Continuous extraction and fermentation apparatus and continuous extraction and fermentation method

Abstract

To provide a continuous extraction fermentation apparatus capable of efficiently recovering the target product at a stable concentration.SOLUTION: The continuous extraction fermentation apparatus includes: a group of extraction and fermentation tanks comprising in which are arranged extraction and fermentation tanks in parallel, each filled with a saccharification liquid and microorganisms in the lower phase and an extractant in the upper phase; first piping configured to extract part or all of the extractant from each of the extraction and fermentation tanks; an intermediate tank configured to mix the extractant extracted from the extraction and fermentation tanks and to level out fluctuations in the concentration of the target product; a distillation column configured to separate and purify the target product from the extractant; second piping configured to return the reproduced extractant from which the target product was separated to the distillation column to the extraction fermenter; and a control unit for initiating, with a predetermined time difference, the supply of the saccharified liquid to the extraction and fermentation tanks, the extraction of the extractant from the extraction and fermentation tanks, and the supply of the extractant reproduced in the distillation column, for each of the extraction and fermentation tanks.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a continuous extractive fermentation apparatus and a continuous extractive fermentation method. [Background technology]

[0002] In recent years, there has been a demand for effective and concrete efforts to reduce carbon dioxide emissions as a measure against global warming. This does not only apply to energy derived from fossil resources, but also to materials such as plastics. While recycling of waste plastics is one possible measure to combat global warming related to plastics, there are limitations in collection and processing capacity, as well as in ensuring quality. Therefore, in Japan, there is an urgent need not only for recycling but also for the bio-based production of newly supplied plastics as a system with a low environmental impact.

[0003] One type of biomaterial is bio-polyethylene terephthalate (bio-PET). However, the current bio-PET is limited to bio-based ethylene glycol, which accounts for approximately 30% of the raw material weight, and terephthalic acid, which accounts for 70% of the raw material weight, remains derived from fossil resources. Terephthalic acid is usually produced from paraxylene. Meanwhile, technological development is underway to produce isobutanol from biomass-derived sugars through fermentation, and then convert this bio-isobutanol into bio-paraxylene using catalytic conversion technology. Establishing this technology will make it possible to produce 100% bio-PET.

[0004] A challenge in isobutanol fermentation technology is low productivity due to the high bacterial toxicity of the target product, isobutanol. Currently, various research and development efforts are underway to avoid this isobutanol toxicity, and extractive fermentation is one effective method. Extractive fermentation involves contacting an isobutanol fermentation broth with an extractant to transfer the target product, isobutanol, from the fermentation broth to the extractant, thereby reducing the isobutanol concentration in the fermentation broth, thereby avoiding isobutanol toxicity and achieving high productivity. The extractant containing the transferred isobutanol can be treated by distillation or other methods to separate and recover the target product, isobutanol.

[0005] For example, Patent Document 1 discloses a method for producing butanol, which includes an extraction step of contacting an extractant containing oleyl alcohol and tributyrin with a culture solution containing butanol produced by a microorganism immobilized on gel beads, thereby extracting the butanol into the extractant. Patent Document 2 also discloses a method for recovering a product alcohol from a fermentation broth, which includes the steps of providing a fermentation broth containing a microorganism that produces a product alcohol, contacting the fermentation broth with at least one extractant, and recovering the product alcohol. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2019-030241 [Patent Document 2] Japanese Patent Application Laid-Open No. 2018-121648 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the extractive fermentation methods described in Patent Documents 1 and 2, as the reaction progresses and the concentration of the target product in the extractant increases, the extraction rate and extraction efficiency decrease, which in turn decreases the fermentation efficiency of the target product, resulting in a problem that productivity improvement is limited to a certain level.

[0008] The present invention has been made in view of the above circumstances, and provides an apparatus and method for continuous extraction and fermentation that can efficiently recover a target product at a stable concentration. [Means for solving the problem]

[0009] That is, the present invention includes the following aspects. (1) A group of extraction fermentation tanks, each of which has two or more tanks arranged in parallel, each tank containing a saccharified solution and microorganisms in a lower phase and an extractant in an upper phase, and which are configured to ferment the saccharified solution with the microorganisms to produce a fermentation solution containing a target product and extract the target substance into the extractant simultaneously; A first pipe configured to extract a part or all of the extractant from each of the two or more extractive fermentation tanks; an intermediate tank configured to mix the extractants extracted from each of the two or more extractive fermentation tanks and level out fluctuations in the concentration of the target product; a distillation column configured to separate and purify the target product from the extractant, the concentration of which has been equalized and which has been withdrawn from the intermediate tank; A second pipe configured to return the extractant recovered by separating the target product in the distillation column to the two or more extractive fermentation tanks; a control unit that controls the supply of the saccharified solution to the extractive fermentation tank, the withdrawal of the extractant from the extractive fermentation tank, and the supply of the extractant regenerated in the distillation column so as to start at a predetermined time interval for each of two or more extractive fermentation tanks; A continuous extractive fermentation apparatus comprising: (2) The continuous extraction and fermentation apparatus according to (1), wherein the control unit is configured to detect the concentration of the target product contained in the extractant in the extractive fermentation tank in real time, and to control the extraction flow rate of the extractant from the extractive fermentation tank, the supply amount of the extractant regenerated in the distillation column, and the operating conditions of the distillation column based on the concentration of the target product contained in the extractant detected in real time. (3) The continuous extraction and fermentation apparatus according to (2), wherein the control unit is further configured to detect the concentration of the target product contained in the fermentation liquor in the extraction and fermentation tank in real time, calculate the transfer rate of the target product from the fermentation liquor to the extractant, and control the extraction flow rate of the extractant from the extraction and fermentation tank, the supply amount of the extractant regenerated in the distillation column, and the operating conditions of the distillation column based on the transfer rate of the target product. (4) The continuous extraction and fermentation apparatus according to any one of (1) to (3), wherein the target product is one or more compounds selected from the group consisting of alcohols, ketones, and organic acids. (5) The continuous extraction and fermentation apparatus according to any one of (1) to (4), wherein the target product is one or more compounds selected from the group consisting of normal butanol, isobutanol, ethanol, and acetone. (6) The continuous extraction and fermentation apparatus according to any one of (1) to (5), wherein the extractant is one or more selected from the group consisting of alcohols, alkanes, and fatty acids, each having a specific gravity of 0.6 to 0.9. (7) The continuous extraction and fermentation apparatus according to any one of (1) to (6), wherein the extractant is oleyl alcohol. (8) The continuous extractive fermentation apparatus according to any one of (1) to (7), wherein the volume ratio of the fermentation liquid to the extractant in the extractive fermentation tank is 1:0.5 to 1:2. (9) a parallel extractive fermentation process in which extractive fermentation is carried out in parallel in two or more extractive fermentation tanks at a predetermined time interval, in the same tank, to produce a target product by fermenting the saccharified solution with microorganisms in the lower phase and extracting and transferring the produced target product to an extractant in the upper phase; A leveling step in which a part or all of the extractant containing the target product is extracted from each of the two or more extraction fermentation tanks and mixed to level out fluctuations in the concentration of the target product; a separation and purification step of separating and purifying the target product from the extractant having a leveled concentration by distillation; a circulation step of circulating the extractant from which the target product has been separated and regenerated to two or more of the extractive fermentation tanks; A continuous extractive fermentation method comprising: (10) The continuous extraction and fermentation method according to claim 9, further comprising a control step of detecting the concentration of the target product contained in the extractant in the extractive fermentation tank in real time, and controlling, based on the concentration of the target product contained in the extractant detected in real time, the flow rate of the extractant withdrawn from the extractive fermentation tank, the amount of the extractant from which the target product has been separated and regenerated that is supplied to two or more extractive fermentation tanks, and the conditions for the separation and purification. (11) The continuous extraction and fermentation method according to (10), wherein the control step further comprises: detecting the concentration of the target product contained in the fermentation liquor in the extractive fermentation tank in real time; calculating a transfer rate of the target product from the fermentation liquor to the extractant; and controlling, based on the transfer rate of the target product, the flow rate of the extractant withdrawn from the extractive fermentation tank, the amount of the extractant from which the target product has been separated and regenerated that is supplied to two or more extractive fermentation tanks, and the conditions for the separation and purification. [Effects of the Invention]

