L-Glutamine Production via Coryneform Bacterium Gene Disruption
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Solution Overview
Problem
Current methods for producing L-glutamine using coryneform bacteria are inefficient, with low yields and high costs due to the high degradation activity of glutaminase enzymes, which hampers the accumulation of L-glutamine in fermentation processes.
Innovation Solution
A coryneform bacterium is modified to reduce intracellular glutaminase activity by disrupting the glutaminase gene, while enhancing glutamine synthetase activity through increased gene expression or copy number, thereby improving L-glutamine production yields and reducing by-product L-glutamic acid accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If glutaminase gene is disrupted to reduce degradation activity, then L-glutamine yield is improved, but L-glutamine producing ability must be maintained through enhanced synthetase activity
Solution Approach 1:
The harmful degradation function is extracted by disrupting the glutaminase gene, removing the ability to convert L-glutamine back to L-glutamic acid. This eliminates the reverse reaction that limits accumulation, allowing L-glutamine to build up without being consumed by degradation pathways.
Solution Approach 2:
The metabolic parameters are changed by simultaneously reducing glutaminase activity (degradation rate) and enhancing glutamine synthetase activity (synthesis rate). This dual parameter adjustment shifts the metabolic equilibrium toward L-glutamine accumulation, resolving the contradiction between yield improvement and production capability maintenance.
2Productivity
If glutaminase activity is reduced to prevent L-glutamine degradation, then fermentation efficiency is improved, but cost-effectiveness depends on maintaining high synthetase activity
Solution Approach 1:
The useful action of L-glutamine synthesis is made continuous and unidirectional by eliminating the degradation pathway. Once L-glutamine is synthesized by glutamine synthetase, it cannot be converted back to L-glutamic acid due to glutaminase gene disruption, ensuring continuous accumulation without metabolic cycling losses.
3Productivity
If promoter sequence is modified to enhance gene expression, then glutamine synthetase activity is improved, but L-glutamine degradation by glutaminase remains a limiting factor
Solution Approach 1:
The harmful degradation activity of glutaminase is converted into a benefit by complete gene disruption. Instead of merely reducing activity, the gene is knocked out entirely, transforming the degradation pathway from a harmful reverse reaction into a non-existent pathway, thereby converting potential L-glutamine loss into guaranteed accumulation.
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 modified bacterium achieves higher L-glutamine yields and reduced by-product formation, enhancing the efficiency and cost-effectiveness of L-glutamine production by maintaining low glutaminase activity and high glutamine synthetase activity, leading to improved fermentation outcomes.
Implementation Method 1
Glutamine (glutamine amidohydrolase) is known as an enzyme that degrades L-glutamine by hydrolysis.
Implementation Method 2
genes encoding glutamine synthetase... are known to be involved in glutamine biosynthesis
Data Source
AI summary
L-glutamine is produced by culturing a coryneform bacterium having L-glutamine-producing ability and modified so that intracellular glutaminase activity is reduced, and preferably also modified so that intracellular glutamine synthetase activity is enhanced. The method of production includes culturing the bacterium in a medium, followed by accumulation of L-glutamine in the medium and collecting the L-glutamine from the medium.