JPH0739368A - Dialysis fermentation method - Google Patents

Abstract

(57) [Summary] [Purpose] In the dialysis fermentation method, when the dialysis solution discharged from the desalting chamber side of the electrodialysis tank is used for fermentation again,
(EN) Provided is a method for maintaining sufficient production ability of a target substance in fermentation without supplementing various trace metal elements which become new divalent cations. 【Structure】 Cation exchange between anode and cathode The fermentation solution is supplied to the desalting chamber of the electrodialysis tank in which the membrane and the anion exchange membrane are alternately arranged, and the fermentation product in the fermentation solution, for example, sodium lactate in lactic acid fermentation, is added to the electrodialysis tank. In the dialysis fermentation method in which the dialysis solution separated into the concentration chamber and discharged from the desalting chamber of the electrodialysis tank is used for fermentation again, as a cation exchange membrane to be placed in the electrodialysis tank, at least one membrane surface layer part A dialysis fermentation method using a cation exchange membrane having an anion exchange group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dialysis fermentation method, more specifically, a fermentation solution in a desalting chamber of an electrodialysis tank in which a cation exchange membrane and an anion exchange membrane are alternately arranged between an anode and a cathode. The present invention relates to a dialysis fermentation method in which the fermentation product in the fermentation liquid is separated into the concentration chamber of the electrodialysis tank, and the dialysis solution discharged from the desalting chamber of the electrodialysis tank is used for fermentation again.

[0002]

2. Description of the Related Art In the microbial industry, as a method for improving the productivity of a target substance by fermentation, a fermentation broth is supplied to a desalting chamber of an electrodialysis tank so that the fermentation product in the fermentation broth is converted into the electrodialysis tank. There is known a dialysis fermentation method in which the dialysis solution separated into the concentration chamber of the electrodialysis tank and discharged from the desalting chamber side of the electrodialysis tank is used again for fermentation (Japanese Patent Laid-Open No. 63-148979, Japanese Patent Laid-Open No. 2-148979). 13386, JP-A-2-283289, etc.). In this method, the target substance can be separated from the fermentation broth very quickly and easily, and the dialysis solution from which the fermentation product has been separated is used again for fermentation, thereby Fermentation can be carried out efficiently without suffering from harmful effects such as growth inhibition of microorganisms due to excessive accumulation in the soil.

[0003]

In carrying out such a dialysis fermentation method using electrodialysis, when the dialysis solution is used again for fermentation, the production amount of the target substance in the fermentation is not reduced. Therefore, it is necessary to newly replenish the dialysis solution with a medium component necessary for growth of microorganisms consumed by fermentation. However, in addition to carbon sources, nitrogen sources, phosphate sources, etc., which are consumed in large quantities as energy sources for growth or main constituents of cells, among these medium components, the physiological effects of microorganisms are required although they are required in small amounts. There are metallic elements that play an important role in.
Specific examples of this metal element include potassium, which becomes a monovalent cation in the medium, and calcium, iron, manganese, zinc, copper, cobalt, molybdenum, etc. which also become a divalent cation in the medium. There are various metallic elements.

As described above, the amount of these metal elements required for the growth of microorganisms is small, and the amount consumed during fermentation is only a small amount, but most of them are fermented during electrodialysis of the fermentation broth. Separated from the liquor along with the fermentation products.
Therefore, as described above, when a medium component is newly supplied to the dialysis solution to be reused for fermentation, the carbon source, the nitrogen source, the phosphoric acid source and the like must be supplemented to some extent with the various metal elements. Even if the dialysis solution is reused for fermentation, it is impossible to maintain a sufficient ability to generate the target substance. Among the metal elements supplied to the dialysis solution, potassium, which becomes a monovalent cation in the medium, is usually added to the dialysis solution in the form of potassium dihydrogen phosphate or potassium monohydrogen phosphate. It is replenished without any particular attention because it is supplemented by a phosphate source or a potassium salt added as a pH regulator of the medium. Therefore, when replenishing the medium components, the metal elements that must be newly added in addition to the carbon source, the nitrogen source, the phosphoric acid source, etc. are mainly divalent cations in the medium solution as exemplified above. A metal element that becomes an ion.

