EFFECTS OF DEOXYRIBONUCLEIC ACID PRODUCTS ON RESPIRATION OF VIRULENT AND AVIRULENT PNEUMOCOCCI

Firshein , W. (Wesleyan University, Middletown, Conn.). Effects of deoxyribonucleic acid products on respiration of virulent and avirulent pneumococci. J. Bacteriol.82: 181–186. 1961.—In the presence of deoxyribonucleic acid (DNA) + deoxyribonuclease + mixtures of deoxynucleosides and deoxynucleotides (supplement-1) which had previously been shown to enhance DNA synthesis in virulent (S) pneumococci without affecting such synthesis in avirulent (R) pneumococci, a significant enhancement of glucose oxidation was observed over control levels in S cells of types I, II, and III. In contrast, this supplement either depressed oxygen uptake or had no effect when R or weakly virulent (I) pneumococci were present. In the absence of glucose, S cells were unable to oxidize supplement-1 extensively, whereas R cells exhibited definite activity in this respect. Supplement-1 enhanced glucose oxidation specifically and was not oxidized in the process. The selective advantage produced by the DNA products in S cells could not be explained on the basis of nitrogen content, since a substance containing twice as much of this element as that found in the entire supplement did not enhance oxygen uptake to the extent that was observed with supplement-1.