title: Effect of Bacteriocins and Conditions that Mimic Food and Digestive Tract on Biofilm Formation, In Vitro Invasion of Eukaryotic Cells and Internalin Gene Expression by Listeria monocytogenes.
abstract: In this report, Listeria monocytogenes isolates were evaluated for their ability to form biofilms, for adhesion/invasion of eukaryotic cells and for differential expression of internalin A (inl A) gene, which is related to virulence potential. The presence of bacteriocins of lactic acid bacteria and incubation at 5 °C were the main factors that influenced biofilm formation by L. monocytogenes, in comparison with BHI (control). In general, adhesion and invasion of Caco-2 cells were significantly lower in low pH (4.5), in incubation at 5 °C and in the presence of Oxgall 0.3 %. On the other hand, two L. monocytogenes isolates (INCQS 353 and Reg 26c) showed higher invasion rates when cultivated in the presence of NaCl 5 % (P < 0.05). One L. monocytogenes isolate (H-2) showed the strongest ability to form biofilm and to invade Caco-2 cells, under selected conditions, suggesting there is a relationship between biofilm formation and virulence potential. For all isolates, expression of inl A gene was down-regulated by the presence of bacteriocins, Oxgall 0.3 %, pH 4.5 and incubation at 5 °C. Nonetheless, for one L. monocytogenes isolate (HU 471), expression of inl A gene was eight times higher in the presence of sucrose, indicating that food components can increase the infectiveness of L. monocytogenes.
authors.affiliation: Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo (FCFRP-USP), Av. do Café s/n, Ribeirão Preto, São Paulo, 14040-903, Brazil.
authors.forename: Lizziane Kretli
authors.initials: LK
authors.lastname: Winkelströter
authors.affiliation: Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo (FCFRP-USP), Av. do Café s/n, Ribeirão Preto, São Paulo, 14040-903, Brazil. edemarti@usp.br.
authors.forename: Elaine C P
authors.initials: EC
authors.lastname: De Martinis
keywords: Bacteriocins; Biofilms; Caco-2 cells; Gene expression; L. monocytogenes