JP2009225755A - Method for continuously producing alcohol - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for continuously producing an alcohol capable of making full use of the ability to produce an alcohol of yeast having a property of coagulation and sedimentation by preventing the outflow of yeast cells and improving the contact efficiency between alcohol raw materials and the yeast in continuously producing the alcohol. <P>SOLUTION: The method for continuously producing an alcohol by which an alcohol is produced by forcibly causing a liquid flow to occur in a lower side of a fermentation tank when alcohol fermentation is performed by supplying alcohol raw materials to the fermentation tank in the presence of the yeast having the property of coagulation and sedimentation, characterized by performing alcohol fermentation in a state where an interface of the yeast is formed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an alcohol continuous production method, and more particularly, to an alcohol continuous production method using yeast having coagulation sedimentation properties.

Patent Document 1 discloses an alcohol production method using a yeast comprising Saccharomyces cerevisiae AM12 strain (hereinafter referred to as AM12 strain if necessary), and AM12 has an excellent alcohol-producing ability. There is a description that it has alcohol resistance and coagulation sedimentation.
JP 59-135896 A

  In the continuous production of alcohol, an alcohol raw material is continuously supplied to a fermentor to perform alcoholic fermentation with yeast, while the obtained alcohol culture solution is drawn from the fermenter. In continuous alcohol production without cell recycling (reuse), cells in the alcohol culture are not returned to the fermenter.

  In the fermenter, since the reaction efficiency increases as the number of contact between the alcohol raw material and the yeast increases, it is preferable to completely mix by stirring or the like. However, if they are completely mixed, when the alcohol culture solution is extracted from the fermenter, high-concentration yeast is extracted together, and the bacterial cell concentration in the fermenter is reduced.

  If the amount of yeast grown is small relative to the amount of alcohol culture withdrawn, the amount of yeast that has flowed out cannot be compensated for. There is a problem that the number of times of contact greatly decreases due to a decrease in yeast, and the efficiency of the alcohol production reaction decreases.

  On the other hand, if the inside of a fermenter is not stirred, the yeast which has coagulation sedimentation will settle, and will deposit on the bottom part of a fermenter. As the fungus body settles, it enters the consolidation area from the sedimentation area after a lapse of a predetermined time, so that a cell layer zone (consolidation zone) is formed at the bottom. When the alcohol raw material is supplied from the bottom of the fermenter, the alcohol raw material passes through this layer zone, and contact between the alcohol raw material and the yeast occurs. Since the amount of yeast cells is excessive with respect to the raw material, there is a problem that the reaction efficiency of the alcohol raw material and yeast becomes extremely poor.

  In particular, AM12 bacteria are characterized by low cell growth ability while exhibiting high alcohol productivity and alcohol resistance, and the above-mentioned problems are noticeable.

  The present invention solves the above problems, and the object of the present invention is to prevent yeast cell outflow in continuous alcohol production, improve the contact efficiency between the alcohol raw material and the yeast, and have a coagulation-precipitation property. It is to provide a continuous alcohol production method capable of fully utilizing the alcohol production capacity of the present invention.

  Other problems of the present invention will become clear from the following description.

  That is, the said subject is solved by each following invention.

(Claim 1)
Continuous production of alcohol that produces alcohol by generating a forced liquid flow below the fermenter when alcohol fermentation is performed by supplying yeast with coagulation sedimentation in the fermenter and supplying alcohol raw material to the fermenter A method,
A method for continuously producing high-concentration alcohol, characterized in that alcohol fermentation is carried out in a state in which a cell interface is formed.

(Claim 2)
The high-concentration alcohol continuous production method according to claim 1, wherein the interface can be observed as a boundary between a layer having a high concentration of yeast cells and a layer having a low concentration formed in an alcoholic fermentation broth in a fermenter. .

(Claim 3)
The method for continuously producing high-concentration alcohol according to claim 1 or 2, wherein the yeast having the aggregation and precipitation property is Saccharomyces cerevisiae AM12 strain.

(Claim 4)
The high-concentration alcohol continuous production method according to any one of claims 1 to 3, wherein an average yeast cell concentration in the fermenter is 20 to 33 g (dry weight) / L.

(Claim 5)
The concentration of yeast cells contained in the alcohol fermentation broth above the interface is less than 14 g (dry weight) / L, and the average yeast cell concentration below the interface is 31-38 g (dry weight) / L. It is L, The high concentration alcohol continuous production method in any one of Claims 1-4 characterized by the above-mentioned.

