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
Enduring cold temperatures alters fat cell epigenetics
19.04.2018 | University of Tokyo
Full of hot air and proud of it
18.04.2018 | University of Pittsburgh
Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...
Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.
The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...
Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.
Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...
In the fight against cancer, scientists are developing new drugs to hit tumor cells at so far unused weak points. Such a “sore spot” is the protein complex...
In an article that appears in the journal “Review of Modern Physics”, researchers at the Laboratory for Attosecond Physics (LAP) assess the current state of the field of ultrafast physics and consider its implications for future technologies.
Physicists can now control light in both time and space with hitherto unimagined precision. This is particularly true for the ability to generate ultrashort...
13.04.2018 | Event News
12.04.2018 | Event News
09.04.2018 | Event News
19.04.2018 | Materials Sciences
19.04.2018 | Physics and Astronomy
19.04.2018 | Physics and Astronomy