Abstract
Summary
A new type of antagonistic substance, designated as streptothricin, has been obtained from a soil Actinomyces. The substance appears to be formed from certain amino acids in the medium. Streptothricin is insoluble in ether, petrol ether or chloroform, and is carried down by precipitating the medium with ethyl alcohol. It is best separated from the medium by adsorption on norit-A, followed by elution with dilute mineral acid. Further concentration is accomplished by neutralization of the acid and concentration in vacuo. The active substance is low in nitrogen, is not affected by proteolytic enzymes and can withstand 100°C, for 15 minutes. Its properties are those of an organic base.
The bacteriostatic action of streptothricin is unique. The addition of 0.1 mg of crude material to 10 cc of nutrient agar inhibits the growth of E. coli and various other gram-negative bacteria; among the gram-positive bacteria, some, like Bac. subtilis and micrococci, are more sensitive, whereas others, like Bac. mycoides, are far more resistant. Streptothricin possesses also marked bactericidal properties, especially upon certain gram-negative bacteria.
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