Like Pac-Man: The good bacteria is a predator and the bad bacteria as its prey. They play hide-and-seek.
[Jerusalem] Antibiotic-resistant bacteria, you scourge of the modern world, meet Bdellovibrio bacteriovorus, your nemesis. It is about to find you in your hiding place.
Whereas the majority of disease-causing bacteria in one’s body are neutralized by the immune system, a growing number of strains [1]that survive the body’s own assault prove resistant also to antibiotics.
It is called the “superbug crisis” and it is one of Hollywood’s favorite blockbuster bugaboos and one of the medical research’s holiest of holy grails.
Researchers at the University of British Columbia [2] have discovered that a rare gray-green clay known as Kisolite, used as medicine by the native Canadian Heiltsuk people for ages, contains antibacterial properties that could be used to treat antibiotic-resistant bacteria.
New research also presents evidence that that vaccines can protect the body [3]against recurrent infections.
Now, experiments performed by scientists at the Hebrew University of Jerusalem show that the bacterial predator Bdellovibrio bacteriovorus is a ruthlessly efficient killer of Gram-negative bacteria, the most well-known of which is the E. coli bacterium.
E.coli: the very same bacterium that afflicted dozens of Chipotle customers [4] in nine states with life-threatening infections late last year. It is present in soil and even in the human gut, where in healthy bodies a complex ecosystem of bacterial inhabitants usually controls it.
But when it doesn’t, B. bacteriovorus is a ferocious predator that penetrates its prey and devours it from within, simultaneously multiplying itself into four or six progeny. It then explodes its prey and begins its hunt for the next bacterium. In a drawing created by Delft University of Technology’s Dr. Felix Hol, one of the scientists trying to understand how B. bacteriovorus works, what looks like the moment of conception is, in fact, a moment of inception.
B. bacteriovorus is extremely quick. Barely one micrometer long, it can attain speeds of up to 160 micrometers per second, making it the “world champion” in speed swimming and ten times faster than the E. coli.
The catch: B. bacteriovorus is a ruthless killer in the lab, but for reasons previously unknown, it seemed much less efficient in the gut, where it counts. Why the difference?
“Bdellovibrio is known to be able to almost completely eradicate Gram negative bacteria such as E. coli,” Dr. Daniel Koster, the head researcher of a team from the Hebrew University of Jerusalem and from the Kavli Institute of Nanoscience at Delft, told The Media Line. “However, most of these studies have been performed in medium that is much unlike the natural habitat of bdello (soil) because soil is “fragmented,” consisting of many small microscopic interconnected chambers. Most previous studies were performed in homogeneous “continuous” media. Using microtechnology, we have tried to imitate the natural microscopic fragmented habitat of soil while following predator-prey dynamics under a microscope.”
E. coli, it turns out, can “conceal” itself from B. bacteriovorus in all the fragmented little parts. The hope, he says, is that the “findings have relevance because aside from soil, also the human gut and human tissues may be considered fragmented. If one wishes to use bdellovibrio as a potential future therapeutic, it may be of importance to take into consideration that the prey could survive better in such a fragmented landscape. It is an effect that one has to deal with.”
“B. bacteriovorus kills bacteria by a whole different mechanism of action than classical antibiotics, and as such, predatory bacteria might in the future constitute a viable alternative to these antibiotics,” he clarifies.
The team of researchers includes experts from microbiology, nanotechnology, ecology and biophysics, who were for the first time able to create fragmented landscapes on a microscale in which to study the bacteria.
Koster explained how E. coli was able to survive in the fragmented environment: “It seems that groups of E. coli ‘hide’ in the many corners of the fragmented environment, where they readily stick as bio-films that probably protect them against B. bacteriovorus. Our findings provide important information because in natural environments, such as our gut, the bacterium also lives in fragmented spaces.”
It is not yet known precisely how E. coli is able to defend itself against predatory bacteria, but the research contributes to the understanding of the behavior of the predatory bacteria, which could become a possible alternative to antibiotics in the future.
“In the future, predatory bacteria might for example be genetically modified to specifically target harmful bacteria, while leaving benign bacteria untouched. As such, B. bacteriovorus might be more selective than the antibiotics currently in use, and anti-bacterial treatment might not require the widespread extermination of the gut flora that is of importance to human health.”