Properties of Pyocin S9 from Pseudomonas aeruginosa UCM В-333

Abstract

The deposited by us highly active bacteriocin producer Pseudomonas aeruginosa UСM B-333 synthesizes pyocins, which intensively inhibit phytopathogenic strains of Pseudomonas syringae — plant pathogens. This strain produces pyocins S1 and S5, as well as microcin-II-like bacteriocins. The aim of this work was to check the presence of other pyocins in P. aeruginosa UCM B-333. Methods. The concentrated bacterial lysate of P. aeruginosa UCM B-333 was separated by ion-exchange chromatography on DEAE cellulose. The fraction with studied bacteriocin was further purified by gel filtration on Sephadex G-75. To determine the belonging of investigated pyocin to a certain subtype, its molecular weight, antimicrobial activity, kinetics of the effect on sensitive microorganisms, and serological homology with carotovoricins of Pectobacterium carotovorum were studied as well as the ability to interact with siderophore receptors and nuclease activity were tested. Results. The isolated pyocin is a protein with a molecular weight of the active part of pyocin of 43.4 kDa and an immune protein — of 9 kDa. Th is substance is characterized by nonspecific DNase activity and affects sensitive cells by the single-hit response kinetics of influence through binding to receptors that are not concerned with iron transport. The revealed pyocin is not related to carotovoricins, its activity spectrum is close to other pyocins’ activities, and it affects clinical multidrug-resistant strains of Pseudomonas aeruginosa. The induction mechanism of this bacteriocin may be different from that described for other pyocins and not concerned with the RecA system. The determination of factors that stimulate the expression of pyocin S9 requires further study. Conclusions. According to the established properties, the studied substance is the closest to the foreseen pyocin S9.