Selfish Freeloading Bacteria Not Welcomed to Bacteria Colony, Study Says

A recent study suggests bacterial colonies would rather starve and die than selfish cheater strains leeching off the colony without pulling their weight. The findings were made by a team of experts that modeled how a colony responds to freeloading bacteria that consume more than they are supposed to.

Bacterial Colony vs. Freeloading Bacteria

(Photo: Edward Jenner from Pexels)

Often, bacteria work together as a colony to ensure their survival, producing vital resources used by other bacteria. For example, bacteria secrete enzymes that break down food sources into needed nutrients that benefit neighboring bacteria. However, sometimes, they can be selfish and consume more resources without pulling their weight.

Alex Moffett, the lead author of the recent study and a computational biologist at York University, Toronto, explains that it's costly for the bacterium to contribute to its community, so for a selfish bacteria, it's simply best to take what is offered without contributing anything. However, this is bad for the rest of the colony; hence, the community needs a way to discourage the behavior.

In the study published in the journal PLOS Computational Biology, titled "Cheater suppression and stochastic clearance through quorum sensing." experts elaborate on how bacterial colonies use a quorum sensing system that allows them to determine the rate of biochemical products depending on the colony's population density.

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Understanding Quorum Sensing

This works by regulating the expression of cooperative genes across the entire population through a small molecule called autoinducers. With more bacteria, more autoinducers accumulate. If the concentration of the molecule rises above critical levels, it triggers changes in the bacteria that have outgrown the resources available.

Through mathematical modeling, the team found that quorum sensing affects and punishes freeloading strains by reducing the available shared resources. However, in some cases, the punishment for cheating strains hurts the survival of all the bacteria in the colony as the producers are also deprived of resources.

The researchers write that with no alternative nutrients available, quorum sensing by producing without the only source of nutrients from the colony's entire population, harming both the producers and cheater strains in terms of the total population's mean extinction time.

Andrew Eckford, a co-author of the study from York University, explains that the team did not expect to observe the astonishing behavior, which can also be categorized as spiteful. However, it shows that quorum sensing is a flexible tool for enforcing fairness within the bacterial colony, reports ScienceAlert.

Researchers describe the phenomenon as a possible example of demographically stochastic evolutionary suicide.

Although assumptions and mathematical models are vital tools that help experts grip complicated and dynamic systems. In this case, understanding the trade-offs that bacterial colonies make to survive, with more research in the future, can shed light on how bacterial infections take hold and cause varying diseases.

The research can help people with cystic fibrosis often contract lung infections due to a drug-resistant superbug.

The mathematical modeling of quorum sensing helps researchers further understand how bacteria colonize the lungs effectively and may lead to new treatments in the future.