WO2012096236A1

WO2012096236A1 - Method for producing starting material for enzymatic saccharification, method for producing sugar, and method for producing ethanol

Info

Publication number: WO2012096236A1
Application number: PCT/JP2012/050199
Authority: WO
Inventors: 悠一柴田; 佳功磯村; 靖敏井口; 雅裕丹羽
Original assignee: Ｊｘ日鉱日石エネルギー株式会社
Priority date: 2011-01-11
Filing date: 2012-01-06
Publication date: 2012-07-19
Also published as: JPWO2012096236A1

Abstract

A method for producing a starting material for enzymatic saccharification according to the present invention comprises: a modified biomass production step for treating a lignocellulose-containing plant biomass material with a treating agent containing ammonia to give a modified biomass; and a water treatment step for immersing the modified biomass in water at 40-100°C and thus eluting polysaccharides in the modified biomass in water to give a starting material to be subjected to an enzymatic saccharification step. Thus, the present invention can provide a method for producing a useful starting material for enzymatic saccharification, said starting material being usable in a method for producing a sugar, enabling efficient performance of the enzymatic saccharification and ensuring an increase in the productivity of the sugar.

Description

Method for producing raw material for enzymatic saccharification, method for producing sugar, and method for producing ethanol

The present invention uses a raw material for enzyme saccharification produced by a method for producing a raw material for enzyme saccharification, which is used for production of sugar, using a plant biomass raw material containing lignocellulose, and the method for producing the raw material for enzyme saccharification. The present invention relates to a method for producing sugar, and a method for producing ethanol using the sugar produced by the method for producing sugar.

In recent years, as part of global warming countermeasures, ethanol has been produced from plant biomass raw materials containing lignocellulose (a complex composed of lignin, cellulose, hemicellulose) such as woody biomass and herbaceous biomass, and will be used as various fuels and chemical raw materials. Attempts to do so are widely made. Production of ethanol from biomass raw material can be performed, for example, by decomposing the collected biomass raw material into sugar in the saccharification step and then converting it to ethanol using a microorganism such as yeast in the fermentation step.

On the other hand, the use of biodegradable polymers is increasing from the viewpoint of reducing environmental impact, and lactic acid is used as one of the raw materials. This lactic acid can also be obtained by fermenting sugar obtained by saccharifying the biomass raw material. Furthermore, organic acids other than lactic acid can be obtained by fermenting the sugar.

The saccharification has been conventionally performed using concentrated sulfuric acid, but from the viewpoint of reducing the environmental load, it is desired to reduce the amount of sulfuric acid used. Therefore, in recent years, saccharification of the biomass raw material using enzymes has been widely studied as a means to replace saccharification with concentrated sulfuric acid. Enzymatic saccharification is a desirable means from the viewpoint of impact on the environment. For this enzymatic saccharification, for the purpose of facilitating the action of the enzyme, the biomass raw material is pretreated in advance, It is necessary to separate cellulose and lignin in the lignocellulose to be formed. Various methods are known as a pretreatment method of this biomass raw material, and among them, steaming treatment with dilute sulfuric acid, pressurized hot water, etc. is common (for example, see Patent Documents 1 to 4 below). However, as described above, in order to obtain a desired degree of enzymatic saccharification, the use of sulfuric acid is not preferable, and when the biomass raw material is subjected to these pretreatments and the resulting processed product is subjected to enzymatic saccharification. However, there are problems that it is necessary to carry out the pretreatment in multiple stages and that the temperature must be raised to 200 ° C. or higher. In addition, some degradation products generated in the steaming treatment also have a problem of exerting an inhibitory action on fermentation by microorganisms such as yeast in the fermentation step after enzymatic saccharification. Furthermore, in the steaming treatment, it is necessary to increase the amount of water in order to fluidize the particles of the biomass raw material. For this reason, the sugar concentration in the sugar solution after enzymatic saccharification is reduced, and the efficiency in the subsequent fermentation process There is also a problem of lowering.

In addition, it is known that chemical and biochemical reactivity are improved by finely pulverizing the biomass raw material by physical means, but when trying to obtain a sufficient enzyme saccharification rate only by pulverization, The pulverization process requires a lot of energy and may lose economic rationality.

In addition, it is disclosed that the enzymatic saccharification rate of biomass is improved by subjecting the biomass raw material to steaming with pressurized hot water and then performing wet mechanical pulverization in the presence of water or the like (for example, the following) (See Patent Document 5). In this case as well, although the enzyme saccharification rate is improved, the problem in the steaming treatment, that is, the problem that the sugar concentration in the sugar solution obtained by the production of an inhibitory substance for fermentation and the enzyme saccharification process is still not solved.

On the other hand, it is known that pretreatment of the biomass raw material with ammonia improves its chemical and biochemical reactivity (see, for example, Patent Document 6 and Non-Patent Document 1 below). The improvement of the enzymatic saccharification efficiency by treating the biomass raw material with ammonia is that the cellulose type I crystal in the biomass raw material is transferred to a cellulose type III crystal having a crystal density lower than that of the cellulose type I crystal. This is known to be caused (see, for example, Patent Document 7).