(Claim 6)
The high-concentration alcohol continuous production method according to any one of claims 1 to 5, wherein the presence or absence of the interface is determined by visual observation from a viewing window formed on a side surface of the fermenter.

(Claim 7)
The high-concentration alcohol continuous production method according to any one of claims 1 to 5, wherein the presence or absence of the interface is measured using a fermentation element and a light-receiving element provided above the liquid level of the fermenter.

(Claim 8)
6. The presence or absence of the interface is detected by a turbidimeter provided in a plurality in the height direction from the liquid level of the alcohol fermentation liquid in the fermenter downward. High concentration alcohol continuous production method.

(Claim 9)
The high-concentration alcohol continuous production method according to any one of claims 1 to 8, wherein the means for forcibly generating a liquid flow below the fermenter is mainly due to rotation of a stirrer.

  According to the present invention, there is provided a continuous high-concentration alcohol production method capable of preventing the outflow of bacterial cells, improving the contact efficiency between the alcohol raw material and the yeast, and sufficiently utilizing the alcohol production ability of the yeast having coagulation sedimentation properties. be able to.

  In the continuous alcohol production method, the present inventors adjust the forced liquid flow below the fermenter using yeast having coagulation sedimentation, and the bacterial cells are produced in the fermenter by the liquid flow derived from stirring or the like. It was found that two layers with different bacterial cell concentrations were formed by the function of soaring and the function of bacterial cells coagulating and sedimenting due to the aggregation and sedimentation properties of yeast, and the boundary between the layers could be observed as an interface.

  The area with high cell density below this interface is different from the compacted area due to coagulation sedimentation, and the cell density on the interface is extremely different from that on the interface, and this interface is formed. In the state, it was found that the reaction was promoted without inhibiting the fermentation reaction of the alcohol raw material. In addition, when an interface under stirring is present, it is possible to prevent bacterial cell outflow by pulling out the fermentation solution at the upper part of the interface, improving the contact efficiency between the alcohol raw material and yeast, and the alcohol production ability of AM12 bacteria I found out that I could make full use of

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  In FIG. 1, 1 is a fermenter, and an alcohol raw material is supplied from a raw material supply port 10 at the bottom of the fermenter 1. In the fermenter 1, yeast having coagulation sedimentation properties is placed.

  For example, when an alcohol raw material is continuously supplied from the raw material supply port 10 into the fermenter 1, alcohol fermentation is performed by yeast to obtain an alcohol fermentation broth. The alcohol fermentation broth is drawn out from the outlet 11. In addition, if the alcohol raw material is supplied from the bottom of the fermenter, the supply method is not limited, and the installation of the raw material supply port 10 is merely an example. Similarly, the extraction method of the alcohol fermentation broth is not limited as long as it is extracted from the upper part.

  In the present invention, continuous alcohol production refers to continuously taking out a product, for example, while continuously supplying a sugar solution, which is an alcohol raw material, to a fermenter. Therefore, even if the supply of the alcohol raw material is discontinuous, the supply amount per hour may be substantially constant.

  In the continuous production of alcohol of the present invention, the outflow of cells from the fermenter is suppressed, but some cells may flow out. However, it is prevented that the microbial cell density | concentration in a fermenter reduces by this microbial cell outflow. In the present invention, a state where the interface is observed, that is, layers having different concentrations in the vertical direction of the fermenter are formed, so the amount of bacterial cell growth in the fermenter is overwhelmingly larger than the outflow amount, It is basically not intended to be added to the fermenter at all times. However, it may be added as an inoculum, and separating the cells that have slightly flowed out and returning them to the fermenter does not impede the effects of the present invention.

  In the present invention, the alcohol fermentation liquid in the fermenter 1 is characterized in that alcohol fermentation is performed in a state where an interface is formed even when a liquid flow is generated by stirring or the like.

  The interface is a linear boundary surface formed in the boundary between two layers having different turbidity (transparency) or hue, which is observed in the alcohol fermentation liquid. In addition, a linear boundary is seen when observing a fermenter from a horizontal direction, and does not need to be a straight line.

  Each layer is recognized as two layers having different turbidity (transparency) or hue because the yeast cell concentration contained in the alcohol fermentation liquid is dramatically different.

  For example, the color of the alcohol fermentation broth itself is observed above the interface, the turbidity is low, and below the interface there are many yeast cells, so the turbidity is opaque and high, so the difference between A and B is clearly known, The presence or absence of an interface can be observed visually.

  Above the interface (A) is a layer where the concentration of yeast cells is extremely low, and below the interface (B) is a layer where the concentration of yeast cells is high.

