Abstract
Mucoid colony variants and dwarf colony variants were isolated from the Mutabile type variants of enteric bacteria by mutation and investigations were made on their mutual relationships. Appearance of the Muc. colony was recoenized when pure cultures of the Mut. variants of Seim. typhi-murium and E. eoli were seeded and incubated on Endo' s plates or galactse-Endo' s plates for 24 hours and then left stancing in the room temperature for 2-3 days. This colony was mucoid on Endo' s or galactose-Endo' s plates but formed D colony on plain agar plates becoming non-mucoid. It was discovered that when Muc. type undergoes reverse mutation to Nonmuc. type, it becomes the starting Mut. variant and at the same time loses the characters of D type. On titrating the sensitivity of each variant against galactose, it was founc that the Muc. variant shows a rather low titer in comparison with that of the starting Muet. variant or reversed Mut. variant but its lactose sensitivity remains unchanged (Muc. varian of E. Coli Mut. variant) .
Muc. type, of course, undergoes variation to the galactose resistant form MT of Murase. This MT, however, is D type and not Muc. type. It was discovered, further, that this D type MT undergoes variation to the same MT as that of the starting Mut. variant. Moreover, MRT mutation of Fukutome et al was recognized on the Muc. type of the Mut. variant of E. coli. This RT formed the mucoid colony also on plain agar plates.
Non-mucoid D type was discovered by mutation from a strain of the Mut. variant of salm. enteritidis. This variant was highly sensitive against galactose. Both MT and RT of this variant were also D type.
In view of the findings stated above, it can be said that the mucoid character observed on the Muc. variant of the Mut. variant is liable to accompany the dwarf character and becomes relatively resistant against galactose but not against lactose. Reverse mutant of this mucoid type is no more D type nor Muc. type. The newly appeared characters (mucoid or dwarf) of the Mut. variant seem to be transmitted to the following generation of the mutation (to MT or RT) whether or not they are disposed at the time of this reverse mutation.
