JP2007074993A - Method for saccharifying biomass containing hemicellulose and saccharide given by the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for saccharifying cellulose, capable of efficiently conducting hydrolysis, even when biomass containing the cellulose is not fine granular, and capable of giving a high yield of a saccharide, and to provide the saccharide given by the method for saccharifying. <P>SOLUTION: This method for saccharifying hemicellulose comprises hydrolyzing and saccharifying the hemicellulose contained in the biomass by using an enzyme, wherein hydrothermal treatment is conducted by using hydrogen peroxide in a previous step in which the hydrolysis is conducted by using the enzyme, so that lignin contained therein is decomposed and removed. Hemicellulase is used as the enzyme for hydrolyzing the hemicellulose and giving the saccharide. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a saccharification method by enzymatic treatment of small pieces of wood pieces and the sugar obtained thereby, and more specifically, hydrothermal treatment with hydrogen peroxide as a pre-stage for treating hemicellulose contained in wood pieces with enzymes. The present invention relates to a method for saccharification of hemicellulose, and to a saccharide obtained by the saccharification method.

Technologies for effectively utilizing so-called biomass such as wood chips, wood chips, rice straw and rice husks have been developed.
Since hemicellulose, which is a component of these biomasses, is present in the waste material, it is also very inexpensive.
There is a need for a technique for producing various substances using hemicellulose as a starting material.
In particular, with the recent demand for alcohol fermentation technology, technology for producing sugar (xylooligosaccharide, cellooligosaccharide, xylose, etc.) from biomass has been developed.

Among these techniques, for example, as a method for saccharifying hemicellulose, there is a method using acetic anhydride or concentrated sulfuric acid.
However, the above method requires a drying step, and the hydrolysis of hemicellulose is also performed vigorously, so that the equipment of the reaction system becomes complicated.
Furthermore, corrosion due to acid is likely to occur in the facility, and extra cost is required for sulfuric acid recovery.
Enzymatic methods capable of performing hydrolysis under mild conditions have been developed as means for solving these problems.

This method hydrolyzes using an enzyme (eg, hemicellulase). When this method is used, the apparatus does not require a pressure-resistant and acid-resistant reaction vessel, and environmental pollution is small.
Examples of saccharification methods using such enzymes include Patent Document 1 and Patent Document 2.

JP 2001-95594 A JP-A-8-308589

However, lignin is generally glued to hemicellulose, and the presence of this lignin is a major obstacle to saccharification.
Due to this lignin, the hydrolysis efficiency of hemicellulose is greatly reduced, and the saccharification rate is extremely low.
Thus, the invention of decomposing and removing lignin was previously achieved by performing ozone treatment (Japanese Patent Application No. 2004-333445).
However, this invention is very effective when the biomass is in the form of finely pulverized granules, but the effect is effective for small pieces of wood of a certain size (size of about 1 cm to 10 cm). It is not demonstrated.
Moreover, since the enzyme used for enzymatic saccharification is very expensive, the use of the enzyme increases the production cost.

The present invention has been made based on such a technical background.
That is, the present invention provides a method for saccharification of cellulose that can be efficiently hydrolyzed even if the biomass containing cellulose is not fine and has a high sugar yield.
Moreover, the sugar obtained by the saccharification method is provided.

  As a result of diligent research on the above problems, the present inventor has performed hydrothermal treatment with hydrogen peroxide before the saccharification treatment with the enzyme, thereby smoothly decomposing and removing lignin that hinders the saccharification treatment with the enzyme. I found it possible.

  That is, the present invention is (1) a method for hydrolyzing and saccharifying hemicellulose contained in biomass by using an enzyme, and hydrothermal treatment using hydrogen peroxide water in a stage prior to hydrolysis using the enzyme. To saccharify hemicellulose by decomposing and removing lignin contained therein.

  Moreover, this invention exists in the saccharification method of the hemicellulose of the said (1) description which uses hemicellulase as an enzyme for hydrolyzing hemicellulose and obtaining saccharide | sugar.

  The present invention also resides in (3) the method for saccharification of hemicellulose according to (1), wherein the biomass is in the form of small pieces.

  Moreover, this invention exists in the saccharide | sugar manufactured by the saccharification method of at least 1 description of (4) and said (1)-(3).

  Further, the present invention resides in (5) the sugar according to (4), wherein the produced sugar is arabinose, galactose, mannose, xylose, xylooligosaccharide, glucose.

  In addition, as long as the objective of this invention is met, the structure which combined said invention suitably is also employable.

Hemicellulose is hydrothermally treated with hydrogen peroxide in advance before enzymatic saccharification, so that the lignin glued to hemicellulose is hydrolyzed in a state where it is decomposed and removed. Arabinose, galactose, mannose, etc.) can be recovered.
Moreover, unlike the ozone treatment with the same lignin decomposition effect, even if it is not a fine granular biomass but small piece biomass, sufficient lignin decomposition effect can be exhibited.
This eliminates the need for energy to pulverize biomass from small pieces to granules, and is very effective in improving energy efficiency in monosaccharide production.

In addition, when hydrothermal treatment is performed with hydrogen peroxide, the same level of monosaccharide can be recovered without using an enzyme.
Since enzymes are generally expensive, this is very effective in reducing monosaccharide production costs.

The present invention is greatly characterized in that lignin is decomposed by first performing hydrothermal treatment with hydrogen peroxide in the process of decomposing and saccharifying hemicellulose using an enzyme.
Hereinafter, the saccharification process will be described with reference to the flowchart of FIG.

