A method for continuous fermentation production of propionic acid

Abstract

The application belongs to the technical field of microbial fermentation, and particularly discloses a method for continuously producing propionic acid. The method inoculates the fermentation liquor of a previous batch into the fermentation medium of a next batch, realizes the recycling of propionic acid bacillus, reduces the production cost, and improves the production efficiency. After the two batches are co-fermented for a certain time, the fermentation liquor with higher activity of the next batch is inoculated into the fermentation liquor of the previous batch, the problem of low activity and slow growth of the bacteria in the late fermentation of the previous batch is solved, the fermentation period is greatly shortened, the problem of low propionic acid yield caused by feedback inhibition of fermentation products is solved, and the propionic acid yield and production rate are significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of microbial fermentation technology, specifically relating to a method for continuous fermentation to produce propionic acid. Background Technology

[0002] Propionic acid, also known as colloidal acid, is a three-carbon carboxylic acid, a short-chain saturated fatty acid, with the chemical formula CH3CH2COOH. Pure propionic acid is a colorless, corrosive liquid with a pungent odor.

[0003] Propionic acid is mainly used as a food preservative and mold inhibitor. It can also be used as an inhibitor of viscous substances in beer and other products, a solvent for nitrocellulose, and a plasticizer. Furthermore, it is used in the preparation of nickel plating solutions, the formulation of food flavorings, and the manufacture of pharmaceuticals, pesticides, and mold inhibitors. Domestically, propionic acid consumption is structured as follows: 60% for grain and feed preservatives and food preservatives; 20% as a raw material for herbicides such as propargite and haloxyfop-R-methyl; and 20% for the production of flavorings and fragrances. Currently, domestic propionic acid production is far from meeting actual demand, necessitating significant reliance on imports.

[0004] The main methods for producing propionic acid are chemical synthesis and microbial fermentation. Chemical synthesis uses petroleum and other chemical products as raw materials, synthesizing propionic acid under heating and pressure conditions using a catalyst. This method is also the primary method for industrial-scale propionic acid production. Microbial fermentation produces propionic acid by utilizing microorganisms to metabolize in a culture medium under normal temperature and pressure conditions.

[0005] Microbial fermentation for propionic acid production is milder than chemical synthesis, produces fewer byproducts, and reduces reliance on petrochemical raw materials. However, most current microbial fermentation methods suffer from long fermentation cycles and low production rates. Chinese patent CN109295118B discloses a cyclic fermentation method for Propionibacterium acnes, comprising the following steps: (1) cultured Propionibacterium acnes cells are fermented in a fermenter containing culture medium to obtain fermentation broth; (2) the fermentation broth from step (1) is filtered through a ceramic membrane to obtain a clear fermentation broth containing propionic acid, and the concentrated broth containing Propionibacterium acnes cells is sent to the fermenter, where fresh culture medium is added for fermentation; (3) step (2) is repeated until the acid production rate decreases significantly, at which point the cycle is stopped; (4) steps (1)-(3) are repeated to begin a new round of cyclic fermentation of Propionibacterium acnes. This method uses a ceramic membrane to filter the cells, realizing the recycling of Propionibacterium acnes, shortening the cell culture cycle, reducing production costs to a certain extent, and improving production efficiency. However, this method still cannot effectively solve the problems of long fermentation cycles and low production rates for propionic acid. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method for continuous fermentation production of propionic acid, which mainly solves the problems of long fermentation cycles, low propionic acid yield, and low production rate caused by factors such as feedback inhibition of fermentation products and slowed cell growth during the microbial fermentation production of propionic acid.

[0007] To solve the above-mentioned technical problems, the present invention provides a method for continuous fermentation to produce propionic acid, comprising:

[0008] Partially inoculate the fermentation broth from the previous batch into the fermentation medium of the next batch, and ferment both batches simultaneously. After fermentation for a certain period of time, partially inoculate the fermentation broth from the next batch into the fermentation broth from the previous batch, and continue fermentation until the fermentation of the previous batch is completed.

