Abstract
Fitness of bacteria is determined both by how fast cells grow when nutrients are abundant and by how well they survive when conditions worsen. Here, we study how prior growth conditions affect the death rate of Escherichia coli during carbon starvation. We control the growth rate prior to starvation either via the carbon source or via a carbon‐limited chemostat. We find a consistent dependence where death rate depends on the prior growth conditions only via the growth rate, with slower growth leading to exponentially slower death. Breaking down the observed death rate into two factors, maintenance rate and recycling yield, reveals that slower growing cells display a decreased maintenance rate per cell volume during starvation, thereby decreasing their death rate. In contrast, the ability to scavenge nutrients from carcasses of dead cells (recycling yield) remains constant. Our results suggest a physiological trade‐off between rapid proliferation and long survival. We explore the implications of this trade‐off within a mathematical model, which can rationalize the observation that bacteria outside of lab environments are not optimized for fast growth.
Highlights
Bacteria are exposed to a variety of environments, from stressful and nutrient-poor to ideal and nutrient-abundant
The death rate depends on the carbon substrate used for growth, with cultures grown on lysogenic browth (LB) dying more than 5 times faster than those on mannose
We reported a quantitative relation between the death rate of E. coli in carbon starvation and its growth rate prior to starvation
Summary
Bacteria are exposed to a variety of environments, from stressful and nutrient-poor to ideal and nutrient-abundant. The average proliferation of bacteria through cycles of famine and feast, i.e., their fitness, depends on the ability to grow rapidly, and on the ability to survive when conditions worsen. While some bacteria can produce dormant endospores that can survive for thousands of years (Vreeland et al, 2000; Setlow, 2007), vegetative bacteria cannot. These bacteria require continuous maintenance to sustain basic cellular functions and prevent cell death. It is clear that the ability to reduce and optimize the maintenance rate is crucial for maximizing survival in limited environments. How cells could achieve this feat is still largely unclear
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