In addition, for the improvement of the enzymatic saccharification efficiency by pretreatment of the biomass raw material with ammonia, the ester bond between hemicellulose and lignin in the biomass raw material is amidated, thereby separating the cellulose and lignin, A mechanism of action that facilitates access of the enzyme to cellulose is also known (see, for example, Non-Patent Document 2).

However, when the pretreatment with ammonia is carried out in a system in which there is no more water than the biomass raw material can hold, even if it is hemicellulose in which the ester bond with lignin is cleaved, a part of it is It is thought that hydrogen bonds are maintained. And this hemicellulose hydrogen-bonded to cellulose maintains its hydrogen bond even in the enzymatic saccharification step, and may act as a three-dimensional obstacle to the access of the enzyme to cellulose.

On the other hand, a lignocellulosic biomass saccharification pretreatment device for performing pretreatment of the biomass with ammonia water is known (for example, see Patent Document 8). When the biomass raw material is pretreated with ammonia water using the apparatus, it is considered that the hemicellulose with the ester bond cleaved is cleaved with hydrogen bond with cellulose and eluted into ammonia water. In order to remove ammonia from a biomass / ammonia water mixture by heating, a large amount of energy is required, which is not suitable for commercial implementation.

From the above, a method for producing an enzyme saccharification raw material for use in an enzymatic saccharification step by pretreatment with ammonia, which can obtain a raw material for enzyme saccharification with sufficiently improved enzyme saccharification efficiency by reasonable energy consumption The technology that can be developed has not been developed.

JP 2006-075007 A JP 2004-121055 A JP-T-2002-541355 JP 2002-159954 A JP 2006-136263 A European Patent Publication No. 77287 JP 2008-161125 A JP 2010-115162 A

This invention makes it a subject to solve the said various problems in the past and to achieve the following objectives. That is, the present invention can efficiently carry out enzymatic saccharification, and thus can improve the production efficiency of sugar, and a useful method for producing a raw material for enzymatic saccharification used in a method for producing sugar, It aims at providing the manufacturing method of sugar, and the manufacturing method of ethanol.

In order to solve the above-mentioned problems, the present inventors repeated intensive studies, and obtained biomass by treating a biomass raw material containing lignocellulose with a treatment agent containing ammonia, soaking this modified biomass in warm water, A part of hemicellulose whose bond with lignin was cleaved was eluted into warm water to obtain a raw material for enzymatic saccharification. It has been found that the enzyme saccharification raw material is enzymatically saccharified to obtain a significantly improved enzyme saccharification rate.

That is, the present invention provides a method for producing a raw material for enzyme saccharification according to the following <1> to <5>, a method for producing a sugar according to <6> below, and a method for producing ethanol according to <7> below. provide.
<1> A plant biomass raw material containing lignocellulose is treated with a treatment agent containing ammonia to obtain a modified biomass, and the modified biomass is immersed in water at 40 to 100 ° C., And a water treatment step of eluting the polysaccharide in the modified biomass into the water and obtaining a raw material for enzymatic saccharification for use in the enzymatic saccharification step.
<2> The method for producing a raw material for enzyme saccharification according to <1>, wherein the temperature of the water in the water treatment step is higher than the treatment temperature in the enzyme saccharification step.
<3> The method for producing a raw material for enzyme saccharification according to <1> or <2>, wherein the temperature of the water in the water treatment step is 50 to 100 ° C.
<4> In any one of <1> to <3>, in the water treatment step, the mass A of the water and the dry mass B of the modified biomass satisfy the relationship of the following formula (1): A method for producing a raw material for enzymatic saccharification according to claim 1.
{A / (A + B)} × 100 ≧ 70 (1)
<5> The method according to any one of <1> to <4>, further comprising a pulverization step of pulverizing the modified biomass between the modified biomass production step and the water treatment step. Of producing raw materials for enzymatic saccharification of
<6> The enzyme saccharification raw material obtained by the method for producing an enzyme saccharification raw material according to any one of <1> to <5> above is subjected to an enzymatic saccharification step to obtain a saccharide. A method for producing sugar.
<7> A method for producing ethanol, wherein the sugar obtained by the method for producing sugar according to <6> is subjected to a fermentation step to obtain ethanol.

According to the present invention, various problems in the prior art can be solved, and enzymatic saccharification can be efficiently performed. Therefore, it is useful for a sugar production method that can improve sugar production efficiency. The manufacturing method of the raw material for enzyme saccharification, the manufacturing method of sugar, and the manufacturing method of ethanol can be provided.

Hereinafter, preferred embodiments of the present invention will be described in detail.

<First Embodiment: Method for Producing Enzymatic Saccharification Raw Material>
The method for producing a raw material for enzymatic saccharification according to the first embodiment of the present invention includes a modified biomass production process for obtaining a modified biomass by treating a plant biomass raw material containing lignocellulose with a treatment agent containing ammonia. A water treatment step of immersing the quality biomass in water at 40 to 100 ° C. to elute the polysaccharide in the modified biomass into the water to obtain a raw material for enzymatic saccharification for use in the enzymatic saccharification step.

