Biology and physics at the biofilm surface

Biofilms are communities of microbes that are surrounded by an extracellular matrix. The matrix functions like a glue to provide structure and protection to the resident microbes. An everyday example of a biofilm is dental plaque. As exemplified by dental plaque, microbes benefit from living in a biofilm by gaining access to hard-to-source nutrients and becoming difficult to remove from a surface. In other environments or situations microbes living in biofilms become resistant to antibiotics and other antimicrobial agents resulting in chronic infections or blockages in pipes and catheters. We are interested in how the biofilm is assembled. The main component parts that are needed have been identified and in this proposal we aim to understand how one of them assembles to form a protective coat around the members of the biofilm community. Understanding this assembly process will allow the development of novel strategies to block, reverse, or enhance biofilm assembly in the natural environment and guide future developments of novel antimicrobial compounds for chronic debilitating biofilm infections.

It is accepted that there is an urgent need to understand the molecular and physical basis of biofilm formation and maintenance. This will identify new targets for the fight against difficult-to-treat chronic bacterial infections and will identify strategies to enhance or disperse biofilm formation. There have been recent advances in our understanding of the key building blocks required for the nucleation and growth of biofilms for many species of bacteria. However it is still not understood how the extracellular components physically interact to allow a three dimensional biofilm to develop. Bacillus subtilis is a suitable model for biofilm formation by Gram-positive bacteria. The organism is very well-characterised, and moreover is of significant industrial importance as a plant growth-promoting organism. B. subtilis forms biofilms that contain differentiated cells that display a complex three-dimensional architecture. We have previously shown that a small secreted protein called BslA is essential for biofilm formation and that it acts in a synergistic manner with the TasA amyloid fibres and the exopolysaccharide found in the extracellular matrix to allow biofilm development. More recently, we have determined the crystal structure of BslA and established its identity as a self-assembling bacterial hydrophobin that forms a protective film around the biofilm. We now wish to exploit this finding to determine the factors controlling partitioning of BslA to the interface and those controlling film formation, the factors that influence biofilm structure and morphology, and the factors influencing the plant colonisation properties of B. subtilis. We also wish to establish how B. subtilis obtains nutrients through what appears to be a highly hydrophobic and minimally permeable barrier. By forming a team we are combining the strengths of biochemical and genetic analyses with molecular biophysics to obtain a multiscale picture of biofilm structure and function.

A. Industry
i) Biotech companies that have active anti-infective research programmes will benefit from the proposed research programme that will generate novel and exciting knowledge on a target relevant to the development of novel antibiofilm agents. BslA has significant potential importance to the food industry. Industry looks for molecules that can be used to replace fats at interfaces so as to develop low-fat foods; protein has the added benefit of improved satiety (i.e. a lower-fat food that keeps you fuller for longer).
ii) It is currently too early in the project to identify industrial partners specifically. CEM is on the management board of the Edinburgh Complex Fluids Partnership, a knowledge-based organisation supporting companies with product innovation, and providing consultancy in formulations, processing and product characterization. Moreover both DVA and CEM have been involved in spinout companies. Together the PIs and institutions will act to protect any intellectual property and to maximise opportunities for licensing.
B. Members of the wider academic community.
i) Our broad-ranging and comprehensive study, integrating a wide range of experimental approaches, will attract a great deal of interest across different disciplines, such as microbiology, molecular genetics, biophysics, structural biology, and among scientists investigating various aspects of microbial communities.
ii) The PDRA and PIs will attend and contribute to a variety of conferences and the PIs will present results through invited research talks, both nationally and internationally. As appropriate, results will be peer-reviewed and published.
C. PDRAs and PIs.
ii) The Universities take training of early career researchers very seriously, thereby ensuring a successful contribution to the knowledge-led economy of UK Plc. The appointed PDRAs will be given multiple opportunities to present their findings at major research conferences, facilitating their career development through the acquisition and refining of key presentational and networking skills. They will also be involved in presenting our findings to industrial collaborators and potential commercial partners, and be encouraged to routinely consider exploitation routes for their findings.
ii) The appointed PDRAs will have access to training in transferable/generic skills through the professional development schemes. In line with the Concordat 2009, the PDRA will be actively encouraged to undertake at least 5 days training in personal professional development per annum. In addition, both institutes have an annual appraisal scheme to actively facilitate the career development of staff, including PDRAs and PIs.
D. The general public.
i) It is important that members of the general public are aware and supportive of how tax payers' money is spent on scientific research. Therefore as part of our work on this project, we will engage with local communities, through face-to-face discussion of our work and family focussed scientific event days.
ii) The applicants are experienced, energetic and ardent science communicators. The PDRAs will have the opportunity to become involved in various events. We would especially like to engage the biophysicists in microbiological outreach activities to highlight the benefits of interdisciplinary work.
E. Collaborations
This proposal brings together three groups from two universities to form a team that, together, possesses the skills and expertise needed to allow this highly innovative interdisciplinary proposal to be successful. Moreover we will draw on the expertise of two other collaborators (both based at the University of Dundee) to allow us to extend our analysis of the study of the importance of biofilm formation to the promotion of growth in model environmentally important plants.