Appearance of Genetic Transforming Activity in Pneumococcal Cultures

Abstract

Growing populations of Pneumococcus were found to release into the culture medium deoxyribonucleate-containing material with genetic transforming activity. Active material was maximally produced at the time when the culture was most responsive to added deoxyribonucleate. Since mixed cultures thus give rise to recombinants, it may be that transformation provides a natural mechanism of genetic recombination for Pneumococcus .