PSEUDOMONAS-AERUGINOSA PHAGES HAVING DNA-STRUCTURE SIMILAR TO THAT OF MU1 PHAGE .3. ISOLATION AND ANALYSIS OF HYBRID PHAGES D3112 AND B39 - LOCALIZATION OF THE IMMUNITY REGION AND SOME GENETIC-FACTORS

Abstract

Several different hybrids were isolated in a cross between heteroimmune Mu-like P. aeruginosa bacteriophages D3112 and B39. Analysis of hybrid phage DNA treated with specific endonucleases and heteroduplex studies permitted mapping of the immunity region of the phages to the left part of the genome. A ts temperature-sensitive mutation in the wild-type B39 and loci influencing the growth of D3112 in P. aeruginosa strain PA0(B39) and in bacteria harboring plasmid RPL11 were localized. All recombinants studied arose by double crossing-over and can be considered as substitutions of different continuous parts of the D3112 genome by fragments of the B39 genome. A comparison of distribution of non-homologous regions in B39 and D3112 genomes as well as locations of endonuclease-sensitive sites gave some unexpected results. In contrast to the B39-D3112 pair, an other pair of related Mu-like phages, B3-D3112, have no visible homology within most of their genomes.