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Method for improving whole-cell catalytic acid production by adjusting pH

A whole-cell, acid-oxidizing technology that is applied in the field of bioengineering to achieve high substrate conversion rates, increase acid yields, and reduce by-product yields

Pending Publication Date: 2021-07-02
NANJING FORESTRY UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Acidobacterium oxidans is the preferred strain for the production of gluconic acid due to its high acid production efficiency, but Acidobacterium oxidans utilizes acid during the fermentation process, so a large amount of by-product 2-ketoacids is accompanied by the conventional production process

Method used

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  • Method for improving whole-cell catalytic acid production by adjusting pH

Examples

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Embodiment 1

[0021] In a 3L bioreactor, add 1L of glucose solution, the initial glucose concentration is 100g / L, maintain the temperature of the reaction system at 30°C, the stirring speed at 450r / min and the ventilation rate at 3.0vvm, insert 2g of Gluconobacter oxidans cells (dry weight ) for whole-cell catalysis, and after the pH of the fermentation broth drops to 3.5, the pH control is started, and 50% sodium hydroxide is used to maintain the pH of the reaction system at 3.5. During the fermentation process, a semi-continuous feeding operation mode was adopted, and 50 g of glucose (based on the volume of the reaction solution) was added each time to ensure that the glucose concentration in the reaction system was not lower than 5 g / L. During the reaction process, 2 mL was sampled from the fermenter every hour, and the content of glucose, gluconic acid and 2-ketogluconic acid in the sample was analyzed by high-performance anion exchange chromatography. Chromatographic conditions: America...

Embodiment 2

[0023] In a 3L bioreactor, add 1L of glucose solution, the initial glucose concentration is 50g / L, maintain the temperature of the reaction system at 30°C, the stirring speed at 500r / min and the ventilation rate at 2.0vvm, insert 3g of Gluconobacter oxidans cells (dry weight ) for whole-cell catalysis, using 50% sodium hydroxide to maintain the pH of the reaction system at 5.5. During the fermentation process, a semi-continuous feeding operation method was adopted, and 50 g of glucose (based on the volume of the reaction solution) was added each time to control the concentration of glucose in the reaction system to not be lower than 5 g / L. During the reaction process, 2 mL was sampled from the fermenter every hour, and the content of glucose, gluconic acid and 2-ketogluconic acid in the sample was analyzed by high-performance anion exchange chromatography. Chromatographic conditions: American Thermo Fisher ICS5000 ion chromatography, equipped with CarboPac TM PA 10 (2mm×250mm)...

Embodiment 3

[0025] In a 3L bioreactor, add 1L of glucose solution, the initial glucose concentration is 50g / L, maintain the temperature of the reaction system at 30°C, the stirring speed at 500r / min and the ventilation rate at 2.0vvm, insert 5g of Gluconobacter oxidans cells (dry weight ) for whole-cell catalysis, using 50% sodium hydroxide to maintain the pH of the reaction system at 2.5. During the fermentation process, a semi-continuous feeding operation method was adopted, and 50 g of glucose (based on the volume of the reaction solution) was added each time to control the concentration of glucose in the reaction system to not be lower than 5 g / L. During the reaction process, 2 mL was sampled from the fermenter every hour, and the content of glucose, gluconic acid and 2-ketogluconic acid in the sample was analyzed by high-performance anion exchange chromatography. Chromatographic conditions: American Thermo Fisher ICS5000 ion chromatography, equipped with CarboPac TM PA 10 (2mm×250mm)...

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Abstract

The invention provides a method for improving whole-cell catalytic production of acid by adjusting pH, which comprises the following steps: (1) mixing thalli with glucose liquid, ventilating and stirring; and (2) adjusting the pH value, adding glucose, and fermenting. The thalli comprise acidobacter oxydans, and the concentration (dry weight) of the thalli is 0.5-10g / L; and the concentration of the glucose liquid is 50-500g / L. According to the method, acid is prepared through biotransformation of the acid oxidizing bacillus, compared with a chemical method, the substrate transformation rate is high, and compared with an enzyme method, the cost is lower; under the action of pH stress, the yield of acid is effectively improved, and the yield of by-products is reduced; in addition, the catalytic thallus cells can be recycled for multiple times for a new round of acid production, and the method has good practicability and industrialization prospects.

Description

technical field [0001] The invention belongs to the technical field of bioengineering, and in particular relates to a method for adjusting pH to improve catalytic production of acid by whole cells. Background technique [0002] Polyhydroxycaproic acid is a common polyhydroxycaproic acid that exists widely in nature and is widely used in construction, food, medicine and other fields. For example, it can be used as a retarding cement or concrete water reducer, as a sour taste regulator for food, etc. In addition, its calcium salt is often used as the first choice for calcium supplements. At present, the production methods of acid mainly include electrolytic oxidation method, biological enzyme method and microbial fermentation method. The by-products of the chemical method are difficult to control due to multiple reactions and are highly polluting; the enzymatic method has a high selectivity and a high yield of acid products, but the recovery of the enzyme is difficult and its...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C12P7/58C12R1/01
CPCC12P7/58
Inventor 赵江琳戴林周鑫徐勇黄天张晓彤
Owner NANJING FORESTRY UNIV