[0009] The continuous fermentation method of the present invention solves the problem of slow cell growth in the later stage of fermentation by inoculating the previous batch of fermentation broth with a fermentation broth of higher cell activity, which greatly shortens the fermentation cycle. At the same time, it also solves the problem of low propionic acid yield caused by feedback inhibition of fermentation products, and significantly improves propionic acid yield and production rate.

[0010] In a preferred embodiment of the present invention, 20-40 vol% of the fermentation broth from the previous batch is inoculated into the fermentation medium of the next batch.

[0011] In a preferred embodiment of the present invention, when the fermentation has been carried out for 64-80 hours, 10-15 vol% of the fermentation broth from the next batch is taken out and inoculated into the previous batch of fermentation broth.

[0012] Meanwhile, 20-40 vol% of the fermentation broth from the next batch is taken and inoculated into the next batch of fermentation medium, and the three batches ferment simultaneously.

[0013] In a preferred embodiment of the present invention, during the fermentation process, a glucose solution is added to maintain the carbon source supply in the culture medium.

[0014] In a preferred embodiment of the present invention, after the subsequent batch of fermentation broth is inoculated into the previous batch of fermentation broth, the feeding of glucose in the previous batch is stopped.

[0015] As a preferred embodiment of the present invention, the method for continuous fermentation to produce propionic acid includes the following steps:

[0016] (1) Inoculate the Propionibacterium seed culture medium into the first batch of fermenters for fermentation culture;

[0017] (2) When the first batch of fermentation has been going on for 64-80 hours, take out 20-40 vol% of the fermentation liquid and inoculate it into the second batch of fermentation tank for fermentation culture;

[0018] (3) When the second batch of fermentation has reached 64-80 hours, take 20-40 vol% of the fermentation broth and inoculate it into the third batch of fermenters for further fermentation. At the same time, take 10-15 vol% of the fermentation broth and inoculate it into the first batch of fermenters for subsequent fermentation until the end of fermentation; and / or,

[0019] (4) Following the method in step (3), when the third batch has fermented for 64-80 hours, take out 20-40 vol% of the fermentation liquid and inoculate it into the fourth batch of fermentation tank for fermentation culture. At the same time, take out 10-15 vol% of the fermentation liquid and inoculate it into the second batch of fermentation tank for subsequent fermentation culture until the end of fermentation, and obtain a fermentation liquid containing propionic acid.

[0020] By following the above method, four or more batches of continuous fermentation culture can be completed to obtain a fermentation broth containing propionic acid.

[0021] In a preferred embodiment of the present invention, during the fermentation process, a glucose solution is added to maintain the residual carbon source (i.e., residual glucose) in the culture medium at 20-50 g / L, preferably 30 g / L. The concentration of the glucose solution is 500-1000 g / L, preferably 700 g / L.

[0022] In a preferred embodiment of the present invention, after the fermentation broth of the next batch is inoculated into the fermentation tank of the previous batch, the glucose feeding of the previous batch is stopped.

[0023] In a preferred embodiment of the present invention, during the fermentation process, a neutralizing agent is used to control the pH value of the fermentation broth between 5.1 and 6.2, preferably between 5.6 and 5.8.

[0024] Preferably, the neutralizing agent is a base and / or a basic salt, selected from one or more of calcium carbonate, calcium hydroxide, and magnesium hydroxide. More preferably, it is one or more of a calcium carbonate solution with a mass concentration of 5-15%, a calcium hydroxide solution with a mass concentration of 15-25%, and a magnesium hydroxide solution with a mass concentration of 10-15%.

[0025] In a preferred embodiment of the present invention, the fermentation temperature is controlled at 25-35℃, preferably 30℃, during the fermentation process.

[0026] In a preferred embodiment of the present invention, during the fermentation process, the stirring speed is controlled at 100-150 rpm, preferably 120 rpm.

[0027] In a preferred embodiment of the present invention, the Propionibacterium is selected from wild-type strains or genetically engineered strains. Preferably, the Propionibacterium is derived from soil and obtained through screening. Its name is Propionibacterium acidipropionici FYPASS1, accession number: CCTCC NO: M 20221001, accession date: June 30, 2022, depositary institution: China Center for Type Culture Collection (CCTCC), depositary address: Wuhan University, Wuhan, Hubei Province, China.

