JP2008259517A - Equipment and method for producing lactic acid from cellulose - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing lactic acid by efficiently carrying out a cellulose saccharification and a lactic acid fermentation simultaneously, and to provide equipment for producing lactic acid by the method. <P>SOLUTION: The equipment for producing lactic acid by simultaneously advancing the cellulose saccharification and the lactic acid fermentation is provided with a saccharifying tank, a fermentation tank, a charging line supplying cellulose material to the saccharifying tank, a first separating means separating sacchrified liquid containing cellulose short fibers from the saccharified product conveyed from the saccharifying tank through a saccharified product taking out line, and conveying the saccharified product to the fermentation tank through a saccharified product supplying line, and returning the residue containing cellulose long fibers to the saccharifying tank through a residue returning line, and a second separating means separating fermentation liquid containing the lactic acid from fermentation product taken out from the fermentation tank through an outlet for fermentation product and taking out through a take out line for fermentation liquid and returning the residue containing the lactic acid fermenting microorganism to the fermentation tank through a fermentation residue returning line. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a lactic acid production apparatus and a lactic acid production method for producing lactic acid from cellulose by saccharifying cellulosic biomass resources such as waste paper resources and then producing lactic acid by lactic acid fermentation.

In recent years, it has been considered to use ethanol or lactic acid as a liquid fuel or chemical raw material obtained by enzymatic degradation of cellulosic biomass, saccharification into its constituent units, glucose and xylose, and fermentation of these saccharification products Has been. Lactic acid obtained by lactic acid fermentation is used as a food additive for the production of sake, soy sauce, beer, soft drinks, pickles, bread making, etc., and as an industrial raw material for the production of leather, fibers, plastics, etc. . Furthermore, in recent years, it has become clear that polylactic acid (PLA) has excellent properties as a biodegradable polymer, and lactic acid as a raw material has attracted attention.
Conventionally, the production of lactic acid by fermentation has been carried out by using a sugar solution obtained from an aqueous sugar solution or starch as a carbon source by a so-called lactic acid bacterium such as Lactobacillus or Lactococcus, and a nutrient such as yeast extract. It is carried out by culturing in a medium with the source added as an auxiliary material. However, although the fermentation method using lactic acid bacteria described above has an advantage of high yield of lactic acid from sugar, it has a disadvantage of high production cost because expensive materials such as sugar and yeast extract are used for the culture. .

In order to solve the above-mentioned problems in the fermentation method using lactic acid bacteria, various methods for producing lactic acid from an inexpensive carbon source using filamentous fungi such as Rhizopus are being developed. The method using filamentous fungi has a lactic acid yield of 70 to 80% at maximum, which is not necessarily a high yield compared to the case of using lactic acid bacteria. Other than sugar, only a small amount of inorganic salt is required, the medium cost is low, the optical purity of L-form is high, and the microbial cells form pellets, so that the microbial cells can be easily separated. is there.
Japanese Patent Laid-Open No. 6-253871 discloses a cell assembly (pellet) produced by inoculating a liquid medium with spores of Rhizopus fungi having lactic acid-producing ability and culturing with stirring by aeration. A method for producing lactic acid, which is characterized by allowing fermentation in a liquid medium.
JP-A-9-173090 uses a bubble column bioreactor in which air is blown from the bottom, and a bacterium belonging to the genus Rhizopus in an aqueous medium containing starch or a saccharified solution thereof or glucose as a carbon source. A method for producing L (+)-lactic acid, characterized by culturing, and a bioreactor for carrying out the method are disclosed.
In addition, attempts have been made to produce lactic acid by lactic acid fermentation of sludge in order to effectively use sludge as waste. For example, JP-A-9-308494 discloses a method for producing lactic acid, which includes a step of adding lactic acid bacteria to sludge and performing lactic acid fermentation. The publication also discloses a method of performing this lactic acid fermentation in the presence of cellulase, a lactic acid-containing liquid obtained by adding lactic acid bacteria to sludge and performing lactic acid fermentation, and denitrifying bacteria, and adding nitrogen to the wastewater. A wastewater treatment method for decomposing contained compounds is described.
Japanese Patent Laid-Open No. 6-253871 JP-A-9-173090 JP-A-9-308494

