Using the pyruvate production strain Escherichia coli YYC202 ldhA::Kan different process alternatives are studied with the aim of preventing potential product inhibition by appropriate product separation. This strain is completely blocked in its ability to convert pyruvate into acetyl-CoA or acetate, resulting in acetate auxotrophy during growth in glucose minimal medium. Continuous experiments with cell retention, repetitive fed-batch, and an in situ product recovery (ISPR) process with fully integrated electrodialysis were tested. Although the continuous approach achieved a high volumetric productivity (QP) of 110 g L(-1) d(-1), this approach was not pursued because of long-term production strain instabilities. The highest pyruvate/glucose molar yield of up to 1.78 mol mol(-1) together with high QP 145 g L(-1) d(-1) and high pyruvate titers was achieved by the repetitive fed-batch approach. To separate pyruvate from fermentation broth a fully integrated continuous process was developed. In this process electrodialysis was used as a separation unit. Under optimum conditions a (calculated) final pyruvate titer of >900 mmol L(-1) (79 g L(-1)) was achieved.
Fed‐batch fermentation was applied to the production of pyruvate by using a recombinant Escherichia coli YYC202 strain. This strain is completely blocked in its ability to convert pyruvate into acetyl‐CoA or acetate, resulting in acetate auxotrophy during growth in glucose minimal medium. By controlling acetate and glucose feed rate, a series of lab‐scale fed‐batch experiments were performed at pH 7 and 37 °C. CO2 production rate (CTR) was used for on‐line regulation of the acetate feed rate. The correlation between CTR and acetate consumption rate (ACR) was determined experimentally. At optimal process conditions a final pyruvate concentration higher than 62 g/L, a space‐time yield of up to 42 g/L/d and pyruvate/glucose molar yield of 1.11 mol/mol were achieved. Experimental evidence was gathered that pyruvate export is active.
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