Studies on Polymyxin: Isolation and Identification of Bacillus polymyxa and Differentiation of Polymyxin from Certain Known Antibiotics

Abstract

The isolation from soil and the identification of B. polymyxa as the organism producing the antibiotic polymyxin are described. Polymyxin is active primarily against the Gram-negative bacteria. Crude fermentation liquor has a small amt. of Gram-positive activity which is practically absent in partially purified concentrates. The Gram-positive activity of fermentation liquor is attributed to another antibiotic which is associated with the cellular substance of B. polymyxa. Its prepn. is briefly described. The points of distinction between polymyxin and certain of the known antibiotics are discussed.