Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Microbe fixes nitrogen at a blistering 92 C

18.12.2006
May offer clues to evolution of nitrogen fixation

A heat-loving archaeon capable of fixing nitrogen at a surprisingly hot 92 degrees Celsius, or 198 Fahrenheit, may represent Earth’s earliest lineages of organisms capable of nitrogen fixation, perhaps even preceding the kinds of bacteria today's plants and animals rely on to fix nitrogen.

The genetic analysis reported in the Dec. 15 issue of Science supports the notion that the gene needed to produce nitrogenase – an enzyme capable of converting nitrogen gas, that's unusable by life, to a form like ammonia that is useable – arose before the three main branches of life – bacteria, archaea and eukaryotes – diverged some 3.5 billion years ago, according to oceanographer Mausmi Mehta, who recently received her doctorate from the UW, and John Baross, UW professor of oceanography. This is opposed to the theory that the nitrogenase system arose within archaea and was later transferred laterally to bacteria.

"There's been lots of evidence that point to high-temperature archaea as the first life on Earth but the question has been, 'So why can’t we find archaea that fix nitrogen at high temperatures"'" says Baross, who’s been on a 20-year quest to find just such a microbe. Archaea are single-celled organisms that live under extreme environmental conditions, such as the high temperatures and crushing pressures below the seafloor. If heat-loving archaea were the first life on the planet, they would have needed a usable source of nitrogen, Baross says.

Known as FS406-22 because of the fluid and culture samples it came from, the archaeon discovered by the UW researchers is the first from a deep-sea hydrothermal vent that can fix nitrogen, says Mehta, first author on the Science paper.

It was collected at Axial Volcano on the Juan de Fuca Ridge off the coast of Washington and Oregon. Fixing nitrogen at 92 C smashes the previous record by 28 C, a record held by Methanothermococcus thermolithotrophicus, an archaeon that was isolated from geothermally heated sand near an Italian beach and fixes nitrogen at temperatures up to 64 C.

Nitrogen is necessary for all life because it is an essential part of amino acids and proteins. To be used by organisms, gaseous nitrogen must be converted to other compounds, or "fixed," which can only be done by certain bacteria and specific archaea. Nitrogen can be fixed into ammonia, nitrate and other products that can be used by land and sea plants, which in turn are eaten by higher animals.

Today's oceans contain nitrogen both as a dissolved gas and as nitrate. Ocean water that percolates down into the seafloor can pick up enough heat from volcanism deep in the earth to cause the fixed nitrogen to revert to its gaseous form. Venting water hotter than 30 C contains very little nitrate so organisms in areas where the subseafloor temperatures are higher would lack nitrogen in a form they can use.

The discovery of FS406-22's nitrogen fixing capabilities at 92 C, therefore, widens the realm of where life can grow in the subseafloor biosphere and other nitrogen-limited ecosystems, perhaps even on other planets, Mehta says.

Scientists have speculated since 1981 that nitrogen fixation was occurring at hydrothermal vents because vent animals had completely different nitrogen isotope ratios than non-vent deep sea animals.

The work that led to FS406-22 was supported by Washington Sea Grant, based at the UW, and the NASA Astrobiology Institute. Mehta worked five years doing some 600 enrichments, with FS406-22 being the only one she was could wean off fixed nitrogen completely. An unimpressive looking sphere of a microbe, FS406-22 is able to grow with gaseous nitrogen as its sole source of nitrogen at temperatures ranging from 58 to 92 C, with the fastest growth at 90 C.

The genetic analysis shows FS406-22 as having one of the deepest-rooted genes and the most primordial characteristics in terms of gene sequence, Baross says.

"We propose that among diazotrophic archaea, the nitrogenase from FS406-22 might have retained the most ancient characteristics, possibly derived from a nitrogenase present in the last common ancestor of modern life," the co-authors conclude in their report.

Sandra Hines | EurekAlert!
Further information:
http://www.washington.edu

More articles from Ecology, The Environment and Conservation:

nachricht Machine learning helps predict worldwide plant-conservation priorities
04.12.2018 | Ohio State University

nachricht From the Arctic to the tropics: researchers present a unique database on Earth’s vegetation
20.11.2018 | Martin-Luther-Universität Halle-Wittenberg

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: An energy-efficient way to stay warm: Sew high-tech heating patches to your clothes

Personal patches could reduce energy waste in buildings, Rutgers-led study says

What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...

Im Focus: Lethal combination: Drug cocktail turns off the juice to cancer cells

A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.

The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...

Im Focus: New Foldable Drone Flies through Narrow Holes in Rescue Missions

A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.

Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...

Im Focus: Topological material switched off and on for the first time

Key advance for future topological transistors

Over the last decade, there has been much excitement about the discovery, recognised by the Nobel Prize in Physics only two years ago, that there are two types...

Im Focus: Researchers develop method to transfer entire 2D circuits to any smooth surface

What if a sensor sensing a thing could be part of the thing itself? Rice University engineers believe they have a two-dimensional solution to do just that.

Rice engineers led by materials scientists Pulickel Ajayan and Jun Lou have developed a method to make atom-flat sensors that seamlessly integrate with devices...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

New Plastics Economy Investor Forum - Meeting Point for Innovations

10.12.2018 | Event News

EGU 2019 meeting: Media registration now open

06.12.2018 | Event News

 
Latest News

Magic number colloidal clusters

13.12.2018 | Life Sciences

UNLV study unlocks clues to how planets form

13.12.2018 | Physics and Astronomy

Live from the ocean research vessel Atlantis

13.12.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>