Abstract
As a step for the investigation of biological characteristics of thick walled bacteria (TWB) existing in the deeper part of human dental plaque, a simple method was devised for the in vitro collection of TWB from the bacterial mass. It consists of the following three steps:
1) A bacterial mass contaminated with TWB found in the stock culture of Strep. mutans JC2 was inoculated into BHI broth for proliferation and the cultivation was continued until its optical density revealed stationary phase.
2) The bacterial mass collected by centrifugation of the above was suspendended in sterile water and left standing until its optical density became stable.
3) Then, the bacterial mass was again placed in BHI broth for cultivation until its optical density revealed stationary phase.
The bacterial mass in each of the above steps was subjected to various biological tests as well as electronmicroscopic observation. As the result, following points were clarified:
1. The TWB contained in the bacterial mass of the first step was only about 10%, but it became as high as approximately 70% by the end of the third step.
2. Elevation of the content of TWB to nearly 100% may be possible by repeating the procedures described herein.
3. When it is difficult to collect TWB in a sufficiently high percentage from the bacterial mass consisting of varying strains by conventional methods, the method described herein will easily enable to collect a large quantity of TWB.
