AN ANTIBIOTIC PRODUCED BY MICROCOCCUS EPIDERMIDIS

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Abstract
A stable antibiotic was produced by a strain of Micrococcus epidermidis that showed a wide range of activity against Gram-positive organisms. A mucoid Streptococcus pyogenes was used as test organism. This strain could be made resistant by being grown in increasing concentrations of antibiotic but the organism reverted to its original susceptibility immediately on transfer to medium without antibiotic. There was no antiluminescent activity when tested on Photobacterium fischeri. The test organism was not lysed by the antibiotic. The active substance was dialyzable, was remarkably heat stable, and was soluble only in water or, providing water was present, in solvents that were completely miscible with water. Purification was successful only to the extent of removing a number of inactive fractions by differential solubilities. The activity was destroyed by trypsin but not by pepsin. The physical and chemical data make it probable that the substance is a polypeptide of low molecular weight.