[Hot water treatment with hydrogen peroxide]
Lignin is glued to the hemicellulose present in the biomass.
In this state, the yield of monosaccharides is poor even if hemicellulose is solubilized and enzymatic saccharification is attempted.
Therefore, lignin is decomposed by performing a hydrothermal treatment in which biomass is heated at a high temperature for a certain period of time using hydrogen peroxide, and lignin is easily leached from hemicellulose.
At this time, lignin becomes an organic acid such as gallic acid, oxalic acid, acetic acid, and formic acid and dissolves in water.
In addition, it is not necessary to make biomass into a granular form at the time of hydrothermal treatment, and even if it is a small piece having a certain size (length: 1 cm to 10 cm), the effect of sufficiently leaching lignin is exhibited.
In the case of performing the hot water treatment, it is usually preferred that the temperature is 140 ° C. to 160 ° C., and the treatment time is 2 hours to 4 hours.

By performing the hot water treatment, hemicellulose that is not originally soluble in water can be solubilized.
That is, in our previous invention (Japanese Patent Application No. 2004-333445), there were two steps of solubilizing lignin by ozone treatment and then solubilizing hemicellulose. Effective in terms of both efficiency.

[Ozone treatment]
In the case of performing ozone treatment, the solution after the hot water treatment is suspended in a container filled with distilled water, and ozone gas is injected into the container by an air diffuser method to perform the treatment for 1 to 3 hours.

[Enzymatic saccharification of hemicellulose]
Add an appropriate amount of enzyme to the hydrothermally treated solution (or hydrothermally treated and ozone treated), leave it at a suitable temperature for a certain period of time to fully hydrolyze it, filter the solution, and xylo-oligosaccharide and / or Alternatively, xylose is obtained.
Here, as the enzyme that hydrolyzes hemicellulose, xylanase, hemicellulase, cellulase and the like are suitably selected and used.
The conditions for the hydrolysis with the enzyme are preferably 40 to 60 ° C., pH 3 to 4 for 24 hours or more from the viewpoint of activating the enzyme most.

  Hereinafter, the present invention will be described with reference to examples. However, the present invention is not limited to the examples, and various modifications are possible.

[Example 1]
First, as a sample, a piece of wood (cedar used in this experiment) in the shape of a small piece of about 2 cm square is used.
Next, 2.5 g of the sample, 2 ml of hydrogen peroxide solution (31 wt%) and water were combined to make a 40 ml test solution, which was placed in a hydrothermal reaction vessel (internal volume 50 ml, made by Hastelloy) at 150 ° C. for 4 hours. Perform hot water treatment.
The hydrothermally treated solution is filtered, and hemicellulase (Cellulosin H100: trade name of HBI) as a hydrolase is added to the filtrate at a rate of 3 mg with respect to 5 ml of the filtrate to perform enzymatic saccharification.
The enzymatic saccharification conditions were pH 4, temperature 50 ° C., and reaction time 24 hours.
The analysis of monosaccharides was performed with an ion chromatograph (manufactured by DIONEX).
As a result of the experiment, hemicellulose-derived monosaccharides (arabinose, galactose, mannose, xylose, xylooligosaccharide) and glucose were detected.

[Example 2]
All procedures were the same as in Example 1 except that enzymatic saccharification was not performed.

Example 3
All procedures were the same as in Example 1 except that ozone treatment was performed for 2 hours after the hot water treatment.

Example 4
All procedures were the same as in Example 3 except that enzymatic saccharification was not performed.

[Comparative Example 1]
The procedure was the same as in Example 1 except that 2.5 g of the sample was suspended in a container filled with distilled water without performing the hot water treatment, and ozone gas was ozone treated by an air diffuser method.

[Comparative Example 2]
All procedures were the same as those in Comparative Example 1 except that enzymatic saccharification was not performed.

[Comparative Example 3]
All procedures were the same as in Comparative Example 1 except that the ozone treatment was not performed.

[Comparative Example 4]
All procedures were the same as in Comparative Example 3 except that enzymatic saccharification was not performed.
Table 1 shows the amount of monosaccharides other than glucose (arabinose, galactose, mannose, xylose, xylooligosaccharide) recovered as a result of Examples 1 to 4 and Comparative Examples 1 to 4 converted to the recovered amount per 1 g of sample. Show.

From Table 1, the hydrothermal treatment with hydrogen peroxide was more effective in decomposing lignin than the ozone treatment, and a large amount of glucose could be recovered.
Furthermore, the amount of monosaccharides recovered when hydrothermal treatment with hydrogen peroxide is performed and no enzyme treatment is performed (Example 2) is the amount of monosaccharides recovered when hydrothermal treatment with hydrogen peroxide and enzyme treatment are performed (Example 1). Approximately 92% of the amount (109 mg / 118 mg) could be recovered.
This recovery amount exceeds the recovery amount of monosaccharides in the case of performing ozone treatment and enzyme treatment (Comparative Example 1), and can be said to be necessary and sufficient as an effect.

[Table 1]

The flowchart which shows the saccharification process of biomass.

Claims (5)

  A method of hydrolyzing and saccharifying hemicellulose contained in biomass using an enzyme, and performing hydrothermal treatment using hydrogen peroxide water before hydrolyzing using an enzyme, and then containing lignin A method for saccharification of hemicellulose, wherein the saccharification is carried out.   The method for saccharifying hemicellulose according to claim 1, wherein hemicellulase is used as an enzyme for hydrolyzing hemicellulose to obtain sugar.   The method for saccharifying hemicellulose according to claim 1, wherein the biomass is in the form of small pieces.   The saccharide | sugar manufactured by the saccharification method of at least 1 among the said Claims 1-3.   The sugar according to claim 4, wherein the sugar produced is arabinose, galactose, mannose, xylose, xylooligosaccharide, glucose.

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