ISOLATION AND PRELIMINARY CHARACTERISTICS OF THREE BACTERIOPHAGES ASSOCIATED WITH A LYSOGENIC STRAIN OF PSEUDOMONAS...

Feary, Thomas W. (Tulane University School of Medicine, New Orleans, La.), Earl Fisher, Jr., and Thelma N. Fisher. Isolation and preliminary characteristics of three bacteriophages associated with a lysogenic strain of Pseudomonas aeruginosa. J. Bacteriol. 87:196-208. 1964.-Three bacteriophages designated 7v, 7m, and 7s were isolated from a lysogenic strain of Pseudomonas aeruginosa designated Ps-7. The three viruses were found to be completely unrelated on the basis of plaque morphology, host range, serology, ultraviolet induction, sensitivity to heat, and particle morphology as revealed by electron microscopy. In addition, it was shown that the three phages were incapable of plaque formation on bacteria other than various strains of P. aeruginosa. Of the three phages, only phage 7v was capable of plaque formation on strain Ps-7. The growth of phage 7v on strain Ps-7 exhibited properties which suggest that this virus arises as the result of mutation in a temperate phage for which strain Ps-7 is lysogenic. Phages 7m and 7s are incapable of plaque formation on strain Ps-7, but are adsorbed at characteristic rates to cell suspensions of strain Ps-7. The relationship between phage 7m and strain Ps-7 was shown to meet the classical criteria for lysogeny. Because phage 7s contains ribonucleic acid as its nucleic acid component, it was concluded that its production by strain Ps-7 and the demonstration of immunity of strain Ps-7 to infection by phage 7s were not sufficient evidence to define the nature of the relationship between phage 7s and P. aeruginosa strain Ps-7. It was observed that under certain conditions the infectious titer of phage 7s preparations are markedly reduced in the presence of ribonuclease.