Chalmers Natalia I, Palmer Robert J, Cisar John O, Kolenbrander Paul E
Department of Biomedical Sciences, University of Maryland Dental School, Baltimore, Maryland 21201, USA.
J Bacteriol. 2008 Dec;190(24):8145-54. doi: 10.1128/JB.00983-08. Epub 2008 Sep 19.
Streptococci and veillonellae occur in mixed-species colonies during formation of early dental plaque. One factor hypothesized to be important in assembly of these initial communities is coaggregation (cell-cell recognition by genetically distinct bacteria). Intrageneric coaggregation of streptococci occurs when a lectin-like adhesin on one streptococcal species recognizes a receptor polysaccharide (RPS) on the partner species. Veillonellae also coaggregate with streptococci. These genera interact metabolically; lactic acid produced by streptococci is a carbon source for veillonellae. To transpose these interactions from undisturbed dental plaque to an experimentally tractable in vitro biofilm model, a community consisting of RPS-bearing streptococci juxtaposed with veillonellae was targeted by quantum dot-based immunofluorescence and then micromanipulated off the enamel surface and cultured. Besides the expected antibody-reactive cell types, a non-antibody-reactive streptococcus invisible during micromanipulation was obtained. The streptococci were identified as Streptococcus oralis (RPS bearing) and Streptococcus gordonii (adhesin bearing). The veillonellae could not be cultivated; however, a veillonella 16S rRNA gene sequence was amplified from the original isolation mixture, and this sequence was identical to the sequence of the previously studied organism Veillonella sp. strain PK1910, an oral isolate in our culture collection. S. oralis coaggregated with S. gordonii by an RPS-dependent mechanism, and both streptococci coaggregated with PK1910, which was used as a surrogate during in vitro community reconstruction. The streptococci and strain PK1910 formed interdigitated three-species clusters when grown as a biofilm using saliva as the nutritional source. PK1910 grew only when streptococci were present. This study confirms that RPS-mediated intrageneric coaggregation occurs in the earliest stages of plaque formation by bringing bacteria together to create a functional community.
在早期牙菌斑形成过程中,链球菌和韦荣氏菌会出现在混合菌群菌落中。一个被认为在这些初始群落组装中起重要作用的因素是共聚作用(基因不同的细菌之间的细胞 - 细胞识别)。当一种链球菌上的凝集素样黏附素识别伙伴菌上的受体多糖(RPS)时,链球菌属内会发生共聚作用。韦荣氏菌也会与链球菌共聚。这些菌属在代谢上相互作用;链球菌产生的乳酸是韦荣氏菌的碳源。为了将这些相互作用从未受干扰的牙菌斑转移到实验上易于处理的体外生物膜模型中,一个由带有RPS的链球菌与韦荣氏菌并列组成的群落通过基于量子点的免疫荧光进行靶向,然后从牙釉质表面微操纵分离并培养。除了预期的抗体反应性细胞类型外,还获得了一种在微操纵过程中不可见的非抗体反应性链球菌。这些链球菌被鉴定为口腔链球菌(带有RPS)和戈登链球菌(带有黏附素)。韦荣氏菌无法培养;然而,从原始分离混合物中扩增出了一个韦荣氏菌16S rRNA基因序列,该序列与我们培养物保藏中心先前研究的生物体韦荣氏菌属菌株PK1910的序列相同,PK1910是一种口腔分离株。口腔链球菌通过一种依赖RPS的机制与戈登链球菌共聚,并且两种链球菌都与PK1910共聚,PK1910在体外群落重建过程中用作替代物。当以唾液作为营养源形成生物膜生长时,链球菌和PK1910菌株形成了相互交错的三菌簇。只有当存在链球菌时,PK1910才会生长。这项研究证实,RPS介导的属内共聚作用通过将细菌聚集在一起形成一个功能群落,发生在菌斑形成的最早阶段。