A biofilm is composed of attached microbial cells encased

A biofilm is composed of attached microbial cells encased within a matrix of extracellular polymeric secretions (EPS), which surround and protect cells. The EPS matrix is typically composed of polysaccharides, proteins, lipids, and extracellular DNA (eDNA). Localized within the EPS matrix (see figure inset) are extracellular enzymes (e-Enzymes). Also present are small pieces of DNA carrying specific genes, called plasmids. Both e-Enzymes and plasmids are protected against degradation with the biofilm. Finally, bacteria release signal molecules for a process of chemical communication called quorum sensing. A biofilm may extend from just a few to hundreds of micrometers above a surface, but is equipped with many inherent adaptations that are not present in planktonic cells.