Microbial Strain Engineering for Stable Carbohydrate Production
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Solution Overview
Problem
Current metabolic engineering methods for producing carbohydrates in microbial organisms are inefficient, often resulting in unstable strains that lose productivity over time, and require complex fermentations and high organism familiarity.
Innovation Solution
Genetically engineered microbial organisms with reduced pyruvate formate lyase (PFL) and pyruvate dehydrogenase (PDH) activities, combined with adaptive evolution and increased mutation rates, are designed using genome-scale metabolic models to enhance carbohydrate production, particularly D-lactate production from glucose.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional metabolic engineering methods are used to produce carbohydrates in microbial organisms, then production capability is achieved, but strain stability deteriorates and productivity is lost over time
Solution Approach 1:
The patent segments the metabolic pathways by introducing multiple independent genetic modifications: knocking out PFL (pyruvate formate lyase), knocking out PDH (pyruvate dehydrogenase), and overexpressing LDH (lactate dehydrogenase). This segmentation allows each pathway component to be independently optimized, creating stable high-yield strains that maintain productivity without the instability associated with traditional single-gene approaches
Solution Approach 2:
The patent systematically changes key metabolic parameters by modifying enzyme activities: reducing PFL activity to prevent formate production, reducing PDH activity to prevent acetate production, and increasing LDH activity to enhance lactate production. These parameter changes are achieved through specific genetic modifications (deletions and overexpressions) that stabilize the metabolic flux toward desired carbohydrate products
2Productivity
If complex fermentations are used to achieve high carbohydrate production, then productivity increases, but process complexity increases
Solution Approach 1:
The patent extracts and eliminates unwanted metabolic byproducts by knocking out the PFL and PDH genes. This removal of harmful metabolic branches simplifies the fermentation process by preventing the formation of formate and acetate, allowing for simpler single-stage fermentations that achieve high productivity without complex multi-stage processes
Solution Approach 2:
The engineered microbial strain performs multiple functions simultaneously: it produces desired carbohydrate products (lactate, succinate, or ethanol), avoids producing harmful byproducts, and maintains stable growth characteristics. This multi-functionality is achieved through the coordinated genetic modifications that optimize the entire metabolic network, eliminating the need for separate process steps for byproduct management
3Manufacturing precision
If high organism familiarity is required for metabolic engineering, then production precision improves, but ease of manufacture deteriorates
Solution Approach 1:
The patent employs adaptive evolution to allow the microbial strain to self-optimize the metabolic pathway. By introducing the initial genetic modifications (PFL knockout, PDH knockout, LDH overexpression) and then allowing the strain to evolve under selective pressure, the system automatically refines the metabolic flux distribution. This self-service approach achieves high production precision without requiring extensive manual optimization expertise, making the process more accessible
Data Source
AI summary
Microbial strains with desirable carbohydrate productions characteristics and methods of making and using the same are provided herein.