Microbial Organisms With Succinyl-CoA Attenuation to Reduce CO2 Loss
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Solution Overview
Problem
Existing microbial organisms experience significant carbon loss through the oxidative tricarboxylic acid (TCA) cycle, leading to excess CO2 production, which hampers the efficiency of carbon flux and biosynthetic pathways.
Innovation Solution
Genetic modifications are introduced in microbial organisms to attenuate succinyl-CoA synthetase and succinyl-CoA converting enzymes, combined with increased expression of pyridine nucleotide transhydrogenase, to reduce carbon flux from succinyl-CoA to succinate, thereby minimizing CO2 production and enhancing the production of bioderived compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the oxidative TCA cycle is active in microbial organisms, then energy production through ATP generation is improved, but carbon loss as CO2 increases
Solution Approach 1:
The patent extracts and removes the harmful CO2-producing steps from the TCA cycle by attenuating succinyl-CoA synthetase and succinyl-CoA converting enzymes. This selectively eliminates the carbon-loss pathway while preserving the energy-generating portions of the cycle, allowing the organism to maintain ATP production without the penalty of excessive CO2 release.
Solution Approach 2:
The patent inverts the conventional TCA cycle operation by blocking the oxidative pathway that produces CO2 and redirecting flux through alternative non-oxidative routes. Instead of allowing succinyl-CoA to be converted to succinate through the traditional oxidative pathway (which releases CO2), the patent uses genetic attenuation to force carbon through different metabolic routes that conserve carbon while still generating energy.
2Productivity
If carbon flux through the TCA cycle is increased to produce more energy, then metabolic activity is improved, but CO2 production increases
Solution Approach 1:
The patent converts the harmful CO2-producing oxidative reactions into beneficial non-oxidative pathways. By attenuating the enzymes responsible for oxidative decarboxylation, the patent redirects carbon flux toward biosynthetic pathways that produce valuable compounds (such as 4-hydroxybutyrate and other bioderived compounds) while eliminating the harmful CO2 byproduct. The metabolic activity is maintained or enhanced through these alternative routes.
3Reliability
If succinyl-CoA synthetase activity is maintained for TCA cycle function, then cycle operation is improved, but carbon flux to succinate increases causing CO2 loss
Solution Approach 1:
The patent applies partial attenuation of succinyl-CoA synthetase and succinyl-CoA converting enzymes rather than complete inhibition. This partial action allows sufficient enzyme activity to maintain TCA cycle function and energy production, while reducing the excessive carbon flux to succinate that leads to CO2 loss. The attenuation level is optimized to balance cycle functionality with carbon conservation.
Data Source
AI summary
The invention is directed to a non-naturally occurring microbial organism comprising a first attenuation of a succinyl-CoA synthetase or transferase and at least a second attenuation of a succinyl-CoA converting enzyme or a gene encoding a succinate producing enzyme within a multi-step pathway having a net conversion of succinyl-CoA to succinate.