  In the process of producing lactic acid from cellulose, it is important to increase the product concentration and the production rate in order to reduce the cost of the product lactic acid. In order to obtain a high product (lactic acid) concentration, it is necessary to increase the sugar concentration as an intermediate substance to about 10% or more. However, the saccharification reaction by cellulase is inhibited by the generated sugar at a high sugar concentration, and the reaction rate Is significantly reduced. In addition, it is desirable to perform the saccharification reaction in an aseptic system because it is easy to contaminate when the saccharification reaction is performed in an open system, but the saccharification process, saccharified solution transport process, and fermentation process must all be aseptic systems, which increases equipment costs. There is.

  As a means for solving this, simultaneous saccharification and fermentation in which saccharification and fermentation with cellulase are carried out in the same koji has been studied, and in particular, in the biomass alcohol field, optimization has been energetically performed. However, in complete simultaneous saccharification and fermentation, the shearing force due to strong stirring effective in the saccharification reaction of cellulase may adversely affect microorganisms, and it is necessary to adjust the stirring speed according to the fermentation microorganisms. In addition, when the fermenting microorganism is an aerobic microorganism, aeration is necessary, but the slurry of cellulose and residue in the saccharified solution may cause passage of the microorganism. In particular, in the case of microorganisms that produce large pellets, they may adhere to cellulose or saccharification residue and further deteriorate the fluidity.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a lactic acid production method and a lactic acid production apparatus that efficiently perform simultaneous saccharification and fermentation in which saccharification of cellulose and lactic acid fermentation are simultaneously performed.

In order to achieve the above object, the present invention is an apparatus for producing lactic acid from cellulose by simultaneously proceeding saccharification of cellulose and lactic acid fermentation, and comprising saccharified koji, fermented koji, and cellulose material in the saccharified koji. The saccharified liquid containing cellulose short fibers is separated from the saccharified product sent from the saccharified mash through the saccharified product take-out line and transferred to the fermented mash through the saccharified product supplied line. A first separation means for returning the residue containing lysate to the saccharified mash via a residue return line, and separating the fermentation liquor containing lactic acid from the fermented product taken out from the fermented mash via the fermented product taking line, And a second separation means for returning the residue containing the lactic acid fermentation microorganisms to the fermenter via the fermentation residue return line, and an apparatus for producing lactic acid from cellulose, To provide.
The lactic acid production apparatus may include a ventilation line for introducing an oxygen-containing gas such as air into the fermentation zone.
The first separation means and the second separation means are solid liquid selected from filtration separation means such as a falling screen, a cylindrical rotary screen and a vacuum filter, or a centrifugal separation means such as a decanter and a cyclone. A separator may be used.

Furthermore, the present invention is a method for producing lactic acid from cellulose by simultaneously proceeding saccharification of cellulose and lactic acid fermentation using the lactic acid production apparatus, wherein saccharification is performed by allowing cellulase to act on the cellulose material in the saccharification syrup, There is provided a method for producing lactic acid, wherein a saccharified product is lactic acid fermented with a lactic acid fermentation microorganism in a fermented koji to obtain a fermentation broth containing lactic acid.
In the lactic acid production method of the present invention, the lactic acid fermentation microorganism is preferably an aerobic microorganism, particularly a bacterium belonging to the genus Rhizopus.
The cellulose material is preferably waste paper.

  ADVANTAGE OF THE INVENTION According to this invention, the lactic acid manufacturing method and lactic acid manufacturing apparatus which perform efficiently simultaneous saccharification fermentation which performs saccharification of cellulose and lactic acid fermentation simultaneously can be provided.

