January 9, 2026

Monique Nguyen

Fountain Valley High School

12th Grade

Bacteria can talk—and they even have different types of languages. As a refresher, bacteria are minuscule prokaryotes (single-celled organisms) that are everywhere: underwater, in volcanoes, and in human bodies. Many are harmless and commonly boost digestion and immune responses, but malicious bacteria will cause infections, such as E. coli and strep throat. 

So, what does bacterial communication have to do with treatments? Well, some strains of bacteria are becoming resistant to antibiotics; they evolve and naturally develop resistance mechanisms, such as destroying the drug with enzymes or blocking access to the drug by selectively limiting their membranes to keep the drug from penetrating them. As a few bacteria survive, they reproduce, and the genes needed to code for those specific proteins with resistance mechanisms are already encoded in the new microbe’s DNA. Some bacteria can also share their tactics with nonresistant strains as well. All of these developments are exceptionally alarming because it becomes even more difficult to kill resistant bacteria, especially because it takes significant time, resources, and research to develop new therapeutics, so it’s even more difficult to curb sickness. This is where anti-quorum sensing drugs come in: rather than killing the bacteria itself with antibiotics, it’s possible to prevent it from launching a group attack by blocking its intraspecies communication with other bacteria.

First, let’s dive into what quorum sensing actually is. Just like the cells in the human body, bacteria rely on chemical signaling to work with other bacteria. Individual bacteria alone cannot impose a significant effect, so they need to be able to perform certain tasks as a colony. For example, individual bacteria need to communicate to aggregate into biofilms, which are complex matrices of bacterial communities, which naturally form to counter external threats, like antibiotics or extremely harsh environments. Another common example is bioluminescence; individual bacteria need to communicate with each other in order to know when to simultaneously produce light. They do this by individually synthesizing a ligand (specifically called an autoinducer), which is a small molecule that acts as a chemical messenger, similar to the words that humans speak. All bacteria within a species will produce the same ligand—that is, the same molecule with the same structure, which allows them to “speak” the same language. Different species of bacteria can communicate through ligands as well, but the shape of the ligand they produce is slightly different, and they have different receptors with specific shapes for interspecies communication.

In intraspecies communication, the autoinducer passively diffuses out of the bacteria through the membrane, and the bacteria continues synthesizing ligands and reproducing. As the population of bacteria increases due to reproduction, the autoinducer concentration on the outside will also increase until a certain point. The “critical mass” is when the autoinducer will stop diffusing out of the cell against its concentration gradient, but the bacteria continues producing ligands, so its intracellular concentration increases. That’s when the autoinducer will bind to its shape-specific receptor on the bacteria and spark a signaling cascade of transduction pathways leading to gene expression. Essentially, reception is like “hearing” the message, the transduction pathways are like "understanding" the message, and the bacteria can then alter its transcription factors to respond to the message. So in brief, bacteria know once there are enough of them in a population when enough ligands are produced, and that’s when they collectively enact a response, like bioluminescence.

Currently, research is being conducted to disrupt this collaborative process, which will prevent (or at the very least, delay) the bacteria from collectively launching an infectious attack. For example, a study done on V. cholerae bacteria (which causes cholera) revealed that increasing the autoinducer concentration artificially while the bacteria was still at a low population density will trigger a premature quorum-sensing response with a much smaller effect than normal (Lu et al.). Other possible methods are rooted in interspecies communication. Some species of bacteria, like Bacillus spores, both have positive immune effects and can curb colonies of a more harmful bacteria called S. aureus by competing for the same autoinducer receptors. 

Overall, this concept of disrupting bacterial communication (either inter- or intraspecies) provides several new pathways for therapeutic development against malignant, persistent, and evolving bacterial strains. While there are no specific anti-quorum sensing drugs available commercially, it has diverse and endless potential for treatments for harmful and pervasive bacterial infections, especially with the development of bacterial resistance mechanisms against current antibiotics.