阅读说明：本技术 从发酵液中提取l-高丝氨酸的方法 (Method for extracting L-homoserine from fermentation liquor ) 是由 黄清荣 冯志彬 张娟 张建龙 于天池 于 2021-03-24 设计创作，主要内容包括：本发明涉及L-高丝氨酸提取领域,尤其涉及一种从发酵液中提取L-高丝氨酸的方法。包括以下步骤：发酵液预处理、脱色、电去离子和浓缩过滤,得到L-高丝氨酸。本发明首次采用电去离子技术对L-高丝氨酸发酵液进行除盐处理,与电渗析技术相比电去离子技术的除盐率提高10%,与离子交换技术相比电去离子技术中添加的树脂不需要再生,减少了大量酸碱的使用,可节省用水量70%。(The invention relates to the field of L-homoserine extraction, in particular to a method for extracting L-homoserine from fermentation liquor. The method comprises the following steps: and (3) pretreating fermentation liquor, decoloring, electrodeionization, concentrating and filtering to obtain the L-homoserine. The method adopts the electrodeionization technology to carry out desalination treatment on the L-homoserine fermentation liquor for the first time, compared with the electrodialysis technology, the desalination rate of the electrodeionization technology is improved by 10%, compared with the ion exchange technology, the resin added in the electrodeionization technology does not need to be regenerated, the use of a large amount of acid and alkali is reduced, and the water consumption can be saved by 70%.)

1. A method for extracting L-homoserine from fermentation liquor, which is characterized by comprising the following steps: the method comprises the following steps:

step 1, fermentation liquor pretreatment: adjusting pH value of the fermentation liquor to 4-5.8, adding 20-80mg/L water-soluble chitosan flocculant, heating to 60-80 deg.C, treating for 20-40 min to promote flocculation and precipitation of water-soluble impurity protein, removing thallus and flocculating constituent with microfiltration membrane to obtain 4.8-5.0L fermentation liquor clear liquid, separating with roll type ultrafiltration membrane separation system, with cut-off molecular weight of 0.5-10KDa and operation pressure of 2.0-4.0MPa, removing small molecular peptide and short chain protein, and collecting 4.7-5.0L ultrafiltration membrane permeate;

step 2, decoloring: introducing the ultrafiltration membrane permeate collected in the step 1 into an activated carbon fiber module device with the specification of 5 inches for decolorization, wherein the decolorizing temperature is 30-50 ℃, the operating pressure is 0.5MPa, 4.7-5.0L of decolorized liquid is obtained, the light transmittance of the decolorized liquid is 78.3-87.2%, and after decolorization, hot water with the temperature of 70 ℃ is introduced into the activated carbon fiber module device for on-line regeneration and recycling;

step 3, electrodeionization: feeding the decolorized solution obtained in the step 2 into a fresh room of an electrodeionization device, operating under the voltage of 30V, continuously detecting the conductivity of the solution in the fresh room, stopping operating when the conductivity is reduced to 500 mu s/cm, desalting to obtain desalted solution, and collecting 4.6-5.0L of the desalted solution;

and 4, concentrating and filtering: and (3) decompressing and concentrating the desalted liquid obtained in the step (3) until the content of L-homoserine is 90% -100%, precooling the temperature of the concentrated liquid to 0-15 ℃, slowly adding an organic solvent into the concentrated liquid according to the volume of 1 time per hour, uniformly stirring at the speed of 50r/min, stopping stirring and crystal growth for 5-8 hours when the addition amount of the organic solvent reaches 6-8 times of the volume of the concentrated liquid, continuously adding the organic solvent according to the volume of 1 time per hour until the volume of the concentrated liquid is 10-12 times of the volume of the concentrated liquid, crystallizing for 16-20 hours at the temperature of 5 ℃, and performing suction filtration and drying to obtain the L-homoserine.

2. The method of extracting L-homoserine from fermentation broth according to claim 1, wherein: the concentration of the fermentation liquor in the step 1 is 30-50 g/L, and the fermentation liquor is produced by using Escherichia coli ZFGs012, and the strain is preserved in China general microbiological culture Collection center on 11 months and 11 days in 2020, with the address: china Beijing, the preservation number is CGMCC NO.21153, and the classification is named as Escherichia coli.

