Burkholderia cenocepacia is an opportunistic pathogen in cystic fibrosis (CF)1, a genetic disease characterised by deterioration of lung functions which in turn promotes colonisation by opportunistic bacteria. Infections lead to pulmonary damage and eventually death. About 20% of CF patients with Burkholderia lung infections dye of the “cepacia syndrome”, a fatal necrotising pneumonia.
In nature and disease microbes grow within biofilms, including Burkholderia species in CF lungs. The biofilm matrix, composed by proteins, extracellular DNA and polysaccharides (PLS), surrounds the bacteria increasing resistance to antibiotics and host defenses2. It is an active macromolecular scaffold3, but the composition may vary from species to species and depends on cultivation media. We investigated B. cenocepacia BTS2, a CF clinical isolate and an abundant biofilm producer, and determined the influence of growth media on the physico-chemical properties of the biofilm matrix, with particular attention to PLS.
Four common bacteriological media and the synthetic cystic fibrosis medium (SCFM)4, simulating the in vivo situation, were used. Proteins and PLS content were determined, and the structure of the latter was established by NMR. Biofilm morphology was visualised by CLSM while AFM was used to investigate the thickness of the matrix. The evaluation of PLS content in biofilm showed that media promoting abundant biofilm formation exhibited the lowest PLS content. This observation prompted an investigation of the role of the PLS produced by B. cenocepacia strain BTS2 in biofilms: experiments demonstrated that PLS have anti-adhesion properties and that they promote detachment of mature biofilms. These properties could be exploited for impeding and/or removing biofilms.
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2) De Lancey Pulcini, E. Nephrologie 2001, 22, 439.
3) Flemming, H.C.; Wingender, J. Nat. Rev. Microbiol. 2010, 8, 623.
4) Palmer, K. L.; Aye, L. M.; Whiteley, M. J. Bacteriol. 2007, 189, 8079.
