Bacteria often live in crowded communities, attached to surfaces. These communities are themselves a living material, and may potentially be useful in industrial and health applications. However, the utility of engineered bacterial communities is currently hampered due to limited understanding of how to control the structure of these bacterial communities. Here, the PIs will study a novel source of design rules: microbial warfare. In nature, bacteria within the same community compete for space and resources. As a result, many bacteria have evolved mechanisms to kill each other. Killing events modify the structure of bacterial communities. Broadly speaking, the mechanisms bacteria use to kill each other fit one of two categories; they either act locally, and require direct contact between cells, or they act at a distance, through toxins or antibiotics that diffuse through liquid. The PIs will uncover the material consequences of local and non-local bacterial killing, and thus develop an understanding of the design rules connecting bacterial killing to community structure. Doing so will facilitate the creation of next-generation synthetic bacterial communities with optimized structures.
Bacteria are the most dominant form of life on earth. They commonly inhabit biofilms, microbial consortia composed of densely packed cells embedded in a matrix of extracellular polymeric substances and often attached to a surface. These crowded structures are ubiquitous in ecological settings and also serve as havens for host-associated bacteria that promote health and also underlie many infections. Because biofilms are densely packed, cell death and reproduction hold emergent materials consequences. When a cell dies and lyses, the biofilm structure may partially 'cave-in;' and when a cell reproduces, it pushes other cells out of its way. These cellular processes create a dynamic process where death and reproduction modify biofilm structure; and structural changes impact subsequent death and reproduction. The focus of this proposal is on cell death within biofilms that is mediated by microbial antagonistic interactions - killing. Broadly speaking, the mechanisms of intercellular killing can be classified as either local or non-local. Local killing mechanisms typically require direct contact between cells, and thus depend on the nearest neighbor interaction network of cells in biofilms. Non-local killing mechanisms typically feature diffusible secreted toxins, and thus depend on the density of killer cells surrounding a target cell. Understanding the dynamics of inter-microbial aggression will facilitate the design of antagonistic probiotics, and help elucidate the ecological role of bacterial antagonism.
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.
