The objective of the proposed activity is to develop novel coarse-grained hydrodynamic simulation methods to model the collective swimming behavior of bacteria and other active particles and to investigate the collective behavior of bacteria in viscoelastic media and near surfaces. The research focuses specifically on bacterial systems because of their importance in infections, experimental data are becoming available, and the possibility of designing new engineered systems. If successful, the research contributions will have a broad range of applications, including chemical and biological engineering, materials science, and social science. If the concentration of bacteria becomes high enough, collective behavior emerges. The importance of chemical signaling (quorum sensing) is such systems is established. However, the emergence can occur even in absence of chemical signaling because of hydrodynamic interactions. Theory and simulation of such systems is the main subject of this project.
Intellectual Merit Mesoscopic phenomena (such as transport phenomena) play an important role in the macroscopic outcome observed in many areas including biology. The research has two central goals: 1) build a coarse-graining framework that allows for tractable simulations which capture the key hydrodynamic features, and 2) use a novel simulation method to study for the first time the impact a non-Newtonian fluid has on the collective behavior. These goals will potentially provide fundamental insights into natural phenomena such as bacterial infections in mucus of the lungs and intestines and biofilm formation, but also provide the tools to design bacterial systems. Preliminary results show that a non-Newtonian fluid can be used to control and interrupt collective behavior. This work will potentially change the paradigm in engineering of bacterial communities by including hydrodynamics and mechanical communication on equal footing with (an integrated together with) genetic manipulation and chemical communication.
Broader Impacts The framework built in this work and the fundamental advances on collective behavior will potentially impact many areas. This includes the following examples: if groups of organisms can undergo chemotaxis more efficiently than individuals, then active agents can work together as drug delivery agents to find and destroy tumors. New active materials can be designed with unique mechanical properties. Fluid mechanics can be used to optimize biofuel production by bacteria. Hydrodynamic interaction is seen as an example in which simple rules can give rise to complex emergent behavior. The research will help us understand which aspects of the emergent behavior are universal and which are particular to hydrodynamic interactions.
Education and Outreach: Research and education both benefit by being strongly tied together by leveraging the curiosity that is generated by visualizing fluid mechanics and biology. Java-based applets will be developed to teach fundamental concepts and encourage underrepresented groups. The applets will allow a user to interactively explore state-of-the-art research concepts. The interactive nature gives the user a greater sense of excitement and drive to learn more. Workshops will also be held at Rensselaer to bring together researchers studying complex fluids from a wide range of disciplines.
