Effect of Growth Nutrients on Attachment of Listeria monocytogenes To Stainless Steel

Listeria monocytogenes cells grown in chemically defined minimal medium (D10), tryptic soy broth (TSB), and modifications of these media were used to determine the effect of growth nutrients on attachment ability. Stainless steel surfaces were submerged in various cell suspensions at 21°C for 4 h, and the numbers of attached cells were compared. Cells grown in D10 showed approximately 50-fold higher attachment than those grown in TSB. Addition of components of D10 to TSB did not affect the attachment ability of cells grown in TSB. The only modifications of D10, which affected attachment ability were a 10-fold increase of ammonium chloride concentration and a 1/10 reduction in iron, both of which resulted in decreases in attachment ability to one third of the D10 control. Replacement of glucose in D10 with mannose, cellobiose, fructose or trehalose did not effect cell attachment. Replacement of nitrogen components in D10 with tryptone decreased cell attachment to the equivalent level of cells grown in TSB. The reduced attachment ability of TSB-grown cells was not the result of hydrolyzed protein absorbing to the cell surface.