Ever notice how animals are able to communicate, move, hunt, and travel in large groups? Bacteria are no different. Quorum sensing, in the simplest sense, is bacteria chatter. Instead of using words, they use chemicals. Once these communication chemicals build up to a certain level, they affect gene expression and transcription.
If you’ve been following along, you probably read about phage therapy, one of the novel ways to treat antibiotic resistance bacteria. As promised, I’m introducing another method: quorum sensing. The goal of quorum sensing research is to figure out how bacteria talk to each other. If we’re able to block their communication (sort of like the aliens in Independence Day blocking our satellite communication), we can prevent their growth and spread in the body. Remember, one cell can’t do much harm to you. In fact, a macrophage will probably come along and eat it (phagocytosis). However, if that one cell is able to talk to other cells and they band together, producing toxins for example, that’s not good news for you.
Ever notice slimy stuff building up in espresso water tanks or dog water bowls? That’s bacteria biofilm! You can think of it like a protective mucus surrounding a large group of bacteria. In human beings, biofilm production is particularly troublesome because it prevents antibiotics from getting to the bacteria. Once again, sort of like the alien shield that protects their space ships (ID4 reference #2). If we can understand how quorum sensing works, we can prevent bacteria from ever putting up a shield. Quorum quenching is the process of blocking bacteria communication.
Since a bunch of extracellular macromolecules make up biofilm, bacteria need a signal from the environment to start production. It doesn’t make sense for one cell to produce biofilm, it only make sense if millions of cells do it all at once. So, bacteria secrete communication molecules and when the concentration of these chemicals build up to a certain level, the biofilm production genes get turned on.
In the next post, we’ll address how nanotechnology can penetrate biofilm to deliver antibiotics. Sometimes, resistance happens because of efflux pumps. Other times, resistance happens because of biofilm. Quorum sensing and quorum quenching is still quite new, but it is one of the promising ways to combat antibiotic resistance by shutting down bacteria communication. I’m pretty sure Martin Luther King Jr. wasn’t talking about bacteria when he said this, but it works in this case:
There is power in numbers and there’s power in unity.