Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Mystery Solved: Marine Microbe Is Source of Rare Nutrient

01.10.2009
A new study of microscopic marine microbes, called phytoplankton, by researchers at Woods Hole Oceanographic Institution (WHOI) and the University of South Carolina has solved a ten-year-old mystery about the source of an essential nutrient in the ocean.

Roughly a decade ago scientists discovered a rare form of organic phosphorus in marine organic matter. Not only were the researchers surprised to find this form of phosphorus, called phosphonate, but the concentrations in which it was found were very high, throughout the ocean. Scientists hypothesized that phosphonate is produced and consumed in the ocean, but no one understood where it came from and why it was so abundant.

Enter Trichodesmium. In 2006, WHOI biologist Sonya Dyhrman along with other WHOI colleagues initiated a field and laboratory study with this phytoplankton group, which is plentiful in low-nutrient warm tropical and subtropical waters. They discovered that Tricodesmium uses phosphonate to fuel its biological processes, including the fixation of carbon and nitrogen.

Their finding was unexpected because, chemically, phosphonate has a very strong carbon-phosphorus bond that requires a lot of energy, and a special set of genes, for Trichodesmium to break.

But Dyhrman and her colleagues’s discovery that Trichodesmium could use this form of phosphorus to support carbon and nitrogen fixation still didn’t solve the basic mystery: where were the high concentrations of this rare compound coming from?

Now, a study newly published in Nature Geoscience by Dyhrman and her colleague Claudia Benitez-Nelson, a marine geochemist with the University of South Carolina, has solved the long-standing mystery.

“We’ve been fascinated by these phosphonate compounds for a while,” said Benitez-Nelson. “Sonya and I decided that something had to be producing them, and we had to start looking at all these organisms to figure out who it was.”

“After culturing several different kinds of phytoplankton and analyzing them using nuclear magnetic resonance (NMR) spectroscopy, we found high concentrations of phosphonate in cultures of a specific Trichodesmium species – in fact an average of 10 percent of the cellular phosphorus is in the form of phosphonate. Ten percent may not sound like much, but this is the most phosphonate ever detected in a marine microbe,” said Dyhrman.

They selected many species of phytoplankton, grew them under different conditions in the laboratory, and then collected the cells onto filters. The filters were dried, and then analyzed by NMR.

“Our procedure is unique in that we are measuring filter samples directly using solid state 31P NMR” said Benitez-Nelson. “By carefully folding the filters, and using a non-destructive NMR method, we avoided subjecting the samples to anything that would break those phosphonate bonds. We got our detection limits down to extremely low levels.”

“When we first saw the phosphonate peak in the Trichodesmium culture, we were stunned, after a 10-year mystery it seemed ironic for Trichodesmium to both consume and produce this compound. We ran it again. We grew them under different nutrient conditions and, sure enough, the results were the same,” said Benitez-Nelson.

Trichodesmium plays an important ecological role in both the global carbon and nitrogen cycles. Like other phytoplankton, it photosynthesizes, drawing carbon dioxide out of the atmosphere to supply the Earth with oxygen and transforming carbon into a solid compound. Even more impressive, Trichodesmium can use nitrogen gas from the atmosphere and transform it into a compound that other organisms can consume. Because the open ocean is nitrogen-barren, nitrogen fixers such as Trichodesmium are critical to the marine food web, supplying nutrients, and stimulating more phytoplankton growth, which in turn moves more carbon and nitrogen through the food web.

This study determined that Trichodesmium transforms a percentage of all dissolved phosphorus into phosphonates – which is not readily consumed by other organisms. Living in low-phosphorus environments, this gives Trichodesmium a potential advantage over its competitors and, as nutrient supplies to the ocean change with climate, could shift the composition of phytoplankton communities in the ocean.

“Not only does this solve a mystery about where these forms of phosphorus are coming from, but the fact that it is Trichodesmium has ramifications for how the phosphorus cycle is linked to the cycling of carbon and nitrogen and how those cycles will function in the future ocean,” said Dyhrman.

There is a lot yet to be learned. “If we don’t understand what kinds of phosphorus are present in the ocean, we have no hope of predicting to what extent marine phytoplankton will sequester carbon in the future ocean,” said Dyhrman.

As ocean surface waters warm, scientists expect even greater limitations on the nutrient supply, particularly phosphorus. This could drive the production of phosphonate and the use of phosphonate as a phosphorus source. For Trichodesmium, which can use phosphonate, this scenario could be beneficial, and, for humans concerned about climate change, it could enhance the extraction of carbon from the ocean. However, Dyhrman and colleagues warn, if the phosphonate used by Trichodesmium is a methylated form, it could produce methane – a powerful greenhouse gas.

It is an interesting wrinkle that will be the focus of future research.

This work was funded by the National Science Foundation and WHOI.

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 oceans and their interaction with the Earth as a whole, and to communicate a basic understanding of the oceans’ role in the changing global environment.

WHOI Media Relations | Newswise Science News
Further information:
http://www.whoi.edu

More articles from Earth Sciences:

nachricht Impacts of mass coral die-off on Indian Ocean reefs revealed
21.02.2017 | University of Exeter

nachricht How much biomass grows in the savannah?
16.02.2017 | Friedrich-Schiller-Universität Jena

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Microhotplates for a smart gas sensor

22.02.2017 | Power and Electrical Engineering

Scientists unlock ability to generate new sensory hair cells

22.02.2017 | Life Sciences

Prediction: More gas-giants will be found orbiting Sun-like stars

22.02.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>