(268d) Construction of a Synergetic Carbon Utilization Mechanism for Biosynthesis of Glucose-Based Compounds

Authors: 
Wu, Y., University of Georgia
Sun, X., Beijing University of Chemical Technology
Lin, Y., BiotecEra Inc.
Yuan, Q., Beijing University of Chemical Technology
Yan, Y., University of Georgia
Shen, X., University of Georgia
Yang, Y., University of Georgia
Jain, R., the University of Georgia
Conventional glucose utilization in Escherichia coli depends on glycolysis and pentose phosphate pathway to achieve catabolism. During this process, important catabolites such as acetyl-CoA and pyruvate contribute to cell growth and product synthesis. Unconventional utilization of glucose involves applying glucose as a C6 building block for production of glucose-based compounds. This non-catabolic usage of glucose conflicts with the catabolism which naturally leads to breakdown of glucose for biomass. To reserve glucose as a building block, blocking catabolic pathways leads to cell growth retardation and thus low productivity. To address this conflict, we introduce a second carbon source glycerol and design a synergetic carbon utilization mechanism to strengthen the connection between glucose and glycerol utilization. This new mechanism couples glucose uptake and catabolism of glycerol via the phosphoenolpyruvate (PEP) as a driving force for glucose transport. We validate the mechanism by introducing glucose-based trehalose biosynthesis model. Before introducing the mechanism, the titer of trehalose is only 1.22 g l-1 by consuming 7.39 g l-1 glucose in 48 h. After enhancement and optimization of the mechanism, the titer of trehalose is 3.67 g l-1 in 48 h by consuming 5.86 g l-1 glucose. The conversion efficiency of glucose to trehalose is improved from 0.16 g trehalose/g glucose to 0.63 g trehalose/g glucose. After extension of cultivation time to 96h, 8.20 g l-1 trehalose is produced in shake flasks. Remarkably, the conversion efficiency of glucose to trehalose reaches 0.86 g trehalose/g glucose, which represents 91% of the theoretic maximum. Hence, this synergetic carbon utilization mechanism, which is established and demonstrated for the first time, can be applied for non-catabolic use of glucose as C6 building block for synthesis of glucose-based compounds. It also provides a novel strategy for industrial microbial production of trehalose.