All living organisms strive to adapt to their environment in order to survive, and bacteria are no exception. In recent decades, some bacterial species have developed resistance to widely used antibiotics and disinfectants, posing significant challenges for medicine and healthcare systems. At the same time, many types of bacteria play an important, and sometimes even critical, role in maintaining human health. This raises the question: is it possible not to destroy bacteria, but rather to influence their behavior to reduce disease and improve health?

How Bacteria Communicate with Each Other

Bacteria are far from silent beings. In the human mouth, there are about 700 different bacterial species that constantly exchange information through a process known as quorum sensing. This chemical communication allows bacteria to coordinate their actions within a group. Many oral bacteria use signaling molecules called N-acyl homoserine lactones (AHLs) to send and receive messages.

Studying Bacterial Communication in Dental Plaque

Researchers from the University of Minnesota’s College of Biological Sciences and School of Dentistry set out to study how bacteria in the mouth interact with each other and whether it is possible to deliberately disrupt their communication. The goal of the study was to determine if interfering with these signals could prevent the formation of dental plaque and help maintain a healthier oral microbiome. The results, published in the journal npj Biofilms and Microbiomes, suggest that this approach could change how doctors think about treating bacterial diseases.

Key Findings of the Study

The researchers identified several important patterns in the organization and communication of oral bacteria:

• Bacteria in dental plaque generate AHL signals in oxygen-rich areas (such as above the gum line), and these signals can be detected by bacteria living in low-oxygen zones (below the gum line).
• Removing AHL signals using special enzymes—lactonases—led to an increase in bacterial species associated with good oral health.

These findings indicate that carefully selected enzymes can be used to alter the composition of microbial communities in dental plaque and help maintain a healthy microbiome balance.

Dental Plaque as a Living Ecosystem

“Dental plaque develops in stages, much like a forest ecosystem,” explains Mikael Elias, associate professor at the College of Biological Sciences. “The first settlers are bacteria such as Streptococcus and Actinomyces. They are usually harmless and linked to good oral health. Later colonizers, including bacteria from the ‘red complex’ like Porphyromonas gingivalis, are closely associated with the development of periodontitis. By managing the chemical signals bacteria use to communicate, we can control the plaque community so that it remains or returns to a health-associated stage.”

Lead author Rakesh Sikdar adds: “It’s especially fascinating how the presence of oxygen changes the whole picture. When we blocked AHL signals in aerobic conditions, we saw an increase in bacteria linked to health. But when AHL was added in anaerobic conditions, the number of pathogenic late colonizers grew. Quorum sensing can play completely different roles above and below the gum line, which is important to consider when treating periodontitis.”

Prospects for Microbiome-Oriented Treatment Methods

In the future, the researchers plan to study how bacterial signaling differs in various areas of the mouth and in patients at different stages of periodontitis. “Understanding how bacterial communities communicate and organize themselves could ultimately give us new tools to prevent periodontitis—not by destroying all oral bacteria, but by strategically supporting a healthy microbial balance,” notes Elias. The team believes this strategy could eventually lead to new therapies for other parts of the body where microbiome disruptions are linked to diseases and certain forms of cancer.