Bacteria are constantly evolving to survive. One major impact is that many harmful microorganisms have become resistant to antibiotics and disinfectants, posing serious problems for medicine and public health. However, not all bacteria are dangerous. In fact, many of them are essential to keeping the human body healthy. Scientists are currently studying whether it is possible to influence the behavior of bacteria, rather than simply destroying them completely.
In the human mouth, bacteria communicate almost constantly. It is home to about 700 species of bacteria, many of which exchange chemical messages through a process called quorum sensing. Some of these microorganisms communicate using signaling molecules known as N-acyl homoserine lactones (AHLs).
Researchers from the School of Biological Sciences and the School of Dentistry set out to investigate how these bacterial signals shape the oral microbiome and whether blocking these signals could prevent harmful plaque buildup while maintaining healthy bacteria. Their findings were; npj biofilm and microbiomewhich could ultimately impact treatments far beyond dentistry.
Scientists are targeting bacterial communication
The research team discovered some important patterns in how bacteria in the mouth interact.
- Bacteria living in dental plaque produce AHL signals in an aerobic environment (e.g., above the gingival margin), but these signals can also affect bacteria in an anaerobic environment (e.g., below the gingival margin).
- Using a special enzyme called lactonase to remove AHL signals increased the number of bacteria associated with oral health.
- The findings suggest that carefully selected enzymes may be able to reshape plaque communities and support a healthier oral microbiome.
“Plaque develops sequentially, like a forest ecosystem,” says Michael Elias, associate professor in the School of Biological Sciences and lead author of the study. “Pioneering species like Streptococcus and Actinobacteria are the first settlers in simple communities. They are generally harmless and are associated with good oral health. Increasingly diverse later colonizers include ‘red complex’ bacteria such as Porphyromonas gingivalishas a deep relationship with periodontal disease. By interfering with the chemical signals that bacteria use to communicate, it would be possible to manipulate the plaque community to either stay at a health-related stage or return to its original stage. ”
Oxygen levels change bacterial behavior
The researchers also discovered that oxygen plays a surprisingly important role in determining how these bacterial messages influence plaque growth.
“What’s particularly surprising is how oxygen availability changes everything,” said lead author Rakesh Sikdar. “When we blocked AHL signaling under aerobic conditions, we observed more health-associated bacteria. However, when we added AHL under anaerobic conditions, we promoted the growth of disease-associated late colonizers. Quorum sensing may play very different roles above and below the gingival margin, and this has major implications for how we approach the treatment of periodontal disease.”
This finding suggests that bacteria communicate differently depending on where they live in the mouth. This insight could help researchers design more targeted approaches to control periodontal disease and maintain a healthier balance of microorganisms.
Future treatments could protect healthy bacteria
The next stage of research will examine how bacterial signaling differs in different areas of the mouth and among people at different stages of periodontal disease.
“Understanding how bacterial communities communicate and organize may ultimately give us new tools to prevent periodontal disease, by strategically maintaining a balance of healthy microbes rather than going to war against all oral bacteria,” Elias said.
Researchers believe this strategy could eventually be expanded beyond oral health. Microbiome imbalances, known as dysbiosis, are associated with numerous diseases throughout the body, including certain cancers. Scientists hope these findings will help lay the groundwork for future treatments that steer microbial communities toward a healthier state, rather than eliminating bacteria entirely.
Funding for this study was provided by the National Institutes of Health.
