探讨原子力显微镜在变形链球菌研究中的应用

目的：探讨原子力显微镜在口腔变形链球菌研究中的应用。方法：应用原子力显微镜在自然干燥状态和在态条件下观察变形链球菌血清c型MT6R菌株和MT8148葡糖基转移酶基因缺陷型菌株B29的超微结构。结果：原子力显微镜在自然干燥观察变形链球菌MT6R可见，表面形态呈不规则状，有大量的不定性物质，有呈囊状突起，菌细胞之间靠大量的不定性物质相互连在一起；水不溶性葡糖基转移酶(GTFI)缺陷型菌株B29菌细胞表面相对光滑，无囊状突起，有颗粒状物，菌细胞间不定性物质较少。在液态条件下观察细菌的超微结构与自然干燥下的相似，但吏加清晰。结论：应用原子力显微镜可以在液态条件下观察变形链球菌表面超微结构，还可以对菌细胞进行三维成像。

Imaging the Surface of Mutans Streptococcus by Atomic Force Microscopy

Objective: To investigate application of atomic force microscopy(AFM) on Mutans Streptococci(MS)by imaging the surface of streptococcus mutans MT6R and streptococcus mutans B29 using AFM. Results: AFM can image morphology of Streptococcus mutans in 2-D display. The cell surfaces of strain MT6R were not regular because of the presence of the amorphous substance on the colony surface, which congergate globular boby, fibrous structure. The cell surfaces of strains B29 were smooth and morphological regularity. Trace amounts of the amorphous substance were observed on the cell surface of B29. AFM can not only image morphology of a bacterial cell that was dried in air , but also in liquid. In liquid display, the amorphous substance covered cells of streptococcus mutans MT6R showed capsule,but the cell surfaces of strains B29 was not capsule. Conclution: Unlike scanning electron microscopy, performance of AFM does not require a vacuum, drying to the critical point, or the coating of the bacterial surface with a metal layer. The digital storage of the information makes it easy to rotate the image, observe the bacterial surface and induced structural alterations from different points of view, and obtain a cross-section at any desired point with precise, automatic measurement of the heights and sizes of bacteria. Use of the new and outstanding technique of AFM will make it possible for researchers to investigate MS.