A novel electrical device demonstrates localized stimulation triggers cell-type-specific proliferation in biofilms*

Biological systems ranging from bacteria to mammals utilize electrochemical signaling. While artificial electrochemical signals have been utilized to characterize neural tissue responses, the effects of such stimuli on non-neural systems remain unclear. To pursue this question, we developed a novel experimental platform that combines a microfluidic chip with a multi-electrode array (MiCMA) to enable localized electrochemical stimulation of bacterial biofilms. The device also allows simultaneous measurement of the physiological response within the biofilm with single-cell resolution. We find that stimulation of an electrode locally changes the ratio of the two major cell types comprising Bacillus subtilis biofilms, namely motile and extracellular matrix-producing cells. Specifically, stimulation promotes the proliferation of motile cells, but not matrix cells, even though these two cell types are genetically identical and reside in the same microenvironment. Our work thus reveals that an electronic interface can selectively target bacterial cell types, enabling control of biofilm composition and development.