Phenotypic variations induced emergence of orientation order and morphology in Bacillus subtilis biofilm growth

During the Bacillus subtilis biofilm growth on the solid MSgg substrate, the biofilm exhibits highly ordered structures such as matrix-producing-cell chains and Van Gogh bundles due to bacterial orientation order. These structures make the biofilm have strong mobility and environmental adaptability, thus making bacteria easier to survive and thrive in biofilms comparing to planktonic bacteria. We tested the behaviors of different phenotypes as well as their impacts on bacterial clusters: motile cells arrange disorderly, the biofilm made up of motile cells tends to be circular and isotropic; matrix-producing cells form cellular chains that guide motile cells along the chain to form a locally nematic phase, the morphology of the biofilm made up of both motile cells and matrix-producing cells is rendered irregular. Combining the results of a coarse-grained and individual-based model, we can control the biofilm growth through regulating environmental friction, bacterial growth rate and adhesion between cells.