In the modified biomass production process, a plant biomass raw material containing lignocellulose (a complex composed of lignin, cellulose and hemicellulose) is treated with a treatment agent containing ammonia (hereinafter, the treatment is simply referred to as “ammonia treatment”). There is also.) By such ammonia treatment, at least a part of the ester bond in the plant biomass raw material is cleaved. The ester bond to be cleaved includes an ester bond between hemicellulose and lignin constituting lignocellulose, and in the enzymatic saccharification step described later by cleavage of the ester bond (that is, amidation cleavage of the ester bond), The hydrolysis of cellulose by an enzyme can be performed efficiently.

The plant biomass raw material is not particularly limited as long as it contains lignocellulose, and can be appropriately selected according to the purpose. For example, “waste biomass” obtained as a residue resulting from production activities such as agriculture and forestry, “resource crop biomass” obtained by intentionally cultivating for the purpose of obtaining energy and the like can be used. Examples of the “waste biomass” include waste building materials, thinned wood, rice straw, straw, rice husk, bagasse, etc., and the “resource crop biomass” is intended to use, for example, celluloses. Birch, eucalyptus, poplar, acacia, willow, cedar, switchgrass, napiergrass, Eliansus, Miscanthus, Susuki, Reed canarygrass and the like that are cultivated as The biomass is also classified into “woody biomass” derived from trees, “herbaceous biomass” derived from grass, and the like. In the present invention, both woody biomass and herbaceous biomass can be used. A plant biomass raw material may be used individually by 1 type, and may use 2 or more types together. In addition, the cellulose contained in the said biomass raw material is comprised from a cellulose I type crystal fundamentally.

The plant biomass raw material used in the modified biomass production process may be collected as it is, but it is easy to handle and use ammonia as particles of the following size by cutting, grinding, etc. From the viewpoint of the efficiency of treatment with a treatment agent containing

There is no restriction | limiting in particular as the magnitude | size of the particle | grains of a plant biomass raw material, Although it can select suitably according to the ease of handling as particle | grains etc., 5 mm or less is preferable as an opening of the mesh which passes, for example, 3 mm or less Is more preferable. When the mesh size of the mesh exceeds 5 mm, the treatment efficiency with a treatment agent containing ammonia described later may be lowered. On the other hand, since pulverization as a unit operation is extremely low in energy efficiency, for example, the amount of energy input used for pulverization is preferably 1 MJ or less per 1 kg of dry biomass. Hereinafter, the process of cutting and pulverizing the collected biomass material may be referred to as “coarse pulverization”.

By performing the coarse pulverization in advance, the treatment with a treatment agent containing ammonia described later can be efficiently advanced. There is no restriction | limiting in particular as a grinder used for the said rough crushing, According to the objective, it can select suitably, For example, a wheelie mill, a cutter mill, a hammer mill, a pin mill etc. can be used.

When the plant biomass raw material containing lignocellulose is treated with a treatment agent containing ammonia, the method is not particularly limited and can be appropriately selected depending on the purpose. For example, a plant biomass material containing lignocellulose and a treatment agent containing ammonia are introduced into a pressure vessel, and the inside of the pressure vessel is set to a desired pressure and temperature and treated for a desired time. be able to. There is no restriction | limiting in particular as said pressure, According to the objective, it can select suitably, For example, it can be set as 0 MPa-12.5 MPa (gauge pressure). The temperature is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the temperature may be −35 ° C. to 180 ° C., preferably 40 ° C. to 150 ° C.

The treatment agent containing ammonia may be in a liquid phase, a gas phase, a gas-liquid mixed phase, or a supercritical state.

The time for treatment with the treatment agent containing ammonia is not particularly limited, and is appropriately determined within a range in which cleavage of the ester bond of a desired degree proceeds according to the amount of plant biomass raw material used, the treatment pressure, the treatment temperature, and the like. Although it can be selected, it is preferably 10 minutes to 10 hours, more preferably 30 minutes to 8 hours, and particularly preferably 30 minutes to 5 hours. If the treatment time is less than 10 minutes, the desired degree of ester bond cleavage may not proceed, and if it exceeds 10 hours, the ester bond cleavage does not proceed any further, resulting in inefficiency as a whole. Sometimes. On the other hand, when the treatment time is within the further preferable range, it is advantageous in that the cleavage of the ester bond can be efficiently advanced, and the enzyme saccharification rate of the obtained enzyme saccharification raw material is improved.

The apparatus for performing the treatment with the treatment agent containing ammonia is not particularly limited, and a batch-type apparatus, a semi-continuous apparatus, a continuous apparatus, and the like are appropriately selected, and from the viewpoint of increasing the efficiency of the treatment, semi-continuous. It is preferable to employ a type device or a continuous type device.

The amount of the treatment agent containing ammonia is not particularly limited and can be appropriately selected depending on the purpose. For example, 10 mg to 300 g of ammonia per 1 g of dry mass of the plant biomass raw material containing lignocellulose. Is preferable, 100 mg to 150 g is more preferable, and 1 g to 50 g is particularly preferable. When the amount of the treatment agent containing ammonia is less than 10 mg as ammonia with respect to 1 g of dry mass of the plant biomass raw material containing lignocellulose, the treatment may be insufficient. May be less efficient. On the other hand, when the amount used is within the particularly preferable range, it is advantageous in that the treatment time can be shortened and the amount of the treatment agent to be used can be reduced.

