Biotechnology Letters, Vol.34, No.6, 1123-1130, 2012
Improvement of d-lactate productivity in recombinant Escherichia coli by coupling production with growth
Coupling lactate fermentation with cell growth was investigated in shake-flask and bioreactor cultivation systems by increasing aeration to improve lactate productivity in Escherichia coli CICIM B0013-070 (ackA pta pps pflB dld poxB adhE frdA). In shake-flasks, cells reached 1 g dry wt/l then, cultivated at 100 rpm and 42A degrees C, achieved a twofold higher productivity of lactic acid compared to aerobic and O-2-limited two-phase fermentation. The cells in the bioreactor yielded an overall volumetric productivity of 5.5 g/l h and a yield of 86 g lactic acid/100 g glucose which were 66% higher and the same level compared to that of the aerobic and O-2-limited two-phase fermentation, respectively, using scaled-up conditions optimized from shake-flask experiments. These results have revealed an approach for improving production of fermentative products in E. coli.
Keywords:Aerobic and microaerobic two-phase fermentation;Escherichia coli;Growth coupling;D-Lactate production