抗生物質耐性菌の生理学的研究 第2編 オーレオマイシン耐性大腸菌の生理学的研究

It has been reported that, in microorganisms, the acquisition of resistance to aureomycin is relatively difficult compared with the other antibiotics. Physiological studies on the aureomycin-resistant bacteria are also few as compared with those on the bacteria resistant to the other antibiotics. The author isolated a strain of Escherichia coli resistant to aureomycin, and studied on some physiological aspects of this strain in comparison with the sensitive strain. The results are summarized as follows: 1) In the culture of this aureomycin-resistant strain, there appeared a number of string-like cells, which might be considered to be produced by inhibition of cell division. No marked change could be observed in the characters of the colony and the staining of this strain. 2) Without addition of aureomycin, no difference was observed between the multiplication of this resistant strain and that of the sensitive stain. In the media containing aureomycin, however, the resistant strain showed a resistance to aureomycin about 10 to 100 times that of the sensitive strain. 3) In the absence of aureomycin, no marked difference existed between the respiratory activity of the resistant strain and that of the sensitive strain. In the presence of aureomycin, however, the respiratory activity of the resistant strain showed a resistance to aureomycin about 3 times that of the sensitive strain. 4) In the inhibitive action of aureomycin to the oxidation of lactate by the cell-free extract, no noticeable difference was observed between the resistant and the sensitive strains. These results suggest that the change of the cytoplasmic membrane of the resistant strain plays the most important role for exhibition of its high resistance to aureomycin.