In addition, the treatment agent containing ammonia may further contain a compound other than ammonia as long as at least a part of the ester bond in the plant biomass raw material can be cleaved. Examples of compounds other than ammonia include carbon dioxide, nitrogen, ethylene, methane, ethane, propane, butane, pentane, hexane, toluene, benzene, phenol, dioxane, xylene, acetone, chloroform, carbon tetrachloride, ethanol, methanol, Examples include propanol and butanol. Moreover, organic amines, such as ethylenedian, monomethylamine, monoethylamine, dimethylamine, diethylamine, and triethylamine, are mentioned. These compounds may be used individually by 1 type, or may be used in combination of 2 or more type.

In the modified biomass production process, the mass of moisture present in the system for ammonia treatment and the dry mass of the plant biomass raw material are expressed as [mass of moisture present in the system for treatment / (inside the system for treatment). The ratio represented by the mass of water present in the water + the dry mass of the plant biomass raw material)] is preferably 0.3 or less, more preferably 0.2 or less, and 0.1 or less. Particularly preferred. If a large amount of water is present in the system for ammonia treatment based on the amount of plant biomass raw material, after the ammonia treatment, the obtained modified biomass and ammonia are separated and recovered for reuse. In order to separate ammonia dissolved in water from water, a large amount of heat energy is required, and the cost of producing modified biomass increases. The smaller the amount of water present in the system for ammonia treatment relative to the amount of plant biomass raw material, the better from the viewpoint of the amount of energy consumed, but if the ratio is 0.3 or less, Consumption is not excessive.

The modified biomass obtained in the modified biomass production process may be used as it is in the water treatment process described later, or may be pulverized in advance before being used in the water treatment process. That is, the method for producing the enzyme saccharification raw material according to the present embodiment may further include a pulverization step of pulverizing the modified biomass between the modified biomass production step and the water treatment step. In the pulverization step, by pulverizing the modified biomass obtained in the modified biomass production step, the enzyme saccharification efficiency of the enzyme saccharification raw material obtained through the water treatment step is further improved.

In the water treatment step, the raw material for enzymatic saccharification for use in the enzymatic saccharification step is obtained by immersing the modified biomass in water at 40 to 100 ° C. and eluting polysaccharides such as hemicellulose in the modified biomass into the water. Is obtained.

In addition, even if a plant biomass raw material is immersed in hot water as it is without passing through the modified biomass manufacturing process, hemicellulose is not substantially eluted in water. On the other hand, the present inventors have confirmed that polysaccharides such as hemicellulose are eluted when the modified biomass obtained after the modified biomass production process is immersed in hot water. From these results, it is considered that polysaccharides such as hemicellulose whose bond with lignin is cleaved are eluted in water.

In addition, the phenomenon in which hemicellulose, whose bond with lignin is cleaved, can be eluted in water can occur even at low temperatures, but the amount and rate of elution of the hemicellulose are affected by temperature, and the higher the temperature, the more efficiently it is eluted. The higher the temperature, the more advantageous. And in order to elute polysaccharides, such as hemicellulose, in water efficiently, it is preferable that the temperature of water is 40 degreeC or more. On the other hand, in order to make the temperature of water over 100 degreeC, since a pressure vessel is required as an apparatus for implementing a water treatment process, installation cost increases. Therefore, the temperature of water is preferably 100 ° C. or lower. For the above reasons, the temperature of water in the water treatment step according to this embodiment is preferably 40 to 100 ° C., more preferably 50 to 100 ° C.

Further, the water temperature in the water treatment step is preferably higher than the treatment temperature in the enzyme saccharification step described later. The enzymatic saccharification step is generally performed in an aqueous medium, and the required time is about several tens of hours. In the case where the water treatment step is not provided before the enzyme saccharification step, it is considered that in the enzyme saccharification step, elution of the polysaccharide into water occurs as in the water treatment step. By setting the temperature of the water in the water treatment step higher than the treatment temperature in the enzyme saccharification step, the water treatment step is compared with the efficiency of elution of polysaccharides in water in the enzyme saccharification step when no water treatment step is provided. The efficiency of elution of polysaccharides in water into water can be increased, and the effects of the water treatment step can be expressed more reliably.

Moreover, in the water treatment process, it is preferable that the mass A of water and the dry mass B of the modified biomass satisfy the relationship of the following formula (1). In addition, when A and B satisfy | fill the relationship of following formula (1), the quantity of the water used in a water treatment process will be the quantity exceeding the saturated water content of the modified biomass to be processed. By performing the water treatment step under such conditions, polysaccharides such as hemicellulose whose bond with lignin is cleaved can be efficiently eluted into water and removed from the biomass solids. Furthermore, you may use the water of the same quantity ratio as the reaction conditions in the below-mentioned enzyme saccharification process.
{A / (A + B)} × 100 ≧ 70 (1)

The raw material for enzyme saccharification according to the present invention is not only a modified biomass-derived insoluble matter (solid matter) derived from the modified water treatment step, but also polysaccharides such as hemicellulose eluted in water and May contain water. That is, in the present invention, the entire suspension obtained by the water treatment step can be directly used for the subsequent enzymatic saccharification. The suspension may be concentrated by distilling off at least a portion of water, or may be diluted by adding water and / or an organic solvent. It is included in the raw material for saccharification. Furthermore, the raw material for enzyme saccharification includes those added with an additive such as a buffer solution for achieving a pH suitable for the enzyme saccharification step.