  Expressed quantitatively in terms of bacterial cell concentration, the average yeast cell concentration in the alcoholic fermentation broth in the fermenter (the concentration of cells measured in a fully mixed state and the total yeast cell mass in the fermenter ( The dry weight: g) is equal to the value obtained by dividing the amount of alcohol fermented liquor (L) in the fermenter by 20 to 33 g (dry weight) / L, more preferably 25 to 32 g (dry weight) / L. More preferably, it is 26 to 31 g (dry weight) / L, whereas the yeast cell concentration in the layer (A) having a low yeast cell concentration above the interface is preferably 14 g (dry weight). ) / L, more preferably less than 10 g (dry weight) / L, still more preferably less than 7 g (dry weight) / L, and the yeast cells in the layer (B) having a high yeast cell concentration below the interface The concentration is preferably 31 to 38 g (dry weight) / L, more preferably Ku is 32～37G (dry weight) / L, and more preferably from 33～36G (dry weight) / L.

  It is important that the interface is formed below the outlet 11 from which the alcoholic fermentation broth is extracted. If it does so, since the alcohol fermentation liquid is extracted from the layer with a low cell density | concentration, the outflow of a yeast cell can be suppressed.

  Since the contained yeast cell concentration is different, of course, in the layer (A) where the yeast cell concentration is low and the layer (B) where the yeast cell concentration is high, the layer (B) where the yeast cell concentration is high is alcohol. Productivity is high. Therefore, productivity is improved when the proportion of the layer (B) having a higher yeast cell concentration than the interface is higher.

  That is, the interface is formed in a depth region of 0.1H to 0.8H (H: liquid level height) downward from the liquid level of the alcohol fermentation liquid in the fermenter, preferably 0.2H to. The layer (B) formed at 0.6H, more preferably 0.2H to 0.5H or having a high yeast cell concentration is 20 to 90%, preferably 40 to 80% of the volume V of the alcohol fermentation broth. More preferably, it occupies 50 to 80% and is formed on the bottom side (downward) of the fermenter.

  FIG. 1 shows a preferred position in the height direction where the interface is formed.

  In a fermenter having a constant cross-sectional area, such as a cylindrical fermenter, the position at which the interface is observed is 0.1H to 0.8H (H from the surface of the alcoholic fermentation broth in the fermenter downward. : Liquid level height), preferably 0.2H to 0.6H, more preferably 0.2H to 0.5H.

  When the interface is formed in a depth region of 0.1H to 0.8H, preferably 0.2H to 0.6H, more preferably 0.2H to 0.5H, the balance between stirring and sedimentation can be achieved. In this state, the bacterial cell concentration in the fermenter 1 is maintained high and the contact efficiency with the alcohol raw material is good, so that ethanol productivity can be increased.

  When the position of the interface is above 0.1H, it is almost close to complete mixing. Then, the bacterial cells easily flow out from the discharge port 11, and the amount of bacterial cells in the fermenter is reduced, so that alcohol production is achieved. This is unfavorable because the nature drops.

  Moreover, when the position of an interface is below 0.8H, the microbial cell in a fermenter begins to deposit at the bottom part of a fermenter, and a sedimentation area | region and a compaction area | region zone are formed. Even if the alcohol raw material is supplied from the bottom of the fermenter, the reaction efficiency between the alcohol raw material and the yeast becomes extremely poor due to too much yeast in the sedimentation area and compaction area. Is not preferable.

  The state in which the interface is not observed may be a case of complete mixing or a state in which the amount of bacterial cells in the fermenter is too small and the concentration difference is not known. This is an undesirable state.

  FIG. 2 shows a preferred interface position in a ratio of the layer (B) having a high yeast cell concentration to the volume V of the alcohol fermentation broth. The interface is formed at the boundary between the layer (A) having a low yeast cell concentration and the layer (B) having a high yeast cell concentration, so that the yeast formed on the bottom side (downward) of the fermenter The position where the interface is formed is defined by setting the ratio of the layer (B) having a high body concentration to 20 to 90%, preferably 40 to 80%, more preferably 50 to 80% of the volume V of the alcohol fermentation broth. it can. Note that V = v1 + v2 where v1 is the volume of the layer (B) having a high yeast cell concentration and v2 is the layer (A) having a low yeast cell concentration.

  If a layer having a high bacterial cell concentration is set based on the concept of volume, the fermenter has a non-constant cross-sectional area, and it is possible to cope with the case where it is difficult to specify the height.

  In the present invention, when the volume v1 of the high layer (B) of yeast cells occupies more than 90% of the volume V of the alcohol fermentation liquid, this is a case where it is close to complete mixing. Is liable to flow out, and the amount of bacterial cells in the fermenter is reduced.

