JP2758797B2 - Polysaccharide extraction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for extracting polysaccharides,
More specifically, the present invention relates to a polysaccharide extraction method capable of recovering a light-colored polysaccharide from an algal culture by a simple operation.

[0002]

2. Description of the Related Art Conventionally, as a method for extracting polysaccharides from microalgae, a method using a strong acid or a strong alkali has been known (Japanese Patent Application Laid-Open No. 58-201993). There was a problem that some of the molecules were reduced in molecular weight due to hydrolysis with alkali. As a method for solving the above-mentioned problem, the present applicant has disclosed in Japanese Patent Application Laid-Open Nos. 4-158794 and 4-222593 that a cell of a wet alga body separated from an algal culture solution is destroyed and then a protease and / or Alternatively, a method for extracting polysaccharides by performing an enzymatic reaction with a fatty acid ester degrading enzyme was proposed. According to this method, a low molecular weight of the polysaccharide can be prevented because a strong acid or a strong alkali is not used. However, since a large amount of alcohol is required to recover the polysaccharide, the cost cannot be reduced, and the wet alga cannot be reduced. There was a drawback that light-colored polysaccharides could not be obtained because pigments contained in the body could not be removed. In addition, polysaccharides are contained not only in the wet alga body but also in the culture solution,
At present, the culture solution is discarded because the recovery rate of the polysaccharide contained in the culture solution is low and the cost is high.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to carry out a simple operation without pigmenting not only wet algal cells but also polysaccharides contained in a culture solution. It is an object of the present invention to provide a polysaccharide extraction method which can be extracted at low cost.

[0004]

According to the present invention, when extracting a polysaccharide from an algal culture, the algal culture is irradiated with light under aseptic conditions, and then left until the pigment of the culture has faded. The present invention relates to a method for extracting a polysaccharide, which comprises extracting a polysaccharide. In the present invention, since the extraction of the polysaccharide is performed after the pigment contained in the microalgae of the alga culture solution is faded, the pigment is not deposited on the polysaccharide during the extraction and purification of the polysaccharide, and therefore, the extraction is not performed. And the operation of purification can be simplified. In addition, not only the wet alga bodies in the algal culture solution but also the polysaccharides contained in the culture solution can be recovered at low cost, so that the polysaccharide recovery rate is improved.

[0005] The microalgae used in the present invention are not particularly limited.
, Fresh water) is preferable because it contains a large amount of polysaccharides. These microalgae are used after being cultured by a known method. The cells of the microalgae contain a large amount of polysaccharides, but the cells themselves are covered not by cell walls but by extracellular polysaccharides, and the polysaccharides are present in the culture solution in a dissolved state.
Algae culture solution used in the present invention, under light irradiation in advance,
Leave aseptically. Light having a wavelength ranging from ultraviolet to visible light, such as sunlight, is used for light irradiation. The standing temperature is usually room temperature, but is not particularly limited. The algal culture is left standing or shaking until the pigment of the culture has faded, specifically until the culture has a milky semi-gel, gel or dryness. Usually, the leaving period is about two weeks to one month.

[0006] There is no particular limitation on the method for extracting polysaccharide from a milky semi-gel or dried solid culture, but in order to obtain a high molecular weight polysaccharide, extraction is performed as follows. Is preferred. First, distilled water is added to the culture to sufficiently dissolve the polysaccharide in the culture, and then homogenized or heated to form a uniform suspension. The suspension is then treated with proteinase, fatty acid esterase, and the like. And the mixture is stirred for 4 hours to overnight to cause an enzyme reaction to decompose protein components. As the proteolytic enzyme, for example, papain or various proteases, which are mixed enzyme agents of neutral or weakly alkaline endo- or exo-type proteases, are used. Lipase, for example, pacreatin is used. These enzymes may be used alone or in combination. The amount of enzyme to be added is usually 10, 10
000 to 50,000 U (unit), and usually 7,500 to 30,000 U for fatty acid esterase. The enzymatic reaction is usually performed at 30 to 80 ° C, preferably at 40 ° C.
Stir or shake at a temperature of ６０60 ° C.

After completion of the enzymatic reaction, a 2/3 to 1 volume of a water-miscible organic solvent such as alcohol is added to collect and suspend the polysaccharide, and after removing the solvent sufficiently, it is dried at 40 ° C.
It can be ground to obtain a polysaccharide product. According to such an extraction method, since the solid-liquid separation operation is insoluble and the washing operation of the recovered polysaccharide with alcohol or the like can be omitted, the extraction and purification steps can be simplified and the amount of alcohol used can be reduced. Can be planned. This polysaccharide is highly viscous and has the effect of reducing fluid frictional resistance.
It can be used as a thickener, a dispersion suspension stabilizer, an emulsifier, and the like.

[0008]

The present invention will be described below with reference to examples. Example 1 Artificial seawater (ASW) was used as a medium using microalgae (Polyphyllium kruentum) as a medium, and a halogen lamp was used as a light source.
Culture was carried out while passing air containing 5% of CO ₂ to obtain an algal culture solution. One liter of the obtained culture solution was transferred to a flask with a cotton stopper sterilized in advance by an autoclave. The flask containing the culture solution was placed in a germicidal lamp (wavelength 253.7 n).
m, output: 2.0 W) and stored at 25 ° C. for one month under irradiation. The culture solution in the flask turned from pale red to milky white gel.

360 ml of distilled water was added to the flask and stirred to obtain a suspension in which the polysaccharide was dissolved at a concentration of 2% by weight. This suspension was homogenized at 10,000 rpm for 1 minute to obtain a uniform suspension. To this, 3 g of protease A (produced by Amano Pharmaceutical Co., Ltd.), which is a protease, was added, and the mixture was stirred at 50 ° C. for 6 hours. The components were decomposed.
After completion of the reaction, an equal amount of ethanol was added, the polysaccharide was suspended and collected by filtration, the solvent was sufficiently removed, vacuum dried at 40 ° C., and pulverized to obtain a polysaccharide product. This product was pale yellowish white.

Comparative Example 1 10 g of wet algal cells were obtained from the algal culture obtained in the same manner as in Example 1.
(Solid content: 13% by weight) was separated by a solid-liquid separation operation.
Homogenized at rpm for 1 minute, then heated at 80 ° C. for 20 minutes. The solution is cooled to room temperature and 1N-NaOH
The pH was adjusted to 8 with 3 g of protease A, and 50 g was added.
The mixture was stirred at 6 ° C. for 6 hours to carry out an enzymatic reaction. After the reaction is completed, an equal amount of ethanol is added to recover the polysaccharide, and
Washing was performed up to 5 times to sufficiently decolorize. Thereafter, the solvent was sufficiently removed, and then vacuum dried at 40 ° C. to obtain a product. The resulting polysaccharide product was greenish brown.

[0011]

According to the method of the present invention, the pigment which has been difficult to remove by deposition on the polysaccharide can be faded before the extraction of the polysaccharide. Can be obtained by simple operations. Further, the washing operation for removing the pigment after the recovery of the polysaccharide is insoluble, so that the operation can be simplified and the amount of the washing solvent used can be reduced. Further, since not only the wet algal cells but also the polysaccharide contained in the culture solution can be extracted, the recovery rate of the polysaccharide is improved, and the cost can be reduced.

Claims (1)

(57) [Claims] When extracting a polysaccharide from an algal culture solution, the algal culture solution is irradiated with light under aseptic conditions, and left until the pigment of the culture solution fades, and then the polysaccharide is extracted. Extraction method for polysaccharides.