Ecology of a Simple Synthetic Biofilm

The ecology in a biofilm—i.e., how the cells relate to each other and their environment—can offer competitive advantages over an autonomous, free-swimming, planktonic environment such as nutrient acquisition via cross-feeding of populations and increased resistance to biocides. To explore this ecology, we investigated the physical parameters governing prokaryotic cell-to-cell signaling in a simple model of a biofilm created using live-cell lithography, comprising bacteria that are genetically engineered to transmit and receive quorum-sensing signals. These experiments, along with the numerical simulations that mirror them, revealed that gene expression resulting from transmitter to receiver communications was vitally dependent on the location within the biofilm elements and the epigenetic memory associated with a bistable switch in the receiver gene, which were both easily accessible in the model. Three-dimensional biofilm models with open channels that include still more complex communication networks for the study of wound repair are in the offing.