First global study of microbial communities at gas seeps in the deep sea shows the distribution and diversity of methane-consuming microorganisms. The specific energy source selects for unique microorganisms, which turn these ecosystems into hotspots of diversity in the deep sea.
Methane seeps are places in the ocean, where methane from deep sediment layers escapes the seabed. Specific microorganisms use the potential greenhouse gas as an energy source and thus form the basis for complex ecosystems.
Methanotrophic microorganisms of methane seep ecosystems.
Micrographs of aerobic methanotrophic bacteria (white), anaerobic methanotrophic archaea (ANME – red) and sulfate-reducing bacteria (SRB – green) visualized by fluorescence in situ hybridization. ANME and SRB perform the anaerobic oxidation of methane (AOM). AOM is a globally relevant process removing 60 million tons, the mass of ten pyramids of Giza, of the greenhouse gas methane from seafloor sediments each year. Courtesy of Katrin Knittel/Emil Ruff, MPI Bremen.
Now an international team of researchers led by the Max Planck Institute for Marine Microbiology has investigated the microbial communities of selected methane seeps from all oceans, and compared those to communities of other marine ecosystems. In the current issue of Proceedings of the National Academy of Sciences (USA), the researchers report that methane seeps contain many endemic microorganisms and therefore are hotspots of biodiversity in the deep sea.
In general, the seep communities are very different from those of other ecosystems. Only a few species of methanotrophs occur at all seeps worldwide, but these microorganisms seem to greatly influence the methane budget of the ocean.
Seafloor ecosystems have unique inhabitants
Each ecosystem in the deep sea is inhabited by certain microorganisms that can be assigned to the three domains of the tree of life: eukaryotes, archaea and bacteria. Eukaryotes have a nucleus and include all plants, fungi, animals and man. Archaea and bacteria are single cells without a nucleus.
The researchers studied the composition and relative abundance of archaea and bacteria at 77 locations of different marine ecosystems, including coastal sediments, deep-sea sediments, black smokers and methane seeps. They extracted the DNA of these organisms from the seabed samples and analyzed it using modern DNA sequencing techniques and mathematical algorithms.
Emil Ruff, scientist at the Max Planck Institute, summarizes: "Almost all of the major groups of archaea and bacteria were present at all examined sites. With increasing resolution, however, the differences between the ecosystems became clearer. At the level of individual species, which are the smallest branches of the tree of life, we found communities that are characteristic for each ecosystem and have a very specific task."
These characteristic communities were defined as the methane seep microbiome. The term microbiome is used to describe all microorganisms of a particular ecosystem and their genetic diversity. Such an ecosystem may be a methane seep, or soil or even the human intestine. The head of the research group, Prof. Dr. Antje Boetius, adds: "This study represents the first global view on microbes inhabiting methane seeps. It was enabled by a large international effort, the International Census of Marine Microbes.”
Methane seeps accommodate many specialists
Natural methane seeps (cold seeps) are found worldwide at continental margins. The gas is formed by decomposition processes in the anoxic layers deep down in the sediment, moves upwards and escapes at the seafloor. The uppermost sediment layers harbor methane oxidizers, which consume about three-quarters of the escaping methane.
This is equivalent to 60 million tons of carbon per year. At methane seeps, the primary energy source is completely different from those of the surrounding seabed. Thus, like oases in the desert methane sources attract particular organisms. These include groups with known function, such as anaerobic methane-oxidizing archaea (ANME) and sulfate-reducing bacteria (SRB). However, the researchers also found microbial groups on the methane sources with unknown function.
Emil Ruff, first author of the study, said: "It was surprising that microorganisms from seeps that are thousands of miles away in different oceans, are so closely related. Many methane oxidizers and sulfate reducers are sensitive to oxygen. Therefore, it is a mystery how they survive the great distances between the methane seeps."
The findings of the researchers suggest that only a few worldwide populations are responsible for the bulk of the methane consumption. The vast diversity of species and the evolution of new species, however, is limited to and can only be found at certain sites. Methane seeps thus contribute greatly to the biodiversity of the deep sea.
Global dispersion and local diversification of the methane seep microbiome
Emil Ruff, Jennifer F. Biddle, Andreas Teske, Katrin Knittel, Antje Boetius, Alban Ramette PNAS 2015, DOI: 10.1073/pnas.1421865112.
Emil Ruff, Max Plank Institute for Marine Microbiology, Bremen: +49 421 2028 942; firstname.lastname@example.org
or from the press officer
Manfred Schlösser, Max Plank Institute for Marine Microbiology, Bremen: +49 421 2028 704 email@example.com
Dr. Manfred Schloesser | Max-Planck-Institut für marine Mikrobiologie
Atomic-level motion may drive bacteria's ability to evade immune system defenses
24.04.2017 | Indiana University
Two-dimensional melting of hard spheres experimentally unravelled after 60 years
24.04.2017 | University of Oxford
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
24.04.2017 | Physics and Astronomy
24.04.2017 | Materials Sciences
24.04.2017 | Life Sciences