Microbial populations are not uniform masses of identical cells. Even genetically identical bacteria display remarkable diversity in behavior and function, which can be mechanistically driven by epigenetic switches, DNA inversions, and other types of phase variation. This phenotypic heterogeneity underlies bet-hedging, division of labor, and collective behaviors that define microbial life, and may hold clues to the origins of multicellularity. Nowhere is this more consequential than in biofilms, where bacteria embedded in a self-produced extracellular matrix organize spatially, cooperate metabolically, and coordinate responses to environmental change.

This program will ask: What rules govern phase variation and phenotypic diversity? How does heterogeneity emerge spatially within biofilms? How do physical properties of the extracellular matrix feed back on cellular differentiation? And how might these mechanisms illuminate the transition to multicellular life? Advances in DNA/RNA sequencing, spatial transcriptomics, single-cell methods, and mathematical modeling now make these questions tractable across scales, ranging from individual genetic switches to population-level collective behavior.

The program will be complemented by the QBio Summer Research Course for graduate students and postdocs, "Quantitative Microbiology across Scales". Summer course details and application will be online in October 2026.