PSEUDOMONAS AERUGINOSA BACTERIOCIN ACTIVITY AGAINST PSEUDOMONAS SYRINGAE PHYTOPATHOGENIC STRAINS

Abstract

The aim of work was the research of Pseudomonas aeruginosa bacteriocin activity against Pseudomonas syringae phytopathogenic strains. Methods. The influence of eleven P. aeruginosa lysates on six P. syringae cultures was tested by double-layer agar and serial two-fold dilution methods. The pyocin concentration in lysate composition was increased by consecutive two-step optimization including conditions of strain-producer cultivation and induction of bacteriocins. The bacteriocin concentration was conducted by salting-out with 70% ammonium sulphate. Results. The bacteriostatic activity of initial P. aeruginosa lysates varied from 20 to 40 AU/ml against certain P. syringae strains. The low-molecular-weight pyocins of S-type were found to be the active components of the lysates. It was revealed that bacteriocin activity can be increased by means of strain-producer cultivation at 28°С in LB medium under intensive aeration and/ or addition of nalidixic acid to 100 mkg/ml final concentrations in the end of exponential growth stage under contact with bacterial suspension for three hours. The effectiveness of cultivation condition optimization and bacteriocin induction depended on a strain-producer. The introduced approaches brought in increase of PAE-22 lysate activity more then in 40 times, resulting into the widening of bacteriocin spectrum against all P. syringae strains and extension of growth absence areas to 26 mm. Conclusions. Pseudomonas aeruginosa low-molecular-weight S-type bacteriocins are characterized by moderate and high activity levels against the majority of researched P. syringae strains. The activity of PAE-22 lysate bacteriocins against phytopathogenic strains depended on cultivation conditions, whereas PAE-8 lysate – on induction optimization. Both mentioned factors influenced on bactriocin activity of other lysates: PAE-19, PAE-24 and PAE-41.