title: Screening of bacterial strains isolated from uranium mill tailings porewaters for bioremediation purposes.
abstract: The present work characterizes at different levels a number of bacterial strains isolated from porewaters sampled in the vicinity of two French uranium tailing repositories. The 16S rRNA gene from 33 bacterial isolates, corresponding to the different morphotypes recovered, was almost fully sequenced. The resulting sequences belonged to 13 bacterial genera comprised in the phyla Firmicutes, Actinobacteria and Proteobacteria. Further characterization at physiological level and metals/metalloid tolerance provided evidences for an appropriate selection of bacterial strains potentially useful for immobilization of uranium and other common contaminants. By using High Resolution Transmission Electron Microscope (HRTEM), this potential ability to immobilize uranium as U phosphate mineral phases was confirmed for the bacterial strains Br3 and Br5 corresponding to Arthrobacter sp. and Microbacterium oxydans, respectively. Scanning Transmission Electron Microscope- High-Angle Annular Dark-Field (STEM-HAADF) analysis showed U accumulates on the surface and within bacterial cytoplasm, in addition to the extracellular space. Energy Dispersive X-ray (EDX) element-distribution maps demonstrated the presence of U and P within these accumulates. These results indicate the potential of certain bacterial strains isolated from porewaters of U mill tailings for immobilizing uranium, likely as uranium phosphates. Some of these bacterial isolates might be considered as promising candidates in the design of uranium bioremediation strategies.
authors.affiliation: Departamento de Microbiología, Campus de Fuentenueva, Universidad de Granada, 18071, Granada, Spain. Electronic address: ivansanchezcastro@gmail.com.
authors.forename: Iván
authors.initials: I
authors.lastname: Sánchez-Castro
authors.affiliation: Departamento de Microbiología, Campus de Fuentenueva, Universidad de Granada, 18071, Granada, Spain.
authors.forename: Ahinara
authors.initials: A
authors.lastname: Amador-García
authors.affiliation: Departamento de Microbiología, Campus de Fuentenueva, Universidad de Granada, 18071, Granada, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Moreno-Romero
authors.affiliation: Departamento de Microbiología, Campus de Fuentenueva, Universidad de Granada, 18071, Granada, Spain.
authors.forename: Margarita
authors.initials: M
authors.lastname: López-Fernández
authors.affiliation: R&D Department, AREVA Mines, La Défense, 92084, Paris, France.
authors.forename: Vannapha
authors.initials: V
authors.lastname: Phrommavanh
authors.affiliation: R&D Department, AREVA Mines, La Défense, 92084, Paris, France.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Nos
authors.affiliation: R&D Department, AREVA Mines, La Défense, 92084, Paris, France.
authors.forename: Michael
authors.initials: M
authors.lastname: Descostes
authors.affiliation: Departamento de Microbiología, Campus de Fuentenueva, Universidad de Granada, 18071, Granada, Spain.
authors.forename: Mohamed L
authors.initials: ML
authors.lastname: Merroun
mesh_terms: D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D001673:Biodegradation, Environmental; D011848:Radioactive Pollutants / Q000378:metabolism; D014501:Uranium / Q000032:analysis / Q000378:metabolism*
chemical_list: D011848:Radioactive Pollutants; D014501:Uranium
keywords: Bacterial isolates; Biomineralization; Bioremediation; Porewaters; STEM/HAADF; Uranium