Biofilm formation by the Gram-positive soil bacterium Bacillus subtilis
Biofilms formed by the Gram-positive soil-dwelling bacterium Bacillus subtilis manifest as architecturally complex, hydrophobic communities on an air-agar interface. Both the structure and the hydrophobicity of the biofilm are the consequence of the cells producing a protective extracellular matrix. The B. subtilis biofilm matrix comprises fibres formed by the secreted protein TasA, an extracellular polysaccharide, and a secreted protein BslA. Together the matrix components surround and protect the resident cells from environmental stress. I will overview the remarkable properties of the proteins in the biofilm matrix that have been uncovered through a cross discipline collaboration. For example we have found that BslA is a bifunctional protein with roles in both biofilm hydrophobicity and structuring. I will move on to highlight the identification of growth arrest as a distinct stage of biofilm formation and talk about an new role for a molecule called pulcherrimin in stopping expansion of the biofilm.