Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Weapon-wielding marine microbes may protect populations from foes

07.09.2012
In some populations, natural antibiotics are produced by a few individuals whose closest relatives carry genes conferring resistance.

Competition is a strong driving force of evolution for organisms of all sizes: Those individuals best equipped to obtain resources adapt and reproduce, while others may fall by the wayside. Many organisms — mammals, birds and insects, for instance — also form cooperative social structures that allow resources to be defended and shared within a population.

But surprisingly, even microbes, which are thought to thrive only when able to win the battle for resources against those nearest to them, have a somewhat sophisticated social structure that relies on cooperation, according to MIT scientists. These researchers have recently found evidence that some ocean microbes wield chemical weapons that are harmless to close relatives within their own population, but deadly to outsiders.

The weapons are natural antibiotics produced by a few individuals whose closest relatives carry genes that make them resistant. The researchers believe that the few antibiotic producers are acting as protectors of the many, using the antibiotics to defend the population from competitors or to attack neighboring populations.

“We can’t know what the environmental interactions really are, because microbes are too small for us to observe them in action,” says Professor Martin Polz of MIT’s Department of Civil and Environmental Engineering (CEE), lead investigator on a study appearing in this week’s issue of the journal Science. “But we think the antibiotics play a role in fending off competitors. Of course, those competitors could also produce antibiotics. It’s a potential arms race out there.”

A population of ocean microbes is defined by genetic likeness and shared ecological activities, such as their preferred microhabitat — say, free-floating or attached to algae — or their ability to harvest a particular substance. Because close relatives within populations have very similar if not identical resource requirements, they must by necessity also be strong competitors with one another.

This makes cooperation involving antibiotics doubly surprising, because the ability to produce antibiotics is a classic example of a “selfish” gene that ought to increase the fitness — or reproductive rate — of the individual carrying the gene. In a strictly competitive environment, the microbe would use this advantage against its closest relatives. But now it looks as if this competition is modulated by social interactions where antibiotics produced by a few individuals act as “public goods”: items that benefit the group, rather than just the individual.

This differentiation of populations into individuals that produce antibiotics and those that are resistant is one of the first demonstrations that microbial populations engage in a division of labor by social role. This observation also provides an explanation for why so many genes are patchily distributed across genomes of closely related microbes. At least some of these genes may be responsible for creating tightly knit social units of bacteria in the wild.

“It’s easy to imagine bacteria in the environment as selfish creatures capable only of reproducing as fast as conditions allow, without any social organization,” says Otto Cordero, a CEE postdoc who is a first author on the Science paper. “But that is the mind-blowing part: Bacterial wars are organized along the lines of populations, which are groups of closely related individuals with similar ecological activities.”

The study also uncovers an untapped source of antibiotics that could have the potential to aid in the fight against human bacterial pathogens, which are rapidly developing resistance to the few antibiotics in use — nearly all of which are produced by soil-living bacteria.

“This paper [shows] that bacteria work together in complex relationships that have largely been underappreciated by the research community as a whole,” says Gerry Wright, a professor of biochemistry and biomedical sciences and director of the Michael G. DeGroote Institute for Infectious Disease Research at McMaster University. He adds, “The impact on our understanding of resistance is critical. … This work is really important in showing that we can, in fact, study these big questions in populations of natural bacteria, and we can learn something important about how we use antibiotics and avoid resistance in the clinic.”

To obtain these findings, the researchers tested about 35,000 interactions among pairs of 185 strains of Vibrionaceae bacteria populations taken from the ocean. They found that 44 percent of the strains were able to inhibit the growth of at least one other strain and 86 percent were inhibited by at least one other strain. They then used genomic analysis to determine genetic kinship.

Co-authors include Sarah Proehl, Lynn Ngo and Fatima Hussain, MIT alumnae who performed much of the testing during their undergraduate years through the MIT Undergraduate Research Opportunities Program. Other co-authors are former MIT postdocs Hans Wildschutte and Benjamin Kirkup, Frederique Le Roux of the IFREMER Laboratory of Genetics and Pathology in France, and Tracy Mincer of Woods Hole Oceanographic Institution.

Funding was provided by the Moore Foundation, the Broad Institute, the National Science Foundation and the Netherlands Organization for Scientific Research.

Sarah McDonnell | EurekAlert!
Further information:
http://www.mit.edu

More articles from Life Sciences:

nachricht Water forms 'spine of hydration' around DNA, group finds
26.05.2017 | Cornell University

nachricht How herpesviruses win the footrace against the immune system
26.05.2017 | Helmholtz-Zentrum für Infektionsforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can the immune system be boosted against Staphylococcus aureus by delivery of messenger RNA?

Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.

Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

How herpesviruses win the footrace against the immune system

26.05.2017 | Life Sciences

Water forms 'spine of hydration' around DNA, group finds

26.05.2017 | Life Sciences

First Juno science results supported by University of Leicester's Jupiter 'forecast'

26.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>