A study published in npj Biofilms and Microbiomes suggests that targeting quorum sensing in gum disease research, specifically by disrupting the chemical signals bacteria use to coordinate behaviour, can shift dental plaque toward species associated with better oral health, without eliminating the microbial community outright.
The research comes from scientists at the College of Biological Sciences and the School of Dentistry, both part of the University of Minnesota. Their central question was whether bacterial behaviour, rather than bacterial survival, could be the target of future treatments for periodontal disease.
What quorum sensing in gum disease actually means
The human mouth is home to roughly 700 species of bacteria, and many of them do not simply coexist passively. They exchange chemical signals through a process called quorum sensing, which allows bacteria to detect how many neighbouring cells are present and coordinate group behaviours accordingly. Some oral bacteria use molecules known as N-acyl homoserine lactones, or AHLs, as part of this signalling system.
The researchers found that bacteria within dental plaque produced AHL signals in aerobic environments, such as above the gumline, where oxygen is available. Crucially, those signals could also be detected by bacteria living in anaerobic environments below the gumline, where oxygen levels are much lower. Conditions beneath the gumline can favour bacteria associated with periodontal disease, so this cross-environment communication had direct implications for how disease progresses.
To test whether that signalling could be interrupted, the team used specialised enzymes called lactonases. These break down AHL molecules, effectively cutting off the chemical conversation. According to the University of Minnesota Twin Cities, removing AHL signals with lactonases enriched health-associated dental plaque species, a finding that the published study supports in detail.
Oxygen levels change everything
One of the more consequential findings concerns how the effect of AHL disruption depended on where in the mouth it occurred. ‘What’s particularly striking is how oxygen availability changes everything,’ said lead author Rakesh Sikdar. ‘When we blocked AHL signalling in aerobic conditions, we saw more health-associated bacteria. But when we added AHLs under anaerobic conditions, we promoted the growth of disease-associated late colonizers. Quorum sensing may play very different roles above and below the gumline, which has major implications for how we approach treatment of periodontal diseases.’
That distinction matters practically. Above the gumline, disrupting AHL signalling appeared to favour bacteria linked with oral health. Below the gumline, adding those signals encouraged later-colonising species associated with disease. Any enzyme-based treatment would therefore need to account for the distinct oxygen environments found across different parts of the mouth.
Mikael Elias, associate professor in the College of Biological Sciences and senior author of the study, framed the plaque community in ecological terms. ‘Dental plaque develops in a sequence, much like a forest ecosystem,’ he said. ‘Pioneer species like Streptococcus and Actinomyces are the initial settlers in simple communities, they’re generally harmless and associated with good oral health. Increasingly diverse late colonizers include the “red complex” bacteria like Porphyromonas gingivalis, which are strongly linked to periodontal disease. By disrupting the chemical signals bacteria use to communicate, one could manipulate the plaque community to remain or return to its health-associated stage.’
The implication is that dental plaque is not a static problem to be scrubbed away, but a dynamic community that can be steered. Early plaque communities may contain relatively harmless bacteria; it is only as the community matures and diversifies that species linked to disease tend to gain ground.
A different strategy for preventing periodontal disease
The researchers are clear that this work is foundational. They now want to investigate how bacterial communication varies across different parts of the mouth and among people at different stages of periodontal disease. The long-term goal is not to develop another antimicrobial agent that broadly suppresses oral bacteria, but to find ways to influence the microbial balance itself.
‘Understanding how bacterial communities communicate and organise themselves may ultimately give us new tools to prevent periodontal disease,’ said Elias, ‘not by waging war on all oral bacteria, but by strategically maintaining a healthy microbial balance.’
The team also noted that microbial imbalances of this kind, sometimes called microbiome dysbiosis, are not confined to the mouth. Similar disruptions occur elsewhere in the body and have been associated with a range of health problems, including certain types of cancer. If quorum sensing gum disease research produces workable enzyme-based interventions, the underlying approach could inform therapies aimed at other microbial communities in the body.
The research was funded by the National Institutes of Health. The full study, authored by Rakesh Sikdar, Mai V. Beauclaire, Mark C. Herzberg, Bruno P. Lima and Mikael H. Elias, is published in npj Biofilms and Microbiomes with the DOI 10.1038/s41522-025-00846-z.