3. The method of extracting L-homoserine from fermentation broth according to claim 1, wherein: the preparation method of the water-soluble chitosan flocculant in the step 1 comprises the following steps:

step 1-1, preparing a chitosan solution with a mass-to-volume ratio of 1: 10;

step 1-2, adding glacial acetic acid to adjust the pH value to 3.8, fully stirring and standing for 12h, wherein the chitosan

The degree of deacetylation of (a) was 95%.

4. The method of extracting L-homoserine from fermentation broth according to claim 1, wherein: and 3, mixing the Cl type 717 resin and the Na type 732 resin in the resin added into the dilute chamber of the electrodeionization device in the step 3, adding 0.02mol/L sodium chloride solution into the concentrated chamber, adding 0.2mol/L sodium sulfate solution into the polar chamber, wherein the operating voltage is 30V, and the conductivity of the obtained desalted liquid is less than 500 mu s/cm.

5. The method of extracting L-homoserine from fermentation broth according to claim 1, wherein: the organic solvent in the step 4 is one of ethanol, methanol and acetone.

Technical Field

The invention relates to the field of L-homoserine extraction, in particular to a method for extracting L-homoserine from fermentation liquor.

Background

L-homoserine (2-amino-4-hydroxybutyric acid) is a non-protein amino acid, and its derivatives can be converted into other important chemical intermediates through enzymatic reaction, and have abundant biological activity, such as the inhibition of sickle red blood cells and antifungal drugs. L-homoserine is also an important intermediate for synthesizing glufosinate-ammonium, a chiral herbicide, so research on L-homoserine in the aspects of pharmacy, biology and the like is more and more emphasized by researchers.

At present, the industrial production method of L-homoserine mainly comprises a chemical synthesis method and a biological method; the chemical synthesis method mainly comprises a methionine method: the method has the advantages that although the yield is high, the methyl iodide is expensive, the reaction time is long, and the waste treatment is complex.

Patent CN101100438A provides a method for preparing L-homoserine at normal pressure in organic solvent by using L-aspartic acid as raw material and using metal complex hydrogen compound as reducing agent, which has the advantages of easily available raw material, high yield, complex purification steps and serious environmental pollution.

Patent CN105506014A provides a method for preparing L-homoserine by catalytic reaction of pyruvic acid and aldehyde compounds as substrates under the action of aldolase, the obtained product is subjected to chromatographic separation, desalting, decoloring, concentration and crystallization, drying and other steps in sequence, and ion exchange resin is adopted as a key extraction step in the extraction process, so that the method has the advantages of high recovery rate, thorough impurity removal, large handling capacity and the like, but a large amount of acid and alkali can be consumed in the regeneration process, a large amount of waste water is generated, the environment is polluted, and formaldehyde in the raw materials has potential safety hazard.

The L-homoserine fermentation broth is a mixture with complex components, and contains a large amount of thalli, proteins, residual sugar, pigments, inorganic salts and other components besides L-homoserine. The removal of proteins, pigments and inorganic salts is the key to the extraction of L-homoserine, and the decolorization and desalting methods commonly used in industry are activated carbon decolorization, ion exchange desalting or electrodialysis desalting. The decolorization of the active carbon can generate a large amount of waste carbon and simultaneously intercept part of fermentation liquor to reduce the yield of the product; the ion exchange desalination generates waste water and consumes a large amount of acid and alkali; the electrodialysis technology has the defects of long treatment time, low desalination rate, low product purity and the like, so that a new method for extracting L-homoserine is urgently needed.

Disclosure of Invention

The present invention addresses the above-described deficiencies of the prior art by providing a method for extracting L-homoserine from a fermentation broth.

