Bifidobacterium breve IPLA20005 affects in vitro the expression of hly and luxs genes, related to the virulence of listeria monocytogenes Lm23

Mechanistic features that characterize the interaction and inhibition of the food-borne pathogen Listeria monocytogenes by members of the genus Bifidobacterium still remain unclear. In the present work, we tried to shed light on the influence that co-cultivation of L. monocytogenes with Bifidobacterium breve may exert on both microorganisms and on virulence of the pathogen. Production of acetate and lactate was measured by gas chromatography and high-performance liquid chromatography, respectively; bacterial counts were obtained by plate count; gene expression was determined by RT-qPCR; and haemolytic activity was analyzed against goat erythrocytes. We found slightly but significantly lower final counts of Listeria and Bifidobacterium (p < 0.05) and lower haemolytic efficiency in L. monocytogenes cells from cocultures than in those from monocultures. In contrast, the hly and luxS genes, which code for the cytolysin listeriolysin O and participate in biofilm formation, respectively, were overexpressed when L. monocytogenes was grown in coculture. This indicates that the presence of Bifidobacterium is able to modify the gene expression and haemolytic activity of L. monocytogenes when both microorganisms grow together.Peer reviewe

Bifidobacterium breve IPLA20005 affects “in vitro” the expression of hly and LuxS genes, related to the virulence of Listeria monocytogenes Lm23

Mechanistic features about the interaction and inhibition of the food borne pathogen Listeria monocytogenes by members of the genus Bifidobacterium still remain unclear. In the present work we tried to shed light into the influence that co-cultivation of L. monocytogenes with Bifidobacterium breve may exert on both microorganisms and on the pathogen virulence. Production of acetate and lactate was measured by gas chromatography and HPLC respectively, bacterial counts were obtained by plate count, gene expression was determined by RT-qPCR and the hemolytic activity was analyzed against goat erythrocytes. We found a slight but significantly lower final counts of Listeria and Bifidobacterium (PThe accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author