Geochemical constraints on the diversity and activity of H2-oxidizing microorganisms in diffuse hydrothermal fluids from a basalt- and an ultramafic-hosted vent.

Perner, Mirjam , Petersen, Jillian M., Zielinski, Frank, Gennerich, Hans-Hermann and Seifert, Richard (2010) Geochemical constraints on the diversity and activity of H2-oxidizing microorganisms in diffuse hydrothermal fluids from a basalt- and an ultramafic-hosted vent. FEMS Microbiology Ecology, 74 (1). pp. 55-71. DOI 10.1111/j.1574-6941.2010.00940.x.

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Abstract

Mixing processes of reduced hydrothermal fluids with oxygenated seawater and fluid-rock reactions contribute to the chemical signatures of diffuse venting and likely determine the geochemical constraints on microbial life. We examined the influence of fluid chemistry on microbial diversity and activity by sampling diffuse fluids emanating through mussel beds at two contrasting hydrothermal vents. The H(2) concentration was very low at the basalt-hosted Clueless site, and mixing models suggest O(2) availability throughout much of the habitat. In contrast, effluents from the ultramafic-hosted Quest site were considerably enriched in H(2) , while O(2) is likely limited to the mussel layer. Only two different hydrogenase genes were identified in clone libraries from the H(2) -poor Clueless fluids, but these fluids exhibited the highest H(2) uptake rates in H(2) -spiked incubations (oxic conditions, at 18 °C). In contrast, a phylogenetically diverse H(2) -oxidizing potential was associated with distinct thermal conditions in the H(2) -rich Quest fluids, but under oxic conditions, H(2) uptake rates were extremely low. Significant stimulation of CO(2) fixation rates by H(2) addition was solely illustrated in Quest incubations (P-value <0.02), but only in conjunction with anoxic conditions (at 18 °C). We conclude that the factors contributing toward differences in the diversity and activity of H(2) oxidizers at these sites include H(2) and O(2) availability.

Document Type: Article
Keywords: Geochemical constraints, diversity, activity, H2-oxidizing microorganisms, diffuse hydrothermal fluids, basalt-hosted, ultramafic-hosted vent.
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1111/j.1574-6941.2010.00940.x
ISSN: 0168-6496
Expeditions/Models/Experiments:
Date Deposited: 11 Oct 2017 07:46
Last Modified: 18 Jul 2018 08:14
URI: http://oceanrep.geomar.de/id/eprint/39793

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