Genetic transformation of colony type in Xanthomonas phaseoli.

The first demonstration of transformation (Griffith, 1928) was concerned with type-specific capsular polysaccharides of pneumococci. Such transformations of capsular types usually are accompanied by a change in colony type since most investigators have studied transformation of R cells which produce little or no capsular material. Coiacomitant transformation of capsular and colony type has been reviewed by Austrian (1952) who also reported that others observed transformation of capsular type without accompanying transformation of colony type. Concomitant transformations are frequent, as are transformations of colony type with transformations of capsular type. However, transformations of capsular type without transformations of colony type are rare. Four colonial variants of Xanthomonas phaseoli which produce different quantities of the same capsular polysaccharide have been described. The amount of polysaccharide produced determines the colony type (Corey and Starr, 1957). This paper presents evidence that these colony types can be transformed.