Jam and Conquer

Mechanical Engineering and Materials Science Seminar Series

Seminars are held weekly on Wednesday at 2:30 PM. Please contact Diana Qiu, Amir Pahlavan, or Rebecca Kramer-Bottiglio with speaker suggestions.

September 29, 2021

"Jam and Conquer"
Oskar Hallatschek, UC Berkeley

Abstract: Microbes often colonize spatially-constrained habitats, such as pores in the skin or crypts in the colon. The resulting micro-communities can be very stable and contribute to the long-term function of our microbiomes. Due to a lack of dynamical observations, it is however unclear how these communities and their ecological functions arise. By monitoring and modeling microbial populations in microfluidic channels of systematically varied size, we find a rich spectrum of scale-dependent dynamical patterns that are controlled by the competition between density-dependent outflow and population growth. Our results show that density-dependent passive diffusion can drive a reproducing populations to a jamming threshold, which entails supreme resilience against invaders at the cost of a total loss of mixing and intra-species competition. These results elucidate how the injection of degrees of freedom, driven by cell proliferation, can drive a non-equilibrium phase transition (different from MIPS) and raise the question of how the mechanical properties of jammed cellular packings influence the genealogical trees of the ensuing microbial population.

Available to meet 1:30-2:30 and 3:45-4:15