[0028] In a preferred embodiment of the present invention, the inoculation volume of the Propionibacterium seed culture medium is 10-30 vol%.

[0029] In a preferred embodiment of the present invention, the culture medium for fermentation is composed of: glucose 30-40 g / L, yeast powder 6-10 g / L, corn steep liquor 5-15 g / L, ammonium chloride 4-7 g / L, diammonium hydrogen phosphate 4-6 g / L, potassium dihydrogen phosphate 3-5 g / L, dipotassium hydrogen phosphate 3-5 g / L, magnesium sulfate 0.1-2 g / L, zinc sulfate 0.1-0.5 g / L, and biotin 0.01-0.2 ml / L.

[0030] Preferably, the fermentation culture medium consists of: 35 g / L glucose, 8 g / L yeast powder, 10 g / L corn steep liquor, 5.3 g / L ammonium chloride, 4.6 g / L diammonium hydrogen phosphate, 3.7 g / L potassium dihydrogen phosphate, 3.7 g / L dipotassium hydrogen phosphate, 0.7 g / L magnesium sulfate, 0.2 g / L zinc sulfate, and 0.1 ml / L biotin.

[0031] As a preferred embodiment of the present invention, the preparation of the Propionibacterium seed culture medium includes: activating Propionibacterium seeds and preparing Propionibacterium seed culture medium.

[0032] The composition of the slant culture medium used for activating Propionibacterium seeds is as follows: glucose 15-25 g / L, yeast powder 5-15 g / L, light calcium carbonate 5-15 g / L, and agar powder 10-20 g / L.

[0033] Preferably, the composition of the slant culture medium is: 20 g / L glucose, 10 g / L yeast powder, 10 g / L light calcium carbonate, and 15 g / L agar powder; sterilized at 115°C for 20 min.

[0034] The seed culture medium used to prepare the Propionibacterium seed culture solution has the following composition: glucose 30-40 g / L, yeast powder 6-18 g / L, corn steep liquor 5-15 g / L, light calcium carbonate 15-25 g / L, ammonium chloride 4-7 g / L, diammonium hydrogen phosphate 4-6 g / L, potassium dihydrogen phosphate 3-5 g / L, dipotassium hydrogen phosphate 3-5 g / L, magnesium sulfate 0.1-2 g / L, zinc sulfate 0.1-0.5 g / L, and biotin 0.01-0.2 ml / L.

[0035] Preferably, the seed culture medium comprises: 35 g / L glucose, 8 g / L yeast extract, 10 g / L corn steep liquor, 20 g / L light calcium carbonate, 5.3 g / L ammonium chloride, 4.6 g / L diammonium hydrogen phosphate, 3.7 g / L potassium dihydrogen phosphate, 3.7 g / L dipotassium hydrogen phosphate, 0.7 g / L magnesium sulfate, 0.2 g / L zinc sulfate, and 0.1 ml / L biotin.

[0036] This invention provides a method for continuous fermentation production of propionic acid. By inoculating the fermentation broth of the previous batch into the fermentation medium of the next batch, the Propionibacterium acnes is recycled, reducing production costs and improving production efficiency. After the two batches ferment together for a certain period of time, the fermentation broth of the next batch with higher bacterial activity is inoculated into the fermentation broth of the previous batch. This solves the problem of low bacterial activity and slow growth rate in the later stage of the fermentation of the previous batch, significantly shortening the fermentation cycle. At the same time, it also solves the problem of low propionic acid yield caused by feedback inhibition of fermentation products, significantly improving propionic acid yield and production rate. Detailed Implementation

[0037] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art should understand that the embodiments described below are only for illustrating the present invention and should not be regarded as limiting the scope of protection of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort, such as embodiments obtained by modification or substitution, are within the scope of protection of the present invention.

[0038] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; the raw materials, reagents, instruments, etc. used are commercially available unless otherwise specified.

[0039] Propionibacterium acidipropionici FYPASS1, accession number: CCTCC NO: M 20221001, accession date: June 30, 2022, depositary institution: China Center for Type Culture Collection (CCTCC), depositary address: Wuhan University, Wuhan, Hubei Province, China.

