Calorimetric Study of Escherichia coli Growth on Bouillon Medium

Heat evolution during the growth of Escherichia coli in a stationary culture on bouillon medium was continuously monitored with a conduction-type batch calorimeter at different pHs and temperatures. The growth thermograms were found to be reproducible within percent errors of ±2.1%, ±0.8% and ±1.5% for the peak time of a thermogram, the peak height and the total heat evolution, respectively. The mean heat evolution for the formation of a unit E. coli cell was co = (1.69 ±0.08) X 10—8 J cell— 1 at pH 6.2 and 37°C. The mean heat evolution rate per unit cell during growth was