  FIG. 1 is a diagram showing an embodiment of an apparatus for producing lactic acid from cellulose according to the present invention. This lactic acid production apparatus has a permeable partition wall 2 through which cellulose short fibers and an aqueous solution can pass through a saccharification zone 3 for saccharifying a cellulose material with cellulase and a fermentation zone 4 for producing lactic acid by fermenting a saccharified solution with a lactic acid fermentation microorganism. A saccharification and fermentation cake 1 partitioned by the above, a charging line 5 for supplying a cellulose material to the saccharification zone 3, and a take-out line 5 for taking out a fermentation liquor containing lactic acid from at least one of the saccharification zone 3 and the fermentation zone 4. It is configured.

  In the lactic acid production apparatus, the liquid-permeable partition wall 2 is preferably a wire mesh or punching metal having a pore diameter of 0.1 to 5.0 mm. By partitioning the inside of the tub with such a liquid-permeable partition wall 2, cellulose long fibers, cell pellets or immobilized cells are held in the respective zones, but short fibers, sugar, lactic acid and enzymes are in both zones. You can go back and forth freely.

  Moreover, in this lactic acid production apparatus, the 1st stirring means 8 which stirs the liquid in the saccharification zone 3, and the 2nd stirring means 9 which stirs the liquid in the fermentation zone 4 milder than this 1st stirring means 8 are used. It is configured to include. As these stirring means, a well-known stirrer that rotates and stirs an impeller placed in a liquid at a desired rotational speed can be used. In particular, the second stirring means 9 damages the cells. It is preferable to have a rotational speed control or impeller shape that can be stirred without any trouble. Since separate stirring means 8 and 9 can be arranged for each zone 3 and 4 and stirring conditions can be set separately, in the saccharification zone 3, relatively strong stirring is performed to perform efficient saccharification, while the fermentation zone In No. 4, simultaneous saccharification and fermentation of enzyme action (saccharification) on short cellulose fibers and lactic acid fermentation by lactic acid fermentation microorganisms are performed efficiently. During saccharification and fermentation, since the saccharification and fermentation cake 1 as a whole is maintained at a low sugar concentration, product inhibition of the saccharification reaction is reduced.

  Furthermore, in this lactic acid production apparatus, an aeration line 6 for introducing an oxygen-containing gas such as air is provided in the fermentation zone 4 so that lactic acid fermentation using aerobic microorganisms can be performed. As shown in the present example, when a microorganism having low auxotrophy, such as Rhizopus oryzae, is used as the lactic acid fermentation microorganism, contamination is unlikely to occur because there are few nutrient salts added to the saccharified solution. In addition, when performing lactic acid fermentation by an anaerobic microorganism, this aeration line 6 becomes unnecessary. In addition, depending on the microorganism used, an air lift system may be adopted as a fermentation zone type, and the consumption power can be reduced by the adoption.

  Among the components constituting the lactic acid production apparatus, that is, among the saccharification and fermentation cake 1, the liquid permeable partition wall 2, the input line 5, the aeration line 6, the extraction line 7, the first stirring means 8 and the second stirring means 9. , At least the part that comes into contact with the fermentation broth is a material with good acid resistance that does not corrode even when it comes into contact with lactic acid, such as stainless steel, titanium alloy, synthetic resin-coated steel such as fluororesin, aluminum (preferably oxide-coated aluminum) Consists of materials such as glass. In addition to the above-described components, the saccharification and fermentation cake 1 includes temperature adjusting means for adjusting and maintaining the saccharified solution and the fermentation solution at a desired temperature, a pH adjusting device for maintaining or changing the pH of the solution at a predetermined value, and a liquid Various measuring devices for measuring the turbidity, sugar content, dissolved oxygen amount, etc. of the sucrose can be attached.

