EFFECT OF HEAT SHOCK ON T4RII MULTIPLICATION IN ESCHERICHIA COLI.

Kasatiya, Shanti-Swaroop (University of Southern California, Los Angeles), and Margaret Lieb. Effect of heat shock on T(4)rII multiplication in Escherichia coli. J. Bacteriol. 88:1585-1589. 1964.-Heating certain strains of Escherichia coli K-12 (lambda) to 45 to 48 C for 12 min before phage infection increased the fraction of bacteria that allowed multiplication of T(4)rII mutants. The effect of heat on interference to T(4)rII was not correlated with induction of the lambda prophage, which occurred in some of the strains studied. Incubation of heated cells at 37 C before infection resulted in the recovery of interference, providing a prophage was still present. The presence of magnesium ion after infection is known to greatly decrease the interference in K-12 (lambda) to T(4)rII. When heat-shocked cells were infected with T(4)rII, and then incubated in medium containing a suboptimal concentration of magnesium ion, more cells produced a burst of T(4)rII progeny than with either treatment alone. It is suggested that factors produced by both the prophage and the bacterium contribute to the structure or substance responsible for interference. The variation in heat sensitivity of interference in various strains is probably due to differences in the bacterial contribution to the postulated structure.