However, in the medium components, there are various kinds of metal elements that become such divalent cations, as described above, and it is extremely complicated to supply such metal elements individually. It is also not economical to replenish such a metal element by adding yeast extract or the like containing the metal element in general, because the amount of the yeast extract, which is a relatively expensive reagent, increases.

From the above background, the present invention provides various trace amounts of new divalent cations when the dialysis solution discharged from the desalting chamber side of the electrodialysis tank is used for fermentation again in the dialysis fermentation method. It is an object of the present invention to provide a method for maintaining a sufficient production ability of a target substance in fermentation without supplementing metal elements.

[0007]

[Means for Solving the Problems] The inventors of the present invention have conducted extensive studies to solve the above problems. As a result, they have found that the above problems can be solved by using an electrodialysis tank that employs a specific cation exchange membrane as the electrodialysis tank applied to the dialysis fermentation method, and have proposed the present invention.

That is, according to the present invention, the fermentation liquid is supplied to a desalting chamber of an electrodialysis tank in which a cation exchange membrane and an anion exchange membrane are alternately arranged between an anode and a cathode, and the fermentation liquid is supplied. In the dialysis fermentation method in which the fermentation product inside is separated into the concentrating chamber of the electrodialysis tank and the dialysis solution discharged from the desalting chamber of the electrodialysis tank is used for fermentation again, the cations placed in the electrodialysis tank The dialysis fermentation method is characterized in that a cation exchange membrane in which an anion exchange group is present in at least one membrane surface layer is used as the exchange membrane.

Fermentation in the present invention can be applied to any known fermentation as long as the fermentation product is an electrolyte. For example, glutamic acid fermentation, lysine fermentation, valine fermentation, ortinin fermentation, threonine fermentation,
Amino acid fermentation such as isoleucine fermentation; inosine acid fermentation,
Nucleic acid fermentation such as guanylic acid fermentation; organic acid fermentation such as citric acid fermentation, fumaric acid fermentation, gluconic acid fermentation, lactic acid fermentation, succinic acid fermentation, acetic acid fermentation and malic acid fermentation.

Further, various culture conditions such as the type of microorganism used in the fermentation in the present invention, the composition of the medium, the culture temperature, the pH of the fermentation broth and the degree of aeration and stirring are known to be applied in the various fermentations described above. The conditions are adopted without any restrictions.

The medium used in this case may be either a synthetic medium or a natural medium as long as it contains a main carbon source, a nitrogen source, an inorganic substance and other growth promoting substances. When electrodialysis is performed, it is preferable to use a synthetic medium from the viewpoint of preventing the ion exchange membrane from being clogged or deteriorated to cause an abnormal increase in voltage and a decrease in current efficiency.

For example, as the carbon source often used, sugars such as sucrose, galactose, fructose, glucose, starch, maltose, xylose and lactose; alcohols such as methanol, ethanol, n-propyl alcohol and glycerin; n-paraffin and the like. Chain hydrocarbons, etc., which may be used as a mixture. As the nitrogen source, inorganic or organic nitrogen compounds such as polypeptone, ammonia, ammonium sulfate, ammonium sulfate, ammonium salt, ammonium phosphate, urea, ammonium acetate, ammonium citrate, etc. are used. Usually, in addition to these, these metal salts as a phosphoric acid source, potassium source, magnesium source, sulfur source,
For example, in the case of the above-mentioned phosphoric acid source and potassium source, potassium dihydrogen phosphate, potassium monohydrogen phosphate, etc. are added. Furthermore, growth promoting substances such as biotin, thiamine and yeast extract, and calcium carbonate and caustic soda may be added as pH adjusters. In addition, it is a preferred embodiment that a substance that reversibly undergoes redox is present in the medium. Such substances include metals such as iron, manganese, copper, zinc and cobalt. The amount of these substances used is not particularly limited, but in consideration of the amount of fermentation production, it is generally preferable to use in the range of 1 mg to 1000 mg / liter in the fermentation liquid.

In the present invention, as the microorganisms to be used in fermentation, the culture solution of the bacterial cells can be used as it is, or the bacterial cells can be immobilized by a known method without any limitation.

