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According to our previous results, S-type bacteriocins of Pseudomonas aeruginosa are characterized by high activity against phytopathogenic Pseudomonas syringae strains. In addition to these pyocins producing strains are able to synthesize microcin-II-like bacteriocins. Presence of interaction between these two killer factors can determine methods of their use and activity increase of bacteriocins with antiphytopathogenic properties. The aim of the work was to test possibility of interaction between S-type pyocins and microcin-II-like bacteriocins of P. aeruginosa. Methods. The objects of the study were pyocins produced by 6 P. aeruginosa strains. Killer factors in composition of induced lysates were concentrated by 70% ammonium sulphate precipitation, dialyzed through dialysis membrane with molecular weight cut-off (MWCO) 3.5 kDa. Then ion-exchange chromatography with DEAE-cellulose, gel filtration with Sephadex G-75 and ultracentrifugation at 215.000 g for 1 and 4 hours were used for their separation. Protein concentration and antimicrobial activity were determined in obtained fractions. Visualization of proteins in active fraction composition was conducted by electrophoresis according to the Laemmli method. Results. Under ion-exchange chromatography with DEAE-cellulose application elution of bacteriocins available in lysate composition occurs simultaneously. The highest indices of activity and protein concentration were in the 4th fraction, containing two protein bands with molecular weight near 58 and 9 kDa, which are typical for S5 pyocin and microcin-II-like bacteriocins of P. aeruginosa. Further gel filtration of sampled fractions through Sephadex G-75 allowed to separate noted killer factors and obtaine purified fraction containing microcin-II-like pyocins only. Application of ultracentrifugation during 1 hour didn’t precipitate studied bacteriocins, whereas during 4 hours – lead to their separation. At the same time a twofold increase of activity indices for S-type pyocins in precipitates and for microcin-IIlike killer factors – in supernatants were observed. However achieved concentration was characterized by short-term effect, since in 14 days activity of supernatants decreased by 4–16 times, and for precipitates – by 80–640 times. Then revealed tendency for activity decrease continued. Conclusions. S-type pyocins and microcin-II-like bacteriocins of P. aeruginosa interact with each other, that ensures their stabilization and protects again destruction. Application of methods that cause separation of these killer factors is inexpedient, since it results into considerable decrease of bacteriocin activity indices.

The aim of work was study of peculiarities of Pseudomonas aeruginosa biofilm formation on media with different concentration of glucose as sole source of carbon and energy. Methods. Three Pseudomonas aeruginosa strains were cultivated in stationary system on glass in Kozer medium with 0.1%, 5% and 20% of glucose. The effect of unfavourable conditions on microorganism growth was analyzed by intensity of biofilm formation and quantities of viable cells in biofilm and planktonic form. Results. It was determined that investigated cultures maintained the ability to grow and form biofilm in the presence of 0.1-20% glucose in Kozer medium. If there was 0.1% of glucose, dynamics of biofilm accumulation was characterized by strain peculiarities. But under increase of carbon source concentration to 20%, these differences became less evident and biofilm formation acquired common for all used cultures regularities. The increase of glucose concentration caused reduction of the sample area covered by biofilm and fall of microorganism quantity in its composition, stabilized the biofilm formation dynamics, but didn't influence on bacterium titre in planktonic form. Conclusions. Under the influence of unfavourable conditions, besides protective function, Pseudomonas aeruginosa biofilm can perform the role of depositary formation, maintaining stable cell quantity in planktonic form.