Why are Microbes Chiral?
This event is part of the Preliminary Oral Exam.
Examining Committee: Kirill Korolev, Pankaj Mehta, Rama Bansil, Steve Ahlen
Abstract: Chiral growth is common in the microbial world and during embryogenesis, but the origins of chirality remain unclear. We show that chiral mutants have a distinct selective advantage, and the chirality at the population level is a result of natural selection rather than an accidental byproduct of evolution.
We developed a minimal reaction-diffusion model to describe the emergence of chiral patterns in microbial populations from the chiral behavior of individual cells. In agreement with recent experiments, the model predicts logarithmic spirals separating different sub-populations in a colony. Competition between strains with different chiralities typically results in the exclusion of the less chiral strain or stable coexistence between strains with opposite chiralities. These outcomes arise from the aggregation of strains with different chiralities and the faster expansion of denser aggregates. We also find that chirality promotes invasion, species intermixing, and can stabilize mutualistic interactions such as cross-feeding. Altogether, our results suggest several mechanisms that provide an advantage to chiral cells and could explain experimental observations of chirality switching in certain microbial populations and during cancer progression.