An advanced system for high-density E. coli fermentation

Eppendorf has demonstrated the use of the BioFlo 320 bioprocess control station to achieve E. coli cultivation. The company’s experiment saw the E. coli K-12 strain grown in a 1 L (working volume) stainless steel dish-bottom BioFlo 320 glass vessel.

The product has been developed for both microbial fermentation and cell culture applications. It features an industrial design, flexibility between autoclavable and single-use vessels, intelligent sensors, ethernet connectivity and an improved software package.

An optical sensor was chosen for dissolved oxygen (DO) control in the experiment, since the control station is compatible with multiple types of DO sensors. One of the advantages of the optical DO sensor is that it does not require the 6 h polarisation time of a traditional polarographic DO sensor, which reduces the turnaround time between fermentation runs.

The BioFlo 320 software offers a selection of automatic gassing control cascades that are dependent on the configuration of the unit. This particular experiment utilised the automatic gas mix and four thermal mass flow controllers (TMFCs) with a flow range of 0–20 SLPM. The DO setpoint was 30%.

Samples were taken periodically to monitor the cell growth (OD600 value), glucose concentration, wet cell weight (WCW) and dry cell weight (DCW). Feeding was initiated when the glucose concentration dropped below 2 g/L, which occurred at 5.25 h of cultivation. Both WCW and DCW increased proportionally with the increase in OD600 value, which reached 215.2 within 12 h.

The Eppendorf BioFlo 320 bioprocess control station was thus able to support high-density E. coli growth using a fed-batch fermentation method.