168 BACTERIOPHAGES 



described rather similar experiments in which solubiHzation of 

 nitrogenous constituents of isolated cell walls by adsorbed phage 

 is measured. The effect is seen with phages T2, T4, T6, and 

 T5, but not with T7. Their results may be summarized as fol- 

 lows. 



The amount of material solubilized corresponds to about 1 

 per cent of the cell wall nitrogen per phage, increasing linearly 

 with multiplicity of adsorption up to about 1 5 per cent solubili- 

 zation, after which attachment of additional phage particles has 

 no effect. This maximal solubilization can also be achieved 

 with fewer phage particles if the mixture is repeatedly centri- 

 fuged, an effect attributed to an increased opportunity of contacts 

 between insoluble phage enzyme and insoluble substrate. In 

 either case, the maximum solubilization produced by T2 is not 

 increased by adsorption of additional particles of either T2 or 

 T4. This result shows clearly that the materials solubilized are 

 not the phage-specific receptor substances. Phosphorus and 

 amino acids are both solubilized. The reaction fails at low tem- 

 peratures, but is not inhibited by pretreatment of the cell walls 

 with heat or with phenol. The role of this reaction in penetra- 

 tion is not clear, especially because of the limited effects observed, 

 but an important role in infection may be surmised. It seems 

 very likely that it prepares the cell for the leakage of cell constit- 

 uents observed by Puck and Lee. It also helps to explain their 

 "sealing reaction," since cell wall materials are very rapidly syn- 

 thesized after infection (Hershey, Garen, Fraser, and Hudis, 

 1954). 



Park (1956) and Adams and Park (1956) described an enzyme 

 present in phage lysates of Klebsiella pneumoniae that acts on the 

 capsular material of these bacteria. The enzyme is found both 

 free in the lysate and attached to phage particles, and the amount 

 produced seems to depend on the hereditary constitution of both 

 bacterium and phage. It is not found in uninfected cells. The 

 role of the enzyme in adsorption and penetration has not yet been 

 studied. 



