The colonial morphology of three strains of cultivable, nonpathogenic treponemes including a human oral treponeme was examined by light and electron microscopy. Treponema phagedenis strains Kazan and Reiter produced large white colonies on the surface of solid media composed of sterility test broth, 0.9 to 3.1% agar, rifampin, and 12.5% rabbit or horse serum. A human oral treponeme, strain G7201, grew as diffused white zones on 0.9 to 3.1% agar plates. Under the cultural conditions employed agar concentrations slightly affected the time of appearance of colonies of the three strains of treponemes. When the colonies of these three strains were viewed by scanning electron microscopy, differences in their colonial morphology were observed. The 11‐day‐old colonies of human oral strain G7201 were very small, 5 to 15 μm in diameter, and had a slight irregular border. Kazan treponemes developed circular, entire and low convex colonies. Scanning and transmission electron microscopy revealed that the colonies of Reiter treponemes contained spherical forms almost up to 5 μm in diameter, each consisting of an outer membrane and a treponemal main body. They were very similar to the spherical bodies produced by strain G7201 in sucrose‐containing broth.

Abstract:The object of this study aimed to investigate the adsorptive properties of a cariogenic Streptococcus mutans including six serotypes and a non-oral bacillus Escherichia coli using an apparatus designed for the measurement of bacterial adsorption to electrostatically charged platinum electrodes in vitrc. Quantitative estimation of the bacterial adsorption by electron microscopy and the conditions affecting the bacterial adsorption to platinum electrodes were examined . Morphological differences in the materials adsorbed to the platinum electrodes which had been inserted into a human oral cavity were also examined as an in vivo experimental system.The bacterial cells used were adsorbed more abundantly to positive electrodes than to negative electrodes. The number of S. mutans strain HS6 (serotype a) adsorbed to the positive electrodes increased with bacterial concentrations and current intensities up to 300uA. The bacterial adsorption to the positive electrodes was promoted by heating the bacterial cells and pretreatment of the electrodes with whole saliva. The bacterial cells of S. mutans adsorbed on the positive electrode were desorbed with time from this surface, when the polarity was changed . Scanning electron microscopy showed that in the human mouth the quantity of materials adsorbed on the positive electrodes placed was larger than those on the negative.Results otained from in vitro and in vivo experiments strongly suggest that adsorption of the cariogenic bacterium S. mutans to positively charged surfaces of restorative materials or tooth surfaces may play a role in producing the dental plaque associated with dental caries and periodontal disease .