[0010] According to the continuous extractive fermentation apparatus and continuous extractive fermentation method of the above aspects, the target product can be efficiently recovered at a stable concentration. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing the configuration of a continuous extraction and fermentation apparatus according to a first embodiment of the present invention. [Figure 2] FIG. 1 is a schematic diagram showing the configuration of a continuous extraction and fermentation apparatus according to a second embodiment of the present invention. [Figure 3]1 is a graph showing the relationship between the amount of glucose consumed and the amount of isobutanol recovered in Reference Example 1. The graph on the left shows the results when the extractant is not circulated, and the graph on the right shows the results when the extractant is circulated. [Figure 4] 1 is a graph showing the change in the isobutanol concentration in the extractant over time (left) and the change in the circulation flow rate of the extractant (right) in a system in Example 1 having one extractive fermentation tank (single tank) and no intermediate tank, and in a system using three extractive fermentation tanks and an intermediate tank. DETAILED DESCRIPTION OF THE INVENTION

[0012] A continuous extraction and fermentation apparatus (hereinafter sometimes abbreviated as "the continuous extraction and fermentation apparatus of this embodiment") and a continuous extraction and fermentation method (hereinafter sometimes abbreviated as "the continuous extraction and fermentation method of this embodiment") according to an embodiment of the present invention will be described in detail below. In this specification and claims, the meanings of various terms are defined as follows.

[0013] <Biomass> The saccharified solution used in the continuous extraction and fermentation apparatus and the continuous extraction and fermentation method of the present embodiment is obtained by enzymatic saccharification of biomass and pretreated biomass. The biomass is not particularly limited as long as it is a reusable organic resource derived from plants or animals (excluding fossil fuels such as petroleum), but is preferably a non-edible resource other than an edible resource used for food purposes. Examples of non-edible resources include blackstrap molasses and lignocellulosic biomass. Among these, lignocellulosic biomass is preferred as the biomass because it is inexpensive and available in large quantities.

[0014] In this specification, "pretreated biomass" refers to biomass that has been pretreated to efficiently carry out a saccharification reaction. Examples of pretreatment methods include steam treatment, ionic liquid treatment, and pulverization using a mill. If necessary, an acid or alkali may be added. There are no particular limitations on the reactor used for pretreatment, but a possible form is to place the biomass in an acid-resistant or alkali-resistant heated and pressure vessel for treatment.

[0015] The lignocellulosic biomass may be of any type, as long as it is at least one selected from the group consisting of woody plants (also called woody biomass), herbaceous plants (also called herbaceous biomass), processed products thereof, and waste products thereof. The lignocellulosic biomass may be pulverized and may be in any form, such as blocks, chips, or powder.

[0016] Examples of the woody plants include cedar, cypress, larch, pine, American pine, American cedar, American hemlock, poplar, white birch, willow, eucalyptus, sawtooth oak, konara oak, oak, castanopsis, beech, acacia, bamboo, bamboo grass, oil palm, sago palm, etc. Among them, cedar is preferred as the woody plant from the viewpoint of stability of properties.

[0017] In addition, bark, branches, fruit bunches, fruit shells, etc. of the above woody plants can also be used. Processed materials such as plywood, fiberboard, and laminated lumber made from the above woody plants can also be used. Components dismantled after use in buildings can also be used. Processed products of lignocellulosic biomass such as paper and recycled paper can also be used.

[0018] Examples of the herbaceous plants include bamboo, palm trees; grasses such as rice (including rice straw), wheat (including wheat straw), sugarcane (including bagasse), reeds, Japanese silver grass, corn (including corn stover, corn cob, and corn hull), sorghum (including sweet sorghum), switchgrass, erianthus, and napier grass; jatropha, cashew, and the like.

[0019] <Cellulose and hemicellulose> As used herein, "cellulose" includes hexoses, which are six-carbon structural units. Thus, when cellulose is hydrolyzed, it produces hexose monosaccharides (such as glucose) and hexose oligosaccharides (such as cellobiose) in which multiple hexose monosaccharides are linked together.

[0020] "Hemicellulose" includes complex polysaccharides such as glucomannan and glucuronoxylan, which are composed of pentoses (C5 sugars) with five carbon units such as xylose, and hexoses (C6 sugars) with six carbon units such as mannose, arabinose, and 4-O-methylglucuronic acid. Therefore, when hemicellulose is hydrolyzed, it produces pentose monosaccharides with five carbons, pentose oligosaccharides in which multiple pentose monosaccharides are linked together, hexose monosaccharides with six carbons, hexose oligosaccharides in which multiple hexose monosaccharides are linked together, and oligosaccharides in which multiple pentose and hexose monosaccharides are linked together.

[0021] In general, the composition ratio and amount of monosaccharides or oligosaccharides produced from hemicellulose or cellulose vary depending on the pretreatment method and the type of biomass used as the raw material.

[0022] <Saccharifying enzymes> As used herein, "saccharifying enzymes" include cellulases that decompose cellulose, hemicellulases that decompose hemicellulose, and amylases that decompose starch.

[0023] The cellulase may be any cellulase that decomposes cellulose into monosaccharides or oligosaccharides such as glucose, and examples thereof include those having at least one of the activities of endoglucanase (EG), cellobiohydrolase (CBH), and β-glucosidase (BGL). From the viewpoint of enzymatic activity, an enzyme mixture having each of these activities is preferred.

[0024] The hemicellulase may be any enzyme that decomposes hemicellulose into monosaccharides or oligosaccharides such as xylose, and examples thereof include enzymes having at least one of the activities of xylanase, xylosidase, mannanase, galactosidase, glucuronidase, and arabinofuranosidase. From the viewpoint of enzymatic activity, an enzyme mixture having each of these activities is preferred.

