Abstract
In the present work, the author obtained a strain of the mutabile type variant (Murase) from the old broth culture of the HK strain of E. coli. When decimal dilutions of the strain wad cultivated in galactose peptone (GP) water, galactose fermenting variant (RT) was obta fined with a minute amount of inoculum. Utilizing this characteristics that such variant as RT is liable to be obtained, comparisons were made between the effects of galactose (a sugar fermentable by the strain) and raffiinose (a sugar non-fermentable by the strain) on the frequency of appearance of RT variant. The above experiments lead to the following results.
In the frequency of the appearance of M type → RT mutation, both of the sugars in question showed approcimate values eath other, being roughly between 0.005% and 0.0005%. In other words, in means that, at a level of extremely small amount of inoculum under raffinose non-fermenting condition, M type→RT mutation is evidently occurring. Moreover, its findings were not so much different from those in the case of the fermentable galactose. The above findings in raffinose peptone (RP) water was found coinciding with those that M type→RT mutation was occurring in GP water under galactose non-fermenting condition.In short, the above observations suggested that the heretofore reported M type →MT mutation belongs to an identical mutation type to that of M type →RT mutation.
