Effect of manganese and enzymatic deoxyribonucleic acid digests on population changes and respiration of Pneumococci.

Firshein, William (Wesleyan University, Middletown, Conn.). Effect of manganese and enzymatic deoxyribonucleic acid digests on population changes and respiration of pneumococci. J. Bacteriol. 84:478-484. 1962.-Deoxyribonucleic acid (DNA; Na salt) treated with deoxyribonuclease and Mn(++) (as MnSO(4)) stimulated R (avirulent) to S (virulent) population changes in vitro. Under certain environmental conditions and with certain strains, Mn(++) alone elicited these changes, but, in most cases, both digested DNA and Mn(++) were necessary for maximal effect. These population changes were due to a selective stimulation of the multiplication of S cells and a delay in S-cell lysis, with either a slight inhibitory effect or no effect against the multiplication of R cells. The magnitude of the population change depended upon the presence of digested DNA, the level of Mn(++), the strain, and the concentration of basal medium. Mn(++) enhanced respiration of S cells while inhibiting that of R cells.