Biofilm formation requires first adhesion steps to surface. Hence, adhesion proteins should be involved in these first steps. The O´Toole´s lab at Dartmouth College has described a large adhesin protein (lapA) in Pseudomonas fluorescens important in first biofilm formation steps. LapA is regulated by a c-di-GMP (cdG) effector system that controls cell adhesion by inside-out signaling and surface protein cleavage. A cdG sensor protein, LapD, is located in the inner membrane and arrest specific LapA protease LapG, when cdG is present in high levels in citosol. This situation prevents LapA release form bacterial surface and enhance biofilm formation. In cdG absence LapG is free to cleave LapA and bacteria detached from surface and begins planktonic life style. As result of intensive collaboration with O´Toole´s group we have described Lap proteins in B. bronchiseptica during my thesis. In this context, the main objective of this project is to study the role of LapA in first steps of biofilm formation. Studies will be performed over abiotic and biotic surfaces to understand LapA role in biofilm formation during infection process.