Bacteria residing in oral biofilms live in a state of dynamic equilibrium with one another. The intricate synergistic or antagonistic interactions between them are crucial for determining this balance. Using the six‐species Zürich “supragingival” biofilm model, this study aimed to investigate interactions regarding growth and localization of the constituent species. As control, an inoculum containing all six strains was used, whereas in each of the further five inocula one of the bacterial species was alternately absent, and in the last, both streptococci were absent. Biofilms were grown anaerobically on hydroxyapatite disks, and after 64 h they were harvested and quantified by culture analyses. For visualization, fluorescence in situ hybridization and confocal laser scanning microscopy were used. Compared with the control, no statistically significant difference of total colony‐forming units was observed in the absence of any of the biofilm species, except for Fusobacterium nucleatum, whose absence caused a significant decrease in total bacterial numbers. Absence of Streptococcus oralis resulted in a significant decrease in Actinomyces oris, and increase in Streptococcus mutans (P < .001). Absence of A. oris, Veillonella dispar or S. mutans did not cause any changes. The structure of the biofilm with regards to the localization of the species did not result in observable changes. In summary, the most striking observation of the present study was that absence of S. oralis resulted in limited growth of commensal A. oris and overgrowth of S. mutans. These data establish highlight S. oralis as commensal keeper of homeostasis in the biofilm by antagonizing S. mutans, so preventing a caries‐favoring dysbiotic state.

中文翻译：

---

口腔链球菌通过拮抗致癌病原体变形链球菌来维持口腔生物膜中的稳态。

口腔生物膜中的细菌彼此处于动态平衡状态。它们之间复杂的协同或拮抗相互作用对于确定这种平衡至关重要。本研究使用苏黎世六种生物“生物膜上膜”生物膜模型，旨在研究与组成物种的生长和本地化有关的相互作用。作为对照，使用了包含所有六个菌株的接种物，而在另外五个接种物中的每一个中，交替存在一种细菌，最后一种，两种链球菌都不存在。生物膜在羟基磷灰石圆​​盘上厌氧生长，并在64小时后收获，并通过培养分析进行定量。为了可视化，使用了荧光原位杂交和共聚焦激光扫描显微镜。与对照相比，缺乏核杆菌，导致总细菌数显着减少。口腔链球菌的缺乏导致放线菌显着减少，变形链球菌增加（P  <.001）。缺位A. ORIS，韦荣球菌毒蛾或变形链球菌没有造成任何改变。关于物种的定位，生物膜的结构没有导致可观察到的变化。综上所述，本研究最引人注目的观察结果是，缺少口头链球菌会导致共生A. oris的生长受限，并导致其过度生长。变形链球菌。这些数据确定高亮口腔链球菌通过拮抗作为生物膜稳态的共生门将变异链球菌，所以防止龋利于dysbiotic状态。