Phages of Pseudomonas aeruginosa: response to environmental factors and in vitro ability to inhibit bacterial growth and biofilm formation

Aims: To examine effects of various environmental factors on adsorption and inactivation of Pseudomonas aeruginosa-specific phages: delta (family Podoviridae), J-1, sigma-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 degrees 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 delta and 001A even at pH 3. Most of the examined carbohydrates and exopolysaccharides of the original host efficiently inactivated phage delta, while phages sigma-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 delta 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 delta is a good candidate for biocontrol of Ps. aeruginosa. Significance and Impact of the Study: The study provides important data on Ps. aeruginosa-specific phage adsorption, inactivation and in vitro lytic efficacy.