• Escherichia coli;
  • maintenance coefficient;
  • turnover

Abstract Maintenance coefficients and rates of turnover of cell protein, cell walls and total cell phosphate were determined during the growth of Escherichia coli ML308 in fed-batch culture at different temperatures. The apparent Arrhenius activation energies (Ea) calculated for maintenance coefficients at temperatures over 30°C were 212–515 kJ· mol−1, indicative of a process thermodynamically similar to denaturation. The corresponding Arrhenius values for turnover were of a different magnitude, 44–115 kJ mol−1, more typical of enzyme-catalysed reactions. Addition of 0.5 M NaCl had a minor effect on maintenance at both temperatures. Turnover of cell material and salt homeostasis were therefore concluded to be minor components of the maintenance requirement of E. coli.