from Nicholas S. Jakubovics writing in Oral Microbial Ecology: Current Research and New Perspectives:
A core component of microbial biofilms is the extracellular matrix, which binds together the assembled micro-organisms and regulates the passage of small molecules to and from cells. The scaffolding of the matrix is composed of biological macromolecules including carbohydrates, nucleic acids and proteins. The production and function of extracellular polysaccharides in oral biofilms has been the subject of a great deal of research over many decades, and is considered in a separate review. More recently, it has become clear that proteins and extracellular DNA (eDNA) play key roles in maintaining the structure of many different biofilms, including oral biofilms. This paper reviews the recent research on proteins and eDNA in the biofilm matrix, and discusses the evidence that oral micro-organisms utilise these macromolecules for specific functions within mixed-species biofilms.
Further reading: Oral Microbial Ecology: Current Research and New Perspectives