[MS08] Movement and growth: modeling and control of cell behaviors from the individual to the population scales

[MS08-04] Stress response trade-offs in a model of bacterial growth under antibiotics: single-cell versus population approaches

*Ignacio Madrid¹ (1. The University of Tokyo (Japan))

Keywords:

Multi-type branching processes,Bet-hedging strategies,Age-structured population dynamics,Phenotypic plasticity,Models of bacterial proliferation

Under antibiotics causing DNA damage, bacteria can trigger a stress response known as the SOS response. While the expression of this stress response can make individual cells transiently able to overcome antibiotic treatment, it can also delay cell division, thus impacting in different ways the population's ability to grow and survive. Our goal is to contrast the different trade-offs that emerge from this phenomenon when we consider the survival probability of the population issued from a single cell, and when we consider the population growth rate (Lyapunov exponent) in constant and periodic environments. We show that the sensitivity of these two different notions of fitness with respect to the parameters describing the phenotypic plasticity differs between the stochastic approach (survival probability) and the deterministic approach (population growth rate). As a consequence, the optimal parameters that characterize the single-cell lineages that survive by the end of the experiment, and the parameters that maximise the exponential growth of the population might not be the same. Finally, under a more realistic configuration of periodic stress, our results indicate that optimal population growth can only be achieved through fine-tuning simultaneously both the induction of the stress response and the repair efficiency of the damage caused by the antibiotic.