Biofilm is a self-assembling microbial community that can serve as a model system for studying emergent collective dynamics of living systems. Bacillus subtilis biofilms resolve a conflict between interior and peripheral cells by electrical signaling and oscillatory colony-growth dynamics. Intriguingly, this dynamics maintain the interior-cell populations within a biofilm, which ultimately improves the survivability against antibacterial treatments as a whole. Beyond intra-biofilm coordination, two biofilms in a microfluidic device can coordinate their oscillatory phases according to the nutrient availability, through which biofilms improve their survivability by effectively utilizing limited resources. While models that can separately simulate intra- and inter- biofilm oscillatory dynamics have been proposed, recapturing these dynamics by a simple phenomenological model remains to be done. Extending from our previous work where we developed a simple reaction-diffusion model that captures the essence of the oscillatory colony growth dynamics of a single biofilm, here we show that a model similar to our previous one can recapitulate the inter- as well as intra-biofilm dynamics.

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.

Altruistic behaviors, such as self-sacrifices, are commonly observed in diverse living systems from bacteria to animal societies. Motivated by the fact that self-sacrifices of individuals can benefit the entire populations, we developed a decentralized control scheme with self-sacrifice by extending the Slimebot model. When an agent is not performing favorably, the agent self-sacrifices by stopping the motion and transferring its energy to nearby agents. We demonstrate via simulations that the proposed control scheme enables the agents to perform tasks effectively under several environments.