Aspergillus niger mutant strain with high yield of glucoamylase and application thereof
A technology of Aspergillus niger strain and saccharification enzyme, which is applied in the directions of glycosylase, mutant preparation, enzyme, etc., can solve the problems of up-regulation, large gap, and low saccharification enzyme activity, and achieves strong specificity, efficient decomposition, and improved The effect of catalytic efficiency
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Embodiment 1
[0033] Mutagenesis and screening of the strain of Example 1
[0034] 1.1 Preparation of mutagen and antidote
[0035] Mutagen: in a biological safety cabinet, draw 0.5 mL of diethyl sulfate into a 50 mL centrifuge tube, add 2 mL of absolute ethanol, fully dissolve the diethyl sulfate, and then add sterile water to make the volume to 20 mL, put in Locked storage in a dedicated refrigerator.
[0036] Antidote: Use sterile water to prepare 25% sodium thiosulfate and store it in a brown bottle.
[0037] 1.2 Preparation of mutagenic strains
[0038] Solid slant activated strain: Take the cryopreserved glycerol tube seeds of Aspergillus niger origin strain CGMCC No. 10788, spread it on the seed slant medium, and cultivate at 34°C for 5 days.
[0039] Seed slant medium formula: sodium nitrate 0.43%, dipotassium hydrogen phosphate 0.2%, magnesium sulfate 0.06%, potassium chloride 0.05%, ferrous sulfate 0.01%, sucrose 2.1%, agar powder 1.5%, the rest is water, pH is natural .
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Embodiment 2
[0049] Example 2 Production of saccharification enzyme by liquid fermentation
[0050] Solid slant activated strain: Take the frozen glycerol tube seeds of Aspergillus niger mutant strain GA-9216, spread them on the seed slant medium, and cultivate at 35°C for 5 days.
[0051] Seed slant medium formula: sodium nitrate 0.2%, dipotassium hydrogen phosphate 0.2%, magnesium sulfate 0.06%, potassium chloride 0.03%, ferrous sulfate 0.01%, sucrose 2.1%, agar powder 2.5%, the rest is water, pH is natural .
[0052] Liquid seed culture: on the above-mentioned seed sloping medium, pick about 2cm*2cm of bacterial grass, insert into 200mL liquid seed medium (use 500mL conical flask), 35 ° C, shaker rotation speed 300 rev / min, cultivate to The solid content of bacteria in the seed solution was 40%.
[0053] Liquid seed medium: sodium nitrate 0.5%, dipotassium hydrogen phosphate 0.2%, magnesium sulfate 0.16%, potassium chloride 0.03%, ferrous sulfate 0.09%, sucrose 4.8%, the rest is water...
Embodiment 3
[0063] Embodiment 3 Enzyme activity assay method adopted in the present invention
[0064] 3.1 Determination method of glucoamylase
[0065] 1) Definition of enzyme activity: 1g solid enzyme powder (or 1ml liquid enzyme), under certain conditions (if not specified, the conditions are: 40°C, pH value 4.6), 1h decomposes soluble starch to produce 1mg glucose, which is 1 Enzyme activity unit, expressed in U / g (U / mL).
[0066] 2) Principle
[0067] Saccharification enzymes have the function of catalyzing the hydrolysis of starch, which can start from the non-reducing end of starch molecules and decompose α-1,4-glucosidic bonds to generate glucose. Glucose molecules contain aldehyde groups, which can be oxidized by sodium hypoiodate. After acidification of excess sodium hypoiodate, iodine is precipitated, and then titrated with sodium thiosulfate standard solution to calculate the enzyme activity.
[0068] 3) Reagents and solutions
[0069] ①Acetic acid-sodium acetate buffer so...
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