  In this illustration, the saccharification and fermentation koji 1 has a circular shape in plan view (see the lower figure in FIG. 1) divided at the center by the liquid permeable partition 2, one of which is a saccharification zone 3 and the other is a fermentation zone 4. However, the shape of the saccharification and fermentation koji 1 is not limited to a circular shape in a plan view, and may be other shapes such as a quadrangular shape in a plan view, an oval shape, or a long band shape as shown in FIG. Further, as shown in FIG. 3, the partition by the liquid permeable partition 2 may be provided concentrically in a bowl, and the outside may be a saccharification zone 3 and the inside may be a fermentation zone 4 (or the inside and outside may be interchanged). Good). The saccharification zone 3 and the fermentation zone 4 may be either side by side or top and bottom, but side by side is preferable because of low aeration power and convenience of operation management. Further, the volume ratio of the saccharification zone 3 and the fermentation zone 4 may be set as appropriate according to the microorganism used. It is preferable to set it to 50% or more and 90% or less with respect to the volume of the whole bowl 1.

  Next, a lactic acid production method using the above-described lactic acid production apparatus will be described. This lactic acid production method is a method of producing lactic acid from cellulose by simultaneously proceeding saccharification of cellulose and lactic acid fermentation using the above-described lactic acid production apparatus. In the saccharification zone 3, saccharification is performed by acting cellulase on the cellulose material. In addition, it includes a step of lactic acid fermentation of the saccharified product by lactic acid fermentation microorganisms in the fermentation zone 4 to obtain a fermentation liquid containing lactic acid.

  In the present lactic acid production method, various cellulose resources can be used as the cellulose material, but among the cellulose resources, a substrate that does not generate cost and is easy to obtain and handle is preferable. One of the substrates. Waste paper is relatively easily hydrolyzed among cellulosic wastes. For example, saccharification with an enzyme (cellulase) can provide a sugar solution having a sufficient concentration even without pretreatment. In general, there are many types of used paper such as newspapers, magazines, office paper, and corrugated paper, and usually recovered paper collected as a mixture thereof is used. Waste paper contains cellulose, hemicellulose, and lignin, and also contains colorants such as printing ink and toner, and fillers. In the present invention, those having a composition with an organic matter ratio of 90% or more, a lignin content of 20% or less, and a hemicellulose content of 20% or less on a dry weight basis can be used, and all ordinary waste paper resources can be used.

Cellulase, an enzyme used to saccharify waste paper in this lactic acid production method, cleaves β-1,4-glucoside bonds of cellulose in an endo form, and finally produces glucose. As this cellulase, various commercially available cellulase preparations obtained from Trichoderma viride or Aspergillus niger can be used. However, in order to use cellulase at low cost and in large quantities, cellulase-producing bacteria belonging to the genus Trichoderma or cellulase-producing bacteria belonging to the genus Aspergillus are cultured, and the enzyme solution from which the fermentation liquid or cells have been removed is saccharified. It is preferable to use for.
As a means for improving cellulase quality, it is possible to produce bacteria capable of producing more powerful cellulase efficiently by using techniques such as gene recombination and cell fusion, and to produce cellulase using the same.

  In the present invention, a bacterium belonging to the genus Rhizopus, preferably Rhizopus oryzae, is used as the lactic acid-fermenting microorganism. The bacteria produce 8-10% L-lactic acid from about 10-12% glucose under aerobic conditions. The bacterium can be used by subculturing a purely cultured preserved strain, and a naturally occurring bacterium or preserved strain is subjected to appropriate mutagenesis treatment such as radiation treatment to create a new strain, A strain having advantageous characteristics in production such as resistance to a growth inhibitory substance contained in the waste paper saccharified solution can be screened and used. When lactic acid fermentation is performed using Rhizopus oryzae, the medium may be a small amount of inorganic salt in addition to the sugar solution that is a carbon source. An example of the medium composition is shown in Table 1.