The most important feature of the present invention is that, when the above fermentation is carried out by a dialysis fermentation method using electrodialysis, an anion is present on at least one membrane surface layer as a cation exchange membrane to be placed in an electrodialysis tank. The point is that a cation exchange membrane having an exchange group is used. Thus, when using an ion exchange membrane having the above-mentioned specific structure as the cation exchange membrane of the electrodialysis tank applied to the dialysis fermentation method, in electrodialysis, divalent metal ions that are necessary components for fermentation are used. Etc. are prevented from being separated from the fermentation liquor, and as a result, the dialysis treatment liquid thus obtained maintains a high ability to produce a target substance even when it is used again for fermentation.

In the present invention, the cation exchange membrane having an anion exchange group on at least one surface layer of the membrane may be any known ion exchange membrane having such a structure without any limitation. Specifically, Japanese Patent Publication 6
0-43857, Japanese Patent Publication No. 62-5179,
It is known from JP-A-62-205135.
Examples of the cation exchange group of such a cation exchange membrane include a sulfonic acid group, a carboxylic acid group, a phosphonic acid group, a sulfuric acid ester group, a phosphoric acid ester group, and the like, and a combination of a plurality of these ion exchange groups. To be The anion-exchange groups to be present on the surface layer of the cation-exchange membrane include primary amino group, secondary amino group, tertiary amino group, and 4
Examples include a combination of a primary ammonium group and a plurality of types of these ion exchange groups. The amount of such anion-exchange group present is not particularly limited, but is generally preferably 0.0001 to 1.0 meq / g. This cation exchange membrane is classified into polymerization type, condensation type, homogeneous type and heterogeneous type, and is derived from the presence or absence of reinforcing core material, hydrocarbon type, fluorine type, material and manufacturing method. Any cation exchange membrane may be used regardless of the type and model of the cation exchange membrane. Further, an aqueous solution of 2N-saline is electrodialyzed at a current density of 5 A / dm ² , and the one having a current efficiency of 70% or more and substantially functioning as a cation exchange membrane is generally called an amphoteric ion exchange membrane. Even if it is one, it can be used as the cation exchange membrane of the present invention. In the present invention, the cation exchange membrane usually has an ion exchange capacity of 0.1 to 20 meq / g, preferably 0.5 to 3.
0 meq / g, and

[0016]

[Equation 1]

It is preferred to use those of

In the present invention, a cation exchange membrane in which an anion exchange group is present on at least one surface layer portion of the membrane, which is preferably used, is exemplified by those obtained by the following production method. That is, a polymer film made of a cloth substrate and a styrene / divinylbenzene polymer is immersed in a mixed solution of chlorosulfonic acid / sulfuric acid to introduce a sulfonyl chloride group into the benzene ring, and then a sulfonyl group is formed on the surface of the film. It is obtained by binding chloride and a polyamine having a polyvalent amino group such as polyethyleneimine, and further hydrolyzing the sulfonyl chloride group inside the membrane with a sodium hydroxide solution.

In addition, as another one, pentamethyliminobispropylamine, which is a trivalent tertiary amine, is reacted with three times the amount of chloromethylstyrene so that a quaternary ammonium base and a vinylbenzyl group are three-specific. Get the compound,
Next, a cation exchange membrane is dipped in an aqueous solution of this compound to adsorb the compound on the surface portion of the cation exchange membrane, and further, a vinyl group on the membrane surface is polymerized to obtain a product.

On the other hand, in the present invention, the anion exchange membrane used for electrodialysis of the fermentation broth is not particularly limited, and a known anion exchange membrane can be used. For example, a primary amino group, a secondary amino group, a tertiary amino group, a quaternary ammonium group, and an anion exchange membrane in which a plurality of these ion exchange groups are mixed can be used. Further, the anion exchange membrane may be of a polymerization type, a condensation type, a homogeneous type or a heterogeneous type, and is derived from the presence or absence of a reinforcing core material, a hydrocarbon type, a fluorine type, a material and a manufacturing method. Any anion exchange membrane may be used regardless of the type and model of the anion exchange membrane. 2N
-A salt solution is electrodialyzed at a current density of 5 A / dm ² , and if it has a current efficiency of 70% or more and substantially functions as an anion exchange membrane, it is generally called an amphoteric ion exchange membrane. However, it can be used as the anion exchange membrane of the present invention.

