2.5. Analysis of power-time curves
The curves that are the output of microcalorimeter are called calorimetric thermograms or poweretime curves. Poweretime curve is a derivation of a standard bacterial growth curve in batch cultures. Calorimetric poweretime curves (see Fig. 1) could be divided into three growth phases (Fig. 1a) essentially the same way as the bacterial growth curves, but with some reservations. Firstly goes the lag-phase, which determines the adjustment period during which bacterial cells adapt to the new environment and start to divide exponentially. The length of the lag-phase was determined as shown on Fig. 1b. The calculation procedure was practically the same as in Swinnen et al. (2004). However, it should be emphasized that in calorimetric experiments length of the lagphase is defined besides physiology of the cell also by the level of sensitivity of a microcalorimeter. Sensitivity of TAM III in registration of heat is 7*104 J (0.5 mW), which means that only a certain number of growing (metabolizing) bacteria can produce heat fluxes surpassing the sensitivity threshold of the instrument. It means that the lag-phase duration measured on the basis of calorimetric curves should be calculated taking into account the time when the heat produced by the growing bacterial population exceeds the