The technical scheme for solving the technical problems is as follows:

a method for extracting L-homoserine from fermentation broth, comprising the following steps:

step 1, fermentation liquor pretreatment: adjusting pH value of the fermentation liquor to 4-5.8, adding 20-80mg/L water-soluble chitosan flocculant, heating to 60-80 deg.C, treating for 20-40 min to promote flocculation and precipitation of water-soluble impurity protein, removing thallus and flocculating constituent with microfiltration membrane to obtain 4.8-5.0L fermentation liquor clear liquid, separating with roll type ultrafiltration membrane separation system, with cut-off molecular weight of 0.5-10KDa and operation pressure of 2.0-4.0MPa, removing small molecular peptide and short chain protein, and collecting 4.7-5.0L ultrafiltration membrane permeate;

step 2, decoloring: introducing the ultrafiltration membrane permeate collected in the step 1 into an activated carbon fiber module device with the specification of 5 inches for decolorization, wherein the decolorizing temperature is 30-50 ℃, the operating pressure is 0.5MPa, 4.7-5.0L of decolorized liquid is obtained, the light transmittance of the decolorized liquid is 78.3-87.2%, and after decolorization, hot water with the temperature of 70 ℃ is introduced into the activated carbon fiber module device for on-line regeneration and recycling;

step 3, electrodeionization: feeding the decolorized solution obtained in the step 2 into a fresh room of an electrodeionization device, operating under the voltage of 30V, continuously detecting the conductivity of the solution in the fresh room, stopping operating when the conductivity is reduced to 500 mu s/cm, desalting to obtain desalted solution, and collecting 4.6-5.0L of the desalted solution;

and 4, concentrating and filtering: and (3) decompressing and concentrating the desalted liquid obtained in the step (3) until the content of L-homoserine is 90% -100%, precooling the temperature of the concentrated liquid to 0-15 ℃, slowly adding an organic solvent into the concentrated liquid according to the volume of 1 time per hour, uniformly stirring at the speed of 50r/min, stopping stirring and crystal growth for 5-8 hours when the addition amount of the organic solvent reaches 6-8 times of the volume of the concentrated liquid, continuously adding the organic solvent according to the volume of 1 time per hour until the volume of the concentrated liquid is 10-12 times of the volume of the concentrated liquid, crystallizing for 16-20 hours at the temperature of 5 ℃, and performing suction filtration and drying to obtain the L-homoserine.

Preferably, the concentration of the fermentation liquid in the step 1 is 30-50 g/L, and the fermentation liquid is produced by using Escherichia coli ZFGs012, and the strain is preserved in China general microbiological culture Collection center (CGMCC) at 11/2020 with addresses: china Beijing, the preservation number is CGMCC NO.21153, and the classification is named as Escherichia coli.

Preferably, the step of preparing the water-soluble chitosan flocculant in the step 1 comprises the following steps:

step 1-1, preparing a chitosan solution with a mass-to-volume ratio of 1: 10;

step 1-2, adding glacial acetic acid to adjust the pH value to 3.8, fully stirring and standing for 12h, wherein the chitosan

The degree of deacetylation of (a) was 95%.

Preferably, the resin added in the weak chamber of the electrodeionization device in the step 3 is a mixture of Cl type 717 resin and Na type 732 resin, 0.02mol/L sodium chloride solution is added in the strong chamber, 0.2mol/L sodium sulfate solution is added in the polar chamber, the operating voltage is 30V, and the conductivity of the obtained desalted liquid is less than 500 mu s/cm.

Preferably, the organic solvent in step 4 is one of ethanol, methanol and acetone.

Compared with the prior art, the invention has the beneficial effects that:

firstly, the fermentation liquor is decolorized by using the activated carbon fiber module, the activated carbon fiber module can be repeatedly used for 100-350 batches, compared with an activated carbon powder decolorization process, the interception amount of the fermentation liquor is less, and processes such as waste carbon treatment and the like are not needed; the decoloring effect is better, the decoloring temperature is normal temperature, and partial energy consumption can be saved.

Secondly, the invention adopts the electrodeionization technology to carry out desalination treatment on the L-homoserine fermentation liquor for the first time, compared with the electrodialysis technology, the desalination rate of the electrodeionization technology is improved by 10 percent, compared with the ion exchange technology, the resin added in the electrodeionization technology does not need to be regenerated, the use of a large amount of acid and alkali is reduced, and the water consumption can be saved by 70 percent.

