Bacteriophages of Pseudomonas syringae: features of isolation and study of main biological properties

Abstract

The article presents the results of studies on isolation and study of biological properties of bacteriophages specific for phytopathogenic bacteria Pseudomonas syringae. 8 new virulent bacteriophages were isolated and selected from environmental objects. The main biological properties of isolated phages, including lytic activity, were studied (according to Appelman, the indicator was equal to from 10-5 to 10-8; by diffusion method in «soft agar» - from 1.0±0.1*106 to 2.0±0.1*109 (PFU/ml), «spot test» - spot test confirmed the results obtained by diffusion method in «soft agar» - n6 – n9) and its diapason, which ranged from 21.4% (Ps.s-13 UlGAU) to 85.7% (Ps.s-7 UlGAU, Ps.s-27 UlGAU), morphology of plaque-forming units (morphology of negative colonies), specificity within genus and species, changes in lytic activity index during storage, features of impact of physical and chemical factors (trichloromethane at the ratio of 1:10, the impact of which during 5-85 minutes does not influence on biological activity of phages when determining by indirect method; urea, whose 30% solution reduces the yield of plaque-forming units of each bacteriophage studied by about 77.6-85.5 %; temperature in the range of -5 to 10°C and from 50 to 100°C). The study of biological properties allowed us to systematize biological features of each of isolated clones of virulent bacteriophages and select the 4 most promising bacteriophages for further research. The research is carried out with the support of Russian Foundation for Basic Research, the project “Fundamental foundations for the development of phage preparation specific to Pseudomonas syringae, and applied aspects of its application for phagoidentification and bioprocessing of food and agricultural raw materials” No 19-44-730014.