Biofilms and biocomplexity

• Biofilms are composed of microorganisms attached to surfaces and encased in a hydrated polymeric matrix containing polysaccharides, proteins, and nucleic acids. • Biofilms function in a manner similar to a tissue, using a primitive circulatory system to pump fluids and nutrients through channels in the matrix by changing the ionic strength of the extracellular milieu, causing periodic contraction of matrix polymers. • Life in a biofilm imparts protection to insult from the outside world, with barriers to the penetration of antimicrobial agents, oxygen, and nutrients, along with depressed growth rates and activated adaptive stress responses. • Biofilm formation is an example of a bacterial developmental process, albeit one that is distinct from fruiting body or endospore formation. • Biofilm formation is a complex process requiring the coordinated action of multiple, regulatory proteins, typically including sensor kinases and response regulators.