Bacteria can ‘divide and conquer’ to vanquish their enemies

A tactic that could be exploited to fight infections.

Retaliation: Toxin producers produce a small amount of toxin all the time (green and red cells). A provoking toxin-producer (right) is sensed through its released toxin by its competitor (left), which in turn becomes more aggressive by producing more toxin, causing significant damage to the provoker. The panels at the bottom show the difference in outcome when a strain is non-provoking (green colony, left panel) or provoking (green colony, right panel) against the same competitor (unlabelled colony in both panels).
Retaliation: Toxin producers produce a small amount of toxin all the time (green and red cells). A provoking toxin-producer (right) is sensed through its released toxin by its competitor (left), which in turn becomes more aggressive by producing more toxin, causing significant damage to the provoker. The panels at the bottom show the difference in outcome when a strain is non-provoking (green colony, left panel) or provoking (green colony, right panel) against the same competitor (unlabelled colony in both panels).

Bacteria frequently take part in ‘warfare’ by discharging toxins or different molecules that harm or slaughter contending strains. This war for assets happens in most bacterial networks, for example, those living normally in our gut or those that cause diseases.

And in addition, creating toxins that specifically execute their rivals, bacteria can discharge toxins that can go about as ‘provoking agents’. These toxins influence different strains to build their aggression levels by boosting their poisonous reaction.

In another investigation, drove by Imperial College London and the University of Oxford, specialists utilized a combination of analyses and numerical models to perceive what happens when bacteria incite their rivals.

Divide and conquer: A provoking toxin producer (right) is sensed through its released toxin by its competitors (left); the competitors are closer to one another than to the provoking strain. Provocation leads to increase in aggression in the competing mixed colony, but in this case the produced toxins wipe out the two competing strains while affecting the provoker less. The panels at the bottom show the difference in outcome when a strain is non-provoking (unlabelled colony, left panel) or provoking (unlabelled colony, right panel) against the same set of competitors (red/green colony in both panels).
Divide and conquer: A provoking toxin producer (right) is sensed through its released toxin by its competitors (left); the competitors are closer to one another than to the provoking strain. Provocation leads to increase in aggression in the competing mixed colony, but in this case the produced toxins wipe out the two competing strains while affecting the provoker less. The panels at the bottom show the difference in outcome when a strain is non-provoking (unlabelled colony, left panel) or provoking (unlabelled colony, right panel) against the same set of competitors (red/green colony in both panels).

Scientists discovered that when used against a single competitor, provocation backfires: the provoked strain mounts a strong toxic counterattack and harms the provoking strain.

In any case, when there is at least three strains exhibit, provocation causes the other contending strains to expand their aggression and attack each other. This can prompt the contenders wiping each other out, particularly when the inciting strain is protected from, or impervious to, their poisons.

Senior author Dr. Despoina Mavridou, from the Department of Life Sciences at Imperial, said: “This behavior is strongly reminiscent of the human ‘divide and conquers’ strategy, famously delineated by Niccolò Machiavelli in his book The Art of War and shows that bacteria are capable of very elaborate warfare tactics.”

Bottom image: Provocation can be beneficial in mixed communities. Colonies consist of three toxin producers (red, green and unlabelled). The strain of interest (red toxin producer) is resistant to the toxins of its two competitors in both cases, but can take over the colony only if it can pit the two other strains against each other (right panel).
Bottom image: Provocation can be beneficial in mixed communities. Colonies consist of three toxin producers (red, green and unlabelled). The strain of interest (red toxin producer) is resistant to the toxins of its two competitors in both cases, but can take over the colony only if it can pit the two other strains against each other (right panel).

Lead author Dr. Diego Gonzalez, from the University of Lausanne, said: “We could envisage exploiting provocation in alternative antimicrobial approaches. For example, exposing established bacterial communities to low levels of known antimicrobials could promote warfare and cross-elimination of different strains.”

Scientists noted that the approach holds the potential to be used in eradicating safe biofilms – layers of bacteria that shape for instance in modern water pipes and are difficult to evacuate. It could likewise be utilized to treat some bacterial contaminations if the synthesis of the bacterial network in charge of the disease is outstanding.

Dr. Mavridou added: “By provoking other strains to attack each other, the toxin of the provoker is more effective than what would be expected based on its real toxicity. Using toxin-mimicking chemicals, we could potentially manipulate microbial aggression to our own benefit.”

The study’s other authors are Akshay Sabnis from the Medical Research Council Centre for Molecular Bacteriology and Infection at Imperial and Professor Kevin Foster from the Department of Zoology at the University of Oxford.

Scientists have reported their study in the journal Proceedings of the National Academy of Sciences.