JP2002262899A - Method for isolating l-arabinose - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for selectively isolating L-arabinose from a solution containing L-arabinose and D-xylose obtained by hydrolysis with an acid or an enzyme of corn grain hulls, corn cobs or the like. SOLUTION: This method for isolating L-arabinose comprises characteristically treating a solution including L-arabinose and D-xylose as main saccharides with a yeast that selectively assimilates D-xylose.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for separating L-arabinose from a solution containing L-arabinose simply and efficiently.

[0002]

2. Description of the Related Art It has been shown that L-arabinose, when taken together with sucrose, suppresses digestion and absorption of sucrose and reduces its energy utilization (Sanai et al., Journal of Japanese Society of Nutrition and Food, vol. 133, p. 133). 1997)), and attention has been paid to a production method together with its physiological activity. L-arabinose is contained in corn grain hulls, corn cobs, wheat bran, soy hulls, mesquite gum, beet pulp, etc. It exists in the form of a complex polysaccharide. As a method for releasing L-arabinose as a monosaccharide from these materials, a hydrolysis method using an acid or an enzyme is generally used. The acid hydrolysis method is mesquite gum (Cramer FB., J. Fr
anklin Institute, 256, (1953) 93-94), corn kernels (Osborn D. and Chen LF., J. Starch / Starke, 3
6, (1984) 393-395), various dietary fibers (JP-A-11-31370).
No. 0), and the enzymatic hydrolysis method is beet pulp (Kusukabe et al., Journal of the Japanese Society of Agricultural Chemistry, 49,
75) 295-305). Separately, a method of allowing a pectinase-producing microorganism to act on pectin-containing substances such as citrus fruits and beet pulp (Japanese Patent Publication No. 35-13650)
No.).

[0003] Regardless of which of these methods is selected, D-xylose, D-xylose,
Carbohydrates such as D-galactose and oligosaccharides coexist. In particular, when L-arabinose is purified from corn kernel and corn cob hydrolyzate, a method for selectively removing D-xylose is an essential technique for industrially obtaining high-purity crystalline L-arabinose. Becomes As a known technique for separating D-xylose and L-arabinose, there is a chromatographic separation method using a cation exchange resin (JP-A-2000-201700). However, it is expensive to treat a large amount of hydrolyzate on an industrial scale. However, there is a problem in that a large-scale apparatus is required, and it is difficult to set chromatographic separation conditions.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a method for selectively producing L-arabinose from a solution containing L-arabinose and D-xylose obtained by hydrolysis of corn hulls, corn cobs, etc. with an acid or an enzyme. It is intended to provide a method for separating.

[0005]

Means for Solving the Problems The present inventors have prepared a yeast obtained by the above hydrolysis, which selectively assimilates D-xylose into a solution containing L-arabinose and D-xylose as main carbohydrates. If acted, D-xylose selectively disappears from the raw material solution, and the yeast used does not produce by-products that adversely affect the separation of L-arabinose, so that L-arabinose can be efficiently separated and purified, The present invention has been completed.

[0006] That is, the present invention relates to the present invention, wherein L-
It is intended to provide a method for separating L-arabinose, which comprises treating a solution containing arabinose and D-xylose with a yeast which selectively assimilates D-xylose.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION As a solution containing L-arabinose and D-xylose as main saccharides used as a raw material in the present invention, a hydrolyzate of a plant tissue containing arabinoxylan can be mentioned. Examples of such plant tissues include corn grain hulls, corn cobs, soy hulls, wheat bran, rice bran, straw, rice straw and the like. Hydrolysis of these plant tissues with a mineral acid such as sulfuric acid, hydrochloric acid, phosphoric acid or the like, or an organic acid such as oxalic acid or acetic acid can release L-arabinose and D-xylose as constituent monosaccharides. By devising hydrolysis conditions such as acid concentration and temperature, L-arabinose can be preferentially released (JP-A-11-313700). The constituent monosaccharides can also be released from the above-mentioned plant tissue by a method using enzymes such as cellulase, hemicellulase, xylanase, arabinase, arabinofuranosidase and pectinase. Enzymatic hydrolysis is slower than acid hydrolysis, but it can liberate L-arabinose more preferentially (Kusakabe et al., Proceedings of the Japanese Society of Agricultural Chemistry 1999 Annual Meeting, p. 35).

In the present invention, it is preferable that the above-mentioned enzymatic or acid hydrolyzate of plant tissue is neutralized before use. In addition, as pretreatment of the separation operation of the present invention, it is preferable to perform treatment such as centrifugation, filtration, desalination, decolorization, and sterilization.

In the present invention, the content ratio (weight ratio) of L-arabinose to D-xylose in the raw material solution is usually 2%.
0: 1 to 1:15. Further, the concentration of L-arabinose is preferably 0.1 to 15% by weight, particularly preferably 0.1 to 5% by weight.

[0010] Examples of yeast that selectively assimilate D-xylose used in the present invention include Williopsis saturnus and Can.
dida utilis or a variant thereof is preferred. Here Willi
A variant of opsi s saturnus is Willopsis saturnus va
r. saturnus . More specifically, Williopsi
s saturnus var. Saturnus IFO 0992, Candida utilis
IFO 0619 and the like.

As means for treating the raw material solution with the yeast, the raw material solution may be inoculated with the yeast and cultured. In the cultivation, it is desirable to add a nitrogen source and inorganic salts used for normal cultivation of yeast. For example, it is effective to add polypeptone, yeast extract and the like as a nitrogen source, and to add potassium phosphate, magnesium sulfate, salt and the like as inorganic salts. In addition, various organic substances and inorganic substances necessary for the growth of yeast and assimilation of D-xylose can be added as needed. It is desirable that the sugar concentration at the start of the culture be high, but 3 to 30% by weight is suitable.