Thirdly, the invention improves the crystal form of the L-homoserine by controlling the feeding rate of the organic solvent and combining the crystal growth in the intermediate process, effectively avoids the formation of cocrystallization of the L-homoserine and trace inorganic salt, and improves the purity of the product. The method for extracting L-homoserine in fermentation liquor has high purity and yield, and the final yield of the L-homoserine extracted by the method is more than 70 percent, and the purity of the L-homoserine is more than 98 percent.

Detailed Description

The principles and features of this invention are described below in conjunction with examples which are set forth to illustrate, but are not to be construed to limit the scope of the invention.

Example 1

A method for extracting L-homoserine from fermentation broth, comprising the following steps:

step 1, fermentation liquor pretreatment: taking 5L of fermentation liquor in a tank, wherein the concentration of homoserine is 35g/L, the pH value of the fermentation liquor is adjusted to be 4, adding 20mg/L of water-soluble chitosan flocculant, heating to 60-80 ℃, treating for 20 minutes, promoting flocculation and precipitation of water-soluble impurity protein, removing thalli and floccules through a microfiltration membrane to obtain 4.8L of fermentation liquor clear liquor, removing substances such as small molecular peptides, short chain proteins and the like in the fermentation liquor clear liquor by utilizing a roll type ultrafiltration membrane separation system, wherein the cut-off molecular weight is 0.5KDa, the operating pressure is 2.0MPa, and collecting 4.7L of ultrafiltration membrane permeate;

step 2, decoloring: introducing the ultrafiltration membrane permeate collected in the step 1 into an activated carbon fiber module device with the specification of 5 inches for decolorization, wherein the decolorizing temperature is 30 ℃, the operating pressure is 0.5MPa, 4.7L of decolorized liquid is obtained, the light transmittance of the decolorized liquid is 78.3%, and after decolorization, 70 ℃ hot water is introduced into the activated carbon fiber module device for online regeneration and recycling;

step 3, electrodeionization: sending the decolorized solution obtained in the step 2 into a fresh room of an electrodeionization device, operating under the voltage of 30V, continuously detecting the conductivity of the solution in the fresh room, stopping operating when the conductivity is reduced to 500 mu s/cm, desalting to obtain desalted solution, and collecting 4.6L of the desalted solution;

and 4, concentrating and filtering: and (3) concentrating the desalted liquid obtained in the step (3) under reduced pressure until the content of L-homoserine is 90% -100%, precooling the temperature of the concentrated liquid to 0 ℃, slowly adding an organic solvent into the concentrated liquid according to the volume of 1 time per hour, uniformly stirring at the speed of 50r/min, stopping stirring and crystal growth for 5 hours when the addition amount of the organic solvent reaches 6 times of the volume of the concentrated liquid, continuously adding the organic solvent according to the volume of 1 time per hour until the volume of the concentrated liquid is 10 times, crystallizing for 16 hours at the temperature of 5 ℃, and performing suction filtration and drying to obtain the L-homoserine, wherein the L-homoserine is 122.85g, the purity is 99.3%, and the yield is 70.2%.

The concentration of the fermentation liquor in the step 1 is 30-50 g/L, and the fermentation liquor is produced by using Escherichia coli ZFGs012, and the strain is preserved in China general microbiological culture Collection center on 11 months and 11 days in 2020, with the address: china Beijing, the preservation number is CGMCC NO.21153, and the classification is named as Escherichia coli.

The preparation method of the water-soluble chitosan flocculant in the step 1 comprises the following steps:

step 1-1, preparing a chitosan solution with a mass-to-volume ratio of 1: 10;

step 1-2, adding glacial acetic acid to adjust the pH value to 3.8, fully stirring and standing for 12h, wherein the chitosan

The degree of deacetylation of (a) was 95%.