In the present invention, the cation exchange membrane and the anion exchange membrane include ultraviolet rays, alcohol, a surfactant,
Those that can be sterilized by a sterilizing agent, acid, base, salt, heat, etc. and can be washed are preferable.

Next, in the present invention, in the electrodialysis tank in which the cation exchange membrane and the anion exchange membrane described above are installed, the cation exchange membrane and the anion exchange membrane are alternately arranged between the anode and the cathode. A known electrodialysis tank having the structure described above can be used without any limitation. FIG. 1 shows a schematic diagram of a typical embodiment of the electrodialysis tank used in the present invention. That is, FIG. 1 shows the anode 3
It is an electrodialysis tank in which an anion exchange membrane (A) and a cation exchange membrane (C) are alternately arranged between the cathode and the cathode 4. In this electrodialysis tank, from the anode side, the anode chamber 1, the concentration chamber 5, the desalting chamber 6,
It is divided into a concentrating chamber 5, a desalting chamber 6 and a cathode chamber 2. The fermenter 11 is connected to the desalting chamber tank 9 of the electrodialysis tank.

In the electrodialysis tank having such a structure, in the electrodialysis of the fermented solution, the fermented solution cultured in the fermenter 11 is first introduced into the desalting chamber 6, and then the fermented product is produced in the desalting chamber 6. It is performed by passing through the anion-cation exchange membrane and moving to the concentration chamber 5. At this time, in order to prevent clogging of the electrodialysis tank, it is preferable that the fermented liquor is clarified in advance by removing insoluble suspension by ultrafiltration, microfiltration or centrifugation.

On the other hand, the dialyzed solution is collected in the fermenter 11. The fermentation product moved to the concentration chamber 5 is collected in the concentration tank 8 together with the concentration liquid circulated in the concentration chamber 5. The supply of the fermented liquid from the fermenter 11 to the electrodialysis tank may be performed by intermittently supplying the fermented liquid from the fermenter 11 to the electrodialysis tank every time fermentation is performed in the fermenter 11. A part of the fermentation liquid may be continuously supplied from the fermentation tank 11 to the electrodialysis tank so that fermentation and electrodialysis are performed in parallel. Further, in FIG. 1, the fermentation tank 11 and the electrodialysis tank are provided independently, and the fermentation and the electrodialysis are performed in separate tanks.
The fermentation can also be carried out in a desalting chamber and / or a cathode chamber.

In the electrodialysis cell shown in FIG. 1, platinum, graphite, nickel or the like is preferably used as the anode 3, and platinum, iron, stainless steel, nickel or the like is preferably used as the cathode 4. As the anolyte 1 and the catholyte 2, known ones can be used, but generally, an aqueous solution of sulfuric acid, sodium sulfate or caustic soda is used as the anion / anolyte. The fermentation broth can also be passed through the cathode chamber without using the catholyte.

In the present invention, the dialysis of the fermented liquor in such an electrodialysis tank is not particularly limited, and it can be carried out under known electrodialysis operating conditions. Generally, the voltage is selected from 0.1 V to 5 V / cell, and the current density is selected from the range of 0.1 to 20 amps / dm ² . When dialysis fermentation is continuously operated for a long period of time, the cell voltage may rise, but at this time, the electrodialysis tank contains a surfactant, bactericide, acid, base, salt, oxidizing agent, and reducing agent. The deterioration of electrodialysis performance can be minimized by performing a sterilization treatment or a washing operation with an agent or a foaming agent.

[0027]

EFFECTS OF THE INVENTION Normally, in the dialysis fermentation method utilizing electrodialysis, even if the dialysis solution is used for fermentation again while supplementing the carbon source, nitrogen source and phosphoric acid source consumed by fermentation, electrodialysis is performed. Since the divalent metal ions necessary for the growth of microorganisms are separated from the fermentation liquor, the ability to produce the target substance is reduced. However, according to the dialysis fermentation method of the present invention using a specific cation exchange membrane in which an anion exchange group is present in at least one membrane surface layer portion as described above as the cation exchange membrane arranged in the electrodialysis tank, Since separation and disappearance of divalent metal ions from the fermentation broth during electrodialysis are prevented, as a result, the ability to produce the target substance is maintained high even when the dialysis treatment liquor is used again for fermentation.

