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Anne Skovager*, Marianne H. Larsen**, Nils Arneborg* and Hanne Ingmer ** PowerPoint Presentation
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Anne Skovager*, Marianne H. Larsen**, Nils Arneborg* and Hanne Ingmer **

Anne Skovager*, Marianne H. Larsen**, Nils Arneborg* and Hanne Ingmer **

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Anne Skovager*, Marianne H. Larsen**, Nils Arneborg* and Hanne Ingmer **

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  1. Growth Conditions Influence Initial Adhesion and Cell Surface Characteristics of Listeria monocytogenes Anne Skovager*, Marianne H. Larsen**, Nils Arneborg* and Hanne Ingmer** * Department of Food Science, Food Microbiology, Faculty of Life Sciences, University of Copenhagen, Rolighedsvej 30, 1958 Frederiksberg C, Denmark ** Department of Veterinary Disease Biology, Section for Microbiology, Faculty of Life sciences, University of Copenhagen, Stigbøjlen 4, 1870 Frederiksberg C, Denmark • Introduction • In the present work, it is hypothesized • that changes in nutrient composition • influence on the initial adhesion of • Listeria monocytogenes. The cell • characteristics may change as a • consequence of different nutrients • present. • Aim • The aim is to examine if different • nutrients (carbohydrates and amino • acids) alter the initial adhesion of • L. monocytogenes to fine polished • stainless steel, and if so to determine • altered surface characteristics. • Conclusion • It can be concluded that specific growth conditions (nutrients) have a significant influence on the initial adhesion rate (IAR) of • L. monocytogenes on fine polished stainless steel and on the cell surface protein composition. • Examine effect of: • Nutrients: • Glucose, mannose, fructose, • L-leucine, L-isoleucine, L-valine • On: • Initial adhesion under liquid flow to stainless steel • Hydrophobicity and electron accepting/ • donating properties (Microbial Adhesion To Solvents, MATS) • Cell size • Fatty acid composition (GLC – of whole cells) • Cell surface proteins (SDS-PAGE) • Results and Discussion • Different nutrients had an influence on IAR (Fig.1A). • 2.5 g/L mannose and 2.5 g/L glucose • +100 mM L-leucine resulted in the lowest and highest • IAR, respectively (P<0.05). • No correlation was found between cell size, • hydrophobicity, electron donating and accepting • properties and IAR. • The different growth conditions resulted in altered • fatty acid composition, however it could not be • correlated to IAR. • Expression of cell surface proteins was dependent on • the growth media composition, notably in the presence • of 2.5 g/L mannose; 2.5 g/L glucose; and 2.5 g/L • glucose +100 mM L-leucine (Fig. 1B). • Proteins with altered expression will be • identified in the future. • Methods • Strain/ growth condition • Listeria monocytogenes EGD/pNF8 • TSB + additional nutrients (22 h at 37°C) • Flow perfusion experiments • Fluorescence microscopy and a flow perfusion system • (shear stress: 0.10 Pa) was used for determination of • IAR under liquid flow (cells/cm2*min) (Fig.2). A B Cells/cm2 ▲●♦ Time (min) Digitalcamera Fluorescence microscope Figure 1. A) Initial adhesion of L. monocytogenes cells, grown with different nutrients (cells/cm2 vs. time). B) SDS-PAGE protein gel of cell surface proteins (3 growth conditions). Pumps Figure 2. Experimental setup: The flow chambers are glued on fine polished stainless steel and placed under a fluorescence microscope, connected with a digital camera. The flow chamber is via tubes connected to two pumps. Between the inlet of the perfusion chamber and the inlet pump aflow equalizing system is installed. Sponsor: The Danish Research Council for Technology and Production Sciences; Contact:Anne Skovager, annesj@life.ku.dk Flow equalizing system Waste Cell suspension Flow perfusion chamber