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 BslA, which self-assembles into an organized lattice at an interface. In the biofilm, production of BslA 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.
Arnaouteli, S., MacPhee, C. E., & Stanley-Wall, N. R. (2016, December 1). Just in case it rains: building a hydrophobic biofilm the Bacillus subtilis way. Current Opinion in Microbiology. Elsevier Ltd. https://doi.org/10.1016/j.mib.2016.07.012