N-acyl homoserine lactone signaling modulates bacterial community associated with human dental plaque.

Dental plaque is a complex oral biofilm responsible for periodontal diseases. Bacterial biofilms are often regulated by Quorum Sensing (QS) mediated by N-acyl homoserine lactones (AHLs). While their presence and roles in oral microbiota have been debated, emerging evidence suggests AHLs influence oral biofilm development. AHLs are detectable in a microbial community derived from human dental plaque cultured under 5% CO2 but not under anaerobic conditions. Manipulating QS in this community via AHL lactonases enriched commensals and pioneer colonizers under 5% CO₂, whereas in anaerobic conditions exogenous AHLs promoted late colonizers. QS disruption reduced biofilm formation, enhanced sucrose fermentation to lactate, and altered metabolic profiles of the community depending on the lactonase substrate specificity. Our findings highlight the importance of AHL-mediated QS in oral biofilm development and suggest its differential roles under aerobic versus anaerobic conditions. Targeting QS may offer a novel strategy for managing oral biofilms and preventing periodontal disease.