The physiological response of bacterial cells to temperature shock

Temperature fluctuations are a ubiquitous part of life for all cells, and enteric bacteria often experience large temperature changes as they enter and exit hosts. While the transcriptional programs that respond to extreme temperatures (cold and heat shock) have been studied extensively, how cellular physiology responds to a temperature shift remains largely mysterious. We developed a device that allows us to track the growth of single cells during rapid temperature shifts. We show that instantaneous growth rate decreases upon a temperature downshift in a manner in quantiative agreement with Arrhenius kinetics. By contrast, upon a temperature upshift, growth rate increases slowly, over more than a generation. We show that these growth rate dynamics are a function of the growth rate at the final temperature, and that the normalized dynamics are conserved across temperature shifts and media. We demonstrate that the shift is linked mechanistically to both membrane and ribosomal synthesis, and provide a framework for understanding temperature shifts broadly across bacteria.