In situ analysis of oxygen consumption and diffusive transport in high-temperature acidic iron-oxide microbial mats


The role of dissolved oxygen as a principal electron acceptor for microbial metabolism was investigated within Fe(III)-oxide microbial mats that form in acidic geothermal springs of Yellowstone National Park (USA). Specific goals of the study were to measure and model dissolved oxygen profiles within high-temperature (65-75 degrees C) acidic (pH = 2.7-3.8) Fe(III)-oxide microbial mats, and correlate the abundance of aerobic, iron-oxidizing Metallosphaera yellowstonensis organisms and mRNA gene expression levels to Fe(II)-oxidizing habitats shown to consume oxygen. In situ oxygen microprofiles were obtained perpendicular to the direction of convective flow across the aqueous phase/Fe(III)-oxide microbial mat interface using oxygen microsensors. Dissolved oxygen concentrations dropped from approximately 50-60 muM in the bulk-fluid/mat surface to below detection (< 0.3 muM) at a depth of approximately 700 mum ( approximately 10% of the total mat depth). Net areal oxygen fluxes into the microbial mats were estimated to range from 1.4-1.6 x 10(-4) mumol cm(-2) s(-1) . Dimensionless parameters were used to model dissolved oxygen profiles and establish that mass transfer rates limit the oxygen consumption. A zone of higher dissolved oxygen at the mat surface promotes Fe(III)-oxide biomineralization, which was supported using molecular analysis of Metallosphaera yellowstonensis 16S rRNA gene copy numbers and mRNA expression of haem Cu oxidases (FoxA) associated with Fe(II)-oxidation.


PubMed ID: 23516993

Projects: Energy and Material Processing

Publication type: Not specified

Journal: Environ Microbiol


Date Published: 21st Mar 2013

Registered Mode: Not specified

Authors: Hans Bernstein, J. P. Beam, M. A. Kozubal, R. P. Carlson, W. P. Inskeep

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Created: 28th Jan 2015 at 18:39

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