SUMMARY: A lethal oedema-producing toxin has been made in vitm in serum cultures of Bacillus anthracis which is identical with the toxin originally recognized in Wiuo. Toxin is produced by the attenuated immunogenic Sterne strain as well as by the virulent N.P. strain. Previous non-recognition of the toxin in cultures was due to its early appearance and rapid disappearance under ordinary growth conditions. A toxin-destroying mechanism was demonstrable in organisms from cultures grown for more than a few hours. Attempts to maintain the toxin concentration or to increase it by addition of various nutrilites to batch culture failed; only by continuous culture have the organisms been kept in their toxigenic growth phase. "races of the toxin appear in cultures in tryptic meat broth; these are increased by the addition of large molecular constituents of serum which appear to play an important role in toxin production.
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