And 3, mixing the Cl type 717 resin and the Na type 732 resin in the resin added into the dilute chamber of the electrodeionization device in the step 3, adding 0.02mol/L sodium chloride solution into the concentrated chamber, adding 0.2mol/L sodium sulfate solution into the polar chamber, wherein the operating voltage is 30V, and the conductivity of the obtained desalted liquid is less than 500 mu s/cm.

The organic solvent in the step 4 is one of ethanol, methanol and acetone.

Example 2

A method for extracting L-homoserine from fermentation broth, comprising the following steps:

step 1, fermentation liquor pretreatment: taking 5L of fermentation liquor fed into a tank, wherein the concentration of homoserine is 35g/L, the pH value of the fermentation liquor is adjusted to 5.8, adding 80mg/L of water-soluble chitosan flocculant, heating to 60-80 ℃, treating for 40 minutes, promoting flocculation and precipitation of water-soluble impurity proteins, removing thalli and floccules through a microfiltration membrane to obtain 5L of fermentation liquor clear liquor, removing substances such as small molecular peptides, short chain proteins and the like in the fermentation liquor clear liquor by utilizing a roll type ultrafiltration membrane separation system, wherein the cut-off molecular weight is 10KDa, the operating pressure is 4.0MPa, and collecting 5L of ultrafiltration membrane permeate;

step 2, decoloring: introducing the ultrafiltration membrane permeate collected in the step 1 into an activated carbon fiber module device with the specification of 5 inches for decolorization, wherein the decolorizing temperature is 50 ℃, the operating pressure is 0.5MPa, 5L of decolorized liquid is obtained, the light transmittance of the decolorized liquid is 87.2%, and after decolorization, 70 ℃ hot water is introduced into the activated carbon fiber module device for on-line regeneration and recycling;

step 3, electrodeionization: sending the decolorized solution obtained in the step 2 into a fresh room of an electrodeionization device, operating under the voltage of 30V, continuously detecting the conductivity of the solution in the fresh room, stopping operating when the conductivity is reduced to 500 mu s/cm, desalting to obtain desalted solution, and collecting 5L of the desalted solution;

and 4, concentrating and filtering: and (3) concentrating the desalted liquid obtained in the step (3) under reduced pressure until the content of L-homoserine is 90% -100%, precooling the temperature of the concentrated liquid to 15 ℃, slowly adding an organic solvent into the concentrated liquid according to the volume of 1 time per hour, uniformly stirring at the speed of 50r/min, stopping stirring and crystal growth for 8 hours when the addition amount of the organic solvent reaches 8 times of the volume of the concentrated liquid, continuously adding the organic solvent according to the volume of 1 time per hour until the volume of the concentrated liquid is 12 times, crystallizing for 20 hours at the temperature of 5 ℃, and performing suction filtration and drying to obtain the L-homoserine, wherein the L-homoserine is 130.9g, the purity is 98.2%, and the yield is 74.8%.

The concentration of the fermentation liquor in the step 1 is 30-50 g/L, and the fermentation liquor is produced by using Escherichia coli ZFGs012, and the strain is preserved in China general microbiological culture Collection center on 11 months and 11 days in 2020, with the address: china Beijing, the preservation number is CGMCC NO.21153, and the classification is named as Escherichia coli.

The preparation method of the water-soluble chitosan flocculant in the step 1 comprises the following steps:

step 1-1, preparing a chitosan solution with a mass-to-volume ratio of 1: 10;

step 1-2, adding glacial acetic acid to adjust the pH value to 3.8, fully stirring and standing for 12h, wherein the chitosan

The degree of deacetylation of (a) was 95%.

And 3, mixing the Cl type 717 resin and the Na type 732 resin in the resin added into the dilute chamber of the electrodeionization device in the step 3, adding 0.02mol/L sodium chloride solution into the concentrated chamber, adding 0.2mol/L sodium sulfate solution into the polar chamber, wherein the operating voltage is 30V, and the conductivity of the obtained desalted liquid is less than 500 mu s/cm.

The organic solvent in the step 4 is one of ethanol, methanol and acetone.

