Antibiotics which inhibit both Gram positive and negative bacteria and which are extracted by the process used for the extraction of streptomycin or streptothricin, that is, by the adsorption to carbon and the elution into acid methanol or by the cation exchange resin process, are produced by various species of actinomycetes. Some of them such as streptomycin and fradiomycin (neomycin)^1~2) have no delayed toxicity, but many others have delayed toxicity. In the systematic screening studies made by the authors, antibiotics showing the delayed toxicity were discarded and those without the delayed toxicity were further studied and purified. Thus, kanamycin was discovered and presented in this paper.

Here it seems to be worthy to note an antibiotic produced by S. roseochromogenus, though it has no relation with kanamycin. Ishida3) first described that he isolated a low toxic antibiotic from the culture liquid of S. roseochromogenus. The authors also obtained a similar substance from another strain belonging to the same species. At the beginning of the study, the antibiotic of this strain did not show the delayed toxicity, but, when the productivity of the strain was improved and the antibiotic was further purified, then the antibiotic showed the delayed toxicity similar to streptothricin. Thereafter, the author failed to isolate the low toxic antibiotic from this strain. In case of kanainycin, the kanamycin-producing strain is clearly different from S. roseochromogenus and the low toxic kanamycin is constantly isolated.

Kanamycin shows dextrorotation, but it is differentiated from the dextrorotatory antibiotics such as fradiomycins (neomycins), catenulin, and geomycin, and it is a new antibiotic.

In this paper the characteristics of the kanamycin-producing strain, the production, the extraction and the purification are presented.