Architecture of Streptococcus mutans biofilms
Objective To observe the architecture of Streptococcus mutans (S.mutans) biofilms utilizing of an experimental model of S.mutans biofilms in confocal laser scanning microscopy (CLSM). Methods S.mutans biofilms were formed on glass slices in 6, 12, 18, 24, 48, 72 h respectively. The scanning picture, depth and the area of green and red light per layer of biofilms were observed by CLSM. Bacterial density and the percentage of vital bacteria were calculated. The three-dimensional reconstruction of biofilm pictures were obtained by special software of scanning data of biofilms. Results It was shown that S.mutans biofilm had three-dimensional spatial architecture with various forms. A lot of vital and dead bacteria gathered densely in biofilms. Bacteria were embeded in rich extracellular polymers. There were abundant channels in biofilms. Among all the biofilms at every time slot we observed, those of 24 h were the thickest in terms of average level. Bacterial density was higher at both the interior and middle layers than at the outer layer. As for the biofilm within 72 h, the percentage of vital bacteria at every time slot increased from the inner layer to the outer. Conclusion S.mutans biofilm had a certain degree of thickness. Its structure was three-dimensioned, heterogeneous, openness and of various forms.