[0025] The origin of these saccharifying enzymes such as cellulases and hemicellulases is not limited, and for example, saccharifying enzymes such as cellulases and hemicellulases derived from microorganisms such as those of the genus Trichoderma, Acremonium, Aspergillus, Bacillus, Pseudomonas, Penicillium, Aeromonus, Irpex, Sporotrichum, and Humicola can be used.

[0026] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In each drawing, parts that are not relevant to the description may be omitted.

[0027] <Continuous extraction and fermentation equipment> The continuous extraction and fermentation apparatus of this embodiment includes an extraction fermentation tank group in which two or more extraction fermentation tanks are arranged in parallel, each tank containing a saccharified solution and microorganisms in a lower phase and an extractant in an upper phase, and the extraction fermentation tanks are configured to simultaneously produce a fermented solution containing a target product by fermenting the saccharified solution with the microorganisms and extract the target substance into the extractant within the same tank; A first pipe configured to extract a part or all of the extractant from each of the two or more extractive fermentation tanks; an intermediate tank configured to mix the extractants extracted from each of the two or more extractive fermentation tanks and level out fluctuations in the concentration of the target product; a distillation column configured to separate and purify the target product from the extractant, the concentration of which has been equalized and which has been withdrawn from the intermediate tank; A second pipe configured to return the extractant recovered by separating the target product in the distillation column to the two or more extractive fermentation tanks; a control unit that controls the supply of the saccharified solution to the extractive fermentation tank, the withdrawal of the extractant from the extractive fermentation tank, and the supply of the extractant regenerated in the distillation column so as to start at a predetermined time interval for each of two or more extractive fermentation tanks; Equipped with.

[0028] In conventional methods, the target product is transferred from the fermentation broth to the extractant without circulating the extractant. Therefore, when the solubility of the target product in a certain amount of extractant reaches saturation, the target product does not transfer to the extractant but remains in the fermentation broth. This causes a problem: the cytotoxicity of the target product reduces the activity of the microorganism that produces the target product, and the productivity of the target product (production concentration and production amount) decreases. Another problem is that the target product that does not transfer to the extractant remains in the fermentation broth and is not recovered, resulting in a decrease in the yield of the target product.

[0029] In contrast, the continuous extraction and fermentation apparatus of this embodiment is equipped with a mechanism for circulating the extractant (specifically, the first piping, the intermediate tank, the distillation column, and the second piping), which prevents a decrease in the transfer rate of the target product from the fermentation liquor to the extractant, thereby keeping the concentration of the target product in the fermentation liquor low and maintaining a high yield of the target product.

[0030] Furthermore, when an extractive fermentation apparatus has a mechanism for circulating the extractant, the culture mode of the fermentation liquid in the extractive fermentation tank is batchwise, so the concentration of the target product in the extracted extractant fluctuates over time. Specifically, at the start of fermentation, the activity of the microorganisms gradually increases, and the concentration of the target product also increases accordingly. After reaching a certain concentration, the concentration of the target product also decreases as the fermentation nears its end due to the decrease in the amount of sugars used as fermentation raw materials. In other words, the concentration of the target product does not remain constant throughout the fermentation time. Alternatively, to maintain a constant concentration of the target product, it is necessary to vary the amount of extracted extractant over time. Therefore, depending on the concentration of the target product in the extractant and the amount of extracted extractant, it is necessary to finely vary the distillation conditions for purifying and separating the target product in the downstream distillation column, which results in unstable and complicated distillation operations.

[0031] In contrast, the continuous extractive fermentation apparatus of this embodiment, equipped with the intermediate tank and the control unit, allows the extractant to be withdrawn from multiple extractive fermentation tanks at different times and the extractants withdrawn from each extractive fermentation tank to be combined in the intermediate tank, thereby leveling out fluctuations over time in the concentration of the target product in the extractant and in the volume of the extractant sent to the distillation column, thereby obtaining a target product with a stable concentration and stabilizing the distillation operation and the circulation volume of the extractant.

[0032] [First embodiment] FIG. 1 is a schematic diagram showing the configuration of a continuous extraction and fermentation apparatus according to a first embodiment of the present invention. Continuous extractive fermentation apparatus 100 includes extractive fermentation tank group 10, which is composed of three extractive fermentation tanks 11, 12, and 13 arranged in parallel, intermediate tank 30, and distillation tank 40, which are connected via first pipes 51, 52, and 53, pipe 31, and second pipes 51, 52, 53, and 57. Control unit 60 is connected to valves 5, 24, 25, 26, 54, 55, and 56.

[0033] As described above, the continuous extraction and fermentation apparatus 100 has the above configuration, which prevents a decrease in the transfer rate of the target product from the fermentation liquor to the extractant, allows the concentration of the target product in the fermentation liquor to be kept low, and maintains a high yield of the target product. Furthermore, by including the intermediate tank 30 and the control unit 60, the continuous extraction and fermentation apparatus 100 can extract the extractant from the extractive fermentation tanks 11, 12, and 13 at different times, and the extractants extracted from the extractive fermentation tanks can be combined in the intermediate tank 30. This allows the concentration of the target product in the extractant and the amount of extractant sent to the distillation column 40 to be leveled out over time, resulting in a target product with a stable concentration and stabilizing the distillation operation and the circulation amount of the extractant.

[0034] (Extraction fermentation tank) Each of the extraction fermentation tanks 11, 12, and 13 is filled with a fermentation liquid containing a target product produced by fermenting the saccharified solution with microorganisms in the lower phase, and an extractant in the upper phase.

[0035] There are no particular limitations on the extractive fermentation tanks 11, 12, and 13, and known extractive fermentation tanks can be used. Specific examples include, but are not limited to, agitated and aerated extractive fermentation tanks. Extractive fermentation tanks 11, 12, and 13 may be extractive fermentation tanks having the same configuration as those described above, or extractive fermentation tanks having different configurations. However, from the viewpoint of standardizing the fermentation conditions for each tank, extractive fermentation tanks having the same configuration are preferred. Furthermore, the extraction and fermentation tanks 11, 12, and 13 may be provided with a temperature control device such as a hot water circulating jacket on the outside of the tank in order to maintain a constant temperature inside the tank.

[0036] 1 illustrates an example in which the number of extractive fermentation tanks is three, but the number may be two or more, for example, three or more, four or more, or five or more. There is no particular upper limit to the number of extractive fermentation tanks, but it can be 10 or less depending on the installation area of ​​the equipment, etc.

[0037] In each extraction fermentation tank, the upper phase is filled with an extractant, and the lower phase is filled with saccharified solution and microorganisms at the start of fermentation. As fermentation progresses, the saccharified solution is replaced with a fermentation solution containing the target product produced by fermenting the microbial solution.

[0038] In the extractive fermentation tank, the respective filling amounts of the fermentation liquid (saccharified liquid at the start of fermentation) and extractant can be adjusted appropriately depending on the size of the extractive fermentation tank. However, the volume ratio of the fermentation liquid to the extractant is preferably 1:0.5 to 1:2, and a ratio of 1:1 is particularly preferred because reducing the size of the extractive fermentation tank allows for a more compact facility. Furthermore, in each extraction fermentation tank, the filling amounts of the fermentation liquid and the extractant, and the volume ratio of the fermentation liquid to the extractant may be the same or different, but it is preferable that they are the same because standardizing the fermentation conditions makes control easier.

