Antibiofilm efficacy of bacteriocins against the emergent pathogen Listeria monocytogenes

CONSTANZA MELIAN; EMILSE BETENCOURT; LUCIA MENDOZA; PATRICIA CASTELLANO; GRACIELA VIGNOLO

Congreso; XII Congreso Argentino de Microbiología General SAMIGE 2017; 2017

Listeria monocytogenes is a foodborne pathogen able to survive in a wide range of environments even at refrigerated conditions. Moreover, some strains of L. monocytogenes can form biofilms which facilitate their persistence in the food processing environments. Recently, major advances have been made in the prevention and control of pathogens biofilm by lactic acid bacteria (LAB) or their bacteriocins. The aim of this work was to investigate the ability of bacteriocins produced by Lactobacillus curvatus CRL705 and L. curvatus CRL1532 to compete with L. monocytogenes FBUNT during biofilm formation on polystyrene microplate. Biofilm formation of Listeria strains (L. monocytogenes FBUNT, CECT 4031T, Scott A) with and without bacteriocins was determined using crystal violet method after 6 days of incubation at 10 °C. The strain L. monocytogenes FBUNT was selected due to its high biofilm-forming ability in the control samples. Both bacteriocins inhibited biofilm development of pathogen microorganism being the bacteriocin produced by L. curvatus CRL 705 the most effective. In addition, the presence and expression of genes related to L. monocytogenes biofilm formation were studied by PCR and real time-PCR, respectively. L. monocytogenes FBUNT showed to harbor luxS and pfs genes encoding enzymes that catalyze S-ribosyl homocysteine and genes of agrBDCA system. During sessile growth expression levels of agrB and luxS genes were 2-fold higher than under planktonic growth. In presence of both bacteriocins higher expression of agrD gene was observed. Expression levels of agrB and luxS genes decreased at higher concentrations of bacteriocins which could indicate that bacteriocin addition affected expression of key genes involved in biofilm formation. These results evidence the potential use of the bacteriocins produced by L. curvatus CRL705 and CRL1532 to inhibit biofilm formation of L. monocytogenes at refrigerated conditions.