(678h) Unravelling Bacterial Ballet: Deciphering Swarming and Biofilm Dynamics through a Multiphase Lens

Bacteria exhibit diverse colony formations in response to their environment, such as swarming in nutrient-rich conditions and biofilm development on hydrated surfaces. In this study, we present a multiphase model to explore the growth dynamics of bacterial colonies on solid substrates. The bacterial swarm is treated as a mixture of cells and aqueous phases, while the biofilm colony is considered a mixture of cells, extracellular matrix (ECM), and nutrient-rich aqueous phases. To simplify the model, we employ the thin-film approximation, given that the colony's height is significantly smaller than its radius.

Our numerical simulations focus on determining the colony height, volume fractions of each phase, and nutrient transport within the colony. Additionally, we investigate the impact of osmotic flow on the dynamic behavior of the colonies. Our findings reveal that the ECM phase plays a crucial role in generating internal osmotic pressure, enhancing nutrient flow, and facilitating biofilm growth. Conversely, surface forces play a pivotal role in the spreading of bacterial swarm colony.

Expanding our approach, we explored the study of pattern formation in bacterial swarming colonies. Our framework incorporates the interaction between mechanical stress resulting from bacterial migration and Marangoni effects within swarm colonies. The mathematical model developed herein elucidates front instability in bacterial colonies, offering insights into the occurrence of various patterns observed in experimental settings.