In this lactic acid production method, in order to produce lactic acid from waste paper, first, the waste paper received in the lactic acid production facility is sent to a pretreatment device, and a pretreatment for sorting incombustibles is performed. This pre-treatment method is appropriately set according to the type and quality of the used paper to be supplied, and the used paper is cut, disaggregated (pulped), or made into a dry fiber, and used for binding as necessary. Remove incombustibles such as synthetic resin films. For removal of these incombustibles, well-known separation techniques and devices such as magnetic sorting, specific gravity sorting, and wind sorting can be used. Further, in order to positively remove oleophilic impurities such as oil-based inks and toners, the oleophilic impurities can be floated and removed by floating sorting after pulping the used paper. In addition, this pre-processing can also be omitted when using the good quality waste paper which does not contain an incombustible material as a raw material.
The used paper that has been pretreated is supplied to the saccharification zone 3 of the saccharification and fermentation koji 1 through the input line 5.

  The saccharification zone 3 can be supplied with cellulase solution, make-up water or pH-adjusted buffer simultaneously with the used waste paper to be supplied or through a separate supply line. The saccharification reaction may be any system such as a continuous system, a batch system, or a semi-batch system. The saccharification zone 3 is maintained at a temperature of 35 ° C. to 60 ° C. and a pH of 3 to 6, and saccharification is performed with stirring. Agitation in the saccharification zone 3 by the first agitation means 8 is preferably performed relatively strongly, and this agitation further promotes disaggregation of used paper and fiber dispersion.

  To the fermentation zone 4, microbial cells (for example, Rhizopus oryzae microbial cells) and nutrient salts are added, and oxygen-containing gas such as air is supplied through the aeration line 6. In the saccharification zone 3, the sugar, oligosaccharide, soluble polysaccharide, and cellulose short fiber produced by partially cutting the cellulose long fiber by the action of cellulase are saccharified through the pores of the liquid permeable partition 2. It moves from the saccharification zone 3 side to the fermentation zone 4 side as a liquid. On the other hand, cellulose long fibers that are insufficiently decomposed and saccharified by cellulase cannot pass through the liquid-permeable partition wall 2 and remain in the saccharification zone 3. Cellulase in the saccharification zone 3 can move to the fermentation zone 4 through the liquid-permeable partition 2 together with the saccharified solution, and the decomposition (saccharification) of cellulose short fibers and the like is continued also in the fermentation zone 4.

Therefore, in fermentation zone 4, saccharification of cellulase of unsaccharified products such as cellulose short fibers and lactic acid fermentation of lactic acid-fermenting microorganisms in which lactic acid is produced from sugars (glucose, xylose, etc.) in the saccharified product proceed simultaneously. . Stirring of the fermentation zone 4 by the second stirring means 9 is a relatively mild condition. In addition, if the inside of this fermentation zone 4 is fully stirred by aeration which pumps air from the ventilation line 6, the 2nd stirring means 9 can be made unnecessary.
The saccharification and fermentation can be performed either continuously or batchwise. However, it is desirable to carry out saccharification using a fed-batch method and fermentation using a batch method in order to prevent contamination and to facilitate operation management.
In this saccharification and fermentation, the liquid temperature and pH in the saccharification and fermentation bowl 1 are the same in the saccharification zone 3 and the fermentation zone 4, but the saccharification zone 3 side is heated and the fermentation zone 4 side is cooled to cause a slight temperature difference. It is possible to provide The flow rate of the liquid from the saccharification zone 3 to the fermentation zone 4 is such that the amount of waste paper and water that are input to the saccharification zone 3 via the input line 5 and the fermentation liquid extracted from the fermentation zone 4 via the extraction line 7. It can be adjusted as appropriate by adjusting the amount of liquid.

  When the lactic acid concentration in the fermentation broth in the fermentation zone 4 reaches a predetermined concentration (for example, about 70 to 90 g / L), stirring and aeration are stopped, and the reaction is terminated. Subsequently, the broth containing lactic acid is extracted from each of the saccharification zone 3 and the fermentation zone 4 through the extraction line 7 and separated into solid and liquid, and the filtrate is sent to a lactic acid production step. A desired purification treatment (filtration, The product is subjected to ion exchange, concentration, vacuum distillation, etc.) to produce product lactic acid, or used as a raw material for polylactic acid.

