Modelling Cystic Fribrosis and measuring microbial stickiness

Understanding Cystic Fibrosis

1) In the first Martins group have been developing a tool to enable the long-term culturing of CF airway-associated bacteria in artificial sputum medium. Using this model, they have been able to maintain polymicrobial communities in remarkably stable steady state titres for long periods of time and the combinations of species they are able to maintain this way are stable in their model setup, but show pronounced instability in other experimental model systems. Their model system allows them to maintain planktonic and biofilm-associated consortia cultured direct from CF sputum. They would like to explore these biofilm-associated consortia further, their data indicates that some species prefer to partition into biofilms whereas others prefer to exist in the planktonic state. This is significant because, to date, most analyses have focused on which species exist in CF sputum with no regard taken of their preferred growth mode. They speculate that those species which prefer to partition into biofilms may be more difficult to clear through antibiotic treatment. So these finding may have very real impact.

Understanding  microbial  “stickiness”

2) In the second project the group have recently procured a “C-trap” (Lumicks.com) device. This unique optical tweezers/microfluidics/microscopy setup will allow us to directly measure the force required to detach individual cells, one at a time, from different surfaces and from cell aggregates (biofilms) on those surfaces. This approach, of directly measuring cell “stickiness” is only possible with the new technology now available. Initially, the group will focus on analysing the adhesion of Pseudomonas aeruginosa, which is widely employed as a model for biofilm formation, and offers the added advantage of having an arrayed library of “off-the-shelf” mutants available. They aim to establish precisely which “glue molecules” contribute most towards surface adhesion vs cell-cell adhesion. A triple-species polymicrobial biofilm setup employing P. aeruginosa, Staphylococcus aureus, and Candida albicans (i.e., representing a Gram-negative, Gram-positive and fungal species, respectively) will be used to examine the mechanical adhesion properties (again, using the C-trap) of each species on different surfaces. [See project 1 for an outline of the model system used to maintain these species together.] To facilitate this, they have already labelled each species with unique tags, allowing to unambiguously establish the identity of each cell as they  measure its specific adhesive properties. To our knowledge, this type of state-of-the-art “cell stickiness” analysis has not been carried out before, and should provide a truly valuable insight into the physics and chemistry of bioadhesion.

 If you would like to connect with Martin and learn more please contact us at Nbic@biofilms.ac.uk