For selective assimilation of D-xylose using a cultured yeast, aeration and agitation culture using a conventional culture tank is suitable. The temperature is not particularly limited as long as it is within a range in which yeast can grow, but is preferably around 30 ° C. The culture solution is sampled with time, and the sugar composition is analyzed by liquid chromatography to determine the D-xylose disappearance rate. When D-xylose has completely disappeared, the yeast culture is terminated. The required culture period depends on the sugar concentration at the start and the nature of the yeast, but is usually 2 to 4 days.

The yeast in the culture tank is removed by a method such as filtration or centrifugation to terminate the carbohydrate utilization reaction by the yeast. After the filtrate or supernatant is decolorized with activated carbon, the purity of L-arabinose is increased by a single or a combination of purification operations such as ion exchange resin, ultrafiltration and gel filtration. By concentrating this solution under reduced pressure, crude L-arabinose crystals can be easily obtained. From the crude crystalline L-arabinose, high-purity crystalline L-arabinose can be obtained in a high yield by a usual recrystallization operation.

[0014]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

Example 1 (1) Arabinoxylan 13 derived from corn kernel
To 6.5 g of sodium acetate buffer (pH 3.5) 300
mL, and β-xylanase activity: 59,460 was added thereto.
Unit, β-xylosidase activity: 90.6 units, α-L
An enzyme containing 213 units of arabinofuranosidase activity (from Cellulase, Penicillium funiculosum , Sigma Ch
emical) was added to initiate hydrolysis. The reaction temperature was 40 ° C., and the reaction time was 72 hours. The main constituent sugars in the supernatant from which insolubles were removed by centrifugation were the monosaccharides L-arabinose and D-xylose. The production rates from the raw materials were 75.8% for L-arabinose and 5% for D-xylose.
6.9%, and L-arabinose was produced preferentially. The results are shown in FIG. 1 (part A).

(2) The hydrolyzed solution of the above enzyme is heat-sterilized and then transferred to a culture tank, and polypeptone 0.1% is used as a nitrogen source.
3% and yeast extract 0.1%, phosphoric acid 1 as inorganic salts
Potassium and magnesium sulfate were added at 0.1% each. This is the yeast Willopsis saturnusvar. Saturnus IFO 0992
And cultured at 30 ° C. for 4 days with aeration and stirring. The stirring speed was 600 revolutions per minute, and the aeration rate was 1.5 L per minute. FIG. 1 (B
As shown in (2), the assimilation of D-xylose became remarkable after about 50 hours of culture, and decreased to 1.1% of that at the start of culture after 96 hours. On the other hand, the residual amount of L-arabinose was 95.2%, which revealed that D-xylose was selectively assimilated. The yeast in the culture tank was removed by centrifugation, and the D-xylose assimilation reaction was terminated. When the culture solution was confirmed by thin-layer chromatography, D-xylose was selectively assimilated and L-xylose was
No by-products were produced that adversely affected the separation of arabinose.

(3) After decolorizing the culture tank supernatant with activated carbon,
Desalting with a cation, exchange resin and anion exchange resin gave a clear solution. The solution was concentrated under reduced pressure to a syrup, and a small amount of L-arabinose seed crystal was added and allowed to stand at room temperature to obtain a crude L-arabinose crystal. 13.1 g of crude crystal L-arabinose
Dissolve in 4 mL of hot water and add 65.7 mL of anhydrous alcohol
After cooling to room temperature, a small amount of a seed crystal of L-arabinose was added, whereby high-purity crystalline L-arabinose could be obtained in high yield.

[0018]

According to the present invention, L-arabinose can be isolated as high-purity crystals from a solution containing L-arabinose and D-xylose such as a hydrolyzate of plant tissue.

[Brief description of the drawings]

FIG. 1 shows the production of L-arabinose and D-xylose by enzymatic hydrolysis of arabinoxylan derived from corn hulls (A) and the D- by yeast treatment of the hydrolyzate.
It is a figure which shows assimilation (B) of xylose.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) C12R 1:72) C12R 1:72) (72) Inventor Toshihiro Park 2-24 Akubo, Tsukuba, Ibaraki Pref. -5 Akemi Heights 203 (72) Inventor Minoru Chin 2-24-5 Akubo, Tsukuba City, Ibaraki Prefecture Akemi Heights 203 (72) Noriyuki Matsuo 798-39 Tamiyacho, Ushiku City, Ibaraki Prefecture (72) Inventor Shigemitsu Osaki 1140-36 Juichi-cho, Kashihara-shi, Nara F term (reference) 4B064 AF02 CA06 CC03 CD09 CE20 DA16

Claims (4)

[Claims] (1) L-arabinose and D-
A method for separating L-arabinose, comprising treating a solution containing xylose with a yeast that selectively assimilates D-xylose. 2. Main sugars of L-arabinose and D-
The method for separating L-arabinose according to claim 1, wherein the solution containing xylose is a hydrolyzate of a plant tissue containing arabinoxylan. 3. The method according to claim 1, wherein the yeast is Willopsis saturnus , Candida u.
L according to claim 1 or 2 which is tilis or a variant thereof.
-A method for separating arabinose. 4. An enzyme comprising Willopsis saturnus var. Satur
The method for separating L-arabinose according to any one of claims 1 to 3, which is nus .