  According to the lactic acid production apparatus and the lactic acid production method using the lactic acid production apparatus according to the present embodiment, the saccharification and fermentation cake 1 obtained by partitioning the saccharification zone 3 and the fermentation zone 4 with a liquid permeable partition wall 2 through which cellulose short fibers and an aqueous solution can permeate. Using the lactic acid production equipment provided, cellulose material such as waste paper and cellulase are put into the saccharification zone 3 and saccharified with stirring, and lactic acid-fermenting microorganisms are put into the fermentation zone 4. The agitation means 8 and 9 can be arranged and the agitation conditions can be set separately. Therefore, in the saccharification zone 3, relatively strong agitation is performed for efficient saccharification, while in the fermentation zone 4, lactic acid fermentation microorganisms are damaged. Enzyme action (saccharification) on short cellulose fibers under relatively mild stirring conditions (or under aeration), and simultaneous saccharification and fermentation of lactic acid fermentation by lactic acid fermentation microorganisms The rate is well done. In addition, during saccharification and fermentation, the saccharification and fermentation cake 1 as a whole is kept at a low sugar concentration, so that product inhibition of the saccharification reaction is reduced. Therefore, lactic acid can be produced efficiently at a high production rate with the cellulose material.

  FIG. 4 is a view showing another embodiment of an apparatus for producing lactic acid from cellulose of the present invention. In this embodiment, the lactic acid production apparatus includes a saccharified cocoon 10 that decomposes and saccharifies the cellulose material with cellulase, a fermented mash 11 that lactically ferments sugars (glucose, xylose, etc.) in the saccharified liquid using lactic acid-fermenting microorganisms, A saccharified solution containing cellulose short fibers from a saccharified product sent from the saccharified culm 10 via a saccharified product take-out line 12 to a cellulose material, water and a cellulase solution, etc., simultaneously or separately. Is separated and transferred to the fermentation cake through the saccharified product supply line 15, and the first separation means 13 for returning the residue containing cellulose long fibers to the saccharified cake 10 through the residue return line 14, and the fermentation cake 11 From the fermented product taken out from the fermented product take-out line 16, the fermentation broth containing lactic acid is separated and taken out through the fermented product take-out line 18, The residue containing the acid fermentation microorganism via the fermentation residue return line 20 is constructed and a second separation means 17 for returning to the fermenter.

  The saccharified koji 10 and the fermented koji 11 are provided with a stirring means (not shown). These stirring means, like the first and second stirring means 8 and 9, have a relatively strong liquid in the saccharified koji 10. The saccharification can be promoted by stirring. On the other hand, in the fermenter 11, one that can perform relatively weak stirring that does not damage the lactic acid fermentation microorganisms in the fermenter 11 can be selected and arranged. . The stirring means of the fermenter 11 can be substituted by aeration. The saccharified mash 10 and the fermented mash 11 include temperature adjusting means for adjusting and maintaining the saccharified liquid and the fermented liquid at a desired temperature, a pH adjusting device for maintaining or changing the pH of the liquid at a predetermined value, turbidity of the liquid, sugar content, Various measuring devices for measuring the dissolved oxygen amount and the like can be attached.

  In this example, an aeration line is provided for supplying the fermenter 11 with an oxygen-containing gas such as air to perform aeration. When a microorganism with low auxotrophy, such as Rhizopus oryzae, is used as the lactic acid fermentation microorganism, contamination is unlikely to occur because there are few nutrient salts added to the saccharified solution. In addition, when performing lactic acid fermentation by an anaerobic microorganism, this aeration line becomes unnecessary. In addition, depending on the microorganism used, an air lift system may be adopted as the form of the fermenter, and the consumption power can be reduced by adopting it.

