Abstract
THOSE who have followed the development of research on penicillin and other substances which inhibit the multiplication of micro-organisms will be familiar with Sir Alexander Fleming's discovery (Brit. J. Exp. Path., 10, 226; 1929), that staphylococci cultured on a plate culture failed to develop around an accidental contamination with the mould Penidllium notatum and were undergoing lysis, and that culture fluid taken from a culture of P. notatum would, even when it was diluted 500–800 times, completely inhibit the growth of the staphylococci. This work, together with other work on penicillin and on various antibacterial substances derived from bacteria and moulds (for example, pyocyanine, gramicidin, actinomycin, aspergillic acid, helvolic acid, etc.), has been summarized in the British Medical Bulletin (2, No. 1; 1944) and elsewhere. In bacterial cultures in which these antibacterial substances are present, areas in which the bacteria fail to develop appear, which are sometimes called 'clearance areas'. Protozoologists have been aware for many years that certain amœbæ ingest readily certain kinds of bacteria, yeasts and similar organisms, and that they can, under appropriate cultural conditions, produce in bacterial cultures 'clearance areas' somewhat similar to those produced by the antibacterial products of moulds and bacteria. The two phenomena are, however, quite distinct. While the amœbæ clear parts of the cultures by actively ingesting the bacteria, the antibacterial products of moulds and bacteria clear them by inhibition of the bacterial growth, or even by lysis of the bacteria.
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LAPAGE, G. Antibacterial Activity of Amœbæ. Nature 155, 182–183 (1945). https://doi.org/10.1038/155182a0
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DOI: https://doi.org/10.1038/155182a0