[0039] In the extractive fermentation tank, the extractant filled in the upper phase may be any extractant having a specific gravity smaller than that of water, and is preferably one or more extractants selected from the group consisting of alcohols, alkanes, and fatty acids, each having a specific gravity of 0.6 to 0.9. An example of the alcohols is oleyl alcohol. Examples of alkanes include dodecane. The fatty acids include, for example, oleic acid. From these, an extractant capable of dissolving the target product can be appropriately selected depending on the type of target product. From the viewpoint of the distillation operation in the distillation column described below, the extractant preferably has a boiling point sufficiently higher than that of the target product, more preferably 10°C or more higher than that of the target product, even more preferably 50°C or more higher than that of the target product, and particularly preferably 100°C or more higher. On the other hand, an extractant with a boiling point 300°C or less higher than that of the target product can be selected because it has a relatively low viscosity and is easy to handle. Among these, when the target product is isobutanol, oleyl alcohol (boiling point of approximately 330°C or higher and 360°C or lower) is preferred because it has a boiling point significantly different from that of isobutanol (boiling point 108°C), is less toxic to microorganisms, and has a relatively low boiling point, which reduces the load on the distillation column described below.

[0040] The saccharified liquid filled in the extraction fermentation tank at the start of fermentation is not particularly limited as long as it is obtained by saccharifying the above-mentioned biomass with a saccharifying enzyme.

[0041] In the extractive fermenter, the microorganisms used for fermentation are not particularly limited as long as they can produce the target product. Specific examples include yeast and bacteria, and genetically modified microorganisms are also preferably used. Genetically modified microorganisms are microorganisms that do not have the enzyme genes necessary for conversion to the target product, but have these genes introduced by genetic engineering techniques, making it possible to produce the target product. Examples of genetically modified microorganisms include genetically modified Escherichia coli that has the fermentation activity of the target product. Among these, microorganisms that are preferably used in the continuous extractive fermentation apparatus of this embodiment are those belonging to the genus Corynebacterium.

[0042] Furthermore, since fermentation products, which are compounds with four or more carbon atoms, are usually highly toxic to microorganisms, microorganisms that are resistant to the fermentation products may be used. However, with the continuous extraction and fermentation apparatus of this embodiment, the fermentation products, which are compounds with four or more carbon atoms, are transferred to an extractant and extracted, thereby shortening the contact time between the microorganisms and the toxic fermentation products. Therefore, even microorganisms that are not resistant to fermentation products, which are compounds with four or more carbon atoms, can be preferably used with the continuous extraction and fermentation apparatus of this embodiment.

[0043] Furthermore, the microorganism may be used as a culture solution containing the microorganism as it is, or may be used as appropriate in the form of a culture solution containing the microorganism concentrated by centrifugation, or in a dried state. The amount of microorganisms to be used may be calculated based on the growth rate of the microorganisms, the size of the extractive fermentation tank, the amount of saccharified solution to be used for fermentation, and the like.

[0044] (First piping) First lines 21, 22, and 23 are configured to extract some or all of the extractant from extractive fermenters 11, 12, and 13, respectively.

[0045] As shown in FIG. 1, the first pipes 21, 22, and 23 may be joined together along the way to form a single pipe and disposed in the intermediate tank 30, or each of the first pipes may be disposed in the intermediate tank 30.

[0046] (intermediate tank) The intermediate tank 30 is configured to mix the extractants extracted from the extractive fermentation tanks 11, 12, and 13, respectively, and to level out fluctuations in the concentration of the target product.

[0047] The intermediate tank 30 is not particularly limited as long as it can mix and temporarily store the extractant, but it preferably has a stirring mechanism such as a stirring blade. The outside of the intermediate tank 30 may be equipped with a temperature control device (not shown), such as a hot water circulating jacket.

[0048] (Distillation column) The distillation column 40 is configured to separate and purify the target product from the extractant, which has been withdrawn from the intermediate tank 30 and has a uniform concentration of the target product.

[0049] Examples of the distillation column 40 include a plate column having a plurality of plates therein, a packed column having a packing material for gas-liquid contact therein, etc. The distillation column may also be equipped with a reboiler for boiling steam, a condenser for condensing steam, etc., as shown in FIG.

[0050] The target product is not particularly limited as long as it is slightly soluble in water (solubility in water at room temperature of 100 g / L or less) and soluble in the extractant consisting of the above-mentioned organic solvent, but is preferably one or more compounds selected from the group consisting of alcohols, ketones, and organic acids. Examples of alcohols include normal butanol, isobutanol, and ethanol. An example of the ketones is acetone. Examples of organic acids include lactic acid, butyric acid, acetic acid, citric acid, malic acid, succinic acid, fumaric acid, and pyruvic acid. Among these, the target product is preferably one or more compounds selected from the group consisting of normal butanol, isobutanol, ethanol, and acetone. Furthermore, isobutanol is more preferred because it is necessary for the synthesis of bio-paraxylene, which can be used as a raw material for bio-polyethylene terephthalate (bio-PET).

[0051] (Second piping) The second pipes 51, 52, and 53 are configured to return the extractant recovered after the target product is separated in the distillation column 40 to the extractive fermenters 11, 12, and 13, respectively.

[0052] As shown in FIG. 1, the second pipe may be a single pipe (second pipe 57) extending from the distillation column to partway, and then branching into three second pipes 51, 52, and 53, which are respectively provided to extraction fermentation tanks 11, 12, and 13; alternatively, three second pipes may extend from distillation column 40 to second pipes 51, 52, and 53, respectively.

[0053] (Control unit) The control unit 60 controls the supply of the saccharified liquid to the extractive fermentation tanks 11, 12, and 13, the extraction of the extractant from the extractive fermentation tanks 11, 12, and 13, and the supply of the extractant regenerated in the distillation column 40 so that these operations are started at a predetermined time interval for each of the extractive fermentation tanks 11, 12, and 13.

[0054] 1 , control unit 60 is connected to valves 5, 24, 25, 26, 54, 55, and 56. This controls the supply of the saccharified solution to extractive fermentation tanks 11, 12, and 13, the withdrawal of the extractant from extractive fermentation tanks 11, 12, and 13, and the supply of the extractant regenerated in distillation column 40, as described above.

[0055] It is preferable that the control unit 60 controls the extractive fermentation in the (N+1)th extractive fermentation tank to start after the production rate of the target product by the microorganisms in the Nth extractive fermentation tank (N is an integer of 1 or more) has reached saturation and before the extractive fermentation is completed. Specifically, when the extractive fermentation time and the cleaning time after completion of extractive fermentation are the same in each tank, it is preferable to control the difference between the start time of extractive fermentation in the Nth extractive fermentation tank and the start time of extractive fermentation in the (N+1)th extractive fermentation tank to be one-fifth to one-third of the total time of the extractive fermentation time and the cleaning time after completion of extractive fermentation. More specifically, when the extractive fermentation time in each of the Nth extractive fermentation tank and the (N+1)th extractive fermentation tank is 72 hours and the time required to clean the extractive fermentation tanks after completion of extractive fermentation is 20 hours, the difference between the start time of extractive fermentation in the Nth extractive fermentation tank and the start time of extractive fermentation in the (N+1)th extractive fermentation tank is preferably 10 hours or more, more preferably 15 hours or more, and even more preferably 20 hours or more. On the other hand, the upper limit of this difference in the start times of extractive fermentation can be set to less than 72 hours, 60 hours or less, 50 hours or less, or 30 hours or less.

