T4 Bacteriophage Average Burst Size Varies with Escherichia coli B23 Cell Culture Age

Host physiology has a dramatic effect on the ability of T4 bacteriophage to infect and produce progeny. Previous studies have shown that as Escherichia coli cells enter stationary phase, many physiological changes to cell size and shape occur. These changes could affect the ability of the T4 bacteriophage to produce progeny. In this study, standard plaque assays were used to investigate the effects of culture age on phage burst size. Cells were grown for 1, 3, 4 and 5 days in liquid H media and infected with T4 bacteriophage. Burst size from day 3 cultures was approximately half of the overnight culture’s burst size, burst sizes from day 4 cultures were lower than that of day 3 by approximately 10-fold and burst sizes from day 5 cultures were greater than day 4 by approximately 350-fold. No overall decreasing trend was seen in burst size perhaps due to biofilm production. The small burst sizes seen in the day 3 and 4 of stationary phase may be due to weakening phage adsorption from altered cell shape. The large burst size seen in day 5 of stationary phase may be due to altered adsorption efficiency from biofilm production or due to the culture undergoing two lytic cycles. The day 5 cultures showed larger plaques, which may be due to inconsistent indicator bacteria concentration or indicator bacteria not being in exponential phase of growth.