Mutualistic Biofilm Communities Develop with Porphyromonas gingivalis and Initial, Early, and Late Colonizers of Enamel

Porphyromonas gingivalis is present in dental plaque as early as 4 h after tooth cleaning, but it is also associated with periodontal disease, a late-developing event in the microbial successions that characterize daily plaque development. We report here thatP. gingivalis ATCC 33277 is remarkable in its ability to interact with a variety of initial, early, middle, and late colonizers growing solely on saliva. Integration ofP. gingivalis into multispecies communities was investigated by using two in vitro biofilm models. In flow cells, bacterial growth was quantified using fluorescently conjugated antibodies against each species, and static biofilm growth on saliva-submerged polystyrene pegs was analyzed by quantitative real-time PCR using species-specific primers.P. gingivalis could not grow as a single species or together with initial colonizerStreptococcus oralis but showed mutualistic growth when paired with two other initial colonizers,Streptococcus gordonii andActinomyces oris , as well as withVeillonella sp. (early colonizer),Fusobacterium nucleatum (middle colonizer), andAggregatibacter actinomycetemcomitans (late colonizer). In three-species flow cells,P. gingivalis grew withVeillonella sp. andA. actinomycetemcomitans but not withS. oralis andA. actinomycetemcomitans . Also, it grew withVeillonella sp. andF. nucleatum but not withS. oralis andF. nucleatum , indicating thatP. gingivalis andS. oralis are not compatible. However,P. gingivalis grew in combination withS. gordonii andS. oralis , demonstrating its ability to overcome the incompatibility when cultured with a second initially colonizing species. Collectively, these data help explain the observed presence ofP. gingivalis at all stages of dental plaque development.