ASU Electronic Theses and Dissertations
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Many acidic hot springs in Yellowstone National Park support microbial iron oxidation, reduction, or microbial iron redox cycling (MIRC), as determined by microcosm rate experiments. Microbial dissimilatory iron reduction (DIR) was detected in numerous systems with a pH < 4. Rates of DIR are influenced by the availability of ferric minerals and organic carbon. Microbial iron oxidation (MIO) was detected from pH 2 – 5.5. In systems with abundant Fe (II), dissolved oxygen controls the presence of MIO. Rates generally increase with increased Fe(II) concentrations, but rate constants are not significantly altered by additions of Fe(II). MIRC was detected in …
- St Clair, Brian, Shock, Everett L, Anbar, Ariel, et al.
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Hydrothermal environments are important locales for carbon cycling on Earth and elsewhere in the Universe. Below its maximum temperature (~73 °C), microbial photosynthesis drives primary productivity in terrestrial hydrothermal ecosystems, which is thought to be performed by bacterial phototrophs in alkaline systems and eukaryotic algae in acidic systems, yet has received little attention at pH values intermediate to these extremes. Sequencing of 16S and 18S rRNA genes was performed at 12 hot springs with pH values 2.9-5.6 and revealed that cyanobacteria affiliated with the genus Chlorogloeopsis and algae of the order Cyanidiales coexisted at 10 of the sites. Cyanobacteria were …
- Fecteau, Kristopher, Shock, Everett L, Gould, Ian R, et al.
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