Vampire-like Predatory Bacteria Could Become A Living Antibiotic

By Douglas Main | November 2, 2011 2:07 pm

The bacterium Micavibrio aeruginosavorus (yellow), leeching
on a Pseudomonas aeruginosa bacterium (purple).

What’s the news: If bacteria had blood, the predatory microbe Micavibrio aeruginosavorus would essentially be a vampire: it subsists by hunting down other bugs, attaching to them, and sucking their life out. For the first time, researchers have sequenced the genome of this strange microorganism, which was first identified decades ago in sewage water. The sequence will help better understand the unique bacterium, which has potential to be used as a “living antibiotic” due to its ability to attack drug-resistant biofilms and its apparent fondness for dining on pathogens.

Anatomy of a Vampire:

  • The bacterium has an interesting multi-stage life history. During its migratory phase it sprouts a single flagellum and goes hunting for prey. Once it find a delectable morsel of bacterium, it attacks and irreversibly attaches to the surface, and sucks out all of the good stuff: carbohydrates, amino acids, proteins, DNA, etc.
  • Sated, the cell divides in two via binary fission, and the now-depleted host is left for dead.

Hungry for Pathogens: 

  • M. aeruginosavorus cannot be grown by itself; it must be cultured along with another bacteria to feed upon. A 2006 study found that it only grew upon three bacterial species, all of which can cause pneumonia-like disease in humans. A more recent study showed that it can prey upon a wider variety of microbes, most of them potentially pathogenic, like E. coli.
  • These studies also found that M. aeruginosavorus has a knack for disrupting biofilms, the dense collection of bacteria that cause harmful plaques on teeth and medical implants alike, and can be up to 1,000 more resistant to antibiotics than free-swimming bugs.
  • The bacteria can also swim through viscous fluids like mucous and kills Pseudomonas aeruginosa, the bacterium that can colonize lungs of cystic fibrosis patients and form a glue-like film.
  • These qualities have caught the eye of researchers who think it could be used as a living antibiotic to treat biofilms and various types of drug-resistant bacteria, which are a growing problem in medicine. Sequencing the organism’s genome is an important step in understanding its biochemistry and how it preys on other microbes.

Clues From the Vampire Code: 

  • The new study found that each phase of life involves the use (or expression) of different sets of genes. The migratory/hunting phase involves many segments that code for flagellum formation and genes involved in quorum sensing. The attachment phase involves a wide variety of secreted chemicals and enzymes that facilitate the flow of materials from the host.
  • Micavibrio aeruginosavorus possesses no genes for amino acid transporters, a rather rare trait only seen in a few other bacterial species that depend heavily upon their host to help them shuttle these vital protein building-blocks. This absence helps explain the bacterium’s dependence on a narrow range of prey, from which it directly steals amino acids. Although it remains unclear exactly how the microbe attaches to and infiltrates other cells.

The Future Holds:

  • The range of microbes upon which Micavibrio aeruginosavorus can survive is expanding; after being kept in laboratory conditions for years it has apparently evolved a more diverse diet. If this expansion continues, that could be a real problem for its use as an antibiotic; it could begin to eat beneficial gut bacteria, for example.
  • Researchers claim it is harmless to friendly gut microbes, but it hasn’t been tested on all the varieties of bacteria present in humans.
  • Several important steps must be taken before testing in people, like learning more about what traits makes another bacteria tasty to Micavibrio aeruginosavorus. Researchers speculate the bacterium may need to be genetically altered in order to go after specific pathogens, or to reduce the risk of it causing unforeseen complications.

Reference: Zhang Wang, Daniel E Kadouri, Martin Wu. Genomic insights into an obligate epibiotic bacterial predator: Micavibrio aeruginosavorus ARL-13. BMC Genomics, 2011; 12 (1): 453 DOI: 10.1186/1471-2164-12-453

Image credit: University of Virginia

  • D Braithwaite

    All nonsense speculation.

    Even if the bacteria were so heavily modified as to be undetectable by the human immune system, which would normally mount a massive assault on these organisms, how would it be cleared? How would the dose be controlled? How would you control their proliferation or trigger their apoptosis? And if you were to terminate treatment by killing them, how would you prevent the oxidising contents of their cytoplasm from damaging human tissues?

    The technology required to implement this “living antibiotic” is so far away from modern techniques as to be firmly in the realm of science fiction. It’s a novel organism and nothing more. Interesting sequences, proteins and concepts may well emerge from research, but to suggest this may become a clinical treatment is science sensationalism at its very worst.

  • Chrysoprace

    The article never claimed this would happen next Wednesday…

  • Gil

    @1 I imagine they have a starting point on many of those issues with phage therapy research.

  • Harry

    This sounds promising until you consider that, after the Micavibrio aeruginosavorus was used once as an antibiotic, the human body would produce antibodies against it so that there would be rapid clearance from the body upon any use a few weeks later. It becomes a one-time-only antibiotic. Likewise, this immunological response problem limits the use of bacteriophage viruses to attack pathogenic bacterial species in the human body (an idea first considered sixty years ago). These both (Micavibrio aeruginosavorus and phages) are one-shot wonders as therapy, which is not what makes for a good antibiotic.

  • Bryan Times

    They need to genetically engineer a “Poison Pill” into these vampire bacteria. Something that is not harmful to humans, but is lethal to the bacteria. That way they can introduce it in people, and be able to kill it off once it’s work is done, or if it begins attacking normal, healthy cells.

  • TheCritic

    @D Braith

    The technology and knowledge to control bacterial populations purposefully placed into humans is so widespread and available that college and even high school students that participate in synthetic biology competitions could tell you it’s possible. Plenty of bacteria have population controls of their own by sensing their own density, and when the density gets too high, some will kill themselves through apoptosis. This gene has long since been identified and the process is well known and experimented with when it comes to bacterial control. Here was one method of population control. There are plenty other methods out there.
    The oxidizing contents? If significant enough to cause damage, then surely the species has catalase in its own cytoplasm which upon release of all the cytoplasm would at least play a certain part in neutralizing it. Not to mention the numerous ways our own cells deal with oxidizing compounds. An infection large enough to cause damage due to total oxidizing contents released would cause more problems than just tissue damage from the oxidizing chemicals. An infection that large would probably already indicate your immune system is severely suppressed, and you may be heading for septic shock very shortly.

  • amphiox

    @4 Harry;

    There are many, many therapies that are one-shots which any particular patient can only have once. That fact by itself does not make a potential therapy invalid or un-useful.

    If all you need is one shot to save someone’s life, and all you have is one shot, you take it.

    (For example, many forms of radiation therapy are one-shot. There is a lifetime limit to how much radiation a person can safely have, and for many cancers, you go straight up to that limit on your first therapeutic regimen. If the therapy fails or the cancer recurs, you can’t give radiation again. But if you succeed and cure the cancer, you don’t have to.)

    And of course they may be a multitude of potential ways to get around the immune memory problem.

  • gendotte

    Having a mother who was killed by pseudomonis sepsis, one time just might be enough.

  • Christina Viering

    Interesting potential.

  • Jim Suhrer

    (Sorry-typo) “plague” I believe should be “plaque” — second bullet after “Hungry for Pathogens”.
    By the way, interesting article.

    Ed: fixed


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