Featured Research

from universities, journals, and other organizations

SAR11, oceans' most abundant organism, has ability to create methane

Date:
July 7, 2014
Source:
Oregon State University
Summary:
The oxygen-rich surface waters of the world's major oceans are supersaturated with methane -- a powerful greenhouse gas that is roughly 20 times more potent than carbon dioxide -- yet little is known about the source of this methane. A new study demonstrates the ability of some strains of the oceans' most abundant organism -- SAR11 -- to generate methane as a byproduct of breaking down a compound for its phosphorus.

Open sea (stock image). SAR11 is the smallest free-living cell known and also has the smallest genome of any independent cell. It dominates life in the oceans and plays a huge role in the cycling of carbon on Earth. These bacteria are so dominant that their combined weight exceeds that of all the fish in the world's oceans. A milliliter of seawater might contain 500,000 of these cells.
Credit: © shime / Fotolia

The oxygen-rich surface waters of the world's major oceans are supersaturated with methane -- a powerful greenhouse gas that is roughly 20 times more potent than carbon dioxide -- yet little is known about the source of this methane.

Now a new study by researchers at Oregon State University demonstrates the ability of some strains of the oceans' most abundant organism -- SAR11 -- to generate methane as a byproduct of breaking down a compound for its phosphorus.

Results of the study are being published this week in Nature Communications. It was funded by the National Science Foundation and the Gordon and Betty Moore Foundation.

"Anaerobic methane biogenesis was the only process known to produce methane in the oceans and that requires environments with very low levels of oxygen," said Angelicque "Angel" White, a researcher in OSU's College of Earth, Ocean, and Atmospheric Sciences and co-author on the study. "In the vast central gyres of the Pacific and Atlantic oceans, the surface waters have lots of oxygen from mixing with the atmosphere -- and yet they also have lots of methane, hence the term 'marine methane paradox.'

"We've now learned that certain strains of SAR11, when starved for phosphorus, turn to a compound known as methylphosphonic acid," White added. "The organisms produce enzymes that can break this compound apart, freeing up phosphorus that can be used for growth -- and leaving methane behind."

The discovery is an important piece of the puzzle in understanding Earth's methane cycle, scientists say. It builds on a series of studies conducted by researchers from several institutions around the world over the past several years.

Previous research has shown that adding methylphosphonic acid, or MPn, to seawater produces methane, though no one knew exactly how. Then a laboratory study led by David Karl of the University of Hawaii and OSU's White found that an organism called Trichodesmium could break down MPn and thus it could be a potential source of phosphorus, which is a critical mineral essential to every living organism.

However, Trichodesmium are rare in the marine environment and unlikely to be the only source for vast methane deposits in the surface waters.

So White turned to Steve Giovannoni, a distinguished professor of microbiology at OSU, who not only maintains the world's largest bank of SAR11 strains, but who also discovered and identified SAR11 in 1990. In a series of experiments, White, Giovannoni, and graduate students Paul Carini and Emily Campbell tested the capacity of different SAR11 strains to consume MPn and cleave off methane.

"We found that some did produce a methane byproduct, and some didn't," White said. "Just as some humans have a different capacity for breaking down compounds for nutrition than others, so do these organisms. The bottom line is that this shows phosphate-starved bacterioplankton have the capability of producing methane and doing so in oxygen-rich waters."

SAR11 is the smallest free-living cell known and also has the smallest genome, or genetic structure, of any independent cell. Yet it dominates life in the oceans, thrives where most other cells would die, and plays a huge role in the cycling of carbon on Earth.

These bacteria are so dominant that their combined weight exceeds that of all the fish in the world's oceans, scientists say. In a marine environment that's low in nutrients and other resources, they are able to survive and replicate in extraordinary numbers -- a milliliter of seawater, for instance, might contain 500,000 of these cells.

"The ocean is a competitive environment and these bacteria apparently won the race," said Giovannoni, a professor in OSU's College of Science. "Our analysis of the SAR11 genome indicates that they became the dominant life form in the oceans largely by being the simplest."

"Their ability to cleave off methane is an interesting finding because it provides a partial explanation for why methane is so abundant in the high-oxygen waters of the mid-ocean regions," Giovannoni added. "Just how much they contribute to the methane budget still needs to be determined."

Since the discovery of SAR11, scientists have been interested in their role in Earth's carbon budget. Now their possible implication in methane creation gives the study of these bacteria new importance.


Story Source:

The above story is based on materials provided by Oregon State University. Note: Materials may be edited for content and length.


Journal Reference:

  1. Paul Carini, Angelicque E. White, Emily O. Campbell, Stephen J. Giovannoni. Methane production by phosphate-starved SAR11 chemoheterotrophic marine bacteria. Nature Communications, 2014; 5 DOI: 10.1038/ncomms5346

Cite This Page:

Oregon State University. "SAR11, oceans' most abundant organism, has ability to create methane." ScienceDaily. ScienceDaily, 7 July 2014. <www.sciencedaily.com/releases/2014/07/140707171113.htm>.
Oregon State University. (2014, July 7). SAR11, oceans' most abundant organism, has ability to create methane. ScienceDaily. Retrieved October 23, 2014 from www.sciencedaily.com/releases/2014/07/140707171113.htm
Oregon State University. "SAR11, oceans' most abundant organism, has ability to create methane." ScienceDaily. www.sciencedaily.com/releases/2014/07/140707171113.htm (accessed October 23, 2014).

Share This



More Earth & Climate News

Thursday, October 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

San Diego Zoo's White Rhinos Provide Hope for the Critically Endangered Species

San Diego Zoo's White Rhinos Provide Hope for the Critically Endangered Species

Reuters - Light News Video Online (Oct. 22, 2014) — The pair of rare white northern rhinos bring hope for their species as only six remain in the world. Elly Park reports. Video provided by Reuters
Powered by NewsLook.com
Trick-or-Treating Banned Because of Polar Bears

Trick-or-Treating Banned Because of Polar Bears

Buzz60 (Oct. 21, 2014) — Mother Nature is pulling a trick on the kids of Arviat, Canada. As Mara Montalbano (@maramontalbano) tells us, the effects of global warming caused the town to ban trick-or-treating this Halloween. Video provided by Buzz60
Powered by NewsLook.com
Traditional Farming Methods Gaining Ground in Mali

Traditional Farming Methods Gaining Ground in Mali

AFP (Oct. 20, 2014) — He is leading a one man agricultural revolution in Mali - Oumar Diatabe uses traditional farming methods to get the most out of his land and is teaching others across the country how to do the same. Duration: 01:44 Video provided by AFP
Powered by NewsLook.com
How Detroit's Money Woes Led To U.N.-Condemned Water Cutoffs

How Detroit's Money Woes Led To U.N.-Condemned Water Cutoffs

Newsy (Oct. 20, 2014) — The United Nations says water is a human right, but should it be free? Detroit has cut off water to residents who can't pay, and the U.N. isn't happy. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins