Recombinant Escherichia coli cultivation in a pressurized airlift bioreactor: assessment of the influence of temperature on oxygen transfer and uptake rates.

Temperature influences the rates of oxygen transfer (OTR) and uptake (q O2) in aerobic bioprocesses. Hence, joint analysis of q O2 and OTR at variable temperature is essential for bioprocess optimization and control. However, no such analyses have yet been reported for cultures of engineered E. coli producing recombinant proteins. E. coli cultivations at different temperatures (27-37 °C) were performed using a 5-L stirred tank bioreactor (STB), and a 5-L airlift bioreactor (ALB) was used to measure k L a and validate models of q O2 and OTR. The equations were then employed to evaluate the cultivation process in the ALB at different pressures (0.1-0.4 MPa) and temperatures (27-37 °C). The results showed that the positive effect of temperature on k L a was more pronounced than the negative influence on oxygen solubility, increasing the OTR in the ALB. The specific growth rate and temperature influenced q O2. In contrast to previous reports, the results showed that q O2 was not explicitly affected by recombinant protein synthesis. In addition, model predictions revealed that biomass concentration and productivity were greatly improved by pressurization of the system and use of a lower temperature.