Mesophilic Mineral-Weathering Bacteria Inhabit the Critical-Zone of a Perennially Cold Basaltic Environment |
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Authors: | Stephen Summers Bruce C. Thomson Andrew S. Whiteley Charles S. Cockell |
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Affiliation: | 1. Earth, Environment and Ecosystems, CEPSAR, The Open University, Milton Keynes Campus, Buckinghamshire, United Kingdom;2. Center for Ecology &3. Hydrology, Crowmarsh Gifford, United Kingdom;4. School of Earth and Environment, University of Western Australia, Crawley, Australia;5. School of Physics and Astronomy, University of Edinburgh United Kingdom |
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Abstract: | The weathering of silicate in the world's critical-zone (rock-soil interface) is a natural mechanism providing a feedback on atmospheric CO2 concentrations through the carbonate-silicate cycle. We examined culturable bacterial communities from a critical-zone in western Iceland to determine the optimum growth temperature and their ability to solubilize phosphate-containing minerals, which are abundant within the critical-zone area examined here. The majority of isolated bacteria were able to solubilize mineral-state phosphate. Almost all bacterial isolates were mesophilic (growth optima of 20–45°C), despite critical-zone temperatures that were continuously below 15°C, although all isolates could grow at temperatures associated with the critical-zone (?2.8–13.1°C). Only three isolates were shown to have thermal optima for growth that were within temperatures experienced at the critical-zone. These findings show that the bacteria that inhabit the western Icelandic critical-zone have temperature growth optima suboptimally adapted to their environment, implying that other adaptations may be more important for their long-term persistance in this environment. Moreover, our study showed that the cold basaltic critical-zone is a region of active phosphate mineral-weathering. |
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Keywords: | bacteria critical-zone MPS soil microbiology weathering |
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