[0040] The preparation method of the Propionibacterium seed culture medium used in the examples and comparative examples is as follows:

[0041] (1) Activation of Propionibacterium seeds

[0042] Propionibacterium was inoculated onto slant culture medium and cultured at 30°C for 96 hours to obtain slant culture.

[0043] The composition of the slant culture medium is: glucose 20g / L, yeast powder 10g / L, light calcium carbonate 10g / L, and agar powder 15g / L; sterilize at 115℃ for 20min.

[0044] (2) Preparation of Propionibacterium seed culture medium

[0045] Under aseptic conditions, the slant culture was inoculated into 1200 mL of seed culture medium and cultured at 30 °C for 96 h. Then, it was inoculated into 6 L of seed culture medium at a 20 vol% inoculation rate and cultured at 30 °C for 72 h to obtain the Propionibacterium seed culture.

[0046] The seed culture medium consisted of: 35 g / L glucose, 8 g / L yeast extract, 10 g / L corn steep liquor, 20 g / L light calcium carbonate, 5.3 g / L ammonium chloride, 4.6 g / L diammonium hydrogen phosphate, 3.7 g / L potassium dihydrogen phosphate, 3.7 g / L dipotassium hydrogen phosphate, 0.7 g / L magnesium sulfate, 0.2 g / L zinc sulfate, and 0.1 ml / L biotin.

[0047] The fermentation medium used in the examples and comparative examples consisted of: glucose 35 g / L, yeast extract 8 g / L, corn steep liquor 10 g / L, ammonium chloride 5.3 g / L, diammonium hydrogen phosphate 4.6 g / L, potassium dihydrogen phosphate 3.7 g / L, dipotassium hydrogen phosphate 3.7 g / L, magnesium sulfate 0.7 g / L, zinc sulfate 0.2 g / L, and biotin 0.1 ml / L.

[0048] Example 1

[0049] This embodiment provides a method for continuous fermentation production of propionic acid in a 50L fermenter, the steps of which are as follows:

[0050] The prepared Propionibacterium seed culture was inoculated into the first batch of fermenters containing 30L of fermentation medium at an inoculation rate of 20 vol%. Fermentation was carried out at 30℃ and 120 rpm. During the fermentation process, a 15% (w / v) calcium hydroxide solution was used to maintain the pH of the fermentation broth at 5.7. At the same time, a 700 g / L glucose solution was added to maintain the residual carbon source in the medium at 30 g / L.

[0051] When the fermentation cycle of the first batch of fermenters reaches 72 hours, 20 vol% of the fermentation broth is taken out and inoculated into the second batch of fermenters for fermentation culture, with the same fermentation conditions as above.

[0052] When the fermentation cycle of the second batch of fermenters reaches 72 hours, 30 vol% of the fermentation broth is taken out. 20 vol% of this broth is inoculated into the third batch of fermenters for fermentation culture under the same conditions as above. The remaining 10 vol% is inoculated into the first batch of fermenters for subsequent fermentation culture. After inoculation, the feeding of glucose solution to the first batch of fermenters is stopped. Other fermentation conditions are the same as above. Fermentation continues until the residual carbon source is ≤5 g / L before being discharged from the fermenter.

[0053] Similarly, when the fermentation cycle of the third batch of fermenters reaches 72 hours, 30 vol% of the fermentation broth is taken out. 20 vol% of this broth is inoculated into the fourth batch of fermenters for fermentation culture under the same conditions as above. The remaining 10 vol% is inoculated into the second batch of fermenters for subsequent fermentation culture. After inoculation, glucose feeding is stopped in the second batch of fermenters, and other fermentation conditions are the same as above. Fermentation continues until the residual carbon source is ≤5 g / L before being discharged from the fermenter.

[0054] Ten batches were continuously fermented. When the fermentation cycle of the tenth batch fermenter reached 72 hours, 10 vol% of the fermentation broth was taken out and inoculated into the ninth batch fermenter for subsequent fermentation. After inoculation, the glucose solution was stopped from being added to the ninth batch fermenter, and other fermentation conditions were the same as above. Fermentation continued until the residual carbon source was ≤5 g / L before being discharged from the fermenter. When the fermentation cycle of the tenth batch fermenter reached 144 hours, the glucose solution was stopped from being added, and fermentation continued until the residual carbon source was ≤5 g / L before being discharged from the fermenter.

