The objective is to study bacterial adhesion and growth at phase interfaces. Two laboratory systems will be used. The first system will study Listeria monocytogenes adherence and growth at liquid/solid interfaces using a microtiter plate adherence/biofilm assay. We will use this system to determine if new protein synthesis is needed for biofilm formation, study the production of exo-polysaccharide during biofilm growth, and to screen insertional mutants for identification of genetic determinants needed for adhesion and biofilm formation. The second system will study E. coli O157:H7 interactions and growth at liquid/liquid interfaces of emulsions. With the emulsion system, we will study the influence of emulsions upon rates of bacterial growth and construct gene fusions of a rpoS Promoter with egfp to monitor cells entering stationary phase.