Abstract

Using differential scanning calorimetry (DSC) and plate count (PC), growth of Escherichia coli was measured in four initial E. coli cell concentrations cultured in tryptic soy broth (TSB) at 35°C. The calorimeter measured the energy released and/or absorbed by E. coli cells during growth and expressed it as thermograms. The resulting thermograms accurately reflected cell growth and activity, and exhibited a close correlation with growth values recorded by PC. Heat release decreased notably in the final stage of the logarithmic growth phase, and no signal was generated once the stationary phase had begun. DSC accurately quantified growth in E. coli at different initial cell concentrations grown in TSB at 35°C. Depending on initial E. coli concentration, DSC detected growth starting after just a few minutes and up to five hours. The detection limit of calorimeter was 4.3 ± 0.4 log₁₀ CFU. DSC is an effective alternative method for measuring bacterial growth in TSB in real time. This is the first report of DSC use for measuring bacterial growth.

Key words: Differential scanning calorimetry (DSC), Escherichia coli, thermograms