Virulence of Listeria Monocytogenes Grown as Biofilms

Non-Technical Summary: Recent outbreaks of foodborne illness caused by consumption of Listeria monocytogenes contaminated, ready-to-eat meat and poultry products demonstrate the critical need to address this serious public health problem. Cells of L. monocytogenes can form biofilms on stainless steel surfaces of processing equipment and contaminate product as the product contacts the listerial biofilm. A biofilm is defined as a biologically active matrix of cells and extracellular substances produced by microorganisms. Virulence of L. monocytogenes cells grown as biofilms may differ from those grown in liquid culture. Little research has been performed to examine this critical question. <P> Approach: Cells of Listeria monocytogenes LCDC will be grown in liquid medium (tryptic soy broth) and in the same medium as a biofilm. The specific activities of listeriolysin O, phospholipase C, catalase and superoxide dismutase will be determined in cells grown free in liquid culture and as biofilms.