Biofilms as Complex Differentiated Communities

Abstract

Prokaryotic biofilms that predominate in a diverse range of ecosystems are often composed of highly structured multispecies communities. Within these communities metabolic activities are integrated, and developmental sequences, not unlike those of multicellular organisms, can be detected. These structural adaptations and interrelationships are made possible by the expression of sets of genes that result in phenotypes that differ profoundly from those of planktonically grown cells of the same species. Molecular and microscopic evidence suggest the existence of a succession of de facto biofilm phenotypes. We submit that complex cell-cell interactions within prokaryotic communities are an ancient characteristic, the development of which was facilitated by the localization of cells at surfaces. In addition to spatial localization, surfaces may have provided the protective niche in which attached cells could create a localized homeostatic environment. In a holistic sense both biofilm and planktonic phenotypes may be viewed as integrated components of prokaryote life.

The Limitations of In Vitro Experimentation in Understanding Biofilms and Chronic Infection

“…There is often little change in the MIC of individual cells, however growth in populations can lead to an increasing tolerance to antibiotics. The cause of such increased tolerances seen in biofilms has been investigated in a number of different studies, focusing on the extracellular matrix, the involvement of quorum sensing (QS), and the physiological factors observed within the biofilm [19,[26][27][28][29]. The extracellular matrix itself has been shown to obstruct the diffusion of some antimicrobial agents through both chemical and physiological means [27,30,31].…”

Enzymatic approaches in paper industry for pulp refining and biofilm control

“…This configuration explains that bacteria in biofilm show greater resistance to biocides compared to their planktonic forms. Established biofilms can tolerate antimicrobial agents at concentrations of 10-100 times higher than those needed to kill genetically equivalent planktonic bacteria, making biofilms extremely difficult to eradicate (Burmolle 2006, Jefferson 2004, Stoodley 2002.…”

Lipid and polymer nanoparticles for drug delivery to bacterial biofilms

“…From the mature biofilm, individual cells or biofilm fragments are released and can colonize new surfaces ( Figure 1). [7] It was observed that biofilm associated bacteria, termed sessile cells, display a profoundly different phenotype compared to their free swimming, planktonic counterparts. [7] The biofilm bacteria are able to communicate and alter each other's phenotype by a process called quorum sensing.…”

“…[7] It was observed that biofilm associated bacteria, termed sessile cells, display a profoundly different phenotype compared to their free swimming, planktonic counterparts. [7] The biofilm bacteria are able to communicate and alter each other's phenotype by a process called quorum sensing. [8][9][10] This allows the biofilm to respond cooperatively to environmental changes and threats.…”