The great majority of microorganisms present in the natural environment
exist within biofilms. Whereas pure cultures of bacteria have been studied
in detail for over a century, research focused on understanding the ecology
of mixed populations began only a short while ago. Biofilms are defined as
‘microbially derived sessile communities characterized by cells that are
irreversibly attached to a substratum or interface or to each other, are
embedded in a matrix of extracellular polymeric substances that they have
produced, and exhibit an altered phenotype with respect to growth rate and
gene transcription’ . Cells present within biofilms are distinctly different from their planktonic counterparts in terms of physiology and response to environmental stresses. Most studies on biofilms have described work with bacteria inhabiting abiotic surfaces; however,
recent studies have also focused on the interaction between biofilms and biotic surfaces (including animal and plant tissues) in order to discern the
interactions between microbe and host.