MycobacteriumおよびNocardiaのDNA含有量の比較

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The content of deoxyribunucleic acids (DNA) was compared in various mycobacteria by Tsukamura, but, since the data were presented inadequately, it was desired again to estimat e the DNA content, applying a more appropriate method, in various mycobacteria and nocardias. Twelve strains of 7 species of Mycobacterium and 12 strains of 5 species of Nocardia were used (Table 1 and 2). The strains had been maintained on Ogawa egg medium at -20°C. After subcultureing test strains on Ogawa egg medium at 37°C (Mycobacterium)or at 28°C(Nocardia), growing organisms were harvested, washed three times in distilled water, and then used for estimation of DNA, ribonucleic acid (RNA) and protein contents. Rapid-growing mycobacteria (Table 3) and nocardias were harvested after incubation for 7 days, slow-growing mycobacteria (Table 3) after incubation for 14 days, and very slowly growing mycobacteria (Table 3) after incubation for 21 days. The organisms were fractionated according to the procedures of Schneider or of Ogur-Rosens. The DNA content was measured by the diphenylamine reaction, the RNA content by the oricinol reactive, and the protein content by the Folin phenol reagent. The estimation was made on three different samples and the results were expressed as μg DNA per mg protein. Influ e nce of the Fractionation Method on DNA Content Estimation The DNA content varied depending on the method of fr a ctionation. Some species showed similar values in both methods, while some showed markedly different ones (Tables 1 and 2). It was noticed that the influence of the fractionation method be consistent in species groups (Table 3). It was suggested that the effect of extraction agents on the DNA extraction be correlated with some taxonomic group (Table 3). The difference of the DNA content between the two fractionation methods would have been produced by either the use of hot trichloroacetic acid (Schneider method) or the use of hot perchloric acid (Ogur-Rosen method) for extraction of the DNA. The effect may be essentially related to the cell wall or cell membrane structure of organisms. RNA content appeared relatively low in the Ogur-Rosen method (Tables 1 and 2). DNA Content in Various Taxonomic Groups 1. When observed in the values obta i ned by the Schneider method, the DNA content of mycobacteria were considerably uniform, whereas that of nocardias differed from strain to strain (Tables 1 and 2). Especially the content in N. polychromogenes was significantly lower than the others (Table 2). 2. When observed i n the values obtained by the Ogur-Rosen method, the DNA content in slow-growing mycobacteria was significantly higher than that in rapid-growing mycbbacteria. The content in M. tuberculosis and M. bovis was low. The nocardias were grouped into two subgroups; one showing low values (M, polychromogenes, N. asteroides and N. farcinica) and another showing high values of the DNA content(N. brasiliensis and N. caviae)(Tab.1 and 2). In view of the results obtained, the DNA content estimated using the Ogur-Rosen meth o d seemed to be more related to taxonomic grouping, and it was believed that the comparison of the DNA content between two fractionation methods, Schneider and Ogur-Rosen methods, contributes to the taxonomy ofkn-abstract=
日本結核病学会の論文

<I>Mycobacterium</I>および<I>Nocardia</I>のDNA含有量の比較

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