Productive phage infection in Escherichia coli with reduced internal levels of the major cations

Abstract

Bacteriophage-induced changes in the intracellular levels of the major cations of Escherichia coli were studied to investigate the role of ion concentrations for bacteriophage assembly in vivo. Infection of E. coli by phage T4, P1, or lambda caused a transient reduction of intracellular levels of potassium, magnesium, and polyamines. Phages T3 and T7, however, had no detectable effect on the cation concentrations within the cell. In all cases, any reduction in the ion concentrations was restored later in infection. When the intracellular potassium concentration was lowered from 325 to 150 mM with a different osmotic growth medium, the number of phage progeny was only slightly reduced (by a factor of two). On additional reduction of the intracellular magnesium concentration from 100 to 50 mM by adding the antibiotic polymyxin B to the infected cells, T4 infections, but not T3 or T7, were markedly affected. These studies show that T3, T4, and T7 phage assembly can efficiently occur in vivo over a broad spectrum of ion concentrations.