362 Marine Microbiology 



assay. These samples were then stored either in the dark at C 

 or in day Hght at room temperature, 20-22 C, and the phage 

 concentration was assayed after various periods up to one month. 

 The anti-coH phage, NCTC 8400, was inckided. 



The anti-coh phage was completely inactivated within eleven 

 days at C and within seven days at 20 C, whereas the marine 

 phages were not inactivated within one month, although some 

 inactivation was becoming evident at the end of this period, 

 particularly at the higher temperature in day light. 



The Effect of the Ionic Environment on the 

 Ability to Lyse the Host Organism 



The phages were isolated by the use of sea water-based 

 media and it was soon observed that three of the phages, P/14, 

 P/L/34 and P/SWl/b would not always grow on tap-water-based 

 media containing 0.5% NaCl. Some preliminary experiments have 

 been carried out on this phenomenon. 



Phage P/14. It was shown that the requirement for sea water 

 based media was not purely osmotic in that the addition to a 

 basal salt-free tap water medium of a variety of salts to a molar 

 concentration equivalent to that of NaCl in the sea water medium 

 did not effect lysis. However, the addition of 0.1 M MgCL- allowed 

 lysis to take place at a minimum concentration of 0.4 M NaCl, 

 while 0.2 M MgCL allowed lysis to take place with 0.1 M NaCl, 

 although not in its virtual absence. It would thus appear that al- 

 though both NaCl and MgCb are required for lysis, there is no 

 requirement for a fixed proportion; to a large extent, but not 

 entirely so, these salts can replace one another. It has not yet 

 been determined whether other salts can replace NaCl orMgCL 

 except that as the phage is citrate insensitive, Ca^"^ is not required 

 for lysis. 



Phage P/L/34. Unlike P/14, phage P/L/34 would give lysis 

 on the tap water media on some occasions but not others. It was 

 again shown that the partial requirement for a sea water based 

 medium was not osmotic, at is could not always be satisfied 

 by the addition of salts to the basal salt-free tap water medium. 

 It was found, however, that although tap water medium con- 

 taining 0.5% NaCl would not always support lysis, the basal 