Further, according to the dialysis fermentation method of the present invention, the concentration of polyvalent metal ions mixed in the fermented product concentrated by electrodialysis is reduced, so that the fermentation product can be easily purified. Furthermore, it should be noted that the concentrations of carbon sources such as carbon sources and amino acids in the fermentation liquor mixed in the fermentation products can be significantly reduced.

[0029]

EXAMPLES In order to describe the present invention more specifically, examples and comparative examples will be described below, but the present invention is not limited to these examples. Example 1 As an inoculum, L-lactic acid producing bacterium Lactobacillus delplutsky IF03534 was used. Glucose 10
g / l, polypeptone 50 g / l, yeast extract 5 g / l
10 ml of a liquid medium (pH 7.0) consisting of was dispensed into a medium-sized test tube, and autoclaved at 121 ° C. for 15 minutes.
1 platinum loop of this inoculum was inoculated into this, and static culture was carried out at 45 ° C. for 24 hours. 10 ml of this culture was sterilized in the same manner as 100 ml of glucose 10 g / l and polypeptone 10 g /
l, yeast extract 5 g / l, sodium acetate 10 g / l in a liquid medium (pH 6.8) and inoculated at 45 ° C for 15
The seed mother was adjusted by static culture for a period of time.

As the medium for the main culture, glucose 100
g / l, yeast extract 20 g / l, polypeptone 8 g /
1, potassium dihydrogen phosphate 0.3 g / l, and magnesium sulfate 0.5 g / l were used. 10 liters of the above-mentioned medium was dispensed into a 20-liter glass fermenter, and after sterilization, when cooled to room temperature, 1 liter of the seed mother was inoculated, and p
While H was adjusted to 6 with an aqueous solution of caustic soda, the culture was gently stirred at 45 ° C. for 2 days.

The fermented liquid was centrifuged to obtain a clear solution, and this liquid was subjected to electrodialysis. The composition of this liquid is shown in Table 1.
(Before electrodialysis).

The cation exchange membrane used in the present invention was obtained as follows. First, 20.1 g (0.1 m of pentamethyliminobispropylamine, which is a trivalent tertiary amine)
ol) and 46 g (0.3 mol) of chloromethylstyrene
Was reacted in 200 ml of methanol for 48 hours,
A compound unique to each of the tertiary ammonium base and the vinylbenzyl group was obtained. Tokuyama Soda Co., Ltd. cation exchange membrane Neoceptor CM-1 in an aqueous solution containing 1000 ppm of this compound.
Was immersed at 30 ° C. for 2 hours, and then potassium persulfate and sodium sulfite as polymerization initiators were added so as to be 1000 ppm each under a nitrogen atmosphere, and the mixture was vigorously stirred for 10 hours. Thus, a cation exchange membrane was obtained.
This cation exchange membrane has an ion exchange capacity of 2.2.
0 meq / g, the abundance of the anion exchange substance in the membrane surface layer part is 0.04 meq / g,

[0033]

[Equation 2]

Was 0.10.

As the anion exchange membrane, anion exchange membrane Neoceptor AMX manufactured by Tokuyama Soda Co., Ltd. was used. The electrodialysis tank is manufactured by Tokuyama Soda Co., Ltd. TS-2 (effective membrane area: ² dm ² /
Used). 10 sheets of anion exchange membranes and 11 sheets of cation exchange membranes were alternately laminated to obtain an electrodialysis tank. 0.72 liter of 11.2 g / l sodium lactate solution was fed to the concentrating chamber, and 5 liter of the clear fermentation broth obtained by the above-described centrifugation was fed to the desalting chamber. Current density is 3 amps / dm
^{At 2} , the power was turned on for 2 hours. Liquid volume and components after electrodialysis are shown in Table 1.
(Example 1 after electrodialysis) The amount of liquid in the concentrating chamber is 2.
Increased to 0 liters, the concentration of sodium lactate is 224g
/ L, magnesium concentration is 15 ppm, glucose and amino acid concentrations are 0.52 g / l and 0.22 g, respectively.
It was / l.

