The Morphology of Staphylococcal Bacteriophage K and DNA Metabolism in Infected Staphylococcus aureus

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Abstract
The morphology and dimensions of bacteriophage K particles were determined by EM. This virus had an icosahedral head (.apprx. 70 nm diameter) and a long (210 nm) thin (15 nm) contractile tail which terminated in a complex basal appendage. The precise dimensions of the particles were dependent on the negative stain employed. The buoyant densities of the K virus particle and its DNA were 1.479 and 1.689 g/ml, respectively. The DNA had a base composition of 30% G + C, a contour length of 16.1 .mu.m and a calculated MW of 33 .times. 106. With S. aureus (NCTC 9318) as host, the latent period was 25 min, the eclipse period 14 min and the average burst size 60 p.f.u. (plaque-forming units)/bacterium. Infection resulted in inhibition of host DNA synthesis and degradation of the bacterial DNA; the products were used for the synthesis of phage DNA. The kinetics of DNA synthesis in infected and uninfected bacteria were examined. There was no initial cessation of DNA synthesis in the infected bacteria.