Factors regulating competence in transformation of streptococci.

Pakula, Roman (University of Toronto, Toronto, Ontario, Canada). Factors regulating competence in transformation of streptococci. J. Bacteriol. 90:1320-1324. 1965.-The highly transformable group H Streptococcus strain Challis produced an exocellular competence-provoking enzyme capable of converting to the state of competency incompetent cells of the homologous strain, and of the very poorly transformable strain Wicky. The competence-provoking activities of culture filtrates of strain Challis prepared at various periods of growth were tested on cells of strain Wicky. In the first 3 hr of growth, a strict correlation was found between the degree of competence and the competence-provoking activity. The period of maximal competency was followed by a rapid decline, although the competence-provoking activity of the filtrates remained at a maximum. The decay of competence was caused by a change in the structure of the cells which rendered them nonreceptive to the action of the competence-provoking enzyme.