Application of bipolar electrodialysis to E.coli fermentation for simultaneous acetate removal and pH control

The application of bipolar electrodialysis (BPED) for the simultaneous removal of inhibitory acetate and pH control during E. coli fermentation was investigated. A two cell pair electrodialysis module, consisting of cation exchange, anion exchange and bipolar membranes with working area of 100 cm2 each, was integrated with a standard 7 l stirred tank bioreactor.

Results showed that BPED was beneficial in terms of in situ removal of inhibitory acetate and a reduction in the amount NH4OH used for pH control. In batch and fed-batch BPED fermentations, base additions were decreased by up to 50% in both cases compared to electrodialysis (ED) fermentations with pH controlled at 6.7 ± 0.1.

Consequently, the final biomass (34.2 g DCW l−1) and recombinant protein (5.5 g l−1) concentrations obtained were increased by up to 37 and 20%, respectively.