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An Origin-of-Life Reactor to Simulate Alkaline Hydrothermal Vents

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journal contribution
posted on 23.02.2016, 13:12 by B. Herschy, A. Whicher, E. Camprubi, C. Watson, Lewis Dartnell, J. Ward, J. R. G. Evans, N. Lane
Chemiosmotic coupling is universal: practically all cells harness electrochemical proton gradients across membranes to drive ATP synthesis, powering biochemistry. Autotrophic cells, including phototrophs and chemolithotrophs, also use proton gradients to power carbon fixation directly. The universality of chemiosmotic coupling suggests that it arose very early in evolution, but its origins are obscure. Alkaline hydrothermal systems sustain natural proton gradients across the thin inorganic barriers of interconnected micropores within deep-sea vents. In Hadean oceans, these inorganic barriers should have contained catalytic Fe(Ni)S minerals similar in structure to cofactors in modern metabolic enzymes, suggesting a possible abiotic origin of chemiosmotic coupling. The continuous supply of H2 and CO2 from vent fluids and early oceans, respectively, offers further parallels with the biochemistry of ancient autotrophic cells, notably the acetyl CoA pathway in archaea and bacteria. However, the precise mechanisms by which natural proton gradients, H2, CO2 and metal sulphides could have driven organic synthesis are uncertain, and theoretical ideas lack empirical support. We have built a simple electrochemical reactor to simulate conditions in alkaline hydrothermal vents, allowing investigation of the possibility that abiotic vent chemistry could prefigure the origins of biochemistry. We discuss the construction and testing of the reactor, describing the precipitation of thin-walled, inorganic structures containing nickel-doped mackinawite, a catalytic Fe(Ni)S mineral, under prebiotic ocean conditions. These simulated vent structures appear to generate low yields of simple organics. Synthetic microporous matrices can concentrate organics by thermophoresis over several orders of magnitude under continuous open-flow vent conditions.

Funding

We would like to acknowledge and thank the Leverhulme Trust (Grant Number: RPG-425) for their funding of this research. We also thank Prof. Don Braben and Prof. David Price (VP Research) for support through the UCL Provost’s Venture Research Fellowship, and the UCL Research Frontiers programme.

History

Citation

Journal of Molecular Evolution (2014) 79:213–227

Version

VoR (Version of Record)

Published in

Journal of Molecular Evolution (2014) 79:213–227

Publisher

Springer Verlag (Germany)

issn

0022-2844

eissn

1432-1432

Acceptance date

21/11/2014

Available date

23/02/2016

Publisher version

http://link.springer.com/article/10.1007/s00239-014-9658-4

Language

en