ANTIBACTERIAL ACTION OF A REACTION PRODUCT OF CYSTEINE AND IRON: I. DEVELOPMENT OF THE SUBSTANCE IN MEDIA FORMYCOBACTERIUM TUBERCULOSIS

Abstract

It is shown that the growth of Mycobacterium tuberculosis or a rapidly growing strain of Mycobacterium in Dubos' medium is not influenced by the addition of low concentrations of cysteine or ferric salts, when added separately. But when cysteine and a ferric salt, both in low concentrations, are autoclaved together in the medium, the medium will not support growth of Mycobacterium. This inhibitory action only occurs when the cysteine–iron containing medium is at pH 6.8 or a more acid reaction. It is concluded that cysteine and ferric iron react in acid solution to produce a toxic end product.