Aguilar Luviano, O. B.; Santos-Escobar, F.; Orozco-Barrera, S.; Pena-Miller, R.

Bacterial phenotypic plasticity enables rapid adaptation to fluctuating environments. Filamentation, a shape-shifting response commonly observed under stress, has often been viewed as a byproduct of cellular damage. However, filamentation might also confer survival advantages by influencing toxin accumulation dynamics. In this study, we examined the adaptive value of filamentation in Escherichia coli using a genetically controlled, SOS-independent induction system to compare isogenic, yet phenotypically distinct cells. By integrating mathematical modeling, single-cell microfluidics, and time-resolved flow cytometry, we evaluate bacterial survival under heavy metal and {beta}-lactam antibiotic stress. Our results show that filamentation can improve survival by decreasing the surface area-to-volume ratio, which slows intracellular toxin accumulation and extends the time available for stress response activation or for external toxin levels to dissipate. These findings suggest that filamentation serves as an effective morphological strategy to transiently withstand environmental toxicity, reinforcing its broader role in bacterial stress adaptation.