Collective dynamics is a behavior of living systems that can improve their survivability in harsh and complex environments. Towards improving the vulnerability of engineering systems against power-source limitations, we focused on an oscillatory-growth dynamics of Bacillus subtilis biofilms. We developed a minimal reaction-diffusion model that captures the essence of the bacterial growth, nutrient consumption and electrical signalling. Numerical simulation of the model successfully recapitulated the oscillatory dynamics of bacterial biofilms. Thus, our model provides a first step forward towards designing biofilm-inspired engineering systems such as swarm robots and power supply networks.