Medium-dependent control of the bacterial growth rate

► Quantitative analysis of bacterial cell adjustments to up-shifts from poor to rich growth media. ► The bacterial growth rate is determined by the growth medium and is not an independent variable. ► The global regulator ppGpp is not the sole determinant of RNA/protein and DNA/protein ratios. ► Just after a medium up-shift, the rate of rRNA synthesis per rRNA equals the post-shift growth rate. ► Pre-inoculation growth conditions affect the exponential growth rate of post-shift cultures.