  Moreover, when the volume v1 of the high layer (B) of yeast cells is less than 20% of the volume V of the alcohol fermentation liquid, the cells in the fermenter begin to deposit on the bottom of the fermenter, and the sedimentation zone or the compaction zone zone Is formed. Even if the alcohol raw material is supplied from the bottom of the fermenter, the reaction efficiency between the alcohol raw material and the yeast becomes extremely poor due to too much yeast in the sedimentation area and compaction area. Is not preferable.

  In the present invention, in addition to the liquid flow generated by supplying the alcohol fermentation liquid, means for generating a forced liquid flow is provided below the fermenter, and the means for forcibly generating the liquid flow is mainly based on the rotation of the stirrer. Those are preferred. That is, only a stirrer or a combination of a stirrer and air aeration may be used, but it is preferable to use only a stirrer in consideration of convenience of control.

  In the examples of FIGS. 1 and 2, a stirrer 12 having a stirring blade is shown as a stirring means.

  The position of the interface can be maintained by appropriately changing the operating conditions for continuous fermentation, such as the strength of stirring, so as to be formed in the preferred region.

  The interface rises when the action of winding up the microbial cells by the liquid flow becomes stronger, and falls when the action of raising the wound becomes weaker due to the progress of sedimentation.

  For example, if the rotation of the stirrer is increased, the interface rises.

  In addition, the increase in the supply of alcohol raw material and air causes the interface to rise if an upward flow occurs.

  Further, when the rotation of the stirrer is stopped or the rotation is lowered in the complete mixing state, an interface is formed.

  Regarding the observation of the presence or absence of the interface, since there is a difference in hue or transparency between the layer (A) having a low yeast cell concentration and the layer (B) having a high yeast cell concentration, it can be visually observed.

  In the case of an opaque fermenter made of stainless steel or the like, a viewing window (observation window) 102 is provided in the fermenter 101 as shown in FIG. 3, and the presence or absence of an interface can be observed.

  In addition, the presence or absence of the interface is confirmed by measuring the bacterial cell concentration by providing two or more turbidimeters with different positions in the vertical direction downward from the surface of the alcoholic fermentation liquid in the fermenter. You can also

  Further, the presence or absence of an interface is determined by using a light emitting element and a light receiving element provided above the liquid level of the fermenter, and the light from the light emitting element is reflected at the interface and the reflected light is received by the light receiving element to obtain a change in the light amount. It can also be measured.

  The yeast having aggregating and precipitating ability may be any yeast having a sedimentation property that forms an interface even if stirring is performed. ) Is used.

  AM12 has been deposited with the National Institute of Advanced Industrial Science and Technology (National Institute of Advanced Industrial Science and Technology, Patent Biological Depositary (IPOD)) as the National Institute of Advanced Industrial Science and Technology, under No. 6749. Available.

  The alcohol raw material used in the present invention is preferably a cereal-derived raw material. For example, rice, wheat, potato and the like have high sugar concentrations, and are preferred examples. The sugar concentration is preferably in the range of 100 to 300 g / L, more preferably in the range of 150 to 200 g / L in terms of glucose, from the viewpoint of saccharification reaction efficiency of the grain raw material.

  The dilution rate (value obtained by dividing the alcohol raw material supply rate by the culture volume) is preferably in the range of 0.1 to 0.3, more preferably in the range of 0.14 to 0.18.

  In alcohol production, the load can be calculated from the dilution rate and the sugar concentration in the alcohol raw material.

  By the alcohol production method for forming the interface of the present invention, by suppressing the outflow of bacterial cells and maintaining a large amount of bacterial cells in the fermenter, yeast having a cohesive precipitation property, preferably AM12 bacteria, is a continuous alcohol with a high load. It becomes possible to cope with production, and as a result, alcohol productivity can be increased.

  In the present invention, it is also preferable to provide an air supply pipe in the fermenter.

  The amount of air is preferably 0.1 to 0.2 (vvm) in terms of oxygen supplementation, more preferably 0.125 to 0.17 (vvm) (vvm: volume gas / (volume liquid / minute) ). In order to promote the growth of yeast cells, it is preferable that as much air as possible can be supplied as long as alcohol fermentation is not inhibited.

  The temperature of the culture solution in the fermenter is preferably 40 ° C. or less, more preferably in the range of 30 to 35 ° C., from the viewpoint of the optimum fermentation temperature for yeast. For temperature adjustment, adjustment means such as a heater and a cooler can be adopted, but there is no particular limitation.

