Figure 5

Fermentation graphs of a repeated batch cultivations of Chondromyces strain SBCm007. CO₂ was kept at 0.3, 0.6 and 1.4% and pO₂ at 20%. Both concentrations were maintained with the method described in this study. The steps in CO₂ concentration indicate medium exchanges. The graph illustrates the calculated value OCQ, pO2, stirrer speed, flow, concentration of CO₂ in the gas phase, and airflow (overall amount of air pumped through the bioreactor). The reduced flow rate at higher CO₂ values led to ‘flow pulses’ because flow rate dropped below 0.2 l/min, the limit of the mass-flow controller which did not affect functionality. The belly of the OCQ value in the first batch, which was expected to be constant, is due to a lower operational limit of the stirrer and illustrates the sensitivity of the calculated OCQ value because deviations in the CO₂ concentration caused by this are not yet obvious but already indicated by the OCQ.