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 reports about: > Broad Institute > CEE > Gates Foundation > Oceanographic Institution > Weapon-wielding > Woods Hole Oceanographic > antibiotic producers > antibiotics doubly surprising > bacterial pathogens > social interaction > social structure > social structures > sophisticated social structure
Could this protein protect people against coronary artery disease?
17.11.2017 | University of North Carolina Health Care
Microbial resident enables beetles to feed on a leafy diet
17.11.2017 | Max-Planck-Institut für chemische Ökologie
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
17.11.2017 | Physics and Astronomy
17.11.2017 | Health and Medicine
17.11.2017 | Studies and Analyses