[0056] 1, control unit 60 is preferably connected to concentration sensors 71, 73, and 75. That is, control unit 60 is preferably configured to perform real-time detection of the concentration of the target product contained in the extractant in extractive fermentation tanks 11, 12, and 13, and to control the extraction flow rate of the extractant from each of extractive fermentation tanks 11, 12, and 13, the supply rate of the extractant regenerated in distillation column 40, and the operating conditions of the distillation column, based on the real-time detected concentration of the target product contained in the extractant. This makes it possible to stably obtain the target product at a constant concentration, and to continuously and stably operate the entire apparatus.

[0057] The concentration of the target product contained in the extractant can be set appropriately depending on the scale of the extraction fermentation tank. For example, when the target product is isobutanol, the concentration can be set to 0.1 g / L or more and 1.0 g / L or less.

[0058] Specifically, when the concentration of the target product contained in the extractant falls below the predetermined concentration, the extraction flow rate of the extractant is reduced, the supply rate of the extractant regenerated in the distillation column 40 is reduced, the reboiler heat quantity in the distillation column 40 is reduced, and the reflux ratio is increased. On the other hand, when the concentration of the target product contained in the extractant rises above the predetermined concentration, the extraction flow rate of the extractant is increased, the supply rate of the extractant regenerated in the distillation column 40 is increased, the reboiler heat quantity in the distillation column 40 is increased, and the reflux ratio is reduced.

[0059] Control unit 60 can also detect the end of extractive fermentation by real-time detection of the concentration of the target product contained in the extractant in extractive fermentation tanks 11, 12, and 13. This allows control so that extractive fermentation in each extractive fermentation tank is terminated, the entire amount of extractant is extracted, and the remaining fermentation liquid is then discharged from the tank.

[0060] 1, the control unit 60 is preferably connected to concentration sensors 72, 74, and 76. Specifically, the control unit 60 is preferably further configured to: detect the concentrations of the target product contained in the fermentation liquor in the extractive fermentation tanks 11, 12, and 13 in real time using the concentration sensors 72, 74, and 76; calculate the transfer rate of the target product from the fermentation liquor to the extractant based on the concentrations of the target product contained in the extractant in the extractive fermentation tanks 11, 12, and 13; and control the flow rate of the extractant withdrawn from the extractive fermentation tanks, the supply rate of the extractant regenerated in the distillation column, and the operating conditions of the distillation column based on the transfer rate of the target product. This allows the target product to be stably obtained at a constant concentration, and the entire apparatus can be operated continuously and stably.

[0061] The concentration of the target product contained in the fermentation broth should be below the threshold concentration that is not toxic to microorganisms, and can be set appropriately depending on the scale of the extraction fermentation tank and the volume ratio of the fermentation broth to the extractant. For example, if the target product is isobutanol, the concentration can be set to 0.5 g / L or more and 15.0 g / L or less. Similarly, the transfer rate of the target product from the fermentation liquid to the extractant can be appropriately set depending on the scale of the extraction fermentation tank and the volume ratio of the fermentation liquid to the extractant. For example, when the target product is isobutanol, the transfer rate can be set to 1 mol / m 2 / second or more 10mol / m 2 / second or less.

[0062] When the transfer rate of the target product from the fermentation liquor to the extractant falls below the predetermined rate, the extraction flow rate of the extractant is reduced, the supply rate of the extractant recycled in the distillation column 40 is reduced, the reboiler heat quantity in the distillation column 40 is reduced, and the reflux ratio is increased. On the other hand, when the transfer rate of the target product from the fermentation liquor to the extractant rises above the predetermined rate, the extraction flow rate of the extractant is increased, the supply rate of the extractant recycled in the distillation column 40 is increased, the reboiler heat quantity in the distillation column 40 is increased, and the reflux ratio is reduced.

[0063] Control unit 60 can also detect the end of extractive fermentation by real-time detection of the concentration of the target product contained in the fermentation liquor in extractive fermentation tanks 11, 12, and 13. This allows control to be performed so that extractive fermentation in each extractive fermentation tank is terminated, the entire amount of extractant is extracted, and the remaining fermentation liquor is discharged from the tank.

[0064] The amount of circulating extractant per hour, i.e., the flow rate of extractant withdrawn from each extractive fermentation tank and the flow rate of extractant regenerated in the distillation column fed to each extractive fermentation tank, may be the same or different. However, it is preferable that they are the same from the viewpoint of maintaining a constant transfer rate of the target product from the fermentation liquid to the extractant by maintaining a constant volume ratio of the fermentation liquid to the extractant in each extractive fermentation tank. Furthermore, between the extractive fermentation tanks, the flow rate of the extractant withdrawn from each extractive fermentation tank and the flow rate of the extractant regenerated in the distillation column fed to each extractive fermentation tank differ depending on the stage of extractive fermentation in each tank. The amount of extractant circulated per hour, i.e., the flow rate of extractant extracted from each extractive fermentation tank and the flow rate of extractant regenerated in the distillation column and fed to each extractive fermentation tank, can be a part or all of the volume filled in the extractive fermentation tank at the beginning of the extractive fermentation. However, since it is preferable that a certain amount of extractant be in contact with the fermentation broth for a certain period of time, it is preferably a part of the volume filled in the extractive fermentation tank at the beginning of the extractive fermentation. The amount of extractant circulated per hour can be appropriately controlled to an optimal circulation amount depending on the sugar concentration of the saccharified solution used, the size of the extractive fermentation tank, etc. Specifically, for example, when the capacity of the extractive fermentation tank is several hundred liters or more, the amount of extractant circulated per hour (m 3 / hour) is the volume of extractant in the extractive fermentation tank (m 3 It is preferable to control the ratio so that the ratio is 3 / 10 or more and less than 10 / 10 of the ratio of the total weight of the material.

[0065] [Second embodiment] FIG. 2 is a schematic diagram showing the configuration of a continuous extraction and fermentation apparatus according to a second embodiment of the present invention. Continuous extraction and fermentation apparatus 200 differs from continuous extraction and fermentation apparatus 100 shown in Fig. 1 in that it includes a second intermediate tank 80 and second pipes 51, 52, and 53 are disposed in the lower phases of extractive fermentation tanks 11, 12, and 13, respectively. In Fig. 2, the same components as those shown in Fig. 1 are denoted by the same reference numerals and will not be described again.

[0066] (Second intermediate tank) The second intermediate tank 80 is configured to temporarily store the extractant regenerated in the distillation column 40 .

