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MICROBIOLOGY: Chemical Crosstalk in a Biofilm
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Caroline Ash

The bacterial pathogens Burkholderia cepacia and Pseudomonas aeruginosa
contribute to the death of cystic fibrosis patients. This association is no
accident. P. aeruginosa produces volumes of slimy polysaccharides and
lipopeptides that form the structural components of a biofilm and help to
shield the bacteria from antibiotics. Biofilm production is regulated by a
density-dependent mechanism called quorum sensing, which is mediated by
hormone-like N-acyl homoserine lactones. These molecules control the
production not only of biofilm matrix material but also of virulence
factors such as proteases, flagellae, and fimbriae.

Huber et al. have found that B. cepacia shares the same quorum-sensing
molecules as P. aeruginosa; thus, these organisms potentially enhance each
other's virulence. Mutations in the cep quorum-sensing system of B. cepacia
resulted in an immature biofilm and an absence of swarming behavior,
although the latter deficit could be reversed by adding biosurfactants. --
CA

Microbiology 147, 2517 (2001).