ISOLATION OF A CRYSTALLINE ANTIBIOTIC SUBSTANCE FROM A STRAIN OF STREPTOMYCES AND ITS IDENTITY WITH CHLOROMYCETIN

Abstract

Numerous strains of streptomyces, producing antibiotic substances in the ordinary nutrient agar and inhibiting the growth of the bacteria around their colonies, have been isolated from soil, and actinomycin A (1), streptothricin-group substances (2), and streptomycin (2) have been extracted in our laboratory. But the streptothricin-group substances were produced by so many kinds of streptomyces and their culture filtrate inhibited so strongly the growth of bacteria, that the isolation of new antibiotic substance inhibiting both gram positive and negative bacteria had been very difficult, until recently a simple method determining an antibiotic of streptothricin-group substance was, found (2) . A streptothricin-fast strain of bacteria becomes not only more resistant against the other streptothricin-group substances but also against streptomycin, and a streptomycin-fast strain is nearly as susceptible to the streptothricin-group substances as the normal culture.In our further search for a new antibiotic, it was found that there was an antibiotic inhibiting both the gram negative and positive bacteria, but different from streptomycin and streptothricin-group, for it could be extracted with ether or ethyl acetate, and neither the streptomycin-fast strain nor the streptothricin-group-fast strain became more resistant to it.While studying this antibiotic substance, we noticed the papers concerning chloromycetin. Chloromycetin was found independently by two groups of American antibiotists, the one, Smith, Joslyn, Gruzit, Mclean, Penner and Ehrlich (3) obtained a chloromycetin-producing Strain after examining numerous organisms isolated and found to possess antibacterial activity in Dr. Burkholder's laboratory, and the other group, Carter, Gottlieb and Anderson (3) isolated the strain from the soil in central Illinois. It is produced in the maltose or glycerol roth and extracted with ethyl acetate at various pH and inhibits not only the growth of both gram negative and positive bacteria but also the growth of rickettsia. The proposed name, chloromycetin, seems to originate in the existence of non-ionic chlorine in the molecule.The characters of the ethyl acetate-soluble antibiotic found by us very closely resembled chloromycetin, so we studied this substance along the line of the experimental process described by Smith and others (3) and Bartz (4), and obtained the crystalline antibiotic, the melting point of which conformed with that of chloromycetin.This paper describes the isolation of the strain, some studies on the cultural conditions and the purification. The details on the characters of the strain, the cultural conditions, and the chemical nature of the crystalline antibiotic substances will be published elsewhere.