食品衛生に関する腸球菌の研究 : 第1報 日常食品の汚染指標としての腸球菌検査術式に関する研究
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概要
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There are several methods available for demonstration of enterococci contained in samples of foods and for determination of their numbers by the table of M. P. N. The author undertook a study of basic problems involved in one of the methods by which the numbers of enterococci are determined on the basis of the result of incubation of the culture of a confirmative medium which has been inoculated with the culture of a presumptive medium generally used to reveal the presence of coliform organisms. The results of the study are summarized as follows: (1) Enterococci of some strains are easily affected by sodium azide; if samples examined for enterococci contain them in minute amounts, multiplication of the micro-organisms would be inhibited. In order to obtain an accurate and reliable result, any inhibitor should not be added to the presumptive medium so that all varieties of enterococci may be allowed to multiply. (2) Experiments revealed that, when lactose broth was used as the presumptive medium, and a medium made by adding 0.03 % sodium azide and 0.00006 % ethyl violet to dextrose broth was used as the confirmative medium, the result was far better than would have been the case if any other methods had been used. The presence of enterococci was proved by morphologic and taxonomic study in nearly all the tubes which had been found positive by the above tests. We might, therefore, be justified in doing without morphologic and taxonomic study in some instances. (3) The method developed by the author makes it possible to carry on the experiments on enterococci side by side with those on coliform organisms at the same time; lactose broth is used as the presumptive medium for the two types of organisms, while brilliant green bile lactose broth and B. T. B. ethyl violet azide dextrose broth (Miyabayashi) are used as the confirmative media for coliform organisms and enterococci, respectively; and the final examinations are performed by the method specific to each type of organisms. It is to the credit of this method that both enterococci and coliform organisms could be examined at the same time using the same specimens, and that little technical complexity is involved in the procedure.