Example 3

A method for extracting L-homoserine from fermentation broth, comprising the following steps:

step 1, fermentation liquor pretreatment: taking 5L of fermentation liquor in a tank, wherein the concentration of homoserine is 40g/L, the pH value of the fermentation liquor is adjusted to 4.5, adding 50mg/L of water-soluble chitosan flocculant, heating to 60-80 ℃, treating for 30 minutes, promoting flocculation and precipitation of water-soluble impurity protein, removing thalli and floccules through a microfiltration membrane to obtain 4.9L of fermentation liquor clear liquor, removing substances such as small molecular peptides, short chain proteins and the like in the fermentation liquor clear liquor by using a roll type ultrafiltration membrane separation system, wherein the cut-off molecular weight is 5KDa, the operating pressure is 3.0MPa, and collecting 4.8L of ultrafiltration membrane permeate;

step 2, decoloring: introducing the ultrafiltration membrane permeate collected in the step 1 into an activated carbon fiber module device with the specification of 5 inches for decolorization, wherein the decolorizing temperature is 50 ℃, the operating pressure is 0.5MPa, 4.8L of decolorized liquid is obtained, the light transmittance of the decolorized liquid is 82%, and after decolorization, 70 ℃ hot water is introduced into the activated carbon fiber module device for on-line regeneration and recycling;

step 3, electrodeionization: sending the decolorized solution obtained in the step 2 into a fresh room of an electrodeionization device, operating under the voltage of 30V, continuously detecting the conductivity of the solution in the fresh room, stopping operating when the conductivity is reduced to 500 mu s/cm, desalting to obtain desalted solution, and collecting 4.8L of the desalted solution;

and 4, concentrating and filtering: and (3) concentrating the desalted liquid obtained in the step (3) under reduced pressure until the content of L-homoserine is 90% -100%, precooling the temperature of the concentrated liquid to 8 ℃, slowly adding an organic solvent into the concentrated liquid according to the volume of 1 time per hour, uniformly stirring at the speed of 50r/min, stopping stirring and crystal growth for 8 hours when the addition amount of the organic solvent reaches 7 times of the volume of the concentrated liquid, continuously adding the organic solvent according to the volume of 1 time per hour until the volume of the concentrated liquid is 11 times, crystallizing for 18 hours at the temperature of 5 ℃, and performing suction filtration and drying to obtain the L-homoserine, wherein the L-homoserine is 145.1g, the purity is 99.1%, and the yield is 72.5%.

The concentration of the fermentation liquor in the step 1 is 30-50 g/L, and the fermentation liquor is produced by using Escherichia coli ZFGs012, and the strain is preserved in China general microbiological culture Collection center on 11 months and 11 days in 2020, with the address: china Beijing, the preservation number is CGMCC NO.21153, and the classification is named as Escherichia coli.

The preparation method of the water-soluble chitosan flocculant in the step 1 comprises the following steps:

step 1-1, preparing a chitosan solution with a mass-to-volume ratio of 1: 10;

step 1-2, adding glacial acetic acid to adjust the pH value to 3.8, fully stirring and standing for 12h, wherein the chitosan

The degree of deacetylation of (a) was 95%.

And 3, mixing the Cl type 717 resin and the Na type 732 resin in the resin added into the dilute chamber of the electrodeionization device in the step 3, adding 0.02mol/L sodium chloride solution into the concentrated chamber, adding 0.2mol/L sodium sulfate solution into the polar chamber, wherein the operating voltage is 30V, and the conductivity of the obtained desalted liquid is less than 500 mu s/cm.

The organic solvent in the step 4 is one of ethanol, methanol and acetone.

