Microbiology (1997), 143, 179–185 Printed in Great Britain Bacteriophage T4 development depends on the physiology of its host Escherichia coli Hilla Hadas, Monica Einav, Itzhak Fishov and Arieh Zaritsky Author for correspondence : Arieh Zaritsky. Tel : 972 7 646 1712972 7 627 8951. Fax : 972 7 627 8951972 7 647 2890. e-mail : ariehzbgumail.bgu.ac.il Department of Life Sciences, Ben-Gurion University of the Negev, PO Box 653, Be’er- Sheva 84105, Israel Several parameters of phage T4 adsorption to and growth in Escherichia coli B/r were determined. All changed monotonously with the bacterial growth rate ( μ), which was modified by nutritional conditions. Adsorption rate was faster at higher μ values, positively correlated to cell size, and increased by pretreatment with low penicillin (Pn) concentrations ; it was directly proportional to total cellular surface area, indicating a constant density of T4 receptors on cell envelopes irrespective of growth conditions. Parameters of phage development and cell lysis were μ-dependent. The rate of phage release and burst size increased, while the eclipse and latent periods decreased with increasing μ. Differentiation between the contribution of several physiological parameters to the development of T4 was performed by manipulating the host cells. A competitive inhibitor of glucose uptake, methyl α-D-glucoside, was exploited to reduce the growth rate in the same effective carbon source. Synchronous cells were obtained by the ‘ baby-machine ’ and large cells were obtained by pretreatment with low Pn concentrations. Lysis was delayed by superinfection, and DNA content and concentration were modified by growing a thy mutant in limiting thymine concentrations. The results indicate that burst size is not limited by cell size or DNA composition, nor directly by the rate of metabolism, but rather by the rates of synthesis and assembly of phage components and by lysis time. The rates of synthesis and assembly of phage components seem to depend on the content of the protein-synthesizing system and lysis time seems to depend on cellular dimensions. Keywords : bacterial growth rate and cell dimensions, adsorption rate, thymine limitation, lysis delay by superinfection, synchronous ‘ baby ’ cells INTRODUCTION Studies on bacteriophage growth and development played a vital role in the history of molecular biology (Cairns et al., 1966 ; Karam, 1994 ; Mathews et al., 1983). The information which was accumulated during the 1940s, particularly with the model species T4, laid the basics for the evolving field (Cairns et al., 1966). The classical one-step growth experiment performed by Ellis & Delbru  ck (1939) defined the latent period, rise time and burst size, and the eclipse period was discovered by the effective procedure devised to disrupt infected bacteria before their spontaneous lysis and without damage to the mature phages (Doermann, 1948). ................................................................................................................................................. Abbreviations : α-MG, methyl α-D-glucoside ; Pn, penicillin ; PSS, protein- synthesizing system. Phage–host interactions begin by a highly specific attachment to one of the cell envelope layers ; the phage tail fibres bind to specific receptors in the bacterial envelope (Goldberg et al., 1994). Adsorption depends on environmental factors as well, and is followed by penetration of the phage DNA through the bacterial wall, which is weakened by the lysozymic activity of the tail baseplate. The infected cell then becomes dedicated to the phage’s needs for efficient multiplication by expressing phage-encoded proteins. Early proteins govern DNA replication and synthesis of coat com- ponents ; late proteins induce cell lysis thus releasing phage progeny. All time and kinetic parameters differ with interacting species and vary over a wide range. By the time bacterial physiology was established as a discipline (Kjeldgaard et al., 1958 ; Schaechter et al., 0002-1042  1997 SGM 179