<Second Embodiment: Method for Producing Sugar>
The sugar production method according to the second embodiment of the present invention includes at least an enzyme saccharification step for enzymatic saccharification of the enzyme saccharification raw material obtained by the enzyme saccharification raw material production method according to the first embodiment. Depending on the situation, other steps are included.
Hereinafter, the sugar production method according to the present embodiment will be described in detail.

The enzyme saccharification raw material used in the enzyme saccharification step according to this embodiment includes cellulose and hemicellulose produced in the modified biomass production step and the water treatment step. In the enzyme saccharification step, the cellulose and hemicellulose are hydrolyzed by bringing the enzyme saccharification raw material into contact with the enzyme, whereby a monosaccharide is obtained.

The enzyme saccharification method used in the enzyme saccharification step is not particularly limited as long as an enzyme is used, and a known method can be appropriately selected. When a chemical saccharification method using sulfuric acid or the like is used, the yield of monosaccharides tends to decrease due to excessive decomposition, and a substance having an inhibitory action is likely to be produced in the fermentation process following saccharification. In contrast to the problem of the tendency and the discharge of environmentally hazardous substances such as sulfuric acid, mild conditions can be selected in the saccharification method using an enzyme. It tends not to occur.

The enzyme used in the enzymatic saccharification step is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include cellulase and cellobiase (β-glucosidase). An immobilized enzyme in which these enzymes are immobilized on an appropriate carrier or matrix can also be used.

The amount of the enzyme used in the enzyme saccharification step is not particularly limited and may be appropriately selected depending on the intended purpose. For example, 0.001 mg to 100 mg per 1 g of solid content dry mass in the enzyme saccharification raw material Is preferable, 0.01 mg to 10 mg is more preferable, and 0.1 mg to 1 mg is still more preferable. If the amount of the enzyme used is less than 0.001 mg relative to 1 g of the solid content dry mass in the enzyme saccharification raw material, enzyme saccharification may be insufficient, and if it exceeds 100 mg, saccharification inhibition may occur. May happen. On the other hand, when the amount of the enzyme used is within the further preferable range, it is advantageous in that the amount of sugar obtained is larger than the amount of enzyme used.

The treatment temperature in the enzymatic saccharification step is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 10 ° C to 70 ° C, more preferably 20 ° C to 60 ° C, and further preferably 30 ° C to 50 ° C. . If the treatment temperature is lower than 10 ° C, enzyme saccharification may not proceed sufficiently, and if it exceeds 70 ° C, the enzyme may be deactivated. On the other hand, when the treatment temperature is within the further preferable range, it is advantageous in that the amount of sugar obtained is larger than the amount of enzyme used.

The pH in the enzymatic saccharification step is not particularly limited and may be appropriately selected depending on the intended purpose. For example, it is preferably 3.0 to 8.0, more preferably 3.5 to 7.0, and 4.0. More preferably, ˜6.0. If the pH is less than 3.0 or more than 8.0, the enzyme may be deactivated. On the other hand, when the pH is within the more preferable range, it is advantageous in that the amount of sugar obtained is larger than the amount of enzyme used.

In the enzymatic saccharification step, glucose is produced from cellulose contained in the raw material for enzymatic saccharification. Hemicellulose produces hexoses such as glucose, galactose and mannose and pentoses such as xylose and arabinose.

The sugar solution containing the monosaccharide obtained by the above enzymatic saccharification step may be directly subjected to the fermentation step described later. For example, a step of adjusting the pH of the sugar solution, a step of adjusting the sugar concentration, etc. Therefore, the sugar solution may be more suitable for fermentation.

The sugar obtained by the sugar production method according to the present embodiment can be used not only in the ethanol production method and lactic acid production method described later, but also as a raw material for producing other substances.

<Third Embodiment: Method for Producing Ethanol>
The method for producing ethanol according to the third embodiment of the present invention includes at least a fermentation process (ethanol fermentation process) for fermenting sugar (sugar solution) obtained by the sugar production method according to the second embodiment. Depending on the above, other steps are included.
Hereinafter, the ethanol production method according to this embodiment will be described in detail.

The fermentation process according to the present embodiment is a process of adding ethanol-fermenting microorganisms to the sugar solution and performing ethanol fermentation.

The ethanol-fermenting microorganism is not particularly limited and may be appropriately selected depending on the intended purpose. However, yeast, bacteria of the genus Zymomonas such as Zymomonas mobilis, etc. are preferred, and yeast is more preferred.

Yeast is not particularly limited and may be appropriately selected depending on the intended purpose, but yeast of the genus Saccharomyces such as Saccharomyces cerevisiae is preferable. However, as described above, hemicellulose constituting the biomass raw material generates pentoses such as xylose and arabinose by enzymatic saccharification, but natural yeasts of the genus Saccharomyces have the ability to assimilate pentoses to produce ethanol. There is no waste. Therefore, in order to effectively use not only hexose but also pentose derived from hemicellulose and convert it to ethanol, yeast that has the ability to assimilate pentose and produce ethanol (pentose-utilizing yeast) It is also preferable to use There is no restriction | limiting in particular as said pentose utilization yeast, Although it can select suitably according to the objective, Pichia stipitis, Candida shihatae, etc. are preferable. In order to efficiently convert hexose sugar and pentose sugar to ethanol, a method of using a yeast of the genus Saccharomyces and the aforementioned pentose-utilizing yeast in combination is also preferably employed. In this case, the yeast of the genus Saccharomyces and the above-mentioned pentose-assimilating yeast may be fermented, or the glucose in the sugar solution is first assimilated by the yeast of the genus Saccharomyces, and then the above-mentioned pentose-assimilating yeast. You may assimilate pentose sugars.

