Abstract
Streptothricin is a well-known antibiotic found by Waksman and his collaborators (1) . However, there are more than two kinds of antibiotic substances which are very similar to streptothricin. Lavendulin and actinorubin reported by Kelner and Morton (2) are very resembling to Streptothricin. E. coli whose resistance to streptothricin has been forcedly raised becomes simultaneously more resistant to lavendul in and actinorub in than the normal culture. Umezawa and his collaborators (3, 4) found that antibiotic substances resembling to streptothricin were produced by various kinds of streptomyces, and called them streptothricin-group-substances.
Streptothricin-group-substances have the following characters. (1) They are produced by strains belonging to streptomyces. (2) They are adsorbed by activated carbon from their neutral solution and eluted into acid methanol. (3) A streptothricin-fast E. coli is more resistant to them than the normal culture. A streptomycin-fast E. coli is almost as susceptible to them as the normal culture. In this character streptothricin-group substances can be easily differentiated from streptomycin.
Ten strains of S. lavendulae, two strains of S. albus, one strain of S. ruber, one strain resembling to S. antibioticus, and five strains of S. fradiae, which all had been isolated by Umezawa and his collaborators (5, 6) were found to produce streptothricin-group-substances. Moveover, during testing the resistances of B. subtilis (N. R. R. L. B-558) and B. anthracis, it was found that antibiotic substances of all strains except the strains of S. fradiae showed a longer inhibition length against B. subtilis than against B. anthracis, but the antibiotic substance of S. fradiae showed a longer inhibition length against B. anthracis than B. subtilis. The antibiotic substance of S. fradiae seemed to be different from other streptothricin-group-substances.
In further studies the antibiotic substance of S. fradiae was found to be different from other streptothricin-group-substances in the antibacterial spectrum and the toxicity. The later appearing toxicity which was specific. for streptothricin was not found in the case of the antibotic of S. fradiae. And we decided to call the antibiotic of S. fradiae Streptothricin B, and the others streptothricin A, for among the streptothricin-group-substances streptothricin, the antibiotic of S. lavendulae, was first discovered.
Now the streptothricin A indicates the streptothricin-group-substances produced by various kinds of streptomyces other than S. fradiae. Whether the streptothricin. A is only one kind of substance or there are more than two kinds of streptothricin A, is not yet determined. Though streptothricin A was produced by various kinds of streptomyces, the later appearing toxicity was always observed. The later appear ing toxicity seems to be common to streptothricin A.
In the present paper the differences of streptothricin A and strepto thricin B are described.
