Effect of nutrients on attachment and biofilm formation of Listeria monocytogenes

The objective of this study was to determine if specific nutritional factors affect attachment and biofilm formation of Listeria monocytogenes on stainless steel. L. monocytogenes cells grown in chemically defined medium (D10), tryptic soy broth (TSB), and modifications of these media were used to determine the effect of growth nutrients on attachment ability. After 4 h exposure of stainless steel surfaces to each standardized cell suspension at 21{dollar}spcirc{dollar}C, the numbers of attached cells were compared. Cells grown in D10 showed approximately 50-fold higher attachment than those grown in TSB. Addition of major components of D10 to TSB did not affect attachment ability of cells grown in TSB. Replacement of glucose with mannose, cellobiose, fructose, or trehalose did not show any effect on attachment ability. Replacement of nitrogen components in D10 with tryptone decreased attachment ability to the equivalent level of cells grown in TSB. However, the reduced attachment ability of TSB-grown cells was not the result of hydrolyzed protein absorbing to the cell surface. This study demonstrates that growth in media containing hydrolyzed protein results in a decreased attachment ability of L. monocytogenes to stainless steel.; The effect of nutrients on the development of biofilm by L. monocytogenes was investigated using semi-continuous culture in chemically defined medium (Modified Welshimer's Broth). Inoculated slides were used for the development of biofilms under various nutrient conditions for 12 d at 21{dollar}spcirc{dollar}C. Biofilm development was quantified by measuring percent area covered by biofilm using computerized image analysis. Increase of amino acids level and replacement of amino acids in MWB with tryptone initially enhanced biofilm development, but the effect was no longer significant after 12 d of incubation. Among the 5 tested carbohydrates, mannose and trehalose enhanced biofilm development after 12 d of incubation. This study demonstrates that nutritional conditions containing trehalose or mannose may enhance development of biofilm of L. monocytogenes on stainless steel. The effects of nutrients on the development of L. monocytogenes biofilm were different from their effects on attachment.