The yeast used in the fermentation process may be a natural yeast or a genetically modified yeast. In particular, it is possible to efficiently convert both hexose and pentose derived from cellulose and hemicellulose into ethanol by using a genetically modified yeast having the ability to assimilate both hexose and pentose. it can.

The amount of yeast used in the fermentation process, additives other than sugar, fermentation temperature, pH, fermentation time and the like are not particularly limited, and known conditions can be appropriately selected and used. 7. The fermentation temperature is preferably about 20 ° C to 37 ° C.

Further, by performing fermentation at a temperature higher than usual using heat-resistant yeast, it is possible to perform fermentation efficiently without the need for cooling equipment and by suppressing the propagation of various bacteria. Examples of the thermostable yeast include thermostable yeast belonging to the genus Kloyveromyces such as Kleiberymyces marxianas. When using these heat-resistant yeasts, the fermentation temperature can be about 37 ° C. or higher and 50 ° C. or lower.

A so-called parallel double fermentation method in which the enzymatic saccharification step and the fermentation step are simultaneously performed may be employed. By employing this parallel double fermentation method, the enzyme saccharification step and the fermentation step can be carried out as a single step, and ethanol can be produced by a simplified step.

In the parallel double fermentation, the enzyme saccharification raw material obtained by the enzyme saccharification raw material production method of the present embodiment is used in the reaction system as it is in the reaction system. A microorganism for ethanol fermentation is added to perform enzymatic saccharification and ethanol fermentation.

The ethanol production method according to the present embodiment may further include steps other than the fermentation step described above. The other steps are not particularly limited as long as the effects of the present invention are not impaired, and can be appropriately selected according to the purpose, but preferably include a purification step.

The purification step is a step of separating and purifying ethanol from the medium containing ethanol obtained in the fermentation step. Through the purification process, ethanol is separated and purified from various substances contained in the fermentation medium and concentrated.

The ethanol separation / purification method is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the fermentation medium is first solidified by centrifuging and / or filtering solid matter such as bacterial cells. Liquid separation is preferred, and an aqueous solution containing ethanol is recovered, and then the aqueous solution is concentrated and purified by distillation, membrane separation, or the like.

According to the method for producing ethanol according to this embodiment, ethanol can be produced efficiently by using the sugar obtained using the raw material for enzyme saccharification. Ethanol obtained by the ethanol production method can be suitably used as, for example, fuel ethanol, industrial ethanol, and the like.

<Production method of lactic acid>
Lactic acid can be produced using the sugar obtained by the sugar production method of the present invention. The method for producing lactic acid in this case includes at least a fermentation step (lactic acid fermentation step) for lactic acid fermentation of the sugar, and further includes other steps as necessary.

The lactic acid fermentation step is a step in which lactic acid bacteria and the like are added to the sugar solution to perform lactic acid fermentation. The lactic acid bacterium is not particularly limited, and a known lactic acid bacterium can be appropriately selected and used. (Streptococcus thermophilus), Lactobacillus bulgaricus (Lactobacillus bulgaricus) and the like. The lactic acid bacterium may be a natural lactic acid bacterium or a genetically modified lactic acid bacterium. There are no particular restrictions on conditions such as the amount of lactic acid bacteria used in the fermentation step, additives other than sugar, fermentation temperature, pH, fermentation time, etc., and known conditions can be appropriately selected and used.

In the method for producing lactic acid, it is preferable to include, for example, a lactic acid purification step as another step other than the fermentation step.

According to the lactic acid production method using the saccharide obtained by the saccharide production method of the present invention, lactic acid can be produced efficiently by using the saccharide obtained using the enzyme saccharification raw material. The lactic acid thus obtained can be used as a raw material for biodegradable polymers such as polylactic acid.

In addition, the saccharide obtained by the method for producing saccharides of the present invention is fermented by using microorganisms that produce the desired organic acid in place of the lactic acid bacteria, so that an organic acid other than lactic acid, for example, citric acid is used. Succinic acid, malic acid, oxalic acid and the like can also be produced.

As mentioned above, the manufacturing method of the raw material for enzyme saccharification of this invention, the manufacturing method of the saccharide | sugar using the raw material for enzyme saccharification manufactured by the manufacturing method of the said raw material for enzymatic saccharification, and the saccharide manufactured by the said manufacturing method of saccharide | sugar A method for producing ethanol and a method for producing lactic acid and the like have been described according to preferred embodiments, but the present invention is not limited to the above-described embodiments without departing from the gist thereof.

Examples of the present invention will be described below, but the present invention is not limited to these examples.

