Factors in Lysis and Lysis Inhibition by Lambda Bacteriophage

Groman, Neal B. (University of Washington, Seattle). Factors in lysis and lysis inhibition by lambda bacteriophage. J. Bacteriol. 90:1563-1568. 1965.-Induced Escherichia coli strain K-12(lambda112) exhibited lysis inhibition at 37 C but lysed at 44 C when incubated in LB medium lacking NaCl [LB - (NaCl)]. In LB medium containing NaCl, the temperatures for lysis and lysis inhibition were reversed. In contrast, induced K-12(lambda) lysed under all of these conditions. At 37 C, the addition of NaCl to LB - (NaCl) at various times after induction of K-12(lambda112) restored lysis. The degree of lysis decreased the longer the addition was delayed, but partial restoration occurred as late as 150 min postinduction. At 44 C, the addition of salt at various times after induction restored lysis inhibition even after lysis had begun. An attempt was made to correlate the conditions for lysis and lysis inhibition with the behavior of lambda112 endloysin. The enzymatic activities of lambda and mutant lambda112 endolysins were compared under various salt-temperature conditions. Both endolysins were progressively and equally inhibited by increasing concentrations of Na(+), K(+), and Li(+) salts, and exhibited similar relative activities at 24 and 37 C. Both were stable at 37 C in the presence and absence of NaCl, and were inactivated at comparable rates at 44 C. The results indicate that the effect of salt and temperature on lysis and lysis inhibition cannot be explained by their direct effect on lambda112 endolysin.