopy; Radionuclides