It is estimated that 80% of bacterial life exists in the context of a biofilm. This makes biofilms one of the key areas of research for many organisms. In Pseudomonas fluorescens, the initial, transitory adherence to a surface is mediated by the Lap system, which is conserved and functional in many other bacterial species. Within this thesis, three aspects of Lap system function and regulation are explored. Chapter 2 discusses the adhesin LapA and its regulation. It was found that several key structural features of LapA contribute to its function as an adhesin which can alternatively released or retained.Chapter 3 presents work done on proteins from Desulfovibrio vulgaris. Several proteins, found in a genomic context similar to that of the Lap system, are key to biofilm formation in this organism. In this study, some of the key features of this Lap-like system have been investigated. The structures and functions of three proteins, DvhD, DvhG and DvhA were and found to be similar in many respects to their predicted Lap system homologs, LapD, LapG and LapA, respectively. DvhG was found to selectively process the N terminus of DvhA. The HD-GYP domain of DvhD in particular was found to be capable of binding c-di-GMP, an important regulator of the Lap system, and possessed a previously uncharacterized binding site. The data obtained about this system suggest that it behaves similarly to the Lap system and represents an important component of biofilm formation in D. vulgaris. Finally, Chapter 4 presents work which explores the ligand binding preferences of diguanylate cyclases (DGCs) in P. fluorescens. The Lap system was shown to be regulated in part by physical interaction between certain DGCs and LapD. This interaction can be enhanced by ligand binding to the DGC. The Cache, or ligand binding, domains of two DGCs were assessed biochemically. The Cache domain from Pfl01_3800 was found to preferentially bind small carboxylic acids and was characterized structurally. This work contributes to our understanding of ligand specificity in Cache domains in general and helped elucidate factors that might enhance biofilm formation in P. fluorescens.