Biofilm dispersal: mechanisms, clinical implications, and potential therapeutic uses

Abstract

Like all sessile organisms, surface-attached communities of bacteria known as biofilms must release and disperse cells into the environment to colonize new sites. For many pathogenic bacteria, biofilm dispersal plays an important role in the transmission of bacteria from environmental reservoirs to human hosts, in horizontal and vertical cross-host transmission, and in the exacerbation and spread of infection within a host. The molecular mechanisms of bacterial biofilm dispersal are only beginning to be elucidated. Biofilm dispersal is a promising area of research that may lead to the development of novel agents that inhibit biofilm formation or promote biofilm cell detachment. Such agents may be useful for the prevention and treatment of biofilms in a variety of industrial and clinical settings. This review describes the current status of research on biofilm dispersal, with an emphasis on studies aimed to characterize dispersal mechanisms, and to identify environmental cues and inter- and intracellular signals that regulate the dispersal process. The clinical implications of biofilm dispersal and the potential therapeutic applications of some of the most recent findings will also be discussed.

Figure 1.

Biofilm dispersal phenotypes of wild-type and dispersin B mutant strains of Aggregatibacter actinomycetemcomitans. (A) Dispersal of A. actinomycetemcomitans strain CU1000 (wild-type) and JK1023 (dispersin B mutant) in broth. (B) Biofilm formation by strains CU1000 and JK1023 over time as measured by crystal violet staining. (C) Detachment of cells from CU1000 and JK1023 biofilms over time as measured by CFU/mL in the broth.

Figure 2.

Cross-sections of biofilm colonies produced by (A) A. actinomycetemcomitans, (B) P. aeruginosa, and (C) S. marcescens. Scale bars = 100 µm in (A), 50 µm in (B), and 200 µm in (C). Panels (B) and (C) are from Ma et al. (2009) and Koh et al. (2007), respectively. Used with permission.

Figure 3.

Dispersal of A. actinomycetemcomitans, N. subflava, and S. mutans biofilms in broth. Biofilms were stained with crystal violet. Scale bar = 1 mm. The panel on the left is from Kaplan and Fine (2002). Used with permission.

Figure 4.

Chemical signals implicated in biofilm dispersal.