ANTIMICROBIAL ACTIVITY OF BACTERIOCIN-PRODUCING Yersinia spp. AGAINST FOODBORNE PATHOGENIC BACTERIAL STRAINS

BRARDA, BRENDA S.; IRIARTE, HEBE J.; SALINAS IBAÑEZ A. GABRIEL; LUCERO ESTRADA, CECILIA; FAVIER, GABRIELA

San Luis

Congreso; XXXIX REUNIÓN CIENTÍFICA ANUAL DE LA SOCIEDAD DE BIOLOGÍA DE CUYO; 2021

Sociedad de Biología de Cuyo

ANTIMICROBIAL ACTIVITY OF BACTERIOCIN-PRODUCING Yersinia spp. AGAINST FOODBORNEPATHOGENIC BACTERIAL STRAINSBrarda BS1, Iriarte HJ1,2, Salinas Ibañez AG1,3, Lucero Estrada CSM1,2, Favier GI1. 1 Área de Microbiología e Inmunología de laUniversidad Nacional de San Luis, San Luis, Argentina. 2 Instituto Multidisciplinario de Investigaciones Biológicas del Consejo Nacionalde Investigaciones Científicas y Técnicas (IMIBIO - CONICET), San Luis, Argentina. 3 Instituto de Física Aplicada del Consejo Nacionalde Investigaciones Científicas y Técnicas (INFAP - CONICET), San Luis, Argentina. brendabrarda@gmail.comBacteriocins (BAC) are bacterial metabolites that act by inhibiting the growth of related or unrelated species; thus, BAC havebeen studied as biocontrollers of foodborne pathogens as these compounds are also considered GRAS (generally recognizedas safe). Non-pathogenic Yersinia species, such as Y. intermedia, Y. frederiksenii, and Y. enterocolitica biotype 1A use tobe BAC producers exhibiting inhibitory effect against pathogenic Y. enterocolitica strains (biotypes 1B, 2-5). The aims ofthis work were: i) to evaluate the antimicrobial activity of BAC produced non-pathogenic Yersinia strains against foodbornepathogens bacterial strains, and ii) to evaluate this activity at different temperatures. For this purpose, four Y. intermedia (10,79, 85, 96), two Y. fredericksenii (73, 74), and two Y. enterocolitica 1A (66, 89) strains were used as bacteriocin-producingstrains (BPS). As indicator strains (IS) eight pathogens were tested: Salmonella sp., Shigella flexneri, Staphylococcus aureus,Pseudomonas aeruginosa, Escherichia coli, Bacillus cereus, Listeria monocytogenes and Y. enterocolitica 1B. The spot-platetechnique was performed on a double-layer agar. BPS and IS were cultured in Luria Bertani broth (LB) at 25°C for 18 h.Inocula were adjusted to a concentration corresponding to a DO610 of 0.2 and 10 μl of each BPS were spot plated ontosemisolid agar previously inoculated with IS. Plates were incubated at 10°C, 25°C and 37°C for 18 h, in duplicate. Thesensitivity of the IS was evident by the presence of halos around the BPS; in addition, the diameters of the halos (mm) weremeasured. Among the eight BPS tested, only two Y. intermedia (96 and79) and two Y. enterocolitica 1A (66 and 89) wereactive against L. monocytogenes and Y. enterocolitica 1B. For L. monocytogenes the inhibition at 10°C was: BPS 66:14.25±1.25 mm, BPS 79: 14±0 mm, BPS 89: 14.5±1 mm, BPS 96: 15±1.5 mm; at 25°C was: BPS 66: 10.75±0.25 mm, BPS79: 14.25±0.25 mm, BPS 89: 14.5±2 mm, BPS 96: 13.15±0.35 mm. For Y. enterocolitica the inhibition at 10°C was: BPS66: 16.5±0.5 mm, BPS 79: 16±1 mm, BPS 89: 16±1 mm, BPS 96: 15.25±1.75 mm; at 25°C was: BPS 66: 15±0 mm, BPS79: 13.5±2 mm, BPS 89: 15.5±0.5 mm, BPS 96: 15.75±0.75 mm. At 10°C and at 25°C there was inhibition, while at 37°Cthere was no inhibition. These results encourage the hypothesis that bacteriocins produced by non-pathogenic Yersinia strainscould be involved in the reduction or elimination of pathogenic strains responsible for causing spoilage or foodborne illnesseven at refrigeration temperatures.