Before the start of autoclaving of the broth for any cultivation experiment, it is essential to calibrate the pH probe (as described above). Thereafter the set point (say 5) and p-band (1.0) is entered on the controller. This essentially means that now the pH controller will control the pH value in the range 4.0 to 6.0 For example if the measured pH value in the bioreactor is 4.5 then the controller will trigger alkali addition to the reactor to bring the measured value to 5.0 and similarly if the pH value is 5.5 it activates the acid pump to bring down the pH value to the set point. It is ensured that the p-band value is not kept too small or else it may lead to oscillation of the measured value around the set point similarly if the p-band is too large then it may give rise to offset between the measured value and set point of the controller. It may also be noted that the activation of acid/alkali pumps is done in a phased manner. For example if the controller is adding alkali to bring down the pH, the addition of the alkali is not done in one shot. In fact the alkali addition pump is kept on for some time and then it is off for some time. This ensures adequate mixing of first installment of acid/alkali in the broth before next installment is added. This strategy avoids over addition of acid/alkali for the pH control. The On/Off time of the controller has to be adjusted by separate experiments and will depend on the buffering capacity of the broth, concentration of acid/alkali etc. However it is absolutely essential to identify & maintain these setting before the start of the experiment in order to have efficient control action of the control which features stable quick control action with-out oscillations &/or off set around set point. There is another knob td in the control panel which provides the setting of the safety time during which if the control action is not achieved it raises the alarm for the operator.