Corporate Banner
Satellite Banner
Scientific Communities
Become a Member | Sign in
Home>News>This Article

Extracellular Vesicles Produced by Ocean Microbes

Published: Monday, January 13, 2014
Last Updated: Sunday, January 12, 2014
Bookmark and Share
Cyanobacteria produce and release vesicles that can serve as food parcels for marine organisms.

Marine cyanobacteria - tiny ocean plants that produce oxygen and make organic carbon using sunlight and CO2 - are primary engines of Earth’s biogeochemical and nutrient cycles. They nourish other organisms through the provision of oxygen and with their own body mass, which forms the base of the ocean food chain.

Now scientists at MIT have discovered another dimension of the outsized role played by these tiny cells: The cyanobacteria continually produce and release vesicles, spherical packages containing carbon and other nutrients that can serve as food parcels for marine organisms.

The vesicles also contain DNA, likely providing a means of gene transfer within and among communities of similar bacteria, and they may even act as decoys for deflecting viruses.

In a paper published this week in Science, postdoc Steven Biller, Professor Sallie (Penny) Chisholm, and co-authors report the discovery of large numbers of extracellular vesicles associated with the two most abundant types of cyanobacteria, Prochlorococcus and Synechoccocus. The scientists found the vesicles (each about 100 nanometers in diameter) suspended in cultures of the cyanobacteria as well as in seawater samples taken from both the nutrient-rich coastal waters of New England and the nutrient-sparse waters of the Sargasso Sea.

Although extracellular vesicles were discovered in 1967 and have been studied in human-related bacteria, this is the first evidence of their existence in the ocean.

“The finding that vesicles are so abundant in the oceans really expands the context in which we need to understand these structures,” says Biller, first author on the Science paper. “Vesicles are a previously unrecognized and unexplored component of the dissolved organic carbon in marine ecosystems, and they could prove to be an important vehicle for genetic and biogeochemical exchange in the oceans.”

Billions and billions of vesicles
Biller’s metagenomic analysis of the vesicles taken from the seawater revealed DNA from a diverse array of bacteria, suggesting that vesicle production is common to many marine microbes. The researchers estimate the global production of vesicles by Prochlorococcus alone at a billion billion billion per day - representing a notable addition of carbon to the scarce nutrient pool of the open seas.

Lab experiments showed that the vesicles are stable, lasting two weeks or more, and that the organic carbon they contain provides enough nutrients to support the growth of nonphotosynthetic bacteria.

Given the dearth of nutrients in the open ocean, the daily release by an organism of a packet one-sixth the size of its own body is puzzling, Chisholm says. Prochlorococcus has lost the ability to neutralize certain chemicals and depends on nonphotosynthetic bacteria to break down chemicals that would otherwise act as toxins. It’s possible the vesicle “snack packets” help make this relationship mutually beneficial.

“Prochlorococcus is the smallest genome that can make organic carbon from sunlight and carbon dioxide and it’s packaging this carbon and releasing it into the seawater around it,” says Chisholm, the Lee and Geraldine Martin Professor of Environmental Studies in MIT’s Department of Civil and Environmental Engineering and Department of Biology, who is lead investigator of the study. “There must be an evolutionary advantage to doing this. Our challenge is to figure out what it is.”

Because the vesicles also contain DNA and RNA, the researchers surmise they could play a role in horizontal gene transfer, a means for developing genetic diversity and sharing ecologically useful genes among the Prochlorococcus metapopulation.

Marine decoy
But perhaps the most unusual potential role of the vesicles is as a decoy for predators: Electron microscopy shows phages (viruses that attack bacteria) attached to vesicles. When a phage injects its DNA into the vesicle (making it impossible for the phage to reproduce in a living cell), it renders the phage inactive, according to Biller, who says the vesicles could be acting like chaff released by a fighter jet to divert missile attacks. A phage attached to a vesicle is effectively taken out of the battle, providing a creative means of deterrence.

“Marine cyanobacteria of the genera Prochlorococcus and Synechoccocus are the two most abundant phototrophs,” says biologist David Scanlan, a professor at the University of Warwick who was not involved in this research. “By releasing extracellular vesicles these organisms shed new light on the importance of such particles in the largest ecosystem on Earth - the open ocean - with implications for marine carbon cycling, mechanisms of horizontal gene transfer, and as a defense against phage attack.”

The vesicles first came to Chisholm’s attention in 2008 when Anne Thompson, then a graduate student, noticed little “blebs” on the surface of Prochlorococcus cells while using electron microscopy. Neither she nor Chisholm nor other ocean biologists who saw the photo were able to identify the spheres. But Biller, who joined Chisholm’s lab in 2010 after completing his graduate studies on soil bacteria, recognized them as vesicles, and began the study resulting in the Science paper.

