Abstract
When E. coli. B is mixed with T3 phage, the T3 phage-resistant colonies appear. Among these colonies, the chewed up sectored colonies are frequently observed. The colonies and lysing phages were maintained by transferring on the agar slant medium. After several transfers, the phage was isolated and designated as T3hs phage, because it was h mutant of T3 phage which produced the irregular plaques on E. coli B wild type strain (Okada, 1958).
The reason why the plaques of T3hs phage on E. coli B were so irregular was disclosed by Doi. The T3hs phage was T3hm phage which manifests its minute character only on E. coli B wild type strain and not on E. coli Bs/3 strain which prepared from the sectored colonies. During the development of T3hm phage on E. coli B, the mutation from m to m+ occured and the area of the development of back mutated T3hm+ was so protruded that the plaques became irregular (Doi, 1958).
Next problem is to determine whether the behavior of Bs/3 strain to T3hm phage is specific for Bs/3 strain or common for B/3 strains. To dissolve this question, several phage resistant bacteria (to T1-T7) were prepared and tested for the behavior to T3hs phage. Then, it was concluded that the mutations of E. coli B to T3, T4 resistance were always accompanied by the alteration of the behavior to T3hs phage.
