As seen from Fig. 2 maximal growth rates mmax are slightly decreasing from 0.56 W/h at inoculation rate 106 cfu/mL to 0.44 W/h at inoculation rate 102 cfu/mL. The maximumvalues of the observed growth rates of the bacteria in the exponential phase in case of high inoculation rates is coinciding with the mmax value measured for these bacteria in liquid cultures using other (conventional) methods.Decrease of the mmax values at lower inoculations rates could beexplained by the fact that in these cases we observe the growth of the cultures with the same number of cells as in case of high inoculation rates, however, as the cells have been grown from the initial low numbers, they have synthesized growth inhibiting lactate to the media, which had led to the inhibition of the growth rate. Besides mmax, the exponential growth phase is characterized by the amount of heat produced by the growing cells that is proportional to the number of bacteria grown. Heat yield coefficient YQ (J/cfu) that links the amount of heat produced per one bacterium synthesized was calculated on the basis of the results obtained from the experiments of bacterial growth in liquid phase in case of different glucose concentrations (2, 5, 10, 20 g/L) and inoculation rates (102e106 cfu/mL). The plate count was carried out
at the end of exponential growth phase and heat amounts produced were calculated from the power-time curves. The value of YQ (J/cfu) was determined to be YQ ¼ (2.58þ/0.44)*109 J/cfu. The
YQ value is used for the description of exponential phase of the liquid culture also in the case of solid-state growth. It was observed that the heat produced during the exponential
growth phase in liquid cultures was practically the same at a value of 0.80þ/0.05 J/mL which corresponds to 3.10*108 cells in case of different inoculation rates ranging from 102e106 cfu/mL and different glucose concentrations (2, 10 and 20 g/L). This fact means that during the exponential growth phase the same number of bacteria was produced independently from the size of inoculum which means that there was no substrate (glucose) limitations in the exponential phase and the termination of the exponential growth was caused by accumulating lactate either through direct inhibition or more probably through the change of the pH of the media. Essentially the same conclusion was drawn from the HPLC and pH measurements e data not shown.
As seen from Fig. 2 maximal growth rates mmax are slightly decreasing from 0.56 W/h at inoculation rate 106 cfu/mL to 0.44 W/h at inoculation rate 102 cfu/mL. The maximumvalues of the observed growth rates of the bacteria in the exponential phase in case of high inoculation rates is coinciding with the mmax value measured for these bacteria in liquid cultures using other (conventional) methods.Decrease of the mmax values at lower inoculations rates could beexplained by the fact that in these cases we observe the growth of the cultures with the same number of cells as in case of high inoculation rates, however, as the cells have been grown from the initial low numbers, they have synthesized growth inhibiting lactate to the media, which had led to the inhibition of the growth rate. Besides mmax, the exponential growth phase is characterized by the amount of heat produced by the growing cells that is proportional to the number of bacteria grown. Heat yield coefficient YQ (J/cfu) that links the amount of heat produced per one bacterium synthesized was calculated on the basis of the results obtained from the experiments of bacterial growth in liquid phase in case of different glucose concentrations (2, 5, 10, 20 g/L) and inoculation rates (102e106 cfu/mL). The plate count was carried out
at the end of exponential growth phase and heat amounts produced were calculated from the power-time curves. The value of YQ (J/cfu) was determined to be YQ ¼ (2.58þ/0.44)*109 J/cfu. The
YQ value is used for the description of exponential phase of the liquid culture also in the case of solid-state growth. It was observed that the heat produced during the exponential
growth phase in liquid cultures was practically the same at a value of 0.80þ/0.05 J/mL which corresponds to 3.10*108 cells in case of different inoculation rates ranging from 102e106 cfu/mL and different glucose concentrations (2, 10 and 20 g/L). This fact means that during the exponential growth phase the same number of bacteria was produced independently from the size of inoculum which means that there was no substrate (glucose) limitations in the exponential phase and the termination of the exponential growth was caused by accumulating lactate either through direct inhibition or more probably through the change of the pH of the media. Essentially the same conclusion was drawn from the HPLC and pH measurements e data not shown.
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