What is Biofilm
"Biofilm" means any group of microorganisms in which sessile populations of microbes live within a self-secreted matrix of extracellular polymers.
Biofilm form when bacteria adhere to surfaces in moist environments by excreting a slimy, glue-like substance. Sites for biofilm formation include a variety of surfaces: natural materials and below ground, metals, plastics, medical implant materials, and plant and body tissue.
A biofilm community can be formed by a single bacterial species however, in nature biofilms almost always consist of mixtures of many species of bacteria, as well as fungi, algae, yeasts, protozoa, other microorganisms, and debris.
Biofilms are generally composed of extracellular DNA proteins, and polysaccharides that are held together by sugary molecular strands, collectively termed, "Extracellular Polymeric Substance" or EPS.
The cells produce EPS and are held together by these strands, allowing them to develop a complex multicellular three-dimensional meshed matrix of resilient, attached communities.
Biofilms can be as thin as a few cell layers or many inches thick, depending on environmental conditions. Bacteria preferentially attach to a variety of surfaces, and EPS bacterial communities exhibit properties, behaviours and survival strategies that far exceed the capabilities as individual bacteria.
The Biofilm Lifecycle
Free-floating, or planktonic, bacteria encounter a submerged surface and within minutes can become attached. They begin to produce slimy extracellular polymeric substances (EPS) and colonize the surface.
EPS production allows the emerging biofilm community to develop a complex, three-dimensional structure that is influenced by a variety of environmental factors. Biofilm communities can develop within hours.
Biofilms can propagate through detachment of small or large clumps of cells, or by a type of "seeding dispersal" that releases individual cells. Either type of detachment allows bacteria to attach to a surface or to a biofilm downstream of the original community.
Source: Center for Biofilm Engineering, Montana State University