The first separation means 13 and the second separation means 17 are selected from a filtration separation means such as a falling screen, a cylindrical rotary screen and a vacuum filter, or a centrifugal separation means such as a decanter and a cyclone. A liquid separator can be used, and a decanter is preferably used. The fermentation liquor extraction line 18 for taking out the fermentation liquor from the second separation means 17 can branch the fermentation liquor return line 19 connected to the saccharification jar 10 on the way, and can perform simultaneous saccharification and fermentation while circulating the fermentation liquor.
Further, as a solid-liquid separation method by the first separation means 13 and the second separation means 17, a gravity sedimentation zone is provided inside the saccharified mash 10 (or the fermented mash 11), and the overflow is fermented by the fermented mash 11 (or saccharified mash 10 ) May be added. This gravity settling zone can be installed in both or one of the saccharification mash 10 and the fermentation mash 11.

  In the lactic acid production apparatus of this embodiment, as in the lactic acid production apparatus according to the previous embodiment, the saccharification jar 10 performs efficient saccharification by relatively strong agitation, while the fermentation mash 11 damages the lactic acid fermentation microorganisms. Under the relatively mild stirring conditions (or under aeration) that are not applied, the action of the enzyme (saccharification) on the short cellulose fibers and the simultaneous saccharification and fermentation of lactic acid fermentation by lactic acid-fermenting microorganisms are performed efficiently. Further, during saccharification and fermentation, since the overall sugar concentration is kept low, product inhibition of the saccharification reaction is reduced. Therefore, lactic acid can be produced efficiently at a high production rate with the cellulose material.

  A stainless steel beaker (diameter 150 mm, height 200 mm, upper opening) with a cylinder (diameter 75 mm, height 200 mm, upper opening) made of an aluminum punch plate (hole diameter 1 mm) is installed as a liquid-permeable partition. The inside of the punch plate cylinder was used as a saccharification zone, and an agitator (impeller; disk turbine blade (diameter 50 mm)) was installed at the top.A venting device was installed as a fermentation zone between the punch plate and the stainless beaker. The reaction was carried out under the following conditions for 2 L. (Example) As a control, the same reaction was carried out at two stirring speeds in a beaker without a punch plate cylinder (Comparative Examples 1 and 2). The amount of waste paper added, the timing of addition, the amount of enzyme, the reaction temperature, the amount of calcium carbonate added were all equal, and sterilization was not performed.

(Experimental conditions)
[Raw material] Used office paper (Pretreatment is disaggregated, filtered and dried)
[Saccharification] Enzyme: Commercial Cellulase Added Enzyme Amount: 10 FPU / g-Waste Paper Used Paper Concentration: 15 w / v% (Total)
Reaction method: fed-batch (adding waste paper and a corresponding amount of enzyme every 5 w / v% at 0, 24, and 48 hours)
Stirring speed: adjusted between 50 and 300 rpm according to the fluidity of the substrate [Fermentation] Cells used: Rhizopus oryzae
pH: 3-7 (addition of calcium carbonate 2 w / v% twice to prevent pH drop)
Ventilation rate: 0.5vvm
Medium: In addition to the waste paper, the inorganic salt medium shown in Table 1 was added.

[Cellulase activity measurement method] FPU: filter paper (Whatman No. 1) 50 mg as a substrate, 0.5 mL of enzyme solution and 1.0 mL of citrate buffer (pH 4.8, 0.05 M) were added thereto, After carrying out the enzyme reaction for 1.0 hour, add 3.0 mL of dinitrosalicylic acid reagent and heat at 100 ° C. for 5 minutes to cause color development. After cooling, 20 mL of ion-exchanged water or distilled water is added thereto, and colorimetric determination is performed at a wavelength of 540 nm. The amount of enzyme that produces reducing sugar corresponding to 1 μmol of glucose per minute was defined as 1 unit (FPU).

