Microbially mediated hydrogen cycling in deep-sea hydrothermal vents
- 1GEOMAR Helmholtz Center for Ocean Research Kiel, Faculty of Mathematics and Natural Sciences, University of Kiel, Germany
Deep-sea hydrothermal vents may provide one of the largest reservoirs on Earth for hydrogen-oxidizing microorganisms. Depending on the type of geological setting, hydrothermal environments can be considerably enriched in hydrogen (up to millimolar concentrations). As hot, reduced hydrothermal fluids ascend to the seafloor they mix with entrained cold, oxygenated seawater, forming thermal and chemical gradients along their fluid pathways. Consequently, in these thermally and chemically dynamic habitats biochemically distinct hydrogenases (adapted to various temperature regimes, oxygen and hydrogen concentrations) from physiologically and phylogenetically diverse Bacteria and Archaea can be expected. Hydrogen oxidation is one of the important inorganic energy sources in these habitats, capable of providing relatively large amounts of energy (237 kJ/mol H2) for driving ATP synthesis and autotrophic CO2 fixation. Therefore, hydrogen-oxidizing organisms play a key role in deep-sea hydrothermal vent ecosystems as they can be considerably involved in light-independent primary biomass production. So far, the specific role of hydrogen-utilizing microorganisms in deep-sea hydrothermal ecosystems has been investigated by isolating hydrogen-oxidizers, measuring hydrogen consumption (ex situ), studying hydrogenase gene distribution and more recently by analyzing metatranscriptomic and metaproteomic data. Here we summarize this available knowledge and discuss the advent of new techniques for the identification of novel hydrogen-uptake and -evolving enzymes from hydrothermal vent microorganisms.
Keywords: hydrogen cycling, Hydrogen consumption, hydrogenases, hydrogen oxidizers, hydrothermal vent
Received: 03 Aug 2018;
Accepted: 08 Nov 2018.
Edited by:Chris Greening, Monash University, Australia
Reviewed by:Carlo R. Carere, University of Canterbury, New Zealand
Xiyang Dong, Department of Biological Sciences, University of Calgary, Canada
Copyright: © 2018 Perner and Adam. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Prof. Mirjam Perner, GEOMAR Helmholtz Center for Ocean Research Kiel, Faculty of Mathematics and Natural Sciences, University of Kiel, Kiel, Schleswig-Holstein, Germany, firstname.lastname@example.org