Comparative example 1

The fermentation liquid prepared in the above example 1 is extracted by an electrodialysis method, which comprises the following steps:

step 1, fermentation liquor pretreatment: taking 5L of fermentation liquor in a tank, wherein the concentration of homoserine is 35g/L, the pH value of the fermentation liquor is adjusted to be 4, adding 20mg/L of water-soluble chitosan flocculant, heating to 60-80 ℃, treating for 20 minutes, promoting flocculation and precipitation of water-soluble impurity protein, removing thalli and floccules through a microfiltration membrane to obtain 4.8L of fermentation liquor clear liquor, removing substances such as small molecular peptides, short chain proteins and the like in the fermentation liquor clear liquor by utilizing a roll type ultrafiltration membrane separation system, wherein the cut-off molecular weight is 0.5KDa, the operating pressure is 2.0MPa, and collecting 4.7L of ultrafiltration membrane permeate;

step 2, decoloring: introducing the ultrafiltration membrane permeate collected in the step 1 into an activated carbon fiber module device with the specification of 5 inches for decolorization, wherein the decolorizing temperature is 30 ℃, the operating pressure is 0.5MPa, 4.7L of decolorized liquid is obtained, the light transmittance of the decolorized liquid is 78.3%, and after decolorization, 70 ℃ hot water is introduced into the activated carbon fiber module device for online regeneration and recycling;

step 3, electrodialysis: desalting the decolorized solution obtained in the step 2 by using an electrodialysis device, injecting the decolorized solution into a dilute chamber at a feeding speed of 5L/H, injecting 2mM Na2SO4 into a concentrated chamber, wherein 0.05M NaOH and 0.05M H2SO4 are respectively used as a cathode and anode solution in the cathode and anode chambers, the operating voltage of the device is 20V, the treatment time is 3H, 18L of obtained analysis solution is obtained, and the electric conductivity of the analysis solution is 800 muS/cm;

and 4, concentrating and filtering: and (3) concentrating the desalted liquid obtained in the step (3) under reduced pressure until the content of L-homoserine is 90% -100%, precooling the temperature of the concentrated liquid to 0 ℃, slowly adding an organic solvent into the concentrated liquid according to the volume of 1 time per hour, uniformly stirring at the speed of 50r/min, stopping stirring and crystal growth for 5 hours when the addition amount of the organic solvent reaches 6 times of the volume of the concentrated liquid, continuously adding the organic solvent according to the volume of 1 time per hour until the volume of the concentrated liquid is 10 times, crystallizing for 16 hours at the temperature of 5 ℃, and performing suction filtration and drying to obtain the L-homoserine, wherein the L-homoserine is 115.6g, the purity is 95.1%, and the yield is 66.0%.

Comparative example 2

The fermentation liquid prepared in the above example 2 is extracted by an electrodialysis method, which comprises the following steps:

step 1, fermentation liquor pretreatment: taking 5L of fermentation liquor fed into a tank, wherein the concentration of homoserine is 35g/L, the pH value of the fermentation liquor is adjusted to 5.8, adding 80mg/L of water-soluble chitosan flocculant, heating to 60-80 ℃, treating for 40 minutes, promoting flocculation and precipitation of water-soluble impurity proteins, removing thalli and floccules through a microfiltration membrane to obtain 5L of fermentation liquor clear liquor, removing substances such as small molecular peptides, short chain proteins and the like in the fermentation liquor clear liquor by utilizing a roll type ultrafiltration membrane separation system, wherein the cut-off molecular weight is 10KDa, the operating pressure is 4.0MPa, and collecting 5L of ultrafiltration membrane permeate;

step 2, decoloring: introducing the ultrafiltration membrane permeate collected in the step 1 into an activated carbon fiber module device with the specification of 5 inches for decolorization, wherein the decolorizing temperature is 50 ℃, the operating pressure is 0.5MPa, 5L of decolorized liquid is obtained, the light transmittance of the decolorized liquid is 87.2%, and after decolorization, 70 ℃ hot water is introduced into the activated carbon fiber module device for on-line regeneration and recycling;

step 3, electrodialysis: desalting the decolorized solution obtained in the step 2 by using an electrodialysis device, injecting the decolorized solution into a dilute chamber at a feeding speed of 5L/H, injecting 2mM Na2SO4 into a concentrated chamber, wherein 0.05M NaOH and 0.05M H2SO4 are respectively used as a cathode and anode solution in the cathode and anode chambers, the operating voltage of the device is 20V, the treatment time is 3H, 18L of obtained analysis solution is obtained, and the electric conductivity of the analysis solution is 800 muS/cm;