  The pH is preferably in the range of 3 to 7, more preferably in the range of 3.5 to 5.0, from the viewpoint of the optimum pH of the yeast. As a pH adjustment method, a pH control system that adjusts pH by continuously supplying a pH adjusting agent based on data measured by a pH meter can be employed.

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

  While supplying an alcohol raw material (glucose) to a fermenter, the fermented liquid (culture liquid) was extracted at the same speed as the supplied raw material, and continuous fermentation was performed without bacterial cell recycling. In the following experiment, AM12 fungal yeast cells present in the fermenter are also simply referred to as fungal cells.

  The fermenter has the configuration shown in FIG. 1, the diameter is 126 mm, the amount of liquid in the fermenter is 1000 mL (about 85 mm from the bottom of the fermenter), and the number of revolutions can be changed (four plates) Blade: The maximum rotation diameter of the stirring blade is 64 mm, and the size of each blade is 15 × 12 mm.

  The operating conditions of the fermenter other than the dilution rate and the rotational speed of the stirrer are as follows: temperature 30 ° C., pH 5, aeration rate 0.15 vvm, and the sugar concentration in the alcohol raw material is 200 g / L.

Example 1
Continuous fermentation was performed with the dilution rate set to 0.18 and the rotation speed of the stirrer set to 50 rpm.
The interface was formed at 0.42H. The ethanol productivity was 17.8 g / L / h.

Example 2
Continuous fermentation was performed with the dilution rate set to 0.14 and the rotation speed of the stirrer set to 150 rpm.
The interface was formed at 0.23H. Ethanol productivity was 12.2 g / L / h.

Comparative Example 1
Continuous fermentation was performed with the dilution rate set to 0.18 and the rotation speed of the stirrer set to 200 rpm.
A complete mixing state occurred, and bacterial cell outflow occurred, resulting in a marked decrease in ethanol productivity.

Comparative Example 2
Continuous fermentation was performed with the dilution rate set to 0.18 and the rotation speed of the stirrer set to 10 rpm.
The interface was formed at 0.95H. Ethanol productivity was 10 g / L / h.

  In addition, since the fermenter of a present Example is a column shape, B layer formed below the interface formed in 0.42H of Example 1 and 0.23H of Example 2 has the range of v1. Satisfies.

Schematic showing the preferred position where the interface is formed in height The schematic diagram which shows the preferable position where an interface is formed with the volume of the layer (B) with a high yeast cell density | concentration Schematic of fermenter with interface observation window

Explanation of symbols

1: Fermenter 10: Raw material supply port 11: Discharge port 12: Stirrer 101: Fermenter 102: Observation window

Claims (9)

Continuous production of alcohol that produces alcohol by generating a forced liquid flow below the fermenter when alcohol fermentation is performed by supplying yeast with coagulation sedimentation in the fermenter and supplying alcohol raw material to the fermenter A method,
A method for continuously producing high-concentration alcohol, characterized in that alcohol fermentation is carried out in a state in which a cell interface is formed.   The high-concentration alcohol continuous production method according to claim 1, wherein the interface can be observed as a boundary between a layer having a high concentration of yeast cells and a layer having a low concentration formed in an alcoholic fermentation broth in a fermenter. .   The method for continuously producing high-concentration alcohol according to claim 1 or 2, wherein the yeast having the aggregation and precipitation property is Saccharomyces cerevisiae AM12 strain.   The high-concentration alcohol continuous production method according to any one of claims 1 to 3, wherein an average yeast cell concentration in the fermenter is 20 to 33 g (dry weight) / L.   The concentration of yeast cells contained in the alcohol fermentation broth above the interface is less than 14 g (dry weight) / L, and the average yeast cell concentration below the interface is 31-38 g (dry weight) / L. It is L, The high concentration alcohol continuous production method in any one of Claims 1-4 characterized by the above-mentioned.   The high-concentration alcohol continuous production method according to any one of claims 1 to 5, wherein the presence or absence of the interface is determined by visual observation from a viewing window formed on a side surface of the fermenter.   The high-concentration alcohol continuous production method according to any one of claims 1 to 5, wherein the presence or absence of the interface is measured using a fermentation element and a light-receiving element provided above the liquid level of the fermenter.   6. The presence or absence of the interface is detected by a turbidimeter provided in a plurality in the height direction from the liquid level of the alcohol fermentation liquid in the fermenter downward. High concentration alcohol continuous production method. The high-concentration alcohol continuous production method according to any one of claims 1 to 8, wherein the means for forcibly generating a liquid flow below the fermenter is mainly due to rotation of a stirrer.

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