IDENTIFICATION OF COLICINS PRODUCED BY CLINICAL ISOLATES FROM PATIENTS SUFFERING GASTROENTERIC DISEASES

JUSTINA RENTERIA; MÓNICA A. DELGADO; MARÍA DE LAS MERCEDES PESCARETTI

Congreso; IV REUNIÓN CONJUNTA DE SOCIEDADES DE BIOLOGÍA DE LA REPÚBLICA ARGENTINA; 2020

Bacteriocins are small molecules secreted by enterobacteria species to compete against others microorganisms for the ecological niche or survival. In this work, we identified and analyzed antimicrobial compounds produced by clinical isolates (CI) of the Shigella genus, which were obtained from patients suffering gastrointestinal infections during the 2013-2018 period in the Northwest region of Argentina (Catamarca, Santiago del Estero and Tucumán). In previous studies we identified 54 CIs able to produce antimicrobial agents that inhibit the growth of E. coli AB1133 strain. Based on the above results, 11 CIs were analyzed to select those capable of producing and secreting into the supernatant the compounds with higher antimicrobial activity. The serological classification of these 11 CIs was confirmed by multiple PCR using specific primers. The antimicrobial activity of the cell-free supernatants was determined against the pathogenic strain E. coli O157:H7 and other pathogenic Salmonella genus CIs obtained in the laboratory. In addition, we studied the resistance pattern of the 11 producer CIs against different antibiotics and their plasmid content in order to identify a relationship between both patterns. Three antimicrobial compounds were selected from the 11 CIs analyzed, since they presented the highest antimicrobial activity and wider spectrum of action. Then, a partial purification of selected compounds was performed by ammonium sulfate precipitation and the antimicrobial activity was determined. Finally, the molecular mass of the antimicrobial compounds was studied by polyacrylamide gel electrophoresis. Our results demonstrated that these 3 compounds were different but had similar characteristics to colicins, mainly their high molecular mass, suggesting that they could be used for new antibiotics or food preservatives development.