[0067] The second intermediate tank 80 is not particularly limited as long as it can mix and temporarily store the regenerated extractant, but it preferably has a stirring mechanism such as a stirring blade. The outside of the second intermediate tank 80 may be equipped with a temperature control device (not shown), such as a hot water circulating jacket.

[0068] The continuous extraction and fermentation apparatus of this embodiment is not limited to the continuous extraction and fermentation apparatus shown in FIGS. 1 and 2, and may be one in which some of the components shown in FIGS. 1 and 2 have been modified or deleted, or one in which other components have been added to those described above, within the scope that does not impair the effects of the present invention.

[0069] For example, as shown in FIGS. 1 and 2, a saccharification tank 1 and a solid-liquid separator 3 may be disposed upstream of the extractive fermentation tank via pipes 2 and 4.

[0070] Saccharification tank 1 is configured to saccharify pretreated biomass with a saccharifying enzyme.

[0071] There are no particular limitations on the saccharification tank 1, and any known saccharification tank can be used. Specific examples include stirring type, aeration stirring type, bubble column type, fluidized bed type, and packed bed type saccharification tanks. The saccharification tank may also be equipped with a temperature control device such as a hot water circulating jacket on the outside of the tank to maintain a constant temperature inside the tank.

[0072] The solid-liquid separator 3 is configured to separate the saccharification product obtained in the saccharification tank 1 into a saccharified solution and a saccharification residue. The saccharification residue separated by the solid-liquid separator contains unsaccharified components such as cellulose and hemicellulose, and can be used as a saccharification raw material by feeding it into the saccharification tank 1.

[0073] The solid-liquid separator 3 is not particularly limited, and examples thereof include a filter, a vibrating sieve, a centrifugal separator, and a screw press.

[0074] For example, as shown in FIGS. 1 and 2, each pipe may be provided with a pump midway along the pipe to adjust the flow rate of the liquid being sent or transferred.

[0075] 1 and 2, a preheater may be provided at the point where the pipe 31 and the second pipe 57 intersect. This allows the heat of the extractant regenerated in the distillation column 40 to heat the extractant sent from the intermediate tank 30 to the distillation column 40, thereby further reducing energy costs.

[0076] For example, a storage tank storing new extractant may be provided so that valves 54, 55, and 56 can be switched via piping. This allows the extraction agent to be filled in order to start the extractive fermentation when the continuous extraction and fermentation apparatus of this embodiment is started up, and after the extraction agent is withdrawn, the shortage of the extraction agent can be supplied.

[0077] A method for continuous extraction and fermentation of a target product using the continuous extraction and fermentation apparatus of this embodiment shown in FIG. 1 will be described below. First, extractive fermentation tank 11 is filled with saccharified liquid, microorganisms, and extractant, and extractive fermentation is initiated. The concentration of the target product is detected by concentration sensors 71 and 72. After the target product concentration reaches a predetermined concentration, i.e., a threshold concentration that is not toxic to the microorganisms, control unit 60 controls valve 24 to withdraw some or all of the extractant and controls valve 54 to supply the extractant instead. When starting up the extractive fermentation system, fresh extractant is used instead of the extractant regenerated in distillation column 40. Therefore, pipe 51 is connected to a storage tank storing fresh extractant during start-up. Fresh extractant is also used during start-up in extractive fermentation tanks 12 and 13, which will be described later. The withdrawn extractant is then pumped to intermediate tank 30 via pipe 21. Next, the extractant sent to the intermediate tank 30 is stirred until a certain amount of extractant accumulates and the concentration of the target product in the extractant falls within a predetermined concentration range, i.e., after the fluctuations in the target product concentration have been leveled out, the extractant is sent to the distillation column 40 via pipe 31. At this time, extractant withdrawn from two or more of the extractive fermentation tanks 11, 12, and 13 is sent to the intermediate tank. The control unit 60 calculates the concentration of the target product from the concentration of the target product in the extractant detected by two or more of the concentration sensors 71, 73, and 75 and the flow rate of the extracted agent sent by controlling two or more of the valves 24, 25, and 26, thereby determining that the fluctuations in the target product concentration have been leveled out. In the distillation column 40, the target product and the extractant are separated by distillation. The extractant from which the target product has been separated and regenerated is supplied to the extractive fermentation tank 11 via pipe 51 and circulated. When the supply of the regenerated extractant to the extractive fermentation tank 11 begins, the supply of the new extractant is stopped and replaced.

[0078] After a predetermined time has elapsed since the start of extractive fermentation in extractive fermentation tank 11, extractive fermentation is initiated in extractive fermentation tank 12 by similarly filling the tank with the saccharified solution, microorganisms, and extractant. The subsequent operations are the same as those in extractive fermentation tank 11.

[0079] After a predetermined time has elapsed since the start of extractive fermentation in extractive fermentation tank 12, extractive fermentation is initiated in extractive fermentation tank 13 by similarly filling the tank with the saccharified solution, microorganisms, and extractant. The subsequent operations are the same as those in extractive fermentation tank 11.

[0080] After a predetermined extractive fermentation time has elapsed in extractive fermentation tank 11 and extractive fermentation is completed, control unit 60 controls valve 24 to remove all of the extractant from extractive fermentation tank 11 and discharge the fermentation liquid remaining in extractive fermentation tank 11. Next, if necessary, the inside of extractive fermentation tank 11 is cleaned for a predetermined period of time using a cleaning solution or the like. After cleaning is complete, extractive fermentation tank 11 is again filled with the saccharified liquid, microorganisms, and extractant, and extractive fermentation is initiated. Extractive fermentation tanks 12 and 13 are also cleaned after extractive fermentation is completed, and extractive fermentation is performed again. By repeating this extractive fermentation and, if necessary, cleaning operation in each tank, extractive fermentation is performed continuously. Since the saccharified liquid is supplied to each extractive fermentation tank in a batchwise manner only at the start of extractive fermentation, the concentration of the target product in the extractant fluctuates over time. However, the continuous extraction and fermentation apparatus 100 is equipped with three extraction and fermentation tanks 11, 12, and 13 and the intermediate tank 30, and by staggering (delaying) the start times of extraction and fermentation in each extraction and fermentation tank by a predetermined time, it is possible to suppress fluctuations in the concentration of the target product in the extractant over time and efficiently recover the target product at a stable concentration, as will be shown in the examples described below.

[0081] <Continuous extraction and fermentation method> The continuous extraction and fermentation method of this embodiment includes: a parallel extractive fermentation step in which extractive fermentation is carried out in parallel in two or more extractive fermentation tanks at a predetermined time interval, in the same tank, to produce the target product by fermenting the saccharified solution with microorganisms in a lower phase and extractively transferring the produced target product to an extractant in an upper phase; A leveling step in which a part or all of the extractant containing the target product is extracted from each of the two or more extraction fermentation tanks and mixed to level out fluctuations in the concentration of the target product; a separation and purification step of separating and purifying the target product from the extractant having a leveled concentration by distillation; a circulation step of circulating the extractant from which the target product has been separated and regenerated to two or more of the extractive fermentation tanks; Includes:

[0082] The continuous extraction and fermentation method of the present embodiment has the above-described configuration, and thus can efficiently recover the target product at a stable concentration.

