All living organisms adapt to survive, and bacteria are no exception. Over several decades, some bacteria have gradually become resistant to widely used antibiotics and disinfectants, creating serious challenges for medicine and public health. At the same time, countless species of bacteria play a helpful and often critical role in maintaining the health of the human body. This raises an important question. Instead of trying to eradicate bacteria, could scientists find ways to influence the way they behave to reduce disease and improve health?
Bacteria are by no means silent. Inside the human mouth, about 700 different bacterial species are constantly exchanging information through a process called quorum sensing. This chemical communication allows the bacteria to coordinate their actions as a group. Many oral bacteria rely on signaling molecules known as N-acyl homoserine lactones (AHLs) to send and receive these messages.
Investigating bacterial communication in dental plaque
Researchers at the University of Minnesota, Twin Cities College of Biological Sciences and School of Dentistry set out to investigate how bacteria in the mouth communicate and whether that communication could be intentionally disrupted. Their goal was to determine whether interfering with these signals could help prevent plaque build-up and support a healthier oral microbiome. The findings were published in the journal npj Biofilms and Microbiomessuggest that this approach could reshape the way doctors think about treating bacterial diseases.
Key findings from the study
The researchers discovered several important patterns in how oral bacteria communicate and organize:
- Bacteria in dental plaque produce AHL signals in oxygen-rich areas (such as above the gum line), and these signals can be detected by bacteria living in oxygen-poor areas (below the gum line).
- Eliminating AHL signals using specialized enzymes called lactonases led to an increase in bacterial species associated with good oral health.
- These results indicate that carefully selected enzymes can be used to reshape dental plaque communities and help maintain a healthy microbial balance.
Dental plaque as a living ecosystem
“Dental plaque grows in a sequence, like a forest ecosystem,” said Michael Elias, associate professor in the College of Biological Sciences and senior author of the study. “Pioneer species such as Streptococcus and Actinomyces are the initial settlers in simple communities — they are generally harmless and associated with good oral health. The increasingly diverse late colonizers include ‘red cluster’ bacteria such as Porphyromonas gingivalis, which are closely associated with periodontal disease. or return to the health-associated stage.”
“What’s particularly striking is how the availability of oxygen changes everything,” said lead author Rakesh Sikdar. “When we blocked AHL signaling under aerobic conditions, we saw more bacteria associated with health. But when we added AHL under anaerobic conditions, we promoted the growth of disease-associated late colonizers. Quorum sensing can play very different roles above and below the gum line, which has important implications for how we approach periodontal disease treatment.”
Towards new microbiome-based therapies
The researchers next plan to examine how bacterial signaling differs in different areas of the mouth and between patients at different stages of periodontal disease. “Understanding how bacterial communities communicate and organize may ultimately give us new tools to prevent periodontal disease — not by fighting all oral bacteria, but by strategically maintaining a healthy microbial balance,” Elias said. The team believes this strategy could eventually lead to treatments for other parts of the body, where imbalances in the microbiome are linked to disease and certain cancers.
Research funding was provided by the National Institutes of Health.
