That ability helps them survive changing conditions, but it can also create problems when harmful species become resistant to antibiotics and disinfectants. At the same time, bacteria are not simply enemies to eliminate. Many species play important roles in human health, including the hundreds of different microbes that live in the mouth.
That raises an intriguing possibility: instead of trying to kill bacteria, could scientists influence how they behave and encourage healthier microbial communities? Research published in 2025 in npj Biofilms and Microbiomes suggests that may be possible. Scientists studying dental plaque found that interfering with the chemical signals bacteria use to communicate can change which species thrive, potentially shifting the community toward bacteria associated with better oral health.
The human mouth is home to roughly 700 species of bacteria. These microbes do not simply grow alongside one another. Many exchange chemical signals through a process called quorum sensing.
Quorum sensing allows bacteria to detect how many neighboring cells are present and coordinate group behaviors. Some oral bacteria communicate using molecules known as N-acyl homoserine lactones (AHLs). Researchers from the College of Biological Sciences and the School of Dentistry examined how these signals shape dental plaque.
Their goal was to determine whether bacterial communication could be manipulated to help maintain a healthier oral microbiome. The oral microbiome refers to the community of microorganisms living in the mouth. When that community becomes unbalanced, potentially harmful bacteria can become more dominant and contribute to conditions such as periodontal disease.
The researchers found that bacteria within dental plaque produced AHL signals in aerobic environments (such as above the gumline), where oxygen is available. Those chemical messages could also be detected by bacteria living in anaerobic environments (beneath the gumline), where oxygen levels are much lower. This connection was important because conditions below the gumline can favor bacteria associated with periodontal disease.
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