CAREER: Collective mechanics, particle transport and morphological adaptation in living multiphase matter: from mechanisms to the control of microbial swarms and films

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This CAREER award will support an integrated research and education plan to study and model the formation and evolution of living multiphase materials - microbial swarms and films. Bacterial and fungal colonies constitute a significant fraction of the biomass on earth. These organisms cause more than two-thirds of human disease including most hospital-acquired infections. Bacteria and fungi typically colonize surfaces and tissue by forming rapidly spreading multicellular swarms and growing fibrous films. The goal of this research is to understand the mechanisms by which these form and to quantifying emergent properties of the composite. The knowledge gained can inspire new technologies to control bacterial and fungal infections in physiologically relevant settings. The research team will investigate the fundamental physical and biochemical mechanisms that underlie formation, growth, and adaptability in microbial swarms and films. The team will use the bacteria Serratia marcescens and Escherichia coli, and the fungus Candida albicans as model experimental systems. Experimental data will be used to develop and test analytical theories and numerical models to identify and understand the mechanisms involved. Insights obtained in the research will be useful in several fields including tissue engineering, soft matter, swarm robotics, and microbiology. The award will also enhance undergraduate and graduate bioengineering curricula through the design of new courses with both wet and dry laboratory components based on the proposed research. The research team will also create a series of customizable, standalone and modular graphics and visualization heavy “SynLab” toolkits and applications inspired by this research. These will be implemented in K- 12 classrooms to motivate students toward STEM careers. The award will enhance education, contribute to community directed outreach, and provide research opportunities for undergraduate and graduate students, especially those from underrepresented groups, including American Indian youth in the Central Valley region of California. Bacteria and fungi cause more than two-thirds of human infections, separately and sometimes as coexisting communities. In the infectious phase, these microbes colonize surfaces by forming rapidly spreading multicellular swarms and films. These living multiphase composites, while composed of independent agents (units), exhibit bulk macroscale properties, and remarkable collective response and adaptations. There are significant gaps in our understanding of how biomechanical and physicochemical mechanisms initiate, develop and stabilize such collective response and composite properties. This project aims to study these fundamental questions through a comprehensive and integrated research, general education and community-engaged outreach program. The research plan builds on the following foundational hypothesis: active multi-scale multiphase frameworks provide a novel, complete and insightful means to interrogate, analyze and understand microbial swarms and films. The PI and his group will combine experiments on the bacteria Serratia marcescens and Escherichia coli, and the fungus Candida albicans, with multiphase continuum theories and stochastic agent-based simulations to understand the collective mechanics, particle transport and morphological adaptation in collectively moving swarms and rapidly growing fungal films. The specific aims are to: 1) interrogate and understand how micro-scale mechanics and transport, cell-cell interactions, and physicochemical interactions control the onset of collective multicellular swarms and films; 2) track evolution of mesoscale spatiotemporal properties and morphology in these composites and quantify any adaptations in response to external flow, chemical, and mechanical perturbations; 3) synthesize experiments with first-principles continuum theories, minimal models and stochastic simulations to identify physical mechanisms underlying the stability of bacteria/fungal microbiomes; 4) significantly enhance undergraduate and graduate bioengineering curricula by incorporating dry and wet laboratory components; 5) create a series of customizable modular graphics based standalone applications inspired by this research; and 6) provide research opportunities for underrepresented students.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.