[Phage-stable mutants of Pseudomonas putida: new types of stability]. / Fagoustoichivnye mutanty Pseudomonas putida: novye tipy ustoichivosti.

More than 170 phage-resistant mutants (PRM) of the first order of Pseudomonas putida strain PpG1 were obtained using newly isolated and previously described bacteriophages specific for this strain. According to the results of analysis of resistance of the mutants to each of 31 phages of PpG1 strain and 8 phages of the PpN strain, the PRM strains were distributed into 20 groups. In most cases, the reason for resistance is loss of absorption capacity of bacteria. However, no direct relation between the level of absorption and efficiency of phage plating was detected. It was shown that some of the PRM of P. putida PpG1 strains acquired the ability to maintain the growth of phages specific for the other P. putida strain, PpN. Frequencies of isolating mutants of various resistance types depend on the concrete phage used. In accordance with their absorption specificity, all phages were distributed into 23 groups, and a tridimensional formal scheme of receptor sites for these phages on the PpG1 strain was drawn. In the process of selection of the PpG1 clones resistant to non-lysogenizing mutant of temperate PP71 phage, a variant of this strain manifesting the phenomenon of "auto-plaquing" was found. These results support the mutational origin of this phenomenon in some cases.

[Study of morphology and genome structure of Pseudomonas putida bacteriophages for their classification]. / Izuchenie morfologii chastits i struktury genomov bakteriofagov Pseudomonas putida s tsel'iu ikh klassifikatsii.

A group of 27 bacteriophages specific for Pseudomonas putida strains PpG1 and PpN has been isolated. The phages were characterized and compared with the previously described virulent (pf 16, af, tf and PMW) and temperate (PP56 and PP71) phages. The new phages belong to B1 and C1 morphotypes, according to Ackerman's classification. Phage DNAs were digested with several endonucleases; the molecular weights and homology of the DNAs were determined. All phages of P. putida isolated up to now were distributed into 10 species (groups), on the basis of particle morphology, genome size and the results of homology studies. Recombination processes are believed to participate in formation of phages belonging to certain species.

[Isolation and comparative characteristics of 2 unrelated temperate phages of Pseudomonas putida PpG1]. / Vydelenie i sravnitel'naia kharakteristika dvukh nerodstvennykh umerennykh fagov Pseudomonas putida PpG1.

Two temperate bacteriophages, PP56 and PP71, specific for bacteria of Pseudomonas putida strain PpG1 have been isolated for the first time. Characterization of the phages was performed. Both of them accomplish stable lysogenization of P. putida PpG1 cells. The phages are inducible. Several groups of clear plaque (c) mutants of PP56 and PP71 with altered processes of establishment and maintenance of lysogenic state have been isolated, according to complementation test. The phages differ in following characters: 1) in morphology of mature phage particles (C and B types, according to Bradley classification); 2) in sizes and genome organizations: DNA of PP56 is permuted (up to 30%), its size is 45 kb, the size of terminal redundancy being 2.5 kb; there is no permutation in PP71 DNA of 48 kb and it has "cohesive" ends; 3) no DNA/DNA homology is shown in tests between PP56 and PP71 DNAs. All the data obtained permitted to consider the phages PP56 and PP71 to belong to different unrelated species (families).

[Genetic and phenogenetic study of the ts-mutant group of Pseudomonas aeruginosa PA01 phage phi KZ]. / Geneticheskoe i fenogeneticheskoe izuchenie gruppy ts-mutantov faga phi KZ Pseudomonas aeruginosa PA01.

A group of ts mutants of phi KZ phage specific for Pseudomonas aeruginosa was isolated and studied. A phi KZ phage particle has a unique feature: a specific structure as an internal body concerned with DNA packaging which is present in the phage capsid. Ts mutants were distributed into complementation groups. The time of the development block when grown at elevated temperatures was determined for mutants from several groups, the exact stage of the block having been defined for some late ts mutants. As was found for ts759, the stage of connection of heads containing DNA and the inner body with tails was blocked. The results obtained with ts759 allowed to prove the circular location of fibrous material (DNA?) around the inner body. The conditions for phage crosses were revealed. The genetic map of phi KZ is circular. It may be concluded, considering the linear phi KZ DNA structure in capsids, that circular permutations of phage DNA take place during phage maturation or DNA packaging.

[Detection of transduction by virulent bacteriophage phi KZ of Pseudomonas aeruginosa chromosomal markers in the presence of plasmid RMS148]. / Vyiavlenie transduktsii virulentnym bakteriofagom phi KZ kromosomal'-nykh markerov Pseudomonas aeruginosa v prisutstvii plazmidy RMS148.

A virulent phage of Pseudomonas aeruginosa, phi KZ which is able to package DNA of 210 MD is a general transducer. The transducing activity of phi KZ can be revealed when using recipient bacteria containing RMS148 plasmid (the P7 group of incompatibility). This plasmid blocks the development of phi KZ and prevents the phage to kill bacteria. General transduction mediated by phi KZ may be useful for the primary localization of genetic markers in P. aeruginosa.