∞ generated and posted on 2016.12.15 ∞

Surface-associated conglomerations of microbial cells that are encased to greater or lesser extents within extracellular polymeric substances.

Biofilms are ubiquitous, coating most surfaces that are in contact with both water and microorganisms, allowing for microbial adherence to a single location, cooperation among cells, and protection from immune systems, antibiotics, and various environmental degradants as well as desiccation.

Biofilms often consist of multiple species, though individual species often can be found as distinct microcolonies within the larger biofilm.

Figure legend: Biofilms are tangled masses particularly of surface-adherent cells, typically bacteria, that are encased within various secreted substances that collectively are referred to as extracellular polymeric substances or EPS. Note that shown is an illustration of a biofilm-like structure rather than a microscopic image of an actual biofilm.

The following video illustrates biofilm formation:

It is thought that a substantial fraction of bacteria, including bacterial pathogens, are normally found existing within biofilms rather than as free-floating (planktonic), individual cells.

From Kolton (2010):

Biofilm formation is a developmental process in which bacteria undergo a regulated lifestyle switch from a nomadic unicellular state to a sedentary multicellular state where subsequent growth results in structured communities and cellular differentiation.

The above is in quotation marks in the original. A reprint of this wonderful article can be found here.

The following video illustrates biofilm formation and persistence in hospital water supplies:

Removal of biofilms (below) from infected, open wounds; not for the excessively queasy!