Universality of phenotypic distributions in bacteria

Some phenotypic properties in bacteria exhibit universal statistics, with distributions collapsing under scaling. The extent and origins of such universality are not well understood. Using phenomenological modeling of growth and division, we identify compound "shape factors"that describe the distributions throughout a large set of single-cell data. We find that the emergence of universal distributions is associated with the robustness of shape factors across conditions, explaining the universality of cell size and highly expressed protein content and the nonuniversality of times between consecutive divisions. A wide range of experimental data sets support our theory quantitatively.