Engineered Corynebacterium diphtheriae for High-Yield CRM197 Production
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Solution Overview
Problem
Current methods for producing CRM 197 with Corynebacterium diphtheriae strain face challenges in achieving high yields, and existing processes are sensitive to process components and parameters, limiting commercial realization.
Innovation Solution
An improved method involving an engineered Corynebacterium diphtheriae strain with an increased copy number of the CRM 197 gene, grown in a fermentation medium containing more than 10 amino acids and supplemented with nutrients based on a metabolic flux model, which is free of animal-derived components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional Corynebacterium diphtheriae strains are used for CRM 197 production, then the production process is simpler, but the yield is low and commercial realization is limited
Solution Approach 1:
The patent applies parameter changes by modifying the gene copy number parameter in the Corynebacterium diphtheriae strain. By increasing the copy number of the tox gene from the native single copy to multiple copies (achieved through integration of phage β carrying the tox gene), the production yield of CRM 197 is significantly enhanced while maintaining the biological system's natural expression mechanisms
Solution Approach 2:
The patent employs the copying principle by replicating the tox gene multiple times within the bacterial genome through phage-mediated integration. The phage β carries the tox gene and integrates into the bacterial chromosome, creating multiple functional copies of the gene that are then transcribed and translated to produce higher levels of CRM 197 toxin
2Reliability
If existing production methods are used, then the process is easier to implement, but the process is highly sensitive to components and parameters
Solution Approach 1:
The engineered strain with increased gene copy number exhibits self-service characteristics by autonomously maintaining high production levels without requiring complex external control mechanisms. The multiple gene copies ensure that the bacteria can sustain high CRM 197 production rates even with variations in fermentation conditions, reducing the need for precise parameter control
Solution Approach 2:
The patent applies beforehand cushioning by creating a strain with built-in genetic redundancy through multiple tox gene copies. This genetic cushioning provides a buffer against process variations, ensuring that production remains stable even when fermentation parameters fluctuate, thereby reducing process sensitivity before problems occur
3Productivity
If traditional fermentation media are used, then the formulation is simpler, but the production yield does not exceed 150 mg/L
Solution Approach 1:
The patent applies parameter changes by optimizing the fermentation media composition with specific amino acids and nutrients that match the metabolic requirements of the engineered strain. The media contains elevated levels of amino acids such as tryptophan, yeast extract, and other nitrogen sources that support the high metabolic flux required for exceeding 150 mg/L CRM 197 production
Solution Approach 2:
The fermentation media employs a composite formulation combining multiple nutrient sources including yeast extract, peptone, amino acids, and trace elements. This composite media provides a synergistic effect where different components work together to support the high-density growth and high-level toxin production of the engineered Corynebacterium diphtheriae strain
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
This approach results in high-yield production of CRM 197, exceeding 150 mg/L, making it suitable for manufacturing conjugate vaccines while being cost-effective and stable across varying process conditions.
Implementation Method 1
growing the strain in a fermentation medium comprising one or more amino acids and is free of animal derived components
Data Source
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AI summary
The present invention provides an improved method for the production of CRM197 with high yield using engineered Corynebacterium diphtheria strain having increased copy number of CRM197 gene, wherein the method comprises growing the strain in a media free of animal derived components with one or more amino acids.