Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

‘Hot-Bunking’ Bacterium Recycles Iron to Boost Ocean Metabolism

11.01.2011
In the vast ocean where an essential nutrient—iron—is scarce, a marine bacterium that launches the ocean food web survives by using a remarkable biochemical trick: It recycles iron.

By day, it uses iron in enzymes for photosynthesis to make carbohydrates; then by night, it appears to reuse the same iron in different enzymes to produce organic nitrogen for proteins.

The bacterium, Crocosphaera watsonii, is one of the few marine microbes that can convert nitrogen gas into organic nitrogen, which (just as it does on land) acts as fertilizer to stimulate plant growth in the ocean. So the ocean’s productivity is limited by nitrogen, which in turn is limited by scanty supplies of iron for the enzymes needed to make organic nitrogen.

This newfound capacity to conserve precious iron and use it in day-night shifts to satisfy two different metabolic demands reveals a surprising key to life on our planet, say scientists at Woods Hole Oceanographic Institution (WHOI) and Massachusetts Institute of Technology (MIT). They reported their findings Jan. 10 in the Proceedings of the National Academy of Sciences.

The scientists call the strategy “hot bunking,” referring to ships that sail with fewer bunks than sailors on board. The bunks are kept continuously hot, as sailors finishing night shifts hop into bunks newly emptied by sailors arising for day shifts.

Crocosphaera uses iron-containing nitrogenase enzymes to convert dissolved nitrogen gas into organic nitrogen (a process called nitrogen “fixing”). As the sun comes up, the bacterium breaks down these enzymes, releasing iron that can be used to make photosynthetic enzymes needed to convert dissolved carbon dioxide into carbohydrates. When the sun goes down, many of the photosynthetic enzymes are broken down, releasing the iron again to be recycled into nitrogenase.

Crocosphaera belongs to a subgroup of bacteria called cyanobacteria. “They have a bit of a Dr. Jekyll and Mr. Hyde lifestyle: photosynthetic by day and nitrogen-fixing by night,” said Mak Saito, a WHOI biogeochemist and lead author of the PNAS paper. Scientists previously knew cyanobacteria had this unusual dual-metabolic capacity, but they did not know how they could accomplish it with meager iron supplies.

The bacterium pays a price in energy needed to destroy and rebuild enzymes each day, but it’s worth it to maximize the use of scarce iron. The scientists estimate that by using the hot bunking strategy, the organism can survive with about 40 percent less iron than it would otherwise need. It allows Crocosphaera to thrive and produce life-sustaining organic nitrogen in iron-poor waters that would otherwise be less productive.

The surprising abundance of cyanobacteria in the ocean was discovered in the 1970s by WHOI microbiologist Stanley Watson and his colleagues Frederica Valois and John Waterbury and, who later continued their pioneering research to elucidate cyanobacteria’s critical ecological roles for the ocean and the planet. Crocosphaera watsonii is named after the late Dr. Watson.

Cyanobacteria have been notoriously difficult to culture in the laboratory. At WHOI, Waterbury, Valois and colleagues established methods to culture cyanobacteria routinely and reliably, and they maintain a collection of cyanobacteria cells in a new building called the Stanley W. Watson Laboratory. The collection is a sort of lending library of cells that provide cultures for scientists all over the world to study, including new generations of WHOI scientists working in the Watson Lab: Saito, graduate student Erin Bertrand, and lab associates Vladimir Bulygin and Dawn Moran.

They applied new biomedical research techniques to the study of the ocean: proteomics. As genomics studies the genes in an organism (its genome), proteomics studies the proteins made from instructions encoded in genes (its proteome).

“We wanted to know not only what could potentially be made from Crocosphaera’s genome, but also what proteins Crocosphaera actually did make,” Saito said.

A key part of the technique involves using mass spectrometers that distinguish and measure the various proteins in an organism by the infinitesimal differences in their masses. The researchers measured the inventory of iron-containing proteins during periods of dark and light. Nitrogen-fixing enzymes were largely absent during the day and present at night; iron-containing photosynthetic enzymes decreased during dark periods and reappeared during light periods. Thus, at any time of day, Crocsophaera required only about half the iron it would need if it maintained both sets of enzymes throughout the day.

To explore the implications of Crocosphaera’s hot bunking ability, scientists at MIT—Stephanie Dutkiewicz, Fanny Monteiro and Mick Follows—used a numerical model that simulates global ocean circulation, biochemistry, and ecosystem dynamics. The model showed that Crocosphaera’s ability to reduce its iron requirements allowed it to inhabit ocean regions with low levels of iron. It also allowed the same iron supply to support more growth of the cyanobacteria and more nitrogen fixation that supports other marine life higher up on the food chain.

Funding for the research came from the National Science Foundation, an Environmental Protection Agency Star Fellowship, the WHOI Ocean Life Institute, the NSF-funded Center for Microbial Research and Education, and the Center for Environmental Bioinorganic Chemistry at Princeton University. The paper was dedicated to co-author Vladimir Bulygin, who passed away in 2009.

The Woods Hole Oceanographic Institution is a private, independent organization in Falmouth, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate a basic understanding of the ocean's role in the changing global environment.

Media Relations | EurekAlert!
Further information:
http://www.whoi.edu

More articles from Ecology, The Environment and Conservation:

nachricht Upcycling 'fast fashion' to reduce waste and pollution
03.04.2017 | American Chemical Society

nachricht Litter is present throughout the world’s oceans: 1,220 species affected
27.03.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

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...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

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...

Im Focus: Deep inside Galaxy M87

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...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

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...

Im Focus: Microprocessors based on a layer of just three atoms

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...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

Scientist invents way to trigger artificial photosynthesis to clean air

26.04.2017 | Materials Sciences

Ammonium nitrogen input increases the synthesis of anticarcinogenic compounds in broccoli

26.04.2017 | Agricultural and Forestry Science

SwRI-led team discovers lull in Mars' giant impact history

26.04.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>