ANTIMICROBIAL ACTIVITY MODULATION OF Bacillus velezensis SL-6 BY THE PRESENCE OF Yersinia enterocolitica

CLIMENT, FERMÍN V.; SUSANA GRACIELA FERRARI; IRIARTE, HEBE J.; COZZOLINO, MARIANA E.; PATRICIA GISELA SILVA

Mendoza

Congreso; XL REUNIÓN ANUAL DE LA SOCIEDAD DE BIOLOGÍA DE CUYO; 2022

Sociedad de Biología de Cuyo

034- ANTIMICROBIAL ACTIVITY MODULATION OF Bacillus velezensis SL-6 BY THEPRESENCE OF Yersinia enterocoliticaCliment FV, Cozzolino ME, Iriarte HJ, Ferrari SG, Silva PGÁrea Microbiología e Inmunología, Facultad de Química, Bioquímica y Farmacia, UNSL. E-mail: marianacozzolino@gmail.comSome Bacillus species, safe for industrial use, are commercially available as biocontrol agents to control crop pests. Also, some of themhave been proposed as probiotic bacteria to regulate human and animal health by their secretion capability of ribosomal and non-ribosomalantimicrobial metabolites, among others. Emergent research studies propose that co-cultivation and biotic additives such as heat-killedcells are novel strategies for the enhancement of secondary metabolite synthesis. The present work describes the influence of Yersiniaenterocolitica W1024 (Ye) on the antibacterial activity of B. velezensis SL-6 (Bv SL-6), a strain with a broad inhibitory spectrum againstpathogenic microorganisms. Bv SL-6 was grown for 24 h at 30 °C with orbital agitation (200 rpm) in a liquid synthetic medium under twodifferent induction conditions. In the co-culture experiments, both bacteria were inoculated at 2% v/v from a fresh cell suspension preparedin saline solution. In addition, batch cultures in the presence of thermally killed cells (autoclaved for 30 min) of Ye at 10% v/v wereperformed. A pure culture of SL-6 strain was included as a control. Cell-free supernatants (CFSs) were obtained by centrifugation andfiltration. The antibacterial activity was determined by the well-diffusion method against Y. enterocolitica W1024, Escherichia coli ATCC25922 (Ec), Listeria monocytogenes (local isolate) and Staphylococcus aureus ATCC 43300 (MRSA), and inhibition zone diameters weremeasured using a digital caliper. Furthermore, the serial two-fold dilution method was used to determine the antimicrobial titer expressedin arbitrary units per milliliter (AU/ml). The CFS obtained from co-culture, increased the diameter inhibition zone against Ye (4.9%), whilea minimal reduction (2.9%) in antagonism against Ec was observed (p