Pantothenate Switch for Acetyl-CoA Fermentation Stability
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Solution Overview
Problem
The production of acetyl-CoA derived compounds in microbial fermentation is hindered by strain degeneration due to the metabolic burden of producing these compounds, leading to reduced stability and efficiency, especially in non-catabolic processes where energy and carbon inputs are high, resulting in decreased yields and productivity.
Innovation Solution
A fermentation process utilizing pantothenate as a non-genetic switch to control the production of acetyl-CoA derived compounds, where cells are cultured in a limiting amount of pantothenate during the 'build' stage to accumulate biomass and then switched to a non-limiting amount during the 'production' stage to enhance compound production, thereby reducing metabolic burden and increasing stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If acetyl-CoA derived compounds are produced continuously during fermentation, then productivity is maintained, but strain stability deteriorates due to metabolic burden and selective pressure favoring non-producing mutants
Solution Approach 1:
The patent implements periodic action by cycling between production and non-production phases. During non-production phases, pantothenate is limited to suppress acetyl-CoA derived compound synthesis, allowing strain stability to be maintained. During production phases, pantothenate is supplied to enable compound synthesis. This periodic switching resolves the contradiction by temporarily sacrificing productivity to preserve strain stability, then restoring productivity when stability is maintained.
Solution Approach 2:
The patent applies parameter changes by manipulating pantothenate concentration as a controllable parameter. By adjusting pantothenate levels between limiting and non-limiting conditions, the system switches between production and non-production states. This parameter control allows the metabolic burden to be modulated, thereby managing the trade-off between productivity and strain stability dynamically throughout the fermentation process.
2Productivity
If pantothenate is supplied at non-limiting levels throughout fermentation, then acetyl-CoA derived compound production is maximized, but metabolic burden increases leading to strain degeneration
Solution Approach 1:
The patent uses periodic action to alternate between periods of high compound production (non-limiting pantothenate) and periods of reduced production (limiting pantothenate). This allows the system to accumulate product during production phases while reducing metabolic burden during non-production phases, preventing strain degeneration that would occur with continuous non-limiting pantothenate supply.
Solution Approach 2:
The patent converts the harmful effect of metabolic burden into a beneficial control mechanism. By intentionally imposing pantothebate limitation during non-production phases, the system exploits the resulting reduced metabolic burden to maintain strain stability and prevent degeneration, thereby enabling sustained production capability over multiple fermentation cycles.
Data Source
AI summary
The present disclosure relates to the use of pantothenate compounds as a non-genetic switch for the production of heterologous acetyl-CoA derived (HACD) compounds in microbial host cells. The invention provides genetically modified microorganisms that are more stable when stored and initially cultured under reduced pantothenate concentrations, cell culture media having reduced concentrations of pantothenate compounds, and methods of producing HACD compounds using the cell culture media and the genetically engineered microorganisms of the invention.