CLASSIFICATION OF ANTIBIOTIC STRAINS OF STREPTOMYCES AND THEIR ANTIBIOTIC SUBSTANCES ON THE BASIS OF THEIR ANTIBACTERIAL SPECTRA

Abstract

The fields of antibiotic substances of streptomyces have been examined most in detail, and actinomycin, streptothricin, streptomycin, grisein, chloromycetin, actidione and aureomycin have been isolated and studied in detail. But there seem to be more other antibiotic substances. In general an antibiotic strain of streptomyces develops on the nutrient agar and produces the antibiotic substance which diffuses in the agar and inhibits the growth of bacteria near around its colony. But it is not always that streptomyces showing the inhibiting zone on the agar produces the antibiotic substance in the nutrient broth by shaking or stationary culture. Besides there is not any strict conformity between the kind of species and the kind of antibiotic substances produced. For example, both a streptomycin-producing and a grisein-producing strain chiefly belong to S. griseus, and streptothricin-group substances are produced by various kinds of streptomyces. In these circumstances, it is necessary to identify the kind of antibiotic substances by testing their antibacterial spectra on the nutrient agar, in order to find a new antibiotic substance.
Since many antibiotic strains had been isolated in our laboratory and some of their antibiotic substances had been determined, such as to be actinomycin, streptothricin-group substances, streptomycin, chloromycetin and grisein, so the antibacterial spectra of all the other strains were examined, in order to find whether there were some strains producing a new antibiotic substances. But it is not easy work to test the complete antibacterial spectrum of each strain against many kinds of bacteria. As shown in our previous report, a strain which resistance to one of the antibiotic substances was forcedly increased does not usually become more resistant to other antibiotic substances. streptomycin-fast strain of B. coli is more resistant to streptomycin than the normal strain, but not to streptothricin and other antibiotic substances.. A streptothricin-fast strain of B. coli increases its resistance only against streptothricin-group substances and streptomycin. A grisein-fast strain increases its resistance specifically against grisein. So if the resistances of the fast strains to an antibiotic are tested, then it can be simply determined to which kind of antibiotic substances it belongs.
In stead of testing resistances of many kinds of bacteria, the resistances of the above three fast strains and the normal strain of B. coli were tested against the antibiotic substances produced around the colonies of antibiotic strains of streptomyces. Moreover, as we had already found that B, subtilis is more resistant to streptomycin that B. anthracis and the latter is more resistant to streptothricin-group substances than the former, so the resistances of these two kinds of bancteria were also tested.
According to the antibacterial spectra, antibiotic strains were at first divided into two large groups, the first inhibiting the growth of B. coli and the second not inhibiting B. coli. Furthermore the first large group could be classified into five groups. In this paper the classification of the first group is described. The classification of the second group will be published later, though it is already found that there are more than two kinds of antibiotic substances which do not inhibit the growth of B. coli, that is, actinomycin and other antibiotic substances.