화학공학소재연구정보센터
International Journal of Hydrogen Energy, Vol.45, No.9, 5687-5696, 2020
Improvement of hydrogen production by metabolic engineering of Escherichia coli: Modification on both the PTS system and central carbon metabolism
Lignocellulosic-based production of bio-hydrogen (H-2) by Escherichia coli requires efficient consumption of pentoses and hexoses. However, carbon catabolite repression (CCR) causes sequential utilization of carbohydrates and in some cases null consumption of less preferred carbohydrates, such as xylose. In this work, we evaluated the effect of elimination of the phosphotransferase system (PTS), responsible for CCR in strain E. coli WDH (Delta hycA) on H-2 production using mixtures of glucose-xylose as carbon source. Elimination of ptsG gene (glucose permease-enzyme IIB), allowed simultaneous consumption of glucose and xylose, and improved H-2 production 1.2-times with respect to the parenteral strain. Whereas, elimination of ptsG gene in combination with deletion of IdhA (D-lactate dehydrogenase) and/or frdD (fumarate reductase) genes, improved H-2 production 2.5-times with a H-2 yield of 0.27 mol.C-mol(-1), using mixtures of glucose/xylose or wheat straw hydrolysate. Interestingly, besides the improvement on H-2 production, E. coli WDH-GFA (Delta hycA, Delta ptsG, Delta frdD, Delta ldhA) strain also produced ethanol as the main carbon by-product. These results show that elimination of ptsG, in combination with a modified central carbon metabolism improves the production of H-2. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.