Acetylene as fast food: Implications for development of life on anoxic primordial earth and in the outer solar system

Astrobiology
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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 a potent inhibitor of many key anaerobic microbial processes, including methanogenesis, anaerobic methane oxidation, nitrogen fixation, and hydrogen oxidation. Fermentation of acetylene was discovered ∼25 years ago, and Pelobacter acetylenicuswas shown to grow on acetylene by virtue of acetylene hydratase, which results in the formation of acetaldehyde. Acetaldehyde subsequently dismutates to ethanol and acetate (plus some hydrogen). However, acetylene hydratase is specific for acetylene and does not react with any analogous compounds. We hypothesize that microbes with acetylene hydratase played a key role in the evolution of Earth's early biosphere by exploiting an available 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. Astrobiology 8, 45–58.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Acetylene as fast food: Implications for development of life on anoxic primordial earth and in the outer solar system
Series title Astrobiology
DOI 10.1089/ast.2007.0183
Volume 8
Issue 1
Year Published 2008
Language English
Publisher Mary Ann Liebert
Contributing office(s) Toxic Substances Hydrology Program
Description 14 p.
First page 45
Last page 58