[0083] Next, each step of the continuous extractive fermentation method of this embodiment will be described in detail below.

[0084] [Parallel extraction and fermentation process] In the parallel extractive fermentation process, the saccharified solution is fermented by microorganisms in the lower phase to produce the target product, and the produced target product is extracted and transferred to an extractant in the upper phase. Extractive fermentation is carried out in parallel in two or more extractive fermentation tanks with a predetermined time lag in the same tank.

[0085] The extractive fermentation conditions in each extractive fermentation tank can be appropriately set depending on the type of microorganism used and the type of target product. The temperature can be, for example, 25°C or higher and 50°C or lower, 28°C or higher and 40°C or lower, or 30°C or higher and 37°C or lower. The extraction and fermentation time depends on the sugar concentration of the saccharified solution used, but can be 24 hours or more and 120 hours or less, 24 hours or more and 96 hours or less, or 24 hours or more and 72 hours or less. The stirring speed in the extractive fermentation tank is not particularly limited as long as it is low enough to keep the upper and lower phases separated.

[0086] The extractive fermentation conditions may be the same or different in each extractive fermentation tank, but are preferably the same in order to facilitate control.

[0087] In the parallel extractive fermentation process, the saccharified solution is preferably supplied to the extractive fermentation tank in a batch manner rather than a continuous manner, which can prevent the microorganisms from flowing out of the tank and reducing the fermentation rate (the rate at which the target product is produced).

[0088] In the parallel extractive fermentation process, it is preferable to start extractive fermentation in the (N+1)th extractive fermenter after the production rate of the target product by the microorganism in the Nth extractive fermenter (N is an integer of 1 or more) has reached saturation but before the extractive fermentation is completed. Specifically, when the extractive fermentation time and the cleaning time after completion of extractive fermentation are the same in each tank, it is preferable to control the difference between the start time of extractive fermentation in the Nth extractive fermentation tank and the start time of extractive fermentation in the (N+1)th extractive fermentation tank to be one-fifth to one-third of the total time of the extractive fermentation time and the cleaning time after completion of extractive fermentation. More specifically, when the extractive fermentation time in each of the Nth extractive fermentation tank and the (N+1)th extractive fermentation tank is 72 hours and the time required to clean the extractive fermentation tanks after completion of extractive fermentation is 20 hours, the difference between the start time of extractive fermentation in the Nth extractive fermentation tank and the start time of extractive fermentation in the (N+1)th extractive fermentation tank is preferably 10 hours or more, more preferably 15 hours or more, and even more preferably 20 hours or more. On the other hand, the upper limit of this difference in the start times of extractive fermentation can be set to less than 72 hours, 60 hours or less, 50 hours or less, or 30 hours or less.

[0089] [Leveling process] In the leveling step, a part or all of the extractant containing the target product is extracted from each of two or more extraction fermentation tanks and mixed to level out fluctuations in the concentration of the target product.

[0090] In the leveling step, as described in the above-mentioned continuous extractive fermentation apparatus, the extractant withdrawn from each extractive fermentation tank is temporarily stored in an intermediate tank to level out fluctuations in the concentration of the target product.

[0091] The temperature, stirring speed and storage time in the intermediate tank are not particularly limited and can be set appropriately depending on the type of extractant and target product.

[0092] Furthermore, the leveling out of fluctuations in the concentration of the target product can be determined by calculating the concentration of the target product from the concentration of the target product in the extractant and the flow rate of the extractant sent to the intermediate tank when the extractant extracted from two or more of the extraction fermentation tanks 11, 12, and 13 is sent to the intermediate tank.

[0093] [Separation and purification process] In the separation and purification step, the target product is separated and purified by distillation from the extractant in which the concentration of the target product has been leveled.

[0094] The conditions for separation and purification by distillation can be appropriately set by known methods depending on the type of target product and extractant.

[0095] [Circulation process] In the recycling step, the extractant from which the target product has been separated and regenerated is recycled to two or more extractive fermentation tanks.

[0096] The amount of circulating extractant per hour, i.e., the flow rate of extractant withdrawn from each extractive fermentation tank and the flow rate of extractant regenerated in the distillation column fed to each extractive fermentation tank, may be the same or different. However, it is preferable that they are the same from the viewpoint of maintaining a constant transfer rate of the target product from the fermentation liquid to the extractant by maintaining a constant volume ratio of the fermentation liquid to the extractant in each extractive fermentation tank. Furthermore, between the extractive fermentation tanks, the flow rate of the extractant withdrawn from each extractive fermentation tank and the flow rate of the extractant regenerated in the distillation column fed to each extractive fermentation tank differ depending on the stage of extractive fermentation in each tank. The amount of extractant circulated per hour, i.e., the flow rate of extractant extracted from each extractive fermentation tank and the flow rate of extractant regenerated in the distillation column and fed to each extractive fermentation tank, can be a part or all of the volume filled in the extractive fermentation tank at the beginning of the extractive fermentation. However, since it is preferable that a certain amount of extractant be in contact with the fermentation broth for a certain period of time, it is preferably a part of the volume filled in the extractive fermentation tank at the beginning of the extractive fermentation. The amount of extractant circulated per hour can be appropriately controlled to an optimal circulation amount depending on the sugar concentration of the saccharified solution used, the size of the extractive fermentation tank, etc. Specifically, for example, when the capacity of the extractive fermentation tank is several hundred liters or more, the amount of extractant circulated per hour (m 3 / hour) is the volume of extractant in the extractive fermentation tank (m 3 It is preferable to control the ratio so that the ratio is 3 / 10 or more and less than 10 / 10 of the ratio of the total weight of the material.

[0097] The continuous extractive fermentation method of this embodiment may further include other steps in addition to the above steps.

[0098] [Control process] In the control step, the concentration of the target product contained in the extractant in the extractive fermentation tank is detected in real time, and based on the detected concentration of the target product contained in the extractant, the flow rate of the extractant withdrawn from the extractive fermentation tank, the amount of the extractant from which the target product has been separated and regenerated that is supplied to two or more extractive fermentation tanks, and the conditions for separation and purification are controlled. The continuous extraction and fermentation method of the present embodiment includes a control step, which makes it possible to stably obtain a target product at a constant concentration and to operate the entire apparatus continuously and stably.

[0099] The concentration of the target product contained in the extractant can be set appropriately depending on the scale of the extraction fermentation tank. For example, when the target product is isobutanol, the concentration can be set to 0.1 g / L or more and 1.0 g / L or less.

[0100] Specifically, when the concentration of the target product contained in the extractant falls below the predetermined concentration, the extraction flow rate of the extractant is reduced, the supply rate of the extractant regenerated in the distillation column 40 is reduced, the reboiler heat quantity in the distillation column 40 is reduced, and the reflux ratio is increased. On the other hand, when the concentration of the target product contained in the extractant rises above the predetermined concentration, the extraction flow rate of the extractant is increased, the supply rate of the extractant regenerated in the distillation column 40 is increased, the reboiler heat quantity in the distillation column 40 is increased, and the reflux ratio is reduced.

