In situ analysis of oxygen consumption and diffusive transport in high-temperature acidic iron-oxide microbial mats
Bernstein HC, Beam JP, Kozubal MA, Carlson RP, Inskeep WP. 2013. In situ analysis of oxygen consumption and diffusive transport in high-temperature acidic iron-oxide microbial mats. Environmental Microbiology. 15(8):2360–2370
Summary 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°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 ∼ 50–60 μM in the bulk-fluid/mat surface to below detection (< 0.3 μM) at a depth of ∼ 700 μm (∼ 10% of the total mat depth). Net areal oxygen fluxes into the microbial mats were estimated to range from 1.4–1.6 × 10−4 μmol 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.
- Type
- Journal Article
- Authors
- Bernstein, Hans; Beam, Jacob; Kozubal, Mark; Carlson, Ross; Inskeep, William
- Units
- GRYN , YELL
- Keywords
- dissolved oxygen, electron acceptor, Fe(III)-oxide microbial mats, geothermal springs, iron-oxidizing microbes, Metallosphaera yellowstonensis, microbial metabolism, Yellowstone
- Subjects
- Ecological Framework: Water | Water Quality | Microorganisms