The flagellum and cell fate differentiation

How do bacteria fulfill different functions within a large population? Bacteria are single celled organisms that live in the natural environment as part of a complex multicellular community called a biofilm. In a biofilm bacteria adhere to a surface and coat themselves in a protective layer of sugars and proteins. Common examples of where biofilms can be found include teeth, in the form of dental plaque, heart valves in the form of a chronic infection, and in the gut as part of the beneficial bacterial community that helps with food digestion. Life in a biofilm gives individual bacteria advantages that they would not have if they lived in isolation. This makes bacteria living in biofilm communities are difficult to eradicate as they are highly resistant to many antibiotics and antimicrobial agents such as bleach. It appears that bacteria living in a biofilm 'club' together and protect each other. My laboratory is interested in understanding how bacteria coordinate their activity to allow bacteria to communicate and come together to form a biofilm. Information about this process will help us understand the mechanisms that bacteria use to associate together in a biofilm community and therefore may allow the development of novel approaches to treat biofilm related infections. We study the process of biofilm formation using a soil bacterium called Bacillus subtilis. This bacterium is commonly used in the laboratory as a model to understand basic processes regarding gene regulation and expression. The information derived from such studies can be applied to other bacteria associated with human infections. In our study we plan to investigate how the flagellum (the machinery that allows the bacterium to swim) controls the behaviour of the individual bacterial cells.

Bacteria are single cell organisms that can live as part of a complex community called a 'biofilm'. In a biofilm the bacterial cells are encased in a self-produced polymeric matrix. Biofilms are of strategic importance as they form the basis of chronic infections and bio-remediation processes. In addition biofilms represent one of the most complex examples of bacterial cells displaying different 'cell fates'. For example in a single species Bacillus subtilis biofilm, cells differentiate so that a subpopulation of cells produces the exopolysaccharide which surrounds all of the cells. Other subpopulations of cells differentiate to fulfil other functions. How this occurs within an isogenic population is a challenging scientific problem to understand. The analysis and understanding of the molecular principles underpinning cell fate differentiation is a field of research with relevance to public health, agriculture and industry. My laboratory is interested in defining the molecular mechanisms used at the level of transcription to control these 'multicellular' behavioural processes. Excitingly we have preliminary data that point to a novel role for the flagellum in co-ordinating the transition between a motile cell and a non-motile matrix producing cell during the development of a B. subtilis biofilm. The aim of this proposal is to investigate how this is mediated. We will address this question using a combination of advanced microscopy, software development, and traditional genetic and biochemical techniques.