If a colony is put up with a cheat strain, it will perform evolutionary suicide.

A group of researchers modeled how a colony would respond to freeloadingbacteria that consume more than their fair share.

The resources that are produced by otherbacteria are used by otherbacteria.

For example,bacteria break down food sources into vitamins and minerals which help neighboringbacteria.

They can be selfish operators that consume resources.

"For a selfish individual, it's best to simply take what's offered without giving anything back," says Alex Moffett, a Computational Biologist at York University, Toronto. The community needs a way to discourage bad behavior.

The rate of biochemical products depends on the density of the colony.

Small molecule called autoinducers are used to regulate the expression of genes across a group ofbacteria.

There are more autoinducers when there are morebacteria. If the concentration of autoinducers goes above critical levels, it will cause changes in thebacteria which have outgrown the available resources.

The researchers found that the effect of punishing freeloaders by reducing the availability of shared resources was caused by quorum sensor.

In some cases, doling out punishment to cheating people hurts the survival of the colony as the producers are not getting enough resources.

In terms of the total population's mean extinction time, producers and cheaters are harmed by the fact that there is only one source of nutrients for the whole population.

"We didn't expect to see this behavior, which you might even call'spiteful'," Andrew says. It shows that there is a flexible way to enforce fairness.

This behavior is described as a possible example of suicide.

Scientists can use mathematical models to understand complicated, dynamic systems. Understanding the trade-offs that the colonies make to survive might shed light on the causes of diseases.

A drug-resistant superbug is a common cause of lung infections in people with cystic fibrosis.

In the lungs, P. aeruginosa forms small, dense biofilms of around 1,000bacteria cells, which act as a tough protective layer, making it harder to kill thebacteria and clear the infection using antibiotics.

According to Moffett, the mathematical modeling of quorum sensing may help researchers understand howbacteria can colonize the lungs so effectively.

The research was published in a scientific journal.