Stochastic pulsing of gene expression enables the generation of spatial patterns in Bacillus subtilis biofilms
Eugene Nadezhdin, Niall Murphy, Neil Dalchau, Andrew Phillips, James Locke
Abstract
Abstract Stochastic pulsing of gene expression can generate phenotypic diversity in a genetically identical population of cells, but it is unclear whether it has a role in the development of multicellular systems. Here, we show how stochastic pulsing of gene expression enables spatial patterns to form in a model multicellular system, Bacillus subtilis bacterial biofilms. We use quantitative microscopy and time-lapse imaging to observe pulses in the activity of the general stress response sigma factor σ B in individual cells during biofilm development. Both σ B and sporulation activity increase in a gradient, peaking at the top of the biofilm, even though σ B represses sporulation. As predicted by a simple mathematical model, increasing σ B expression shifts the peak of sporulation to the middle of the biofilm. Our results demonstrate how stochastic pulsing of gene expression can play a key role in pattern formation during biofilm development.