Sludge Substrate Fermentation for γ-PGA Production
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Solution Overview
Problem
Current methods for producing γ-polyglutamic acid are costly due to expensive fermentation media and inefficient purification processes, which include high inorganic salt impurities and complex sludge substrates, making the product less competitive in the market.
Innovation Solution
A method involving sludge substrate fermentation, including pretreatment of sludge, activation and domestication of Bacillus strains, secondary metabolic fermentation, acidification, centrifugation, and purification using organic solvents with polar repulsion to produce high-purity γ-polyglutamic acid, reducing inorganic salt impurities and operational costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional fermentation medium (natto, dipotassium hydrogen phosphate) is used, then γ-polyglutamic acid can be produced, but the fermentation medium cost becomes high
Solution Approach 1:
The patent changes the composition parameters of the fermentation medium by replacing traditional expensive components (natto, dipotassium hydrogen phosphate) with sludge substrate containing glutamic acid, thereby reducing medium cost while maintaining production capability
Solution Approach 2:
The patent uses sludge, an abundant and inexpensive organic waste material, as the fermentation substrate instead of expensive traditional media components, achieving cost reduction while providing sufficient nutrients for γ-polyglutamic acid production
2Manufacturing precision
If traditional purification methods are used, then γ-polyglutamic acid can be purified, but inorganic salt impurities increase and purification cost becomes high
Solution Approach 1:
The patent utilizes phase transition of organic solvents (ethanol, acetone, or butanol) from liquid to solid through freezing, enabling separation and removal of inorganic salt impurities while purifying γ-polyglutamic acid. The frozen solvent forms solid crystals that can be easily separated from the purified product
Solution Approach 2:
The patent introduces organic solvents (ethanol, acetone, or butanol) as intermediary substances to facilitate purification. These solvents precipitate γ-polyglutamic acid while leaving inorganic salts in solution, enabling effective separation without introducing additional harmful impurities
3Ease of manufacture
If sludge substrate is used for fermentation, then production cost decreases, but the complex composition of sludge makes it difficult to ensure efficient γ-PGA production
Solution Approach 1:
The patent performs preliminary treatment of sludge substrate including adjustment of physical and chemical parameters (pH, moisture content, particle size) before fermentation. This preliminary preparation ensures the sludge provides optimal nutrients for Bacillus subtilis, guaranteeing reliable γ-polyglutamic acid production while maintaining low cost
Solution Approach 2:
The patent implements feedback control by monitoring fermentation process parameters and adjusting conditions to optimize γ-polyglutamic acid production from sludge substrate. This ensures consistent high efficiency despite the complex and variable composition of sludge material
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 significantly reduces production costs, simplifies operations, and achieves high-purity γ-polyglutamic acid production using abundant organic waste as a substrate, with a cost per kilogram of 60-100 yuan compared to the market price of over 150 yuan/kg, while addressing the challenges of inorganic salt impurities and substrate costs.
Implementation Method 1
inoculating the activated and domesticated Bacillus obtained from step C into the supernatant of step B, performing a proper ventilation to ensure sufficient oxygen supply, and adjusting fermentation conditions to obtain a fermentation product containing γ-polyglutamic acid
Implementation Method 2
Synthesis of γ-Polyglutamic Acid by Secondary Metabolism: D. secondary metabolic fermentation
Implementation Method 3
F. precipitation based on polar repulsion: restoring the pH level of the supernatant obtained in step E and using organic solvents with repellent polar to precipitate the γ-polyglutamic acid
Implementation Method 4
G. purification and impurity removal: dissolving the precipitation obtained in step F in deionized water to obtain a γ-polyglutamic acid solution, dialyzing at 4° C. for 6 h-24 h, removing small molecular organic substances and inorganic salt impurities by a dialysis bag with a molecular weight cut-off of 8-12 kDa
Implementation Method 5
H. drying: performing a vacuum freeze-drying on the dialysate obtained in G for 24-72 h to obtain pure γ-polyglutamic acid
Implementation Method 6
performing a vacuum freeze-drying
Data Source
AI summary
A regulation method for preparing γ-polyglutamic acid by sludge substrate fermentation includes: 1) extraction of glutamic acid from sludge protein (high pressure hydrothermal treatment, gravity pressure filtration treatment), 2) secondary metabolic synthesis of γ-polyglutamic acid (activation of domesticated strains and secondary metabolic fermentation strains); and 3) preparation of pure γ-polyglutamic acid (acidification, centrifugation, filtration, precipitation based on polar repulsion, purification, impurity removal and drying). The present invention realizes a recycling of high-value carbon and nitrogen sources of sludge without secondary pollution, and has advantages of simplified operation, good feasibility, and low preparation cost. The synthesized γ-polyglutamic acid has high economic value and broad application prospect.