On the Origin of Virus Phosphorus

Abstract

When phage is propagated in bacteria in a chemically defined medium, the medium itself can be the ultimate source of 70% of virus P. The remaining virus P is derived directly from the bacterial host, chiefly from some P fraction other than low-molecular-wt., acid-soluble compounds. Phage was harvested in the super-centrifuge and isolated by differential centrifugation. It had an avg. infectivity of 10-15.89 gm. N per infectious unit. In the electron microscope the phage showed typical tadpole-shaped particles. Virus containing P32 was isolated after multiple infection of labeled or of unlabeled bacteria. Three types of expts. were done in synthetic medium using 1) unlabeled cells in medium with P32, 2) washed labeled cells in unlabeled medium, or 3) differentially labeled cells in unlabeled medium. In each case the bacteria were infected with 3 phage particles per bacterial cell to produce a single virus generation without further bacterial growth. The P of the virus was found to be derived chiefly from inorganic phosphate of the medium.