Just in case it rains: building a hydrophobic biofilm the Bacillus subtilis way

Over the millennia, diverse species of bacteria have evolved multiple independent mechanisms to structure sessile biofilm communities that confer protection and stability to the inhabitants. The Gram-positive soil bacterium Bacillus subtilis biofilm presents as an architecturally complex, highly hydrophobic community that resists wetting by water, solvents, and biocides. This remarkable property is conferred by a small secreted protein called BsIA, which self-assembles into an organized lattice at an interface. In the biofilm, production of BsIA is tightly regulated and the resultant protein is secreted into the extracellular environment where it forms a very effective communal barrier allowing the resident B. subtilis cells to shelter under the protection of a protein raincoat.