Subtilin-Antibiotic Produced by Bacilius subtilis. II. Toxicity of Subtilin to Living Embryonic Tissue.

Abstract

Subtilin, an antibiotic extracted from Bacillus subtilis, was found to be antagonistic chiefly against Gram-positive organisms, including Mycobacterium tuberculosis and other acid-fast bacteria. Two notable exceptions were Neisseria catarrhalis and N. gonorrhoeae, both Gram-negative but also antagonized by subtilin. The antibiotic showed an extremely low toxicity for embryonic chick heart tissue fragments cultivated in vitro. Subtilin was approximately 20 times more toxic to Staphylococcus aureus than to chick heart tissue, a remarkably low tissue toxicity. A unit of subtilin is defined as the arat. (expressed in mg.) contained in 1 ml. of the highest dilution capable of killing S. aureus in 10 min. at 37[degree] C (F.D.A. phenol coeff. method).