Threshold accumulation of a constitutive protein explains E. coli cell-division behavior in nutrient upshifts

Significance The mechanism leading to cell division in the bacteriumEscherichia coli is unknown, but we know that it results in adding a roughly constant size every cell cycle, regardless of size at birth. While most available studies try to infer information on cell division from steadily dividing cells in constant nutrient conditions, this study leverages a high-resolution device to monitor single-cell growth division upon nutrient changes. Comparing these data with different mathematical models, we are able to discriminate among fundamentally different mechanisms of cell-division control, and we show that the data support a model where an unregulated protein accumulates to a threshold and triggers division.