Biofilms are attached microbial communities embedded in exopolymers…
Since the term was coined in the 1980s by Bill Costerton and co-workers, a plethora of papers has appeared on this phenomenon. Also a gaggle of definitions…
Here are but a few:
“For the purpose of this review, biofilms are broadly defined as assemblages of microorganisms and their associated extracellular products at an interface and typically attached to an abiotic or biotic surface” (Davey & O’Toole 2000. Microbial biofilms: from Ecology to Molecular Genetics. Microb and Molecular Biol Rev. 64(4): 847-867).
“Biofilms are now recognized as complex and dynamic communities in which substantial phenotypic diversification allows microorganisms to adapt to different environments” (Battin et al. 2007. Microbial landscapes: new paths to biofilms research. Nature Reviews 5: 76-81.)
“Biofilms are now commonly perceived as the predominant form in which microorganisms exist in natural and human-made environments.” (Schooling & Beveridge 2006. Membrane vesicles: an Overlooked Component of the Matrices of Biofilms. Jnl Bacteriol 188(16): 5945-5957).