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A microbial strain with high yield of citric acid and method for producing citric acid by fermenting starch sugar

A technology of citric acid and bacterial strains, which is applied in the field of fermentation engineering, can solve the problems of unstable fermentation process, high energy consumption of stirring, and production of various miscellaneous acids, so as to reduce the energy consumption of aeration and stirring in the fermentation process, improve labor production efficiency, The effect of eliminating calcium sulfate waste residue

Active Publication Date: 2021-07-23
TIANJIN UNIV OF SCI & TECH
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AI Technical Summary

Problems solved by technology

[0006] (1) Use corn flour liquefaction liquid and co-ferment with some corn dregs, resulting in viscous fermented mash. At present, the total sugar of fermented mash is 17%-18%. If the total sugar of fermented mash is increased, the material liquid will become viscous If the temperature is further increased, the fermentation process requires too much energy for ventilation and stirring to achieve dissolved oxygen, and it is impossible to realize industrialization. In this way, the acid production of a single tank is limited to about 18%, which cannot be improved.
[0007] (2) Corn liquefaction liquid contains dextrin, oligosaccharides, oligosaccharides, maltose, isomaltose and other sugars, and contains different types of proteins, resulting in complex fermentation products and a variety of miscellaneous acids
[0008] (3) At present, the citric acid fermentation is over, and the Aspergillus niger mycelium balls in the fermented solid waste are mixed with the unusable corn dregs, which can only be dried and sent to the feed market, while the Aspergillus niger mycelium balls can be used to extract glucosamine and High value-added products such as sterols
[0009] (4) Since citric acid fermentation uses corn flour liquefied liquid as raw material, it is greatly affected by the quality of corn, such as the drying temperature of corn kernels, the place of origin of corn, the variety of corn, and the storage time of corn, etc. will all affect the carbon and nitrogen ratio in the corn liquefied liquid , causing the fermentation process to be unstable and affecting the production of citric acid
[0010] (5) At present, citric acid fermentation uses corn flour liquefaction liquid as raw material, which leads to difficulties in the measurement and control of dissolved oxygen and pH during the fermentation process, and the automatic control and continuous production of the fermentation process cannot be realized

Method used

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  • A microbial strain with high yield of citric acid and method for producing citric acid by fermenting starch sugar
  • A microbial strain with high yield of citric acid and method for producing citric acid by fermenting starch sugar
  • A microbial strain with high yield of citric acid and method for producing citric acid by fermenting starch sugar

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Experimental program
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Effect test

Embodiment 1

[0104] A method for constructing a fermentation strain of high-yielding citric acid microorganisms, the bacterial strain is to integrate multiple copies of the pyruvate carboxylase PC gene, pyruvate dehydrogenase PD gene and alternate oxidase Aox1 gene in the Aspergillus niger genome into the Aspergillus niger genome, using The recombinant Aspergillus niger strain ferments to produce citric acid; the expression of the pyruvate carboxylase PC gene is regulated by the Pgla promoter, and the pyruvate dehydrogenase PD gene and the alternate oxidase Aox1 gene are regulated by the PgpdA promoter.

Embodiment 2

[0106] Aspergillus niger Aspergillus niger The method for preparing citric acid from the 101-HAC11 preservation number CGMCC No.12480 strain:

[0107] (1) The fermentation strain used is Aspergillus niger strain Aspergillus niger 101-HAC11 preservation number CGMCCNo.12480, fermentation medium composition (g / L): glucose 200g, corn steep liquor 60 g / L, (NH 4 ) 2 SO 4 9g / L, MgSO 4 ·7H 2 O 0.05g / L, K 2 HPO , 4g / L, CuSO 4 0.8 mg / L ZnSO 4 0.02 g / L, CaCl 2 2.0 g / L, KCl 0.1 g / L, FeSO 4 0.34mg / L pH 5.0~5.5;

[0108] (2) Fermentation culture control conditions: 10% (v / v) inoculum amount is controlled, the seed age is controlled at 27 hours, the cultured seeds are inserted into the fermentation medium, the culture temperature is 30°C, and the fermentation ventilation volume is 0.1m 3 / m 3 .min, tank pressure 0.07 MPa, stirring speed 80 rpm, fermentation time 50 hours, sterile air was introduced during the fermentation process, the fermentation result of citric acid...

Embodiment 3

[0110] Aspergillus niger Aspergillus niger The method for preparing citric acid from the 101-HAC11 preservation number CGMCC No.12480 strain:

[0111] (1) The fermentation strain used is Aspergillus niger strain Aspergillus niger 101-HAC11 preservation number CGMCCNo.12480, fermentation medium composition (g / L): glucose 260g, corn steep liquor 80 g / L, (NH 4 ) 2 SO 4 11 g / L, MgSO 4 ·7H 2 O 0.15g / L, K 2 HPO , 6g / L, CuSO 4 0.8 mg / L ZnSO 4 0.02 g / L, CaCl 2 2.0 g / L, KCl0.1 g / L, FeSO 4 0.34mg / L pH 5.0~5.5;

[0112] (2) Fermentation culture control conditions: 15% (v / v) inoculum amount is controlled, the seed age is controlled at 27 hours, the cultured seeds are inserted into the fermentation medium, the culture temperature is 40°C, and the fermentation ventilation volume is 0.15m 3 / m 3 .min, tank pressure 0.12 MPa, stirring speed 100 rpm, fermentation time 60 hours, sterile air was introduced during the fermentation process, the fermentation result of citric a...

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Abstract

The invention discloses a microbial strain with high citric acid production and a method for fermenting starch saccharides to produce citric acid. At the same time, a medium formula and a fermentation process control technology for fermenting and producing citric acid with starch saccharide as a carbon source are also disclosed. The yield of citric acid produced by this strain can reach 166.8g / L. Compared with the prior art, the citric acid yield of the recombinant Aspergillus niger strain was 220.34 g / L, and the yield was increased by 32.10%. The method has the characteristics of rapidity, simple production process, no toxic residues in the product and high safety.

Description

technical field [0001] The invention belongs to the technical field of fermentation engineering, and relates to a method for producing citric acid by genetic engineering construction of Aspergillus niger strains with high fermentation strength and fermentation of starch and sugar. More specifically: a method for constructing a strain of Aspergillus niger with high fermentation intensity by genetic engineering, using starch sugar as a fermentation carbon source to add other organic and inorganic nitrogen sources, and a method for fermenting necessary metal salt components to produce citric acid. Background technique [0002] Citric acid (Citric acid) is a common organic acid, which is widely used in the food and beverage, pharmaceutical and chemical industries, and cosmetics industries. It is currently the organic acid with the largest demand in the world. [0003] In 1784, C.W. Scheele produced citric acid by calcium citrate precipitation. At the end of the 19th century, th...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C12N1/14C12P7/48C12R1/685
CPCC12P7/48C12N1/145C12R2001/685
Inventor 王德培张鸿飞秦郦张建华侯莉
Owner TIANJIN UNIV OF SCI & TECH
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