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High pH microbial ecosystems in a newly discovered, ephemeral, serpentinizing fluid seep at Yanartaş (Chimera), Turkey

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posted on 20.01.2016 by D.R. Meyer-Dombard, K.M. Woycheese, E.N. Yargıçoğlu, D. Cardace, E.L. Shock, Y. Güleçal-Pektas, M. Temel
Gas seeps emanating from Yanartaş (Chimera), Turkey, have been documented for thousands of years. Active serpentinization produces hydrogen and a range of carbon gases that may provide fuel for life. Here we report a newly discovered, ephemeral fluid seep emanating from a small gas vent at Yanartaş. Fluids and biofilms were sampled at the source and points downstream. We describe site conditions, and provide microbiological data in the form of enrichment cultures, Scanning electron microscopy (SEM), carbon and nitrogen isotopic composition of solids, and PCR screens of nitrogen cycle genes. Source fluids are pH 11.95, with a Ca:Mg of ~200, and sediments under the ignited gas seep measure 60°C. Collectively, these data suggest the fluid is the product of active serpentinization at depth. Source sediments are primarily calcite and alteration products (chlorite and montmorillonite). Downstream, biofilms are mixed with montmorillonite. SEM shows biofilms distributed homogeneously with carbonates. Organic carbon accounts for 60% of the total carbon at the source, decreasing downstream to <15% as inorganic carbon precipitates. δ13C ratios of the organic carbon fraction of solids are depleted (−25 to −28‰) relative to the carbonates (−11 to −20‰). We conclude that heterotrophic processes are dominant throughout the surface ecosystem, and carbon fixation may be key down channel. δ15N ratios ~3‰, and absence of nifH in extracted DNA suggest that nitrogen fixation is not occurring in sediments. However, the presence of narG and nirS at most locations and in enrichments indicates genomic potential for nitrate and nitrite reduction. This small seep with shallow run-off is likely ephemeral, but abundant preserved microterracettes in the outflow and the surrounding area suggest it has been present for some time. This site and others like it present an opportunity for investigations of preserved deep biosphere signatures, and subsurface-surface interactions.

Funding

We would like to acknowledge the support and efforts of Dr. Nuri Uzunlar (South Dakota School of Mines and Technology) for introducing us to our Turkish field locations, N. Zolotova, R. Debes, K. Fecteau, K. Robinson, G. Boyer, and P. Prapaipong for valuable discussion and analytical assistance, and Eric Staley and Andrew Dombard for production of Figure ​Figure2.2. Support for travel to the field site was awarded to D'Arcy R. Meyer-Dombard and Dawn Cardace by the NASA Astrobiology Institute (NAI) International Collaboration Fund, to Erin N. Yargıçoğlu by the NAI Early Career Collaboration Award, and to D'Arcy R. Meyer-Dombard by the Illinois Space Grant Consortium (ISGC). Analytical expenses were covered by an early career award from the ISGC to D'Arcy R. Meyer-Dombard. Kristin M. Woycheese is supported by a Graduate Student Fellowship from C-DEBI. This is EDGElab contribution #3.

History

Publisher Statement

This Document is Protected by copyright and was first published by Frontiers. All rights reserved. It is reproduced with permission. © The Author(s).

Publisher

Frontiers

issn

1664-302X

Issue date

01/01/2014

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