Behavior of motile bacteria at liquid crystal interfaces

Bacteria are known to live in complex environments such as biofilms and mucus with rich viscoelastic properties, anisotropy and defects. Therefore, it is important to study their behavior in environments similar to these natural habitats, to understand their interactions and impacts, in order to develop antimicrobial strategies and to control their dynamics. While the behavior of bacteria near solid surfaces and simple fluid interfaces is well studied, little is known about their behavior near complex fluid interfaces. In this study, we use the liquid crystal 4-octyl-4′-cyanobiphenyl (8CB) as a model system to investigate how living microorganisms behave near these complex fluid interfaces. We investigate how the molecular ordering at the interface, anchoring property, and the structure of topological defects affect the individual and collective behavior of motile bacteria, B. subtilis and E. coli. We show how controlling and engineering the properties of the interface may lead to controlled dynamics. Our work offers important insights into the fundamental behavior of bacteria in complex environments, providing a foundation for the design of micromotors and micromachines that hold great potential for applications in bioremediation, biosensing, and beyond.