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