The ecological relationships between amoebae and their bacterial prey has been sparsely investigated. Although these relationships are highly pertinent to the enfierging role played by protozoa in harbouring pathogenic bacteria, research has focussed largely on post-infection genetic and nfiolecular events within the protozoan cell. The v\/ork in this thesis aimed to throw light on the processes taking place prior to such events and the influencing factors. Amoebae are largely surface-dwellers, thus natural or man-made mixed bacterial biofilms where amoebae may be the principle predators, provide an ideal locus for these interactions, and the first paper established that amoebae do feed exclusively in attached mode.