Rhamnolipids mediate detachment of Pseudomonas aeruginosa from biofilms.
The process of detachment, through which bacteria use active mechanisms to leave biofilms and return to the planktonic (free-living) state, is perhaps the least understood aspect of the biofilm life cycle. Like other stages of biofilm development, detachment is a dynamic, regulated process, controlled by specific genes, and induced by particular environmental cues. In previous work we discovered Pseudomonas aeruginosa variants that exhibit accelerated biofilm detachment. These hyper-detaching variants arise spontaneously from biofilms at a high frequency, and they exhibit robust detachment under different biofilm growth conditions. Here we show that these variants detach by a mechanism requiring the biosurfactant rhamnolipid and that this detachment mechanism rapidly restores antibiotic sensitivity to separating bacteria. We also show that rhamnolipids can bring about detachment in wild-type P. aeruginosa biofilms. These findings raise the possibility that this detachment mechanism may be useful as a treatment to disrupt established biofilms. Interestingly, the rhamnolipid-mediated detachment mechanism involves the formation of cavities within the centre of biofilm structures. Our data suggest a model to explain detachment that occurs via this pattern.
Boles
Blaise R
BR
Department of Microbiology, University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, IA 52242, USA.
Thoendel
Matthew
M
Singh
Pradeep K
PK
D001422:Bacterial Adhesion; D018441:Biofilms / Q000254:growth & development*; D006017:Glycolipids / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D011550:Pseudomonas aeruginosa / Q000166:cytology / Q000235:genetics / Q000502:physiology*
D006017:Glycolipids; C418382:rhamnolipid