title: Phenotypic Characterisation of Shewanella oneidensis MR-1 Exposed to X-Radiation.
abstract: Biogeochemical processes mediated by Fe(III)-reducing bacteria such as Shewanella oneidensis have the potential to influence the post-closure evolution of a geological disposal facility for radioactive wastes and to affect the solubility of some radionuclides. Furthermore, their potential to reduce both Fe(III) and radionuclides can be harnessed for the bioremediation of radionuclide-contaminated land. As some such sites are likely to have significant radiation fluxes, there is a need to characterise the impact of radiation stress on such microorganisms. There have, however, been few global cell analyses on the impact of ionizing radiation on subsurface bacteria, so here we address the metabolic response of S. oneidensis MR-1 to acute doses of X-radiation. UV/Vis spectroscopy and CFU counts showed that although X-radiation decreased initial viability and extended the lag phase of batch cultures, final biomass yields remained unchanged. FT-IR spectroscopy of whole cells indicated an increase in lipid associated vibrations and decreases in vibrations tentatively assigned to nucleic acids, phosphate, saccharides and amines. MALDI-TOF-MS detected an increase in total protein expression in cultures exposed to 12 Gy. At 95 Gy, a decrease in total protein levels was generally observed, although an increase in a putative cold shock protein was observed, which may be related to the radiation stress response of this organism. Multivariate statistical analyses applied to these FT-IR and MALDI-TOF-MS spectral data suggested that an irradiated phenotype developed throughout subsequent generations. This study suggests that significant alteration to the metabolism of S. oneidensis MR-1 is incurred as a result of X-irradiation and that dose dependent changes to specific biomolecules characterise this response. Irradiated S. oneidensis also displayed enhanced levels of poorly crystalline Fe(III) oxide reduction, though the mechanism underpinning this phenomenon is unclear.
authors.affiliation: Williamson Research Centre for Molecular Environmental Science, University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom; Research Centre for Radwaste and Decommissioning, University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom; School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom.
authors.forename: Ashley R
authors.initials: AR
authors.lastname: Brown
authors.affiliation: Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester, M1 7DN, United Kingdom.
authors.forename: Elon
authors.initials: E
authors.lastname: Correa
authors.affiliation: Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester, M1 7DN, United Kingdom.
authors.forename: Yun
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester, M1 7DN, United Kingdom.
authors.forename: Najla
authors.initials: N
authors.lastname: AlMasoud
authors.affiliation: Dalton Cumbrian Facility, University of Manchester, Westlakes Science and Technology Park, Moor Row, Cumbria, CA24 3HA, United Kingdom; School of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom.
authors.forename: Simon M
authors.initials: SM
authors.lastname: Pimblott
authors.affiliation: Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester, M1 7DN, United Kingdom; School of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom.
authors.forename: Royston
authors.initials: R
authors.lastname: Goodacre
authors.affiliation: Williamson Research Centre for Molecular Environmental Science, University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom; Research Centre for Radwaste and Decommissioning, University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom; School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom.
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Lloyd
mesh_terms: D001426:Bacterial Proteins / Q000032:analysis / Q000096:biosynthesis; D004307:Dose-Response Relationship, Radiation; D005290:Ferric Compounds / Q000378:metabolism; D011829:Radiation Dosage; D020592:Shewanella / Q000737:chemistry / Q000378:metabolism / Q000528:radiation effects*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014965:X-Rays
chemical_list: D001426:Bacterial Proteins; D005290:Ferric Compounds; C000499:ferric oxide