Water is added to the above desalting chamber solution which is a dialysis solution.
Glucose, potassium dihydrogen phosphate, and magnesium sulfate were added to give concentrations of glucose 100 g /
l, potassium dihydrogen phosphate 0.3 g / l, magnesium sulfate 0.5 g / l to make the final medium again,
The desalting compartment solution was subjected to fermentation again. 10 liters of the above medium was dispensed into a 20 liter glass fermentor, 1 liter of the seed mother was inoculated, and the pH was adjusted to 6 with an aqueous solution of caustic soda while gently stirring and culturing for 2 days at 45 ° C. went.

The fermented broth was centrifuged to obtain a clear solution, and the concentration of sodium lactate in this liquor was measured. As a result, the concentration was 108 g / l, and the lactic acid production capacity of the medium was almost unchanged. It was

Comparative Example 1 The same operation was carried out except that Neoceptor CM-1 was used as the cation exchange membrane in Example 1, and electrodialysis was carried out until the sodium lactate concentration in the desalting chamber reached 32.3 g / l. .
Table 1 (Comparative Example 1 after electrodialysis) shows the liquid amounts and components in the concentrating chamber and the desalting chamber at this time. The magnesium concentration in the concentrating chamber was 180 ppm, which was significantly higher than that in the examples.
Further, glucose and amino acids also leaked to the concentrating chamber more frequently than in the examples.

Water is added to the above desalting chamber solution which is a dialysis solution.
Glucose, potassium dihydrogen phosphate and magnesium sulfate are added to give a concentration of 100 g / l glucose, 0.3 g / l potassium dihydrogen phosphate and 0.5 g magnesium sulfate.
The culture medium was readjusted to give a final medium of 1 / l, and the solution in the desalting compartment was subjected to fermentation again. 10 liters of the above medium was dispensed into a 20 liter glass fermentor, 1 liter of the seed mother was inoculated, and the pH was adjusted to 6 with an aqueous solution of caustic soda while gently stirring and culturing for 2 days at 45 ° C. went.

This fermentation broth was centrifuged to obtain a clear solution, and the concentration of sodium lactate in this liquor was measured. The concentration was only 96 g / l.

[0041]

[Table 1]

Example 2 As the inoculum, Candida giamandy IFO 0566 having an ability to produce citric acid was used. Sucrose 5
1 platinum loop of a slant medium was inoculated into a liquid medium consisting of 0 g / l, asparagine 2.5 g / l, potassium dihydrogen phosphate 0.4 g / l, and magnesium sulfate 0.5 g / l at 30 ° C.
After shaking culture for 2 days, the cells were collected by centrifugation.

As a medium for the main culture, sucrose 10
0 g / l, ammonium chloride 4 g / l, potassium dihydrogen phosphate 0.4 g / l, magnesium sulfate 0.5 g / l,
Using a liquid medium consisting of 1 g / l of yeast extract, inoculate it with 1 g of cells, perform aeration stirring at 30 ° C. and 200 rpm, and ferment for 4 days while controlling the pH to 5.0 by adding an aqueous solution of caustic soda. I went.

The fermentation broth was centrifuged to obtain a clear solution, which was subjected to electrodialysis. The components of this liquid are shown in Table 2.
(Before electrodialysis).

The cation exchange membrane was obtained as follows.
A polyvinyl chloride cloth base material and a polymer film containing a styrene / divinylbenzene polymer as a main component are immersed in a mixed solution of chlorosulfonic acid / sulfuric acid (1: 1) at 40 ° C. for 30 minutes to sulfonyl the benzene ring. The chloride group was introduced. Then, it was sequentially diluted with sulfuric acid and washed with water to obtain a polymer film having a sulfonyl chloride group. Then, add 1
It was immersed in a 0% polyethyleneimine aqueous solution at 25 ° C. for 24 hours to bond the sulfonyl chloride group and polyethyleneimine. Then, the sulfonyl chloride group inside the membrane was hydrolyzed with a 10% aqueous sodium hydroxide solution to obtain a cation exchange membrane. In addition, this cation exchange membrane is
The ion exchange capacity is 2.00 meq / g, the existing amount of the anion exchange material in the membrane surface layer part is 0.05 meq / g,

[0046]

[Equation 3]

Was 0.12.

As the anion exchange membrane, anion exchange membrane Neoceptor AMX manufactured by Tokuyama Soda Co., Ltd. was used.

