Close encounter with a biofilm

August 07, 2012

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Top left) A robust biofilm formed by growing two V. cholerae mutants unable to produce matrix proteins (red) and an exo-polysaccharide (green).

(Top right) Three-dimensional architecture of V. cholerae biofilm where the bacterial cells, shown in blue, are surrounded by three essential matrix proteins depicted in grey, red and green, respectively.

(Bottom right) Super-resolution image of the V. cholerae biofilm components showing one of the matrix proteins (green) and an exo-polysaccharide (red).

(Bottom left) Three-dimensional super-resolution image of a single V. cholerae cell covered with secreted exo-polysaccharide. Arrow indicates a ball-like structure of the exo-polysaccharide.

In a collaborative effort from two research laboratories in UC Santa Cruz and UC Berkeley, researchers have developed a novel super-resolution approach to observe in real-time how bacteria form biofilm. Biofilms formed by many human pathogenic bacteria, such as Vibrio cholerae and Pseudomonas aeruginosa, is a problem in both medical and industrial settings, as biofilm components protect the constituent bacterial cells from drug treatments and environmental stresses. Using V. cholera, the leading researchers, Veysel Berk (Chu research group, UC Berkeley) and Jiunn Fong (Yildiz research group, UC Santa Cruz), were able to visualize the temporal and sequential accumulation of the different biofilm components (matrix proteins and an exo-polysaccharide) and unveil the complementary roles of each of these biofilm components. In order to visualize in real-time how a complex biofilm develop from a single cell, small tags were inserted into the genes encoding the biofilm components, resulting in proteins that can be recognized with fluorescently-labeled antibodies, followed by the use of single-molecule labeling, continuous immunostaining and a super-resolution microscope. This super-resolution approach can also be adapted to other bacterial species and aid in the development of new approaches to fight biofilm-related infections. These findings were reported in the journal Science (July 13 issue).

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