Biofilms are communities of microbial cells that grow on natural and synthetic surfaces. They may be beneficial, for example when protecting plant roots from pathogens. However, in most cases they are related with disease; when they develop on catheters or in the lungs of Cystic Fibrosis patients they most likely lead to death. Irrespective of whether biofilms are beneficial or detrimental to the host, their extracellular matrix is critical to their development and survival. The extracellular matrix is a mesh of biopolymers, mainly polysaccharides, proteins and nucleic acids that connects the biofilm’s cells together. It is also related with an increased resistance of biofilms to antibiotics relative to single cells. Indeed, there has been an immense progress in the study of biofilms’ extracellular matrix from a genetic perspective yet a molecular understanding of the formation, the chemical and the physical properties of this complex 3D network from its components is still lacking. We study the basic interactions between the biopolymers in the matrix and their interaction with cells. Our model organism for biofilm formation is the soil bacterium, Gram positive Bacillus subtilis (figure 1, shown on an agar plate). A Scanning electron view of a thin section in a B. subtilis biofilm is shown in figure 2, exposing the extracellular material that interconnects the cells.
1. Isolation, characterization, and aggregation of a structured bacterial matrix precursor. Chai L, Romero D, Kayatekin C, Akabayov B, Vlamakis H, Losick R, Kolter R. J. Biol. Chem., 288, 175559 - 68 (2013).
2. Extracellular Signals Regulate Differentiation of Cells in Biofilms., Chai L, Vlamakis H, Kolter R., MRS bulletin, 36, 374-379 (2011)
3. Large area, molecularly smooth (0.2 nm rms) gold films for surface forces and other studies. Chai L, Klein J., Langmuir, 23, 7777 – 83 (2007).
4. Role of ion ligands in the attachment of poly(ethylene oxide) to a charged surface. Chai L, Klein J., J. Am. Chem. Soc., 127, 1104 - 5 (2005).