Biofilm formation: A complicated microbiological process

Bacteria employ certain basic survival strategies one of which is to form in natural and industrial systems biofilms, within which they are protected from antibacterial chemicals, environmental bacteriophages, and phagocytes. In contrast to planktonic form of microorganisms, biofilm is a microbially derived sessile community 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. Biofilms may form on a wide variety of surfaces, including living tissues, indwelling medical devices, industrial or potable water system piping, or natural aquatic systems. Biofilms are preferentially formed in very high shear environments.The solid-liquid interface between a surface and an aqueous medium provides an ideal environment for the attachment and growth of microorganisms. The solid surface may have several characteristics that are important in the attachment process. Proximity of cells within the microcolony (or between microcolonies) provides an ideal environment for creation of nutri­ent gradients, exchange of genes, and quorum sensing. Bacteria within biofilms may be subject to predation by free-living protozoa, bacteriophage, and polymorphonuclear leukocytes. Biofilms present both heterogeneity and a constant flux, as they adapt to changing environmental conditions and the composition of the community and may be dispersed with various mechanisms for will undoubtedly emerge. The key to success for biofilm prevention and control may hinge upon a more complete understanding of what makes the biofilm phenotype so different from the planktonic phenotype.