The electrodialysis tank is an electrodialysis tank TS manufactured by Tokuyama Soda Co., Ltd.
-2 (effective membrane area: ² dm ² / sheet) was used. 10 sheets of anion exchange membranes and 11 sheets of cation exchange membranes were alternately laminated to obtain an electrodialysis tank. An 8.6 g / l sodium citrate solution was fed to the concentrating chamber, and a clear fermentation broth obtained by the above-described centrifugation was fed to the desalting chamber. Current density is 3 amps / dm ²
Then, it was energized for 2 hours. Table 2 shows the liquid volume and components after electrodialysis.
(Example 2 after electrodialysis)

Water is added to the above desalting chamber solution which is a dialysis solution.
Sucrose, ammonium chloride, potassium dihydrogen phosphate and magnesium sulfate are added to give a concentration of 100 g / l sucrose, 4 g / l ammonium chloride, 0.4 g / l potassium dihydrogen phosphate, 0.5 g magnesium sulfate /
The culture medium was readjusted to 1 to give a main medium, and the desalting compartment solution was again subjected to fermentation. Inoculate this with 1 g of bacterial cells, and
Fermentation was carried out for 4 days while controlling the pH to 5.0 by performing aeration stirring at 200 rpm and adding a caustic soda aqueous solution.

The fermentation broth was centrifuged to obtain a clear solution, and the concentration of sodium citrate in this liquor was measured. As a result, the concentration was 88 g / l, and the citric acid production capacity of the medium was almost reduced. Didn't.

Comparative Example 2 The same operation was carried out except that the cation exchange membrane used in Example 2 was not treated with polyethyleneimine. The sodium citrate concentration in the desalting compartment solution is 12.
It was electrodialyzed to 4 g / l. Concentration room at this time,
Table 2 shows the liquid volume and the composition of components in the desalting chamber (Comparative Example 2 after electrodialysis)
It was shown to. The magnesium concentration in the concentrating chamber was 188 ppm, which was significantly higher than that in the examples. Further, glucose and amino acids also leaked to the concentrating chamber more frequently than in the examples.

Water is added to the above desalting chamber solution which is a dialysis solution.
Sucrose, ammonium chloride, potassium dihydrogen phosphate and magnesium sulfate are added to give a concentration of 100 g / l sucrose, 4 g / l ammonium chloride, 0.4 g / l potassium dihydrogen phosphate, 0.5 g magnesium sulfate /
The culture medium was readjusted to 1 to give a main medium, and the desalting compartment solution was again subjected to fermentation. Inoculate this with 1 g of bacterial cells, and
Fermentation was carried out for 4 days while controlling the pH to 5.0 by performing aeration stirring at 200 rpm and adding a caustic soda aqueous solution.

The fermentation broth was centrifuged to obtain a clear solution, and the concentration of sodium citrate in this liquor was measured. As a result, the concentration was only 76 g / l.

[0055]

[Table 2]

[Brief description of drawings]

FIG. 1 is a schematic view of a typical embodiment of an electrodialysis tank used for dialysis fermentation of the present invention.

[Explanation of symbols]

 1 Anode Chamber (Liquid) 2 Cathode Chamber (Liquid) 3 Anode 4 Cathode 5 Concentration Chamber 6 Desalting Chamber 7 Electrode Tank 8 Concentrate Tank 9 Desalination Tank 10 DC Power Supply 11 Fermenter C Cation Exchange Membrane A Anion Exchange membrane

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location // (C12P 7/48 C12R 1:72) (C12P 7/56 C12R 1: 225)

Claims (1)

[Claims] 1. Fermentation liquid is supplied to a desalting chamber of an electrodialysis tank in which cation exchange membranes and anion exchange membranes are alternately arranged between an anode and a cathode, and fermentation production in the fermentation liquid is performed. In the dialysis fermentation method in which the substance is separated into the concentrating chamber of the electrodialysis tank, and the dialysis liquid discharged from the desalting chamber of the electrodialysis tank is used for fermentation again, as a cation exchange membrane arranged in the electrodialysis tank, A dialysis fermentation method characterized by using a cation exchange membrane having an anion exchange group on at least one membrane surface layer portion.