It has been known for a while that the particularly abundant diatoms (unicellular algae with a silicate frustule) are also able to survive in the dark bottom of the ocean, where neither photosynthesis nor respiration with oxygen is possible. Scientists of the Max Planck Institute for Marine Microbiology now disclose this artifice of the algae in the journal Proceedings of the National Academy of Sciences: In darkness, the diatoms breathe with nitrate in place of oxygen.
Laser-scanning-fluorescence image of the marine diatom Amphora coffeaeformis. Red: auto-fluorescing chloroplasts, green: lipid membranes (stained with MDY-64). Martin Beutler, bionsys GmbH, Bremen, Germany (www.bionsys.de).
Microalgae often measure only a few hundredths of a millimeter, but due to their vast abundance in the world’s oceans they are responsible for about 40% of the marine primary production, i.e., the biomass production via carbon dioxide fixation in the sunlight. They often appear as massive blooms near the sea surface or as greenish-brownish meadows on the sea floor, if still reached by sunlight. However, diatoms (unicellular algae with a silicate frustule) are also able to survive in the absence of sunlight and oxygen, for instance, buried in the sea floor.
Anja Kamp, Dirk de Beer, Jana L. Nitsch, Gaute Lavik, and Peter Stief, scientists at the Max Planck Institute for Marine Microbiology in Bremen cultivated several diatom species in the laboratory to explore the metabolic process that allows the tiny algae to survive in darkness. A correlation was found between the nitrate that is stored by a diatom cell and its ability to survive in the absence of sunlight and oxygen. The more nitrate the cell contained, the longer it could survive in darkness where the cell does not have the possibility to produce oxygen via photosynthesis for its own respiration. In experiments with the coffee-bean-shaped diatom Amphora coffeaeformis, the scientists proved that diatoms use the nitrate stored in their cells for respiration in the absence of oxygen. Within just one day, most of the stored nitrate is used up, converted to ammonium, and excreted by the cell.
A key finding of the Max-Planck scientists was that diatoms use nitrate just for respiration rather than for biomass production, as would be the case in sunlight. Anja Kamp says: “The rapid consumption of nitrate and the absence of biomass production tell us that nitrate respiration in diatoms is a metabolic process that only serves to prepare the cell for a resting stage and therefore nitrate respiration is not sustained for longer time periods.”
In bacteria, nitrate respiration in the absence of oxygen is nothing exceptional, as many of the bacteria studied at the Max-Planck-Institute are able to breathe with nitrate, sulfate, or even iron compounds. It is more spectacular to discover that algae, i.e., organisms with a cell nucleus, are able carry out both photosynthesis and nitrate respiration, each under different environmental conditions. These results have just been published in the renowned interdisciplinary journal Proceedings of the National Academy of Sciences.Further inquiries to:
Dr. Manfred Schloesser | Max-Planck-Institut
Zap! Graphene is bad news for bacteria
23.05.2017 | Rice University
Discovery of an alga's 'dictionary of genes' could lead to advances in biofuels, medicine
23.05.2017 | University of California - Los Angeles
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.
In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...
Dental plaque and the viscous brown slime in drainpipes are two familiar examples of bacterial biofilms. Removing such bacterial depositions from surfaces is...
23.05.2017 | Event News
22.05.2017 | Event News
17.05.2017 | Event News
23.05.2017 | Physics and Astronomy
23.05.2017 | Life Sciences
23.05.2017 | Medical Engineering