Physical limits on the evolution of bacterial chemotactic behavior Victor Sourjik

The chemotaxis of swimming bacteria is one of the most studied quantitative models of behavior, environmental sensing, and signal processing by a cellular network. Already early seminal studies of bacterial chemotaxis suggested that the ability to follow chemical gradients is limited by the physics of bacterial motion and molecular counting. Furthermore, bacterial motility requires high investment of cellular resources in the biosynthesis and operation of flagella, implying a fundamental trade-off between motility and growth. To investigate how bacterial gradient sensing is evolutionary optimized under such physical constrains and resource investment trade-offs, we use targeted modulation of bacterial swimming and chemotaxis, combined with experimental evolution and theoretical analysis. Our results demonstrate how the interplay between physical and physiological trade-offs shapes the evolution of bacterial chemotactic behavior.