Taking Inspiration from the structure and function of bacterial biofilms

Biofilms are communities of microbial cells that underpin diverse processes including sewage bioremediation, plant growth promotion, chronic infections and industrial biofouling. The cells in the biofilm are encased within a self-produced exopolymeric matrix that commonly comprises lipids, proteins, eDNA and exopolysaccharides. This matrix fulfils a variety of functions for the community, from providing structural rigidity and protection from the external environment, to controlling gene regulation and nutrient adsorption. Critical to the development of strategies to control biofilm infections, or the ability to capitalise on the power of biofilm formation for industrial and biotechnological uses, is an in-depth knowledge of the biofilm matrix. Surprisingly little is understood about the primary and three dimensional structures of the key component parts, how they co-assemble, and the emergent biophysical and mechanical properties of such biofilm molecular composites. Analysis to date strongly indicates that the biofilm matrices of diverse species comprise chemically distinct components that have convergent physical/mechanical properties. For example, one strategy adopted by a wide range of bacteria is to impart structural integrity/rigidity to the biofilm via the synthesis of protein fibres. These fibres are believed to form a scaffold onto which the cells and other matrix components (such as exopolysaccharides) are attached. Other components in the matrix fulfil a common, protective function for the inhabitants. For example, the bacterial hydrophobin BslA forms a water-resistant raincoat over the Bacillus subtilis biofilm (see figure); similarly the cellulose produced by Escherichia coli biofilms increases the resistance of the community to desiccation. I will describe our recent successes in understanding how B. subtilis assembles a (close to) superhydrophobic biofilm, and how we can use this information for the generation of complex formulations with superior properties.