EFFECT OF MANGANESE AND ENZYMATIC DEOXYRIBONUCLEIC ACID DIGESTS ON POPULATION CHANGES AND RESPIRATION OF PNEUMOCOCCI

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Abstract
Deoxyribonucleic acid (DNA; Na salt) treated with deoxyribonuclease and Mn++ (as MnSO4) 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.