Role of Bacterial Electrophysiology in Biofilm Development

Abstract

Contrary to the view of bacteria as free swimming, solitary individuals, most species of bacteria spend the majority of their time embedded within multicellular structures called biofilms. Biofilms are formed by communities of bacteria that secrete polysaccharides, proteins, and DNA to build gel-like matrices that form protective microenvironments for the cells. Previous studies of biofilms have focused mostly on broader biofilm morphology or on the molecular composition of the matrix. In addition, due to limitations in technology, most traditional studies of bacteria physiology focused on global, population-wide dynamics and ignored the heterogeneity of individual cells. Single-cell imaging of biofilms using optogenetic sensors can fill this conceptual gap in our understanding of how the physiology of individual cells change as they transition into the biofilm phenotype. Presented here is a new technique to image developing biofilms as they grow from a single cell, and a new set of computational tools to track individual cells and their lineages. Using these tools, we have discovered long-term Ca2+ oscillations in the cytosol of Escherichia coli following cell division. These occur with a period of about 40 minutes which correlates closely with the reported replication rate of the genomic DNA.