Although exopolysaccharides are important and often essential compounds of the biofilm matrix, recent evidences suggest that a group of surface proteins plays a leading role during the development of the microbial communities. The first member of this group of proteins was described in a Staphylococcus aureus bovine mastitis isolate and was named Bap, for biofilm-associated protein. Later on, other surface proteins homologous to Bap and involved in biofilm development have been described in many gram-positive and gram-negative bacteria. In this review, we have summarized our knowledge about three members of this group of proteins: Bap of S. aureus, Esp of Enterococcus faecalis and BapA of Salmonella enterica ser. Enteritidis. To cite this article: C. Latasa et al., C. R. Biologies 329 (2006).