[Example 1]
(Plant biomass raw material)
Elianthus was used as biomass containing lignocellulose.
(Pulverization)
The Eliansus was pulverized using a cutter mill while controlling the particle size with a screen having an opening of 4 mm. The average particle diameter (d50) measured by the laser diffraction method was 975 μm.
(Dry)
The Eliansus after pulverization was dried overnight under reduced pressure at a temperature of 40 ° C. and 5 kPaA before being subjected to the modified biomass production process. The moisture content of the Elianthus after drying was 0.5% by mass based on the mass of the Elianthus after drying.
(Modified biomass production process)
A stainless steel autoclave equipped with a stirrer with an internal volume of about 5 L was filled with 200 g of ground and dried Eliansus. Next, introduction / depressurization of pressurized nitrogen gas into the autoclave was repeated to remove air in the autoclave and replace it with nitrogen gas. Thereafter, the autoclave was heated to 120 ° C. After raising the temperature, the autoclave was depressurized and further reduced in pressure to exhaust nitrogen gas. On the other hand, pressurized ammonia was introduced into a separate pressure vessel, and the ammonia was heated to a temperature slightly higher than 120 ° C. Thereafter, ammonia was introduced into the autoclave so that the pressure became 1.2 MPaA at a temperature of 120 ° C. by opening a valve installed in a pipe connecting the autoclave and the pressure vessel. The Elianthus was treated with ammonia under stirring at this temperature and pressure condition for 2.5 hours. Thereafter, the pressure was released and ammonia was discharged. Further, nitrogen gas was circulated through the autoclave to remove ammonia remaining in the Elianthus particles to obtain a modified biomass.
In addition, since the ammonia used does not substantially contain moisture, the moisture present in the autoclave during the ammonia treatment is only the moisture contained in the dried Elianthus. The mass ratio of Eliansus to the mass was 0.5% by mass.
(Water treatment process)
About the obtained modified biomass, water treatment was performed by the following operation. Take 0.3 g of modified biomass precisely weighed in a polypropylene tube with an internal volume of 50 ml, and prepare a suspension sample solution so that the modified biomass concentration is 3% (mass / vol) and pH 4.5 (acetate buffer) did. This sample solution was heated for 10 minutes in a hot water bath at 50 ° C. under atmospheric pressure. At this time, [{A / (A + B)} × 100] (A represents the mass of water and B represents the dry mass of the modified biomass) was 97%.
(Enzyme saccharification process)
An enzyme saccharification reaction solution was prepared by adding an enzyme to the sample solution after water treatment by the following operation. That is, Cellluclast (registered trademark) 1.5L and Novozyme (registered trademark) 188 (both trade names, manufactured by Novozyme) as enzymes were each 0.01% (mass / vol) of each enzyme, a total of 0.02% (mass / vol.) to obtain an enzyme saccharification reaction solution. Using this shaker (manufactured by TAITEC), this reaction solution was shaken at 37 ° C. and 200 rpm for 72 hours to carry out an enzymatic saccharification reaction. The glucose concentration in the supernatant obtained by centrifuging the reaction solution after the reaction was measured using a biosensor (manufactured by Oji Scientific Instruments), and the glucose yield was calculated.
The glucose yield is defined by the following formula.
Glucose yield (%) = [mass of glucose in enzyme saccharification reaction solution / (mass of modified biomass in water-treated sample solution × total glucosylation rate / 100)] × 100
Total glucosylation rate (%): (mass of glucose obtained when the biomass raw material is completely hydrolyzed separately / mass of biomass raw material) × 100 (corresponding to the theoretical yield based on biomass raw material)
The results are shown in Table 1 together with the conditions for the water treatment process.
Moreover, in order to show the effect of the glucose yield improvement by water treatment, the difference which reduced the glucose yield in the comparative example 1 (enzymatic saccharification of the modified biomass which has not performed water treatment) mentioned later from the glucose yield " It is calculated as “Δglucose yield” and is also shown in Table 1.

[Comparative Example 1]
First, a modified biomass production process was performed in the same manner as in Example 1. Next, using the obtained modified biomass, a suspension sample solution is prepared in the same manner as in Example 1 so that the modified biomass concentration becomes 3% (mass / vol) and pH 4.5 (acetate buffer). did. And without performing a water treatment process, an enzyme is added to this sample liquid by the same operation as the enzyme saccharification process of Example 1, and an enzyme saccharification reaction liquid is prepared, The same as the enzyme saccharification process of Example 1 The operation was subjected to an enzymatic saccharification step. In addition, after preparing the said sample liquid, the temperature was kept at room temperature (about 25 degreeC), and the enzyme was added rapidly and it used for the enzyme saccharification process. After completion of the enzymatic saccharification reaction, the glucose yield was determined in the same manner as in Example 1. The results are shown in Table 1.

[Examples 2 to 7, Comparative Example 2]
[Examples 2 to 7, 11 and Comparative Example 2]
In Examples 2 to 7, 11 and Comparative Example 2, the temperature of water in the water treatment step, the treatment time, and [{A / (A + B)} × 100] (A and B are the same as those described in Example 1. .) Was performed as shown in Table 1, and the modified biomass production process, the water treatment process and the enzymatic saccharification process were carried out in the same manner as in Example 1, and compared with the glucose yield and the glucose yield, respectively. The Δglucose yield, which is the difference from the glucose yield in Example 1, was calculated. The obtained results are shown in Table 1.

