Deregulating Escherichia coli Non-Growth Metabolism for High Productivity Chemical Synthesis without Carbon Loss to Growth

Substantial feedstock carbon (e.g. glucose) is converted to biomass during cell growth and is unavailable for product formation. Product synthesis is commonly growth-coupled, so a dilemma arises: continual growth production strategies are necessary for productivity, but these methods limit product yields and introduce processing/separation challenges. Ideally, carbon fed to non-growing cells would be solely and rapidly converted to product. However, E. coli cells entering stationary phase naturally (e.g. nutrient limitation) have drastically reduced overall metabolism.  Therefore, deregulating non-growth metabolism is essential to achieving efficient stationary phase chemical production.

We have evaluated the effect of metabolic gene deletions coupled with different nutrient limitations on central carbon metabolism.  We have identified promising non-growth conditions that generate E. coli with rapid glucose uptake rates and organic acid secretion profiles that would be ideal catalytically active, non-growing cells.  We will use metabolomics to identify regulatory bottlenecks in central carbon metabolism for future strategies to increase non-growth metabolism and divert carbon to valuable products.  This work should be applicable to improving the yields and productivities for the biosynthesis of a wide range of different chemicals and fuels.