Heterogeneity and Pattern Formation in Bacterial Biofilms
Even bacterial colonies composed of one species generate great physiological heterogeneity. Cells enter diverse states of growth and gene expression at different points in colony development. For example, biofilms formed by Bacillus subtilis contain both vegetative cells and dormant spores. Through time-lapse imaging of biofilm-forming strains of B. subtilis, we show that variations in genetic circuit timing, which may be small at the cellular level, can lead to qualitatively different patterns of cell phenotypes as colonies grow. With a simple mathematical model of biofilm growth, we can predict patterns that strains with different cell differentiation dynamics will generate as they form biofilms. Our results establish the opportunity to control emergent structure of bacterial colonies by manipulating well-studied gene expression circuits. Control over cellular heterogeneity will allow us to test intriguing hypotheses on the functional role of heterogeneity in bacterial biofilms, such as division of labor and bet-hedging.