GlcN6P Responsive Element for N-acetylglucosamine Synthesis
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Solution Overview
Problem
Existing methods for producing N-acetylglucosamine using recombinant Bacillus subtilis are complicated and costly due to the need for xylose as a carbon source and the addition of an inducing agent, which increases production costs and operational complexity.
Innovation Solution
A method is developed to use a GlcN6P responsive element to control the expression of glucosamine 6-phosphate N-acetyltransferase GNA1 and dynamically regulate the N-acetylglucosamine synthesis pathway, allowing for efficient synthesis using glucose as the sole carbon source without the need for xylose or an inducing agent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If xylose is used as a carbon source to weaken competitive pathways, then N-acetylglucosamine synthesis efficiency is improved, but production cost increases and operations become complicated
Solution Approach 1:
The patent implements self-service by enabling the bacterial strain to automatically regulate its own metabolic pathways in response to glucose availability. The engineered strain uses endogenous regulatory mechanisms to dynamically adjust the expression of genes involved in competitive pathways (glycolysis, pentose phosphate pathway, peptidoglycan synthesis) without requiring external inducing agents like xylose. This eliminates the need for manual intervention and complex operational procedures while maintaining high synthesis efficiency.
Solution Approach 2:
The patent applies parameter changes by modifying the metabolic state of the bacterial strain through genetic engineering. Specifically, it alters the expression levels of key enzymes in competitive pathways by introducing regulatory elements that respond to glucose metabolism intermediates. This dynamic parameter adjustment allows the system to automatically shift metabolic flux toward N-acetylglucosamine synthesis when glucose is the sole carbon source, achieving high efficiency without external inducers.
2Productivity
If xylose is used as a carbon source to weaken competitive pathways, then N-acetylglucosamine synthesis efficiency is improved, but production cost increases
Solution Approach 1:
The patent employs cheap short-living objects by replacing the expensive xylose inducer with inexpensive glucose, which is a common and economical carbon source. The engineered strain uses transient metabolic intermediates from glucose metabolism to trigger the desired pathway suppression, eliminating the need for continuous addition of costly inducing agents throughout the fermentation process.
Solution Approach 2:
The system achieves self-service by utilizing the bacterial strain's own metabolic machinery to generate the regulatory signal. Glucose metabolism naturally produces intermediates that activate the engineered regulatory pathways, allowing the system to self-regulate without external input of expensive substances like xylose, thereby significantly reducing production costs.
3Productivity
If multiple competitive pathways are weakened to promote N-acetylglucosamine synthesis, then synthesis efficiency is improved, but metabolic network regulation complexity increases
Solution Approach 1:
The patent applies universality by designing a single regulatory mechanism that simultaneously controls multiple competitive pathways (glycolysis, pentose phosphate pathway, and peptidoglycan synthesis). The engineered strain uses a common regulatory element that responds to glucose metabolism and coordinately suppresses all three competing pathways, achieving multi-functionality through a unified control system rather than separate controls for each pathway.
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 method enables continuous and efficient synthesis of N-acetylglucosamine, achieving high yields of up to 131.6 g/L in a 15 L fermenter, while avoiding by-product accumulation and simplifying operational processes.
Implementation Method 1
The GlcN6P responsive element includes the transcription factor GamR of Bacillus subtilis and a promoter containing a GamR binding site
Implementation Method 2
using the GlcN6P responsive element to regulate a compound formed by binding the expressed dCas9 protein to three sgRNA expression fragments acting on zwf, pfkA and glmM genes, to dynamically weaken the glycolysis pathway, the pentose phosphate pathway and the peptidoglycan synthesis pathway
Implementation Method 3
controlling the expression of glucosamine 6-phosphate N-acetyltransferase GNA1 by using a GlcN6P responsive element to dynamically regulate the N-acetylglucosamine synthesis pathway
Data Source
AI summary
The present invention provides a method for promoting N-acetylglucosamine synthesis by using the GlcN6P responsive element. In the present invention, Bacillus subtilis BSGNY-Pveg-glmS-P43-GNA1 is used as a starting strain, in which a CRISPRi system regulated by GlcN6P responsive element is integrated into the genome to dynamically weaken the N-acetylglucosamine synthesis competitive pathway; a GlcN6P responsive promoter is used to regulate the expression of GNA1 on the plasmid to dynamically regulate the N-acetylglucosamine synthesis pathway; and the key gene alsSD involved in the acetoin synthesis pathway is knocked out. During fed-batch fermentation with this strain in a 15 L fermenter, the production of N-acetylglucosamine reaches 131.6 g/L and no by-product acetoin is accumulated, which lays a foundation for the production of GlcNAc by industrial fermentation.