[0055] Example 2

[0056] This embodiment provides a method for continuous fermentation production of propionic acid in a 50L fermenter, the steps of which are as follows:

[0057] The prepared Propionibacterium seed culture was inoculated into the first batch of fermenters containing 30L of fermentation medium at an inoculation rate of 25 vol%. Fermentation was carried out at 25°C and 150 rpm. During the fermentation process, a 15% (w / v) calcium carbonate solution was used to maintain the pH of the fermentation broth at 5.7. At the same time, a glucose solution with a concentration of 800 g / L was added to maintain the residual carbon source in the medium at 35 g / L.

[0058] When the fermentation cycle of the first batch of fermenters reaches 70 hours, 25% vol% of the fermentation broth is taken out and inoculated into the second batch of fermenters for fermentation culture under the same conditions.

[0059] When the fermentation cycle of the second batch of fermenters reaches 70 hours, 35 vol% of the fermentation broth is taken out. 25 vol% of this broth is inoculated into the third batch of fermenters for fermentation culture under the same conditions as above. The remaining 10 vol% is inoculated into the first batch of fermenters for subsequent fermentation culture. After inoculation, the feeding of glucose solution to the first batch of fermenters is stopped. Other fermentation conditions are the same as above. Fermentation continues until the residual carbon source is ≤5 g / L before being discharged from the fermenter.

[0060] Similarly, when the fermentation cycle of the third batch of fermenters reaches 70 hours, 35 vol% of the fermentation broth is taken out. 25 vol% of this broth is inoculated into the fourth batch of fermenters for fermentation culture under the same conditions as above. The remaining 10 vol% is inoculated into the second batch of fermenters for subsequent fermentation culture. After inoculation, glucose feeding is stopped in the second batch of fermenters, and other fermentation conditions are the same as above. Fermentation continues until the residual carbon source is ≤5 g / L before being discharged from the fermenter.

[0061] Ten batches were continuously fermented. When the fermentation cycle of the tenth batch fermenter reached 70 hours, 10 vol% of the fermentation broth was taken out and inoculated into the ninth batch fermenter for subsequent fermentation. After inoculation, the glucose solution was stopped from being added to the ninth batch fermenter, and other fermentation conditions were the same as above. Fermentation continued until the residual carbon source was ≤5 g / L before being discharged from the fermenter. When the fermentation cycle of the tenth batch fermenter reached 144 hours, the glucose solution was stopped from being added, and fermentation continued until the residual carbon source was ≤5 g / L before being discharged from the fermenter.

[0062] Comparative Example 1

[0063] This comparative example provides a method for producing propionic acid by fermentation in a 50L fermenter, the steps of which are as follows:

[0064] The prepared Propionibacterium seed culture was inoculated into a fermenter containing 30 L of fermentation medium at an inoculation rate of 20 vol%. Fermentation was carried out at 30 °C and 120 rpm. During fermentation, a 15% (w / v) calcium hydroxide solution was used to maintain the pH of the fermentation broth at 5.7, while a 700 g / L glucose solution was added to maintain a residual carbon source concentration of 30 g / L in the medium. After 144 hours of fermentation, glucose addition was stopped, and fermentation continued until the residual carbon source concentration was ≤5 g / L before being transferred to the fermenter. Ten batches were repeated.

[0065] Comparative Example 2

[0066] This comparative example provides a method for continuous fermentation production of propionic acid in a 50L fermenter, the steps of which are as follows:

[0067] The prepared Propionibacterium seed culture was inoculated into the first batch of fermenters containing 30L of fermentation medium at an inoculation rate of 20 vol%. Fermentation was carried out at 30℃ and 120 rpm. During the fermentation process, a 15% (w / v) calcium hydroxide solution was used to maintain the pH of the fermentation broth at 5.7. At the same time, a 700 g / L glucose solution was added to maintain the residual carbon source in the medium at 30 g / L.

