title: Monitoring microbial redox transformations of metal and metalloid elements under high pressure using in situ X-ray absorption spectroscopy.
abstract: X-ray absorption spectroscopy is a well-established method for probing local structural and electronic atomic environments in a variety of systems. We used X-ray absorption near-edge structure (XANES) spectroscopy for monitoring in real-time conditions selenium reduction in situ in live cultures of Shewanella oneidensis MR-1 under high hydrostatic pressure. High-quality XANES data show that Shewanella oneidensis MR-1 reduces selenite Se(IV) to red elemental selenium Se(0) up to 150 MPa without any intermediate redox state. MR-1 reduces all selenite provided (5-10 mM) between 0.1 and 60 MPa. Above 60 MPa the selenite reduction yield decreases linearly with pressure and the activity is calculated to stop at 155 ± 5 MPa. The analysis of cultures recovered after in situ measurements showed that the decrease in activity is linked to a decrease in viability. This study emphasizes the promising potential of XANES spectroscopy for real-time probing in situ microbial redox transformations of a broad range of metal and metalloid elements in live samples, including under high hydrostatic pressure.
authors.affiliation: Laboratoire de Sciences de la Terre, Université de Lyon, Ecole Normale Supérieure de Lyon, CNRS, Université Lyon 1, Lyon, France. apicard@mpibremen.de
authors.forename: A
authors.initials: A
authors.lastname: Picard
authors.forename: I
authors.initials: I
authors.lastname: Daniel
authors.forename: D
authors.initials: D
authors.lastname: Testemale
authors.forename: I
authors.initials: I
authors.lastname: Kieffer
authors.forename: P
authors.initials: P
authors.lastname: Bleuet
authors.forename: H
authors.initials: H
authors.lastname: Cardon
authors.forename: P M
authors.initials: PM
authors.lastname: Oger
mesh_terms: D006874:Hydrostatic Pressure; D010084:Oxidation-Reduction; D012643:Selenium / Q000737:chemistry / Q000378:metabolism*; D020592:Shewanella / Q000378:metabolism*; D018038:Sodium Selenite / Q000737:chemistry; D056928:X-Ray Absorption Spectroscopy
chemical_list: D012643:Selenium; D018038:Sodium Selenite