Meningococcal Biofilm Formation: Let's Stick Together

Extracellular DNA (eDNA) is an essential constituent of the extracellular matrix of biofilms of many microorganisms. In spite of many studies, it has long remained unclear how exactly eDNA exerts its role in biofilm formation. Here, we describe recent advances that have been made in understanding biofilm formation in the human pathogen Neisseria meningitidis. Several cell-surface-exposed proteins have been identified that bind DNA and other negatively charged polymers, such as heparin, by electrostatic interactions. By virtue of these proteins, eDNA can act as an adhesive that binds the bacteria together. We provide examples that indicate that the mechanism of binding eDNA via DNA/heparin-binding proteins is a conserved feature in biofilms of many different microorganisms, including fungi.