ムタビール型変異 (村瀬) 菌の娘型に関する研究

1.M型のgalactose抵抗獲得様式に就いて

抄録

M-type variants (Murase) were isolated from the strain 396 of Salm. enteritidis by old broth culture method. Strain mt₁, was isolated from the daughter colony of M type variant, strain mt₂ was isolated from that of mt₁ and strain mt₃ was isolated from that of mt₂. Strain mt₄ was isolated from the tube of mt₃ cultured in galactose peptone water for one week and failed to ferment it. Galactose sensitivity of those mt strains was investigated by the paper disk method.
Those which have demonstrated full resistance to galactose were called MT. As for mode of the acquisition of resistance, it can be said there are two ways that some acquire full resistance by a single step and the others by several steps. Generally speaking, the acquistion of galactose resistance by mt strains seem to belong to the streptomycin type of Demerec.
With regard to antibotics, it is highly difficult to develope sensible strains by the use of an excessively high concentration. While, in the present study, in spite of the use of galactose in such a high concentration of 5, 000γ/cc, both sensible M-type variants and resistant daughter mt can grow on it.
Some of the deep-cultured colonies were found to consist of full resistant bacteria.
In case of antibiotics, sensible strains are wild strains and resistant ones are those which likely developed variation in some charactors. On the other hand, galactose sensible strains discussed in the prepent study are variants at the beginning and the resistant strains are rather those reversing to the original from it. Accordingly, it can be said that similar acquisition of resistance was confirmed to follow the variation to reverse direction suggesting the presence of some rules in the hereditary processes related with the acquisition of resistance to the other chemical agents.