[0068] When the fermentation cycle of the first batch of fermenters reaches 72 hours, 20 vol% of the fermentation broth is taken out and inoculated into the second batch of fermenters for fermentation culture, with the same fermentation conditions as above.

[0069] When the fermentation cycle of the second batch of fermenters reaches 72 hours, 20 vol% of the fermentation broth is taken out and inoculated into the third batch of fermenters for fermentation culture, with the same fermentation conditions as above. At this time, the glucose solution is stopped from being added to the first batch of fermenters, and the other fermentation conditions are the same as above. Fermentation continues until the residual carbon source is ≤5 g / L before being discharged from the tank.

[0070] Similarly, when the fermentation cycle of the third batch of fermenters reaches 72 hours, 20 vol% of the fermentation broth is taken out and inoculated into the fourth batch of fermenters for fermentation culture, with the same fermentation conditions as above; at this time, glucose feeding is stopped in the second batch of fermenters, and other fermentation conditions are the same as above. Fermentation continues until the residual carbon source is ≤5 g / L before being discharged from the tank.

[0071] Ten batches were continuously fermented. When the fermentation cycle of the tenth batch reached 72 hours, the glucose solution was stopped from being added to the ninth batch fermenter. Other fermentation conditions were the same as above. Fermentation continued until the residual carbon source was ≤5g / L before being discharged from the fermenter. When the fermentation cycle of the tenth batch fermenter reached 144 hours, the glucose solution was stopped from being added. Fermentation continued until the residual carbon source was ≤5g / L before being discharged from the fermenter.

[0072] Test case

[0073] The fermentation broths of Example 1, Comparative Example 1 and Comparative Example 2 were randomly selected for testing, and the results are shown in Table 1 below.

[0074] The method for determining the residual carbon source (g / L) was as follows: the carbon source was determined using a biosensor analyzer SBA-40D (Shandong Academy of Sciences).

[0075] The conversion rate (%) is calculated as follows: propionic acid yield (g) ÷ total carbon source (g) × 100%.

[0076] The fermentation production rate (g / L·h) is calculated as follows: propionic acid yield (g / L) ÷ fermentation time (h).

[0077] Table 1. Test results of fermentation broth from the examples and comparative examples.

[0078]

[0079] The above comparative results show that the continuous fermentation method for producing propionic acid provided by the present invention solves the problem of slow cell growth in the later stage of fermentation by inoculating the previous batch of fermentation broth with a fermentation broth of higher cell activity, significantly shortens the fermentation cycle, and also solves the problem of low propionic acid yield caused by feedback inhibition of fermentation products, thus significantly improving propionic acid yield and production rate.

[0080] Although the present invention has been described in detail above with general descriptions, specific embodiments, and experiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for the continuous fermentation production of propionic acid, characterized in that, The method comprises the following steps: propionibacterium seed culture solution is inoculated into the first batch of fermentation tank for fermentation culture; when the first batch of fermentation is fermented for 64-80h, 20-40vol% of the fermentation liquor is taken out to inoculate into the second batch of fermentation tank for fermentation culture; when the second batch of fermentation is fermented for 64-80h, 20-40vol% of the fermentation liquor is taken out to inoculate into the third batch of fermentation tank for fermentation culture, and 10-15vol% of the fermentation liquor is taken out to inoculate into the first batch of fermentation tank for subsequent fermentation culture until the fermentation is completed; when the third batch of fermentation is fermented for 64-80h, 20-40vol% of the fermentation liquor is taken out to inoculate into the fourth batch of fermentation tank for fermentation culture, and 10-15vol% of the fermentation liquor is taken out to inoculate into the second batch of fermentation tank for subsequent fermentation culture until the fermentation is completed; after four batches or more of continuous fermentation culture, the fermentation liquor containing propionic acid is obtained; the propionibacterium is propionibacterium acidipropionici FYPASS1, and the preservation number is CCTCC NO: M 20221001.

