Properties of Pyocin S9 from pseudomonas aeruginosa UCM B-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. Th is strain produces yocins S1 and S5, as well as microcin-II-like bacteriocins. Th e aim of this work was to check the presence of other pyocins in P. aeruginosa UCM B-333. Methods. Th e concentrated bacterial lysate of P. aeruginosa UCM B-333 was separated by ion-exchange chromatography on DEAE cellulose. Th e fraction with studied bacteriocin was further purifi ed by gel fi ltration on Sephadex G-75. To determine the belonging of investigated pyocin to a certain subtype, its molecular weight, antimicrobial activity, kinetics of the eff ect 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. Th e 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 nonspecifi c DNase activity and aff ects sensitive cells by the single-hit response kinetics of infl uence through binding to receptors that are not concerned with iron transport. Th e revealed pyocin is not related to carotovoricins, its activity spectrum is close to other pyocins’ activities, and it aff ects clinical multidrug-resistant strains of Pseudomonas aeruginosa. Th e induction mechanism of this bacteriocin may be diff erent from that described for other pyocins and not concerned with the RecA system. Th e 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