Transformation of Bacterial Types. ∗

Abstract

In previous papers the isolation and description of numerous variant forms of Micrococcus tetragenus was reported. 1 It was at first believed that these interchangeable variants composed a complex system of bacterial variation different from the orderly one associated with other bacteria. A clue to the solution of the problem was provided many months later by the detection of typical rough colonies among the pink colonies already studied. An orderly arrangement of most of the variants and a basis for comparison with other bacteria was then made possible. 2

With the rough-pink form at hand, this form and the mucoid-pink and pink were grouped together as the usual M, S, and R culture-phases of a given bacterial type. On this basis it was predicted 2 that the yellow, white, pink, pink-yellow, and brown forms represented distinct types of M. tetragenus and that each possessed the respective culture-phases. In subsequent investigation involving the aging of 100 cc. broth cultures of the types at hand for months at room-temperature, most of the predicted forms missing from the scheme were detected, isolated, and studied, namely, the mucoid-pink-yellow, mueoid-brown, rough-yellow, rough-pink-yellow, and rough-brown forms. The rough form of the white type has not yet been obtained although several methods known to favor dissociation were employed. The white type under these manipulations changed either into mucoid or translucent form and yellow colonies occasionally appeared. The studies will be published in detail elsewhere. The variant forms of M. tetragenus isolated were arranged as follows:

It appears that M. tetragenus provides a unique opportunity for the study of type and culture-phase transformation.