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Aims: To examine effects of various environmental factors on adsorption and inactivation of Pseudomonas aeruginosa-specific phages: d (family Podoviridae), J-1, r-1 and 001A (family Siphoviridae) and their ability to inhibit bacterial growth and biofilm formation. Methods and Results: The phages examined in the study were clonally different, as revealed by RFLP. The temperature in the range 7-44°C had no influence on the adsorption of Podoviridae, but did affect Siphoviridae adsorption, particularly 001A. All phages were significantly stable at pH 5-9, and phages d and 001A even at pH 3. Most of the examined carbohydrates and exopolysaccharides of the original host efficiently inactivated phage d, while phages r-1 and J-1 were inactivated considerably only by the amino acid alanine. Silver nitrate efficiently inactivated all the phages, while Siphoviridae were more resistant to povidone-iodine. Serum of nonimmunized rats had no influence on phage inactivation and adsorption. Only phage d showed ability to effectively inhibit in vitro bacterial growth and biofilm formation. Conclusions: The examined environmental parameters can significantly influence the adsorption and viability of Ps. aeruginosa-specific phages. The phage d is a good candidate for biocontrol of Ps. aeruginosa.

The aim of the study was to screen various kinds of samples for Pseudomonas aeruginosa specific phages and to isolate and partially characterize those with broad activity spectra. The Pseudomonas specific phages were isolated using an enrichment procedure with single strains or the cocktail of P. aeruginosa strains as hosts. Using the described procedure, phages were successfully isolated only from water samples, while in soil and feces no Pseudomonas specific phages were detected. The lytic spectra of isolated phages were determined by spot method on lawns of 33 P. aeruginosa strains and five species belonging to family Enterobacteriaceae. The results showed that among isolated phages, 001A, delta, and I possessed the broad activity spectra, as were able to plaque on more than 50% of tested P. aeruginosa strains, while none of the phages were able to lyse the other tested species. Significant differences in phage activity spectra were not observed when P. aeruginosa cocktail was applied for sample enrichment. The most of the phages examined by electron microscopy belonged to family Siphoviridae, while the broad activity spectra isolates, except for 001A, possessed morphological characteristics of family Podoviridae. Digested DNA of the phages delta and I showed similar patterns, indicating the prevalence and success of this phage type in the environment.

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