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A citric acid-producing microorganism strain and a method for producing citric acid by fermenting starch sugar thereof

A technology of citric acid and microorganisms, applied in the field of fermentation engineering, can solve the problems of complex fermentation products, inability to upgrade, and the production of various miscellaneous acids, etc., and achieve the effects of simple production process, high conversion rate of sugar and acid, and high production efficiency

Active Publication Date: 2019-01-15
TIANJIN UNIVERSITY OF SCIENCE AND TECHNOLOGY
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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 citric acid-producing microorganism strain and a method for producing citric acid by fermenting starch sugar thereof
  • A citric acid-producing microorganism strain and a method for producing citric acid by fermenting starch sugar thereof
  • A citric acid-producing microorganism strain and a method for producing citric acid by fermenting starch sugar thereof

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Experimental program
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Embodiment 1

[0104] A method for constructing a fermentation strain of a high-yielding citric acid microorganism, the strain integrates multiple copies of the pyruvate carboxylase PC gene, the pyruvate dehydrogenase PD gene and the alternate oxidase Aox1 gene in the Aspergillus niger genome into the Aspergillus niger genome, using The recombinant Aspergillus niger strain produces citric acid by fermentation; 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 strain Aspergillus niger The method for preparing citric acid by strain 101-HAC11 preservation number CGMCC No.12480:

[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 0.34 mg / L pH 5.0~5.5;

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

Embodiment 3

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

[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 0.34 mg / L pH 5.0~5.5;

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

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Abstract

The invention discloses a citric acid-producing microorganism strain and a method for producing citric acid by fermenting starch sugar thereof. The strain is Aspergillus niger 101-HAC11 with an accession number of No. CGMCC No. 12480. At that same time, a culture medium formula and a fermentation process control process for producing citric acid by using starch sugar as carbon source are also disclosed. The yield of citric acid produced by the strain is 166.8 g / L. Compared with the prior art, the citric acid yield of the recombinant Aspergillus niger strain is 220.34 g / L, and the yield is increased by 32.10%. The method has the characteristics of high speed, simple production process, non-toxic residue and high safety.

Description

technical field [0001] The invention belongs to the technical field of fermentation engineering, and relates to a method for generating citric acid by using starch saccharide fermentation to construct a high fermentation strength Aspergillus niger strain by genetic engineering. More specifically, it is a method for constructing a high fermentation intensity of Aspergillus niger strain by genetic engineering, adding other organic and inorganic nitrogen sources and necessary metal salt components by using starch sugar as fermentation carbon source to produce citric acid by fermentation. Background technique [0002] Citric acid is a common organic acid that is widely used in food and beverage, pharmaceutical, chemical, and cosmetic industries, and is currently the most demanded organic acid in the world. [0003] In 1784, C.W. Scheler used calcium citrate precipitation to obtain citric acid. At the end of the 19th century, the biological fermentation method took shape. In 19...

Claims

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Application Information

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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 UNIVERSITY OF SCIENCE AND TECHNOLOGY
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