[result]
Example: Simultaneous saccharification and fermentation with partition by punch plate cylinder (constant at a stirring speed of 300 rpm)
Comparative Example 1: Simultaneous saccharification and fermentation without partitioning (constant at a stirring speed of 300 rpm)
Comparative Example 2: Simultaneous saccharification and fermentation without partitioning (constant at a stirring speed of 100 rpm)
For each of these Examples and Comparative Examples 1 and 2, samples were taken every predetermined time from the start of simultaneous saccharification and fermentation, and the lactic acid content was measured. The results are summarized in FIG.
As can be seen from the results shown in FIG. 5, in the simultaneous saccharification and fermentation (Example) in which a partition by a punch plate cylinder is installed, lactic acid having a concentration of 70 g / L or more can be produced from waste paper in 4 to 6 days.
On the other hand, in simultaneous saccharification and fermentation without comparison (Comparative Examples 1 and 2), the amount of lactic acid produced was clearly lower than that in Examples.

It is a schematic block diagram which shows one Embodiment of the lactic acid manufacturing apparatus of this invention. It is a top view which shows another example of a shape of the saccharification fermenter of a lactic acid manufacturing apparatus. It is a top view which shows another example of shape of the saccharification and fermentation fermenter of a lactic acid manufacturing apparatus. It is a schematic block diagram which shows other embodiment of the lactic acid manufacturing apparatus of this invention. It is a graph which shows the result of the Example which concerns on this invention, and shows the amount of lactic acid production per hour of an Example and Comparative Examples 1 and 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1A-1C Saccharification and fermentation rice cake 2 Permeable partition 3 Saccharification zone 4 Fermentation zone 5 Input line 6 Aeration line 7 Extraction line 8 1st stirring means 9 2nd stirring means 10 Saccharification rice cake 11 Fermented rice cake 12 Saccharification product extraction line 13 1st separation means 14 Residue return line 15 Saccharified product supply line 16 Fermented product takeout line 17 2nd separation means 18 Fermentation liquid takeout line 20 Fermentation residue return line

Claims (7)

An apparatus for producing lactic acid from cellulose by simultaneously proceeding saccharification of cellulose and lactic acid fermentation,
A saccharified product obtained by separating a saccharified solution containing cellulose short fibers from a saccharified product sent from the saccharified product through a saccharified product extraction line A first separation means for transferring the residue containing cellulose long fibers to the saccharified mash through a residue return line, and a fermented product taken out from the fermented mash through a fermented product extraction line. And a second separation means for separating the fermented liquor containing lactic acid from the fermented liquor and taking it out through the fermented liquor take-out line and returning the residue containing the lactic acid fermenting microorganisms to the fermented koji via the fermented residue return line. Lactic acid production equipment from cellulose.   The apparatus for producing lactic acid from cellulose according to claim 1, comprising a ventilation line for introducing an oxygen-containing gas such as air into the fermentation zone.   Solid-liquid separation wherein the first separation means and the second separation means are selected from filtration separation means such as a falling screen, a cylindrical rotary screen and a vacuum filter, or a centrifugal separation means such as a decanter and a cyclone. The apparatus for producing lactic acid from cellulose according to claim 1 or 2, which is a machine.   A method for producing lactic acid from cellulose by simultaneously proceeding saccharification of cellulose and lactic acid fermentation using the lactic acid production apparatus according to any one of claims 1 to 3, wherein cellulase is allowed to act on the cellulose material in the saccharified koji. And saccharifying the saccharified product in a fermented rice cake with a lactic acid-fermenting microorganism to obtain a fermentation broth containing lactic acid.   The method for producing lactic acid according to claim 4, wherein the lactic acid fermentation microorganism is an aerobic microorganism.   The method for producing lactic acid according to claim 4 or 5, wherein the lactic acid-fermenting microorganism is a bacterium belonging to the genus Rhizopus.   The method for producing lactic acid according to any one of claims 4 to 6, wherein the cellulose material is waste paper.

Images