In addition to Biller, Chisholm, and Thompson, other co-authors on the paper are Florence Schubotz and Roger Summons, of MIT’s Department of Earth, Atmospheric and Planetary Sciences, and Sara Roggensack, a former MIT lab technician who is now a graduate student at Tufts University.

Further Information
Access to this exclusive content is for Technology Networks Premium members only.

Join Technology Networks Premium for free access to:

  • Exclusive articles
  • Presentations from international conferences
  • Over 2,600+ scientific posters on ePosters
  • More Than 3,800+ scientific videos on LabTube
  • 35 community eNewsletters

Sign In

Forgotten your details? Click Here
If you are not a member you can join here

*Please note: By logging into you agree to accept the use of cookies. To find out more about the cookies we use and how to delete them, see our privacy policy.

Related Content

Messing With The Monsoon
Manmade aerosols can alter rainfall in the world’s most populous region.
Friday, October 02, 2015
A Natural Light Switch
MIT scientists identify and map the protein behind a light-sensing mechanism.
Tuesday, September 29, 2015
Biologists Find Unexpected Role for Amyloid-Forming Protein
Yeast protein could offer clues to how Alzheimer’s plaques form in the brain.
Monday, September 28, 2015
How Flu Viruses Gain The Ability To Spread
New study reveals the soft palate is a key site for evolution of airborne transmissibility.
Friday, September 25, 2015
Viruses Join Fight Against Harmful Bacteria
Engineered viruses could combat human disease and improve food safety.
Friday, September 25, 2015
Targeting DNA
Protein-based sensor could detect viral infection or kill cancer cells.
Tuesday, September 22, 2015
Targeting DNA
Protein-based sensor could detect viral infection or kill cancer cells.
Tuesday, September 22, 2015
Personalized Heart Models For Surgical Planning
System can convert MRI scans into 3D-printed, physical models in a few hours.
Friday, September 18, 2015
Learning About Human Health Using Sewage
PhD student Mariana Matus studies human waste to understand individual and community health.
Thursday, September 17, 2015
Intensity of Desert Storms May Affect Ocean Phytoplankton
MIT study finds phytoplankton are extremely sensitive to changing levels of desert dust.
Tuesday, September 01, 2015
Searching Big Data Faster
Theoretical analysis could expand applications of accelerated searching in biology, other fields.
Thursday, August 27, 2015
Protein Found to Play a Key Role in Blocking Pathogen Survival
Calprotectin fends off microbial invaders by limiting access to iron, an important nutrient.
Wednesday, August 26, 2015
A Metabolic Master Switch Underlying Human Obesity
Researchers find pathway that controls metabolism by prompting fat cells to store or burn fat.
Friday, August 21, 2015
Capturing Cell Growth in 3-D
Spinout’s microfluidics device better models how cancer and other cells interact in the body.
Monday, August 17, 2015
Better Estimates of Worldwide Mercury Pollution
New findings show Asia produces twice as much mercury emissions as previously thought.
Thursday, August 13, 2015
Scientific News
Fixing Holes in the Heart Without Invasive Surgery
UV-light enabled catheter is a medical device which represents a major shift in how cardiac defects are repaired.
Chromosomal Chaos
Penn study forms basis for future precision medicine approaches for Sezary syndrome
Enzyme Malfunction May be Why Binge Drinking Can Lead to Alcoholism
A new study in mice shows that restoring the synthesis of a key brain chemical tied to inhibiting addictive behavior may help prevent alcohol cravings following binge drinking.
Key to Natural Detoxifier’s Reactivity Discovered
Results have implications for health, drug design and chemical synthesis.
New Treatment for Obesity Developed
Researchers at the University of Liverpool, working with a global healthcare company, have helped develop a new treatment for obesity.
New Protein Found in Immune Cells
Immunobiologists from the University of Freiburg discover Kidins220/ARMS in B cells and demonstrate its functions.
Will Brain Palpation Soon Be Possible?
Researchers have developed non-invasive brain imaging technique which provides the same information as physical palpation.
Shaking Up the Foundations of Epigenetics
Researchers at the Centre for Genomic Regulation (CRG) and the University of Barcelona (UB) published a study that challenges some of the current beliefs about epigenetics.
Groundbreaking Computer Program Diagnoses Cancer in Two Days
Researchers have combined genetics with computer science and created a new diagnostic technology can with 85 per cent certainty identify the source of the disease and thus target treatment and, ultimately, improve the prognosis for the patient.
Michigan Researchers Use Raman Spectroscopy
inVia confocal Raman microscope used in the study of various childhood diseases.
Scroll Up
Scroll Down
Skyscraper Banner

Skyscraper Banner
Go to LabTube
Go to eposters
Access to the latest scientific news
Exclusive articles
Upload and share your posters on ePosters
Latest presentations and webinars
View a library of 1,800+ scientific and medical posters
2,600+ scientific and medical posters
A library of 2,500+ scientific videos on LabTube
3,800+ scientific videos