Abstract
The present paper deals with the studies on the mutabile type variant of para-colon type E. coli which possesses a characteristic lactose fermentation formula.
When this organism was cultivated in lactose peptone water, a lactose weak f ermeter V1 was produced in the first place, then, lactose strong fermenter V2 produced showing g lactose fermentation.
From this strain of E. coli, M-type variant was isolated. By cultivating this M-type variant in galactose peptone water, RT (galactose fermenting daughter of Fukutome et al) was obtained in addition to MT (daughter mutabile type variant of Murase) .
This M-type pariant or MT did not ferment either galactose or lactose. Further, on this occasion, lactose fermenting variant could not be found. Nevertheless, RT fermented galactose but not lactose. Furthermore, when RT was cultivated in lactose peptone water, apparently lactose weak fermenter V2 was isolated in the first place, and then lactose strong fermenter V2 was produced from this V1. In other words, this RT was considered to demonstrate a galactose fermenting mode identical to the original type which is mother type of the M-type variant. As reported previously in Report 1- Report 3, the RT isolated from mutabile type variant demonstrated in every case the lactose fermenting mode which is almost indistinguishable from that of the starting original type. Also in the present report, similar mode was demonstrated in the case with the M-type variant of E. coll.
