On July 20th, 2008, scientists from the Center of Marine Environmental Sciences (MARUM) at Bremen University and their Japanese colleagues published an article on microbial life deep beneath the seafloor.
The researchers show that - expressed in terms of carbon mass - this so-called deep biosphere contains about 90 billion tons of microbial organisms. That corresponds to about one tenth of the amount of carbon stored globally in tropical rainforests. Applying novel methods, the German-Japanese team concluded that about 87 percent of the deep biosphere consists of Archaea. This is in stark contrast to former reports, which suggested that Bacteria dominate the subseafloor ecosystem.
A team led by Prof. Kai-Uwe Hinrichs investigated sediment samples from several hundred meters beneath the seafloor. The sediment cores were retrieved in the Atlantic and the Pacific Oceans as well as in the Black Sea, most of them well below the ocean floor during expeditions of the Integrated Ocean Drilling Program (IODP). The scientists pursued two main objectives: "We wanted to find out which microorganisms can be found in the seafloor, and how many of them are living down there", states biogeochemist Kai-Uwe Hinrichs.
For quite a long time, scientists believed that the extreme conditions such as high pressure, lack of oxygen, low supply of nutrients and energy would make deep sub-seafloor environments inhabitable for any life form. But now they know better: Sea-going expeditions have proven the existence of the deep biosphere. "In general, life at and below the seafloor is dominated by minute monocellular organisms. According to our analyses, Bacteria dominate the upper ten centimeters of the seafloor. Below this level, Archaea appear to take over the major fraction of the biomass pool", says MARUM researcher Julius Lipp, who has just completed his PhD on this subject.
According to Lipp, Archaea make up at least 87 percent of organisms that colonize the deep biosphere. "These subsurface Archaea can be viewed as starvelings. Compared to Bacteria, Archaea appear to be better adapted to the extreme, chronic deficiency of energy that characterizes this habitat - a consequence of the only food being stable, fossil remnants of plants that were pre-digested by generations of other microorganisms"", says Lipp.
Next to Bacteria, Archaea represent one of three domains in the systematics of life. Both groups can be identified by fat-like molecules, so-called lipids that make up their cell membranes. To date, estimations of the deep biosphere biomass range from about 60 to 300 billion tons of carbon. "Our measurements determined by entirely independent means are with 90 billion tons of carbon right in this bracket", says Prof. Hinrichs, head of the Organic Geochemistry Group at MARUM and the Department of Geosciences, Bremen University. The authors of the Nature paper assume that about 200 million cubic kilometers of mud below the ocean floor are inhabited by microorganisms - a volume roughly corresponding to a 600 kilometer-long cube.
Because all current techniques aimed at detecting biomass in the deep biosphere arrive at different conclusions regarding its quantity and composition, Prof. Hinrichs has initiated an international "ring experiment". Currently, his colleagues in German, European, US-American, and Japanese laboratories are investigating standardized sediment samples from the seafloor with different methods. Moreover, they want to find out whether identical methods applied in different labs lead to dissimilar results. The aim is to gain a more reliable picture of life in the deep biosphere. In September, the researchers involved in the experiment will present and discuss their findings at MARUM. "All participants hope that this experiment will shed a bit more light on the dark deep biosphere" Hinrichs states.
Further information/interviews/photos:Yasmin Khalil
Yasmin Khalil | idw
Newly discovered bacteria-binding protein in the intestine
08.12.2016 | University of Gothenburg
The balancing act: An enzyme that links endocytosis to membrane recycling
07.12.2016 | National Centre for Biological Sciences
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
08.12.2016 | Materials Sciences
08.12.2016 | Materials Sciences
08.12.2016 | Physics and Astronomy