[Example 8]
The modified biomass production process, the water treatment process and the enzymatic saccharification process were carried out in the same manner as in Example 1 except that the temperature in the modified biomass production process was set to 80 ° C. and the ammonia pressure was set to 3.8 MPaA. The rate was calculated. The obtained results are shown in Table 2. Moreover, in order to show the effect of the glucose yield improvement by water treatment, the difference which reduced the glucose yield in the comparative example 3 (enzymatic saccharification of the modified biomass which has not performed water treatment) mentioned later from the said glucose yield " It is calculated as “Δglucose yield” and is also shown in Table 1.

[Example 9]
The temperature of water in the water treatment step and [{A / (A + B)} × 100] (A and B are the same as those described in Example 1) are as shown in Table 2, and are the same as in Example 8. Thus, a modified biomass production process, a water treatment process and an enzymatic saccharification process were carried out. And it carried out similarly to Example 8, and computed (DELTA) glucose yield which is a difference of this glucose yield and the glucose yield in the comparative example 3 mentioned later. The results are shown in Table 2.

[Comparative Example 3]
The modified biomass production process and the enzymatic saccharification process (without performing the water treatment process) are the same as in Comparative Example 1 except that the temperature in the modified biomass production process is 80 ° C. and the ammonia pressure is 3.8 MPaA. And the glucose yield and Δglucose yield were calculated. The results are shown in Table 2.

[Example 10]
As the raw material biomass, Elianthus of a lot different from that used in Examples 1 to 9 and Comparative Examples 1 to 3 was used, and thereafter, a modified biomass production process was carried out by the same operation as in Example 9. Then, before subjecting the obtained modified biomass to the water treatment step, a modified biomass pulverization step using a disk mill is provided, and then the water treatment step and the enzymatic saccharification step are carried out in the same manner as in Example 9. The glucose yield was calculated.
Moreover, in order to show the effect of improving the glucose yield by water treatment, the glucose yield in Comparative Example 5 (enzymatic saccharification of modified biomass that has been pulverized and not subjected to water treatment) described later is reduced from the glucose yield. The difference is calculated as “Δglucose yield” and is also shown in Table 1.

[Comparative Example 4]
The modified biomass obtained by the modified biomass production process performed in the same manner as in Example 10 was subjected to the enzymatic saccharification process by the same operation as in Comparative Example 1 without passing through the water treatment process, and the glucose yield was calculated. . The results are shown in Table 2.

[Comparative Example 5]
The modified biomass obtained in the modified biomass production process as in Example 10 was subjected to a pulverization process using a disk mill. Then, without passing through the water treatment step, the enzyme was subjected to the saccharification step by the same operation as in Comparative Example 1, and the glucose yield was calculated. The results are shown in Table 2.

In addition, Δglucose yield in each example described in Table 1 and Table 2 is modified before the corresponding water treatment process (after the modified biomass production process and after the pulverization process for those subjected to the pulverization process). The increase in glucose yield is shown in comparison with a comparative example in which enzymatic saccharification of sucrose biomass is performed. That is, it corresponds to an increase in glucose yield due to the water treatment step in each example.

From the results shown in Table 1, it is understood that the glucose yield by enzymatic saccharification is improved by treating the modified biomass obtained by the ammonia treatment with water at 40 to 100 ° C. Further, from the results shown in Table 2, even when the modified biomass having higher enzyme saccharification efficiency (glucose yield) obtained under different ammonia treatment conditions is treated with water at 40 to 100 ° C., It can also be seen that the glucose yield is improved (Examples 8 and 9). Moreover, by subjecting the modified biomass to the pulverization step, enzymatic saccharification efficiency (glucose yield is improved (Comparative Example 5 / Comparative Example 4)), but by treating the modified biomass supplied to the pulverization step with water, Furthermore, it turns out that a glucose yield improves.

Claims

A modified biomass production process for obtaining a modified biomass by treating a plant biomass raw material containing lignocellulose with a treatment agent containing ammonia; and
A water treatment step of immersing the modified biomass in water at 40 to 100 ° C. to elute the polysaccharide in the modified biomass into the water to obtain an enzyme saccharification raw material for use in the enzyme saccharification step;
A process for producing a raw material for enzymatic saccharification, comprising:
The method for producing a raw material for enzyme saccharification according to claim 1, wherein the temperature of the water in the water treatment step is higher than the treatment temperature in the enzyme saccharification step.
The method for producing a raw material for enzymatic saccharification according to claim 1 or 2, wherein the temperature of the water in the water treatment step is 50 to 100 ° C.
4. In the water treatment step, the mass A of the water and the dry mass B of the modified biomass satisfy the relationship of the following formula (1). Of producing raw materials for enzymatic saccharification of
{A / (A + B)} × 100 ≧ 70 (1)
The raw material for enzymatic saccharification according to any one of claims 1 to 4, further comprising a pulverization step of pulverizing the modified biomass between the modified biomass production step and the water treatment step. Manufacturing method.
A method for producing sugar, characterized in that the enzyme saccharification raw material obtained by the method for producing an enzyme saccharification raw material according to any one of claims 1 to 5 is subjected to an enzyme saccharification step to obtain sugar.
A method for producing ethanol, wherein the sugar obtained by the method for producing sugar according to claim 6 is subjected to a fermentation step to obtain ethanol.