Studies on the Specimen Preparation Methods for Scanning Electron Microscopy : Part III. Drying Method of Microbial and Free Cell Materials : 3. Comparative Studies of Three Methods of Air-, Critical Point- and Freeze-drying

Three methods of drying technique in the preparation for Scanning Electron Microscopy (SEM), such as air-drying (AD), critical point drying (CPD) and freeze-drying (FD), were compared by using three kinds of spiral microbes. The AD-technique provided a good result for the preservation of the spiral spore chain of genus Streptomyces, but was not good for the helical cell bodies of genus Spirillum and of genus Borrelia. The results of the CPD-technique was opposite to that of the AD-technique. The FD-technique was good for all materials in average. From the viewpoints of simplicity efficiency and content of the results, the combination of material and method must be checked preliminarily and decided. In conclusion, the authors recommend the FD-technique as a routine method for the reasons mentioned above.