2. The method of continuously fermentative production of propionic acid according to claim 1, characterized in that, during the fermentation culture, glucose solution is added to maintain the residual amount of carbon source in the culture medium at 20-50g / L; and / or, after the fermentation liquor of the latter batch is inoculated into the fermentation tank of the former batch, the glucose addition of the former batch is stopped.

3. The method of continuously fermentative production of propionic acid according to claim 2, characterized in that, during the fermentation culture, glucose solution is added to maintain the residual amount of carbon source in the culture medium at 30g / L.

4. The method for continuous fermentation production of propionic acid according to claim 1, characterized in that, during the fermentation culture, a neutralizing agent is used to control the pH value of the fermentation liquor to be between 5.1 and 6.2; and / or, during the fermentation culture, the fermentation temperature is controlled to be 25-35℃; and / or, during the fermentation culture, the stirring speed is controlled to be 100-150rpm.

5. The method of continuously fermentative production of propionic acid according to claim 4, characterized in that, during the fermentation culture, a neutralizing agent is used to control the pH value of the fermentation liquor to be between 5.6 and 5.8; and / or, during the fermentation culture, the fermentation temperature is controlled to be 30℃; and / or, during the fermentation culture, the stirring speed is controlled to be 120rpm.

6. The method for continuously fermentative production of propionic acid according to claim 1, characterized in that, the inoculation amount of the propionibacterium seed culture solution is 10-30vol%.

7. The process for the continuous fermentative production of propionic acid according to any one of claims 1 to 6, characterized in that the culture medium for the fermentation culture comprises: glucose 30-40g / L, yeast powder 6-10g / L, corn syrup 5-15g / L, ammonium chloride 4-7g / L, diammonium phosphate 4-6g / L, potassium dihydrogen phosphate 3-5g / L, dipotassium hydrogen phosphate 3-5g / L, magnesium sulfate 0.1-2g / L, zinc sulfate 0.1-0.5g / L, and biotin 0.01-0.2ml / L.

8. The method for continuously fermenting to produce propionic acid according to claim 7, wherein the culture medium for the fermentation culture comprises: glucose 35g / L, yeast powder 8g / L, corn syrup 10g / L, ammonium chloride 5.3g / L, diammonium phosphate 4.6g / L, potassium dihydrogen phosphate 3.7g / L, dipotassium hydrogen phosphate 3.7g / L, magnesium sulfate 0.7g / L, zinc sulfate 0.2g / L, and biotin 0.1ml / L.

9. The process for the continuous fermentation production of propionic acid according to any one of claims 1 to 6, characterized in that The preparation of the propionic acid bacteria seed culture solution comprises: activating the propionic acid bacteria seed, and preparing the propionic acid bacteria seed culture solution; The slant medium used in the activation of the propionic acid bacteria seed comprises: glucose 15-25 g / L, yeast powder 5-15 g / L, light calcium carbonate 5-15 g / L, and agar powder 10-20 g / L; And / or, the seed culture medium used in the preparation of the propionic acid bacteria seed culture solution comprises: glucose 30-40 g / L, yeast powder 6-18 g / L, corn syrup 5-15 g / L, light calcium carbonate 15-25 g / L, ammonium chloride 4-7 g / L, diammonium hydrogen phosphate 4-6 g / L, potassium dihydrogen phosphate 3-5 g / L, dipotassium hydrogen phosphate 3-5 g / L, magnesium sulfate 0.1-2 g / L, zinc sulfate 0.1-0.5 g / L, and biotin 0.01-0.2 ml / L.

10. The method of continuously fermentative production of propionic acid according to claim 9, characterized in that, The slant medium comprises: glucose 20 g / L, yeast powder 10 g / L, light calcium carbonate 10 g / L, and agar powder 15 g / L; And / or, the seed culture medium comprises: glucose 35 g / L, yeast powder 8 g / L, corn syrup 10 g / L, light calcium carbonate 20 g / L, ammonium chloride 5.3 g / L, diammonium hydrogen phosphate 4.6 g / L, potassium dihydrogen phosphate 3.7 g / L, dipotassium hydrogen phosphate 3.7 g / L, magnesium sulfate 0.7 g / L, zinc sulfate 0.2 g / L, and biotin 0.1 ml / L.

Images