Lysis of Streptococcus mutans by hen egg white lysozyme and inorganic sodium salts

Abstract

S. mutans BHT was grown in a synthetic medium containing radioactive thymidine to monitor deoxyribonucleic acid release. Kinetic experiments demonstrated that although lysozyme alone could not liberate deoxyribonucleic acid, cellular deoxyribonucleic acid was liberated from lysozyme-treated cells by addition of low concentrations of inorganic sodium salts. When the salts were tested for their ability to dislodge cell-bound tritiated lysozyme, the extent of the initial release of enzyme by individual anions correlated with the anion potency for deoxyribonucleic acid liberation (SCN ->ClO 4->I -> NO 3->Cl ->F -), although the total amount of lysozyme dislodged did not correspond directly with cell lysis. Differences in the effectivenesses of anions (SCN -,HCO 3-, Cl -, and F -) in potentiating cell lysis could be enhanced or minimized by varying the lysozyme, anion, and bacterial cell concentration. As the anion concentration was increased for each enzyme concentration and cell concentration, the lysis increased, in some cases markedly, until maximum levels of released deoxyribonucleic acid were attained. The maximum levels of lysis for SCN - and HCO 3- were similar and were greater than those for Cl - and F -. In addition, the maximum levels were observed to increase for each of the anions as the concentration of lysozyme increased.