Methanol-Engineered Microbial Organisms for Higher BDO Yield
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Solution Overview
Problem
Existing methods for producing 1,4-butanediol (BDO) are limited by insufficient reducing equivalents, leading to suboptimal yields due to loss of reducing equivalents to byproducts, particularly when using carbohydrate feedstocks.
Innovation Solution
Engineering non-naturally occurring microbial organisms with enhanced methanol metabolic pathways, including specific enzymes, to generate and utilize reducing equivalents for BDO production, combined with BDO pathways and formaldehyde assimilation pathways, and disrupting genes involved in ethanol, glycerol, acetate, lactate, formate, CO2, and amino acid production to enhance yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If carbohydrate feedstocks are used for BDO production, then the production process is simple and cost-effective, but the yield is suboptimal due to loss of reducing equivalents to byproducts
Solution Approach 1:
The patent changes the chemical parameters of the feedstock from carbohydrates to methanol, which fundamentally alters the metabolic pathway and reducing equivalent availability. Methanol metabolism generates excess reducing equivalents that can be directed to BDO production, resolving the yield limitation while maintaining process simplicity
Solution Approach 2:
The patent introduces methanol as an intermediary substrate that serves as a better source of reducing equivalents. The engineered methanol metabolic pathway acts as a mediator to generate the necessary reducing power (NADH, NADPH) for high-yield BDO production without the byproduct losses associated with carbohydrate fermentation
2Productivity
If methanol metabolic pathway is engineered to enhance reducing equivalents, then BDO yield increases, but the organism complexity increases
Solution Approach 1:
The patent segments the methanol metabolic pathway into distinct enzymatic steps (methanol dehydrogenase, formaldehyde dehydrogenase, formate dehydrogenase) that can be independently engineered and optimized. This modular approach allows precise control over reducing equivalent generation while managing genetic complexity through systematic pathway construction
Solution Approach 2:
The engineered methanol metabolic pathway serves multiple functions: it provides carbon for BDO production, generates reducing equivalents (NADH, NADPH), and can be integrated with existing central metabolism. This multi-functionality justifies the increased genetic complexity by delivering multiple benefits simultaneously
3Productivity
If genes for byproduct production are disrupted, then reducing equivalents are preserved for BDO, but the organism's metabolic flexibility decreases
Solution Approach 1:
The patent converts the harmful loss of reducing equivalents to byproducts into a benefit by disrupting the pathways that produce these byproducts. Gene disruptions in ethanol, glycerol, acetate, lactate, and formate production pathways prevent reducing equivalent waste, redirecting them exclusively to BDO synthesis and thereby increasing yield
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The approach significantly increases the yield of BDO by optimizing the availability of reducing equivalents, allowing for higher production of BDO and other valuable compounds like 4-hydroxybutyrate, leveraging methanol as a cost-effective feedstock.
Implementation Method 1
at least one exogenous nucleic acid encoding a methanol dehydrogenase expressed in a sufficient amount to enhance the availability of reducing equivalents in the presence of methanol and/or expressed in a sufficient amount to convert methanol to formaldehyde
Implementation Method 2
a formaldehyde dehydrogenase
Implementation Method 3
a formate dehydrogenase
Data Source
AI summary
Provided herein is a non-naturally occurring microbial organism having a methanol metabolic pathway that can enhance the availability of reducing equivalents in the presence of methanol. Such reducing equivalents can be used to increase the product yield of organic compounds produced by the microbial organism, such as 1,4-butanediol (BDO). Also provided herein are methods for using such an organism to produce BDO.