It was shown for Streptococcus pneumonia and Escherichia coli that albumin inhibits biofilm formation on various surfaces [15, 16]. It is very likely that this effect also occurs in our model during colonization of the discs. However, even though the initial attachment VEGFR inhibitor of the bacteria is prevented to a certain degree, all ten learn more organisms were able to persist on the discs and were not washed away during dip-washing. Independent

of the used medium, the biofilms showed a phase with a pronounced increase in thickness and bacterial abundance. This phase took about 20 h regardless of the used medium, however, the medium does affect its onset. Concluding this, it seems that a certain number of bacteria attached to the disc is required to promote “exponential” biofilm formation. Our experimental setup did not allow defining the reason(s) behind this phenomenon. Possibly, it is triggered by quorum sensing, as it was shown for several oral species that AI-2 or CSP signalling is involved

in biofilm formation [17]. Alternatively, it could be that early biofilm formation under different nutritional conditions leads to different degrees of biofilm rigidity and therefore to different levels of sensitivity to shear-forces applied during biofilm dip-washing. The iHS medium produced significantly higher cell numbers of T. RG7420 solubility dmso denticola per biofilm compared to mFUM4 or SAL medium. However, P. gingivalis and T. forsythia were not affected by the higher serum concentration. This is surprising, since P. gingivalis was reported to profit from gingival crevicular fluid as well as from menaquinone secreted by veillonellae [17], and since one of the main growth factors of T. forsythia, N-acetyl-muramic acid [18], should be

plenty available in thicker biofilms with probably increased proportions of lysing cells. On the other hand both species are known to be quite fastidious and Janus kinase (JAK) our data indicate that it will be necessary to optimize further media components to increase their growth rates. S. anginosus, A. oris, and V. dispar showed mathematically significant reactions to the different growth media as well. However, in neither case the differences were greater than one log, which can hardly be considered as “biologically significant”. The biofilms proliferating in iHS medium showed a consistent structure throughout the replicates and the organisms showed interactions as they could be expected according to literature. Zjinge et al. described three different layers in in vivo subgingival samples [13]. Our model biofilms showed differences between top- and basal layers as well, however, it was not possible to clearly define an intermediate layer. It rather seems that there is a fluent transition between top- and basal layer of the biofilms. The two layers show distinct characteristics.