細菌分類学研究の過去，現在，そして未来

抄録

In 1872, bacteria were classified by Ferdinand J. Cohn, a botanist and microbiologist, for the first time in the world. This classification was based on morphology. Cohn’s concept was reasonable to a point, but it soon became unsuitable because bacteria have quite low levels of morphological variation. At the beginning of the 20th century, Sigurd Orla- Jensen, a biochemist, proposed a new taxonomic system grounded in physiology, and by half a century later modern bacterial taxonomy based on polyphasic comparison of morphological, physiological, and biochemical characteristics had been established. At the end of the 20th century, bacterial taxonomy entered a new epoch thanks to the great insight of the molecular evolutionist Carl R. Woese. The ribosomal RNA that he noticed turned out to be a molecule useful for revealing phylogenetic relationships, not only among all living organisms but also within bacteria. Use of this excellent evolutionary marker also allowed scientists other than bacterial taxonomists to study bacterial classification and identification, thus accelerating progress in bacterial taxonomy. Today, a new era is again about to begin in this intersection of bacteriology, as a result of rapid progress in the development of DNA sequencing technology and computer science.