BIOCHEMICAL STUDIES OF ENVIRONMENTAL FACTORS ESSENTIAL IN TRANSFORMATION OF PNEUMOCOCCAL TYPES

Abstract

The phenomenon of transformation of pneu-mococcal types provides an outstanding example of the induction of specific and heritable modifications in microorganisms. Basically the phenomenon rep-resents the transformation of a nonencapsulated (R) variant derived from o.ne specific type of Pneu-mococcus into encapsulated (S) cells of heterolo-gous specific type. By the technique mployed at present, this is accomplished by growing the non-encapsulated cells in a special serum broth to which has been added the active fraction extracted from encapsulated pneumococci of a heterologous type. The production of a new polysaccharide capsule is induced in the R cells so that they acquire the type-specificity of the organisms from which the extract