Monitoring microbial redox transformations of metal and metalloid elements under high pressure using in situ X-ray absorption spectroscopy

• Published in: Geobiology Vol. 9; no. 2; pp. 196 - 204
• Main Authors: PICARD, A, DANIEL, I, TESTEMALE, D, KIEFFER, I, BLEUET, P, CARDON, H, OGER, P.M
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.03.2011; Wiley Subscription Services, Inc; Wiley
• Subjects: Absorption spectroscopy; Analytical methods; Earth Sciences; High pressure; Hydrostatic Pressure; In situ measurement; Metals; Oxidation-Reduction; Pressure; Redox properties; Sciences of the Universe; Selenite; Selenium; Selenium - chemistry; Selenium - metabolism; Shewanella - metabolism; Shewanella oneidensis; Sodium Selenite - chemistry; Spectrum analysis; X-Ray Absorption Spectroscopy; RALSTONIA-METALLIDURANS CH34; HYDROSTATIC-PRESSURE; SHEWANELLA-ONEIDENSIS; SPECIATION; DEEP-SEA; DIAMOND-ANVIL CELL; SEAWATER SAMPLES; NEAR-EDGE STRUCTURE; GIGAPASCAL PRESSURES; SELENIUM
• ISSN: 1472-4677; 1472-4669
• DOI: 10.1111/j.1472-4669.2010.00270.x

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.