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SEMINAR: Biogeochemistry Seminar - Dr. Ronald S. Oremland, Monday, March 26, 2012 @ 1:30PM
| From: | Erica Calderon <ecalderon@rsmas.miami.edu> |
| Subject: | SEMINAR: Biogeochemistry Seminar - Dr. Ronald S. Oremland, Monday, March 26, 2012 @ 1:30PM |
| Date: | Mon, 26 Mar 2012 13:23:01 +0000 |
|
Biogeochemistry Seminar
Dr. Ronald S. Oremland Acetylene Metabolism and The Search For Extraterrestrial Life In Lieu Of Arsenic
TODAY, March 26, 2012
1:30PM
RSMAS campus, SLAB Seminar Rm 103 BACKGROUND (currently an adjunct professor at RSMAS)
ABSTRACT Acetylene occurs, by photolysis of methane, in the atmospheres of jovian planets and Titan.
In contrast, acetylene is only a trace component of Earth’s current atmosphere. Nonetheless,
a methane-rich atmosphere has been hypothesized for early Earth; this atmosphere would
also have been rich in acetylene. This poses a paradox, because acetylene is an inhibitor
of many key anaerobic microbial processes, including methanogenesis, anaerobic methane
oxidation, nitrogen fixation, and hydrogen oxidation. Fermentation of acetylene was discovered
30 years ago, and Pelobacter acetylenicus was shown to grow on acetylene by virtue of
acetylene hydratase, which forms acetaldehyde. Acetaldehyde subsequently
dismutates to ethanol and acetate. However, acetylene hydratase is specific for acetylene and does not react with any analogous compounds. Anaerobic microbes having acetylene hydratase may have played a role in the evolution of Earth’s
early biosphere by exploiting an available, reactive source of carbon from the atmosphere and in so
doing formed protective niches that allowed for other microbial processes to flourish. Furthermore,
the presence of acetylene in the atmosphere of a planet or planetoid could possibly
represent evidence for an extraterrestrial anaerobic ecosystem. Aspects of this hypothesis will be discussed with particular reference to the possibility of life on Enceladus, a satellite of Saturn. Erica Calderon N Gros 353/SLAB 112 http://www.rsmas.miami.edu/academics/divisions/marine-atmospheric-chemistry |
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