and 4, concentrating and filtering: and (3) concentrating the desalted liquid obtained in the step (3) under reduced pressure until the content of L-homoserine is 90% -100%, pre-cooling the temperature of the concentrated liquid to 15 ℃, slowly adding an organic solvent into the concentrated liquid according to the volume of 1 time of each hour, uniformly stirring at the speed of 50r/min, stopping stirring and crystal growth for 8 hours when the addition amount of the organic solvent reaches 8 times of the volume of the concentrated liquid, continuously adding the organic solvent according to the volume of 1 time of each hour until the volume of the concentrated liquid is 12 times, crystallizing for 20 hours at the temperature of 5 ℃, and performing suction filtration and drying to obtain the L-homoserine, wherein the L-homoserine is 118.9g, the purity is 94.5%, and the yield is 67.9%.

Comparative example 3

The fermentation liquid prepared in the above example 3 is extracted by an electrodialysis method, which comprises the following steps:

step 1, fermentation liquor pretreatment: taking 5L of fermentation liquor in a tank, wherein the concentration of homoserine is 40g/L, the pH value of the fermentation liquor is adjusted to 4.5, adding 50mg/L of water-soluble chitosan flocculant, heating to 60-80 ℃, treating for 30 minutes, promoting flocculation and precipitation of water-soluble impurity protein, removing thalli and floccules through a microfiltration membrane to obtain 4.9L of fermentation liquor clear liquor, removing substances such as small molecular peptides, short chain proteins and the like in the fermentation liquor clear liquor by using a roll type ultrafiltration membrane separation system, wherein the cut-off molecular weight is 5KDa, the operating pressure is 3.0MPa, and collecting 4.8L of ultrafiltration membrane permeate;

step 2, decoloring: introducing the ultrafiltration membrane permeate collected in the step 1 into an activated carbon fiber module device with the specification of 5 inches for decolorization, wherein the decolorizing temperature is 50 ℃, the operating pressure is 0.5MPa, 4.8L of decolorized liquid is obtained, the light transmittance of the decolorized liquid is 82%, and after decolorization, 70 ℃ hot water is introduced into the activated carbon fiber module device for on-line regeneration and recycling;

step 3, electrodialysis: desalting the decolorized solution obtained in the step 2 by using an electrodialysis device, injecting the decolorized solution into a dilute chamber at a feeding speed of 5L/H, injecting 2mM Na2SO4 into a concentrated chamber, wherein 0.05M NaOH and 0.05M H2SO4 are respectively used as a cathode and anode solution in the cathode and anode chambers, the operating voltage of the device is 20V, the treatment time is 3H, 18L of obtained analysis solution is obtained, and the electric conductivity of the analysis solution is 800 muS/cm;

and 4, concentrating and filtering: and (3) concentrating the desalted liquid obtained in the step (3) under reduced pressure until the content of L-homoserine is 90% -100%, precooling the temperature of the concentrated liquid to 8 ℃, slowly adding an organic solvent into the concentrated liquid according to the volume of 1 time per hour, uniformly stirring at the speed of 50r/min, stopping stirring and crystal growth for 8 hours when the addition amount of the organic solvent reaches 7 times of the volume of the concentrated liquid, continuously adding the organic solvent according to the volume of 1 time per hour until the volume of the concentrated liquid is 11 times, crystallizing for 18 hours at the temperature of 5 ℃, and performing suction filtration and drying to obtain L-homoserine, wherein the content of L-homoserine is 137.0g, the purity is 96.1%, and the yield is 68.5%.

In order to better embody the benefits of the present invention, the results of the tests on the indexes of examples 1 to 3 and comparative examples 1 to 3 are described as follows:

in the comparative examples 1 to 3, L-homoserine is extracted by adopting an electrodialysis method, and through comparative analysis of various index test results of the examples 1 to 3 and the comparative examples 1 to 3, the comparative examples have obvious advantages in comparison with the comparative examples in terms of L-homoserine quality, L-homoserine purity, L-homoserine yield and the like, so that the electrodeionization method is more suitable for extracting L-homoserine than the electrodialysis method.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.