Recombinant Bacillus subtilis for Acetylglucosamine Fermentation
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Solution Overview
Problem
Current methods for producing acetylglucosamine using Bacillus subtilis face challenges such as central carbon metabolism overflow, excessive generation of NADH, and metabolic by-products like acetoin, which reduce yield and efficiency.
Innovation Solution
A recombinant strain of Bacillus subtilis is developed by integrating genes for pyruvate carboxylase, glyceraldehyde-3-phosphate ferredoxin dehydrogenase, isocitrate NAD+ dehydrogenase, malate quinone dehydrogenase, pyruvate ferredoxin oxidoreductase, and nitrogenase ferritin, which replace NADH-generating reactions in glycolysis and the tricarboxylic acid cycle, balancing reducing force and reducing by-product formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Bacillus subtilis is used to synthesize acetylglucosamine through fermentation, then acetylglucosamine can be produced as an alternative to chitin hydrolysis, but excessive NADH is generated which negatively affects the maximum theoretical yield
Solution Approach 1:
The patent extracts and removes the harmful NADH accumulation from the metabolic pathway by introducing alternative enzymes (ferredoxin-based dehydrogenases and oxidoreductases) that bypass the NADH-generating steps in glycolysis and TCA cycle, thereby eliminating the negative effect on acetylglucosamine yield
Solution Approach 2:
The patent changes the redox cofactor parameter in the metabolic pathway by replacing NAD+-dependent enzymes with ferredoxin-dependent enzymes, fundamentally altering the reducing force balance and enabling high-yield acetylglucosamine production without NADH accumulation
2Use of energy by moving object
If NADH is oxidized to produce ATP during fermentation, then energy is generated, but a large amount of oxygen is consumed and excessive bacterial cells are produced
Solution Approach 1:
The patent extracts the NADH oxidation step from the energy metabolism pathway by introducing ferredoxin-based enzymes that do not couple electron transport to ATP synthesis, thereby decoupling energy production from oxygen consumption and excessive cell growth
3Reliability
If Bacillus subtilis synthesizes acetylglucosamine, then the product is safe and suitable for medical and nutritional use, but central carbon metabolism overflow occurs resulting in massive synthesis of by-product acetoin
Solution Approach 1:
The patent converts the harmful metabolic overflow that produces acetoin by-product into a beneficial pathway by introducing ferredoxin-based enzymes that redirect carbon flux away from acetoin synthesis and toward acetylglucosamine production, maintaining product safety while eliminating by-products
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 significantly increases acetylglucosamine yield, eliminates central carbon metabolism overflow, and avoids the synthesis of by-products like acetoin, enhancing the economic efficiency of carbon atom utilization in acetylglucosamine production.
Implementation Method 1
The reaction formula for producing acetylglucosamine by fermentation of Bacillus subtilis is: 5/2glucose+ATP+5NAD++2NH3→GlcNAc+glutamate+ADP+SNADH+2CO2+phosphate
Data Source
AI summary
The invention relates to a recombinant strain of Bacillus subtilis, wherein pyruvate carboxylase BalpycA, glyceraldehyde-3-phosphate ferredoxin dehydrogenase gor, isocitrate NAD+ dehydrogenase icd, malate quinone dehydrogenase mqo, pyruvate ferredoxin oxidoreductase porAB and nitrogenase ferritin cyh are integrated and expressed in the recombinant strain. The invention also discloses use of the recombinant strain in fermentation production of acetylglucosamine. The recombinant Bacillus subtilis of the invention eliminates the central carbon metabolism overflow of the Bacillus subtilis and balances the intracellular reducing force, and the fermentation yield of acetylglucosamine is greatly improved.