[0101] Furthermore, in the control step, the concentration of the target product contained in the fermentation liquor in the extractive fermentation tank is detected in real time, the transfer rate of the target product from the fermentation liquor to the extractant is calculated, and based on the transfer rate of the target product, the flow rate of the extractant withdrawn from the extractive fermentation tank, the amount of the extractant from which the target product has been separated and regenerated that is supplied to two or more extractive fermentation tanks, and the conditions for separation and purification are controlled. By further performing the above control in the control step, it is possible to stably obtain the target product at a constant concentration and to operate the entire apparatus continuously and stably.

[0102] The concentration of the target product contained in the fermentation broth should be below the threshold concentration that is not toxic to microorganisms, and can be set appropriately depending on the scale of the extraction fermentation tank and the volume ratio of the fermentation broth to the extractant. For example, if the target product is isobutanol, the concentration can be set to 0.5 g / L or more and 15.0 g / L or less. Similarly, the transfer rate of the target product from the fermentation liquid to the extractant can be appropriately set depending on the scale of the extraction fermentation tank and the volume ratio of the fermentation liquid to the extractant. For example, when the target product is isobutanol, the transfer rate can be set to 1 mol / m 2 / second or more 10mol / m 2 / second or less.

[0103] When the transfer rate of the target product from the fermentation liquor to the extractant falls below the predetermined rate, the extraction flow rate of the extractant is reduced, the supply rate of the extractant recycled in the distillation column 40 is reduced, the reboiler heat quantity in the distillation column 40 is reduced, and the reflux ratio is increased. On the other hand, when the transfer rate of the target product from the fermentation liquor to the extractant rises above the predetermined rate, the extraction flow rate of the extractant is increased, the supply rate of the extractant recycled in the distillation column 40 is increased, the reboiler heat quantity in the distillation column 40 is increased, and the reflux ratio is reduced.

[0104] [Concentration process] In the concentration step, the target product obtained in the separation and purification step is concentrated, and this step allows the target product to be obtained with a higher purity.

[0105] The concentration method can be appropriately selected depending on the type of target product, and examples thereof include known concentration methods such as membrane separation methods such as pervaporation (PV) and vapor permeation (VP), and pressure swing adsorption (PSA) using an adsorbent.

[0106] The saccharified solution used in the continuous extraction and fermentation method of the present embodiment is not particularly limited as long as it is obtained by saccharifying biomass with a saccharifying enzyme. As for saccharification conditions, for example, the temperature can be 45° C. or higher and 70° C. or lower, 45° C. or higher and 55° C. or lower, or 50° C. The saccharification time can be 12 hours or higher and 120 hours or lower, 24 hours or higher and 96 hours or lower, or 24 hours or higher and 72 hours or lower.

[0107] The saccharified product obtained by the above saccharification method is subjected to solid-liquid separation as needed to obtain a saccharified solution to be used in the continuous extraction and fermentation method of this embodiment. As a method for solid-liquid separation, any known method capable of separating solids and liquids can be used, and examples thereof include, but are not limited to, filtration using a filter, a vibrating sieve, or the like, centrifugation, and separation using a screw press.

[0108] Furthermore, the biomass used in the above-mentioned saccharification method may be pretreated using a known method in order to carry out the saccharification reaction efficiently. Examples of pretreatment methods include steam cooking using only steam, a method using an ionic liquid, and a mill pulverization method. In the pretreatment method, an acid or alkali may be mixed as needed. The acid may be selected from sulfuric acid (including dilute sulfuric acid), hydrochloric acid, nitric acid, phosphoric acid, and the like, and these may be used alone or in combination. Among these, sulfuric acid, which is inexpensive and readily available, is particularly preferred for industrial use. The alkali may be selected from sodium hydroxide, potassium hydroxide, and ammonia, and these may be used alone or in combination. Among these, the dilute sulfuric acid cooking method using dilute sulfuric acid is preferred as the pretreatment method. [Example]

[0109] The present invention will be described below with reference to examples, but the present invention is not limited to the following examples.

[0110] [Reference example 1] (Comparative test of isobutanol recovery rate with and without extractant circulation mechanism) Using a simulation model calculated from laboratory test data using Microsoft Office Excel 2016, the recovery rate of isobutanol (IBA) was compared with and without an extractant circulation mechanism.

[0111] Specifically, in a system using one 1-L extractive fermentation tank, 300 mL of saccharified solution (initial glucose concentration 140 g / L), 300 mL of extractant (type of extractant: oleyl alcohol), and fermentation microorganisms (Corynebacterium genus bacteria), extractive fermentation was carried out for 72 hours. The following calculation formula was used to compare the temporal fluctuations in isobutanol concentration with and without an extractant circulation mechanism. In addition, the circulation flow rate in systems with a circulation mechanism was set to 150 mL / hour. In the following formula, the symbols are defined as follows: Borg: IBA concentration in extractant (g / L) Baq: IBA concentration in the fermentation broth (g / L) Glu: glucose concentration in the fermentation broth (g / L) Glu_i: initial glucose concentration in the fermentation broth Coli: Number of bacteria in the fermentation liquid (10 3 cells / L) t: time m2: Interfacial area between the fermentation liquid phase and the extractant phase m3: volume of extractant in the extractive fermenter Total_IBA: (cumulative IBA concentration) / (m3 in fermentation broth)

[0112] (Amount of IBA transferred from fermentation broth to extractant) Formula I: Borg_t = (m2 / m3)×K1×(P×Baq_t-n - Borg_t-n)×Δt+Borg_t-n

[0113] (Glucose consumption in the fermentation liquid) Equation II: Glu_t = Glu_i - (K2μ+K3)Coli_t×Δt

[0114] (IBA production amount) Formula III: Baq_t = Baq_t-n+Kb(Glu_t-n - Glu_t)

[0115] (Bacteria growth amount) Equation IV: Coli_t = Coli_t-n×e μ_t-n×Δt )

[0116] (specific growth rate) Formula V: μ = Ki×Total_IBA+μmax

[0117] (Overall transfer coefficient) Equation VI: K1 = A×(Borg_t-n -B )×3600

[0118] In the above formula, the following constants are values ​​calculated from data obtained in laboratory tests. P=3 K2=3.6 K3=0.34 Kb=0.25 Ki=-0.001 μmax=-0.0026 A=0.002 B=0.2

[0119] In addition, the conditions for the extractant regenerated by distillation (hereinafter sometimes referred to as "regenerated extractant") were set to an IBA recovery rate of 92% in distillation and a regenerated extractant with an IBA concentration of 0.1 g / L was circulated to the extraction fermentation tank, thereby eliminating the need to set a distillation calculation formula.

[0120] The recovery rate of IBA was calculated using the following formula VII: The results are shown in Figure 3.

[0121] (IBA recovery rate) Equation VII: Recovery (%) = {Amount of IBA in the extractant (+ amount of IBA recovered by distillation)} / (Total amount of IBA produced)

[0122] In a system with an extractant circulation mechanism, the amount of IBA in the extractant is the sum of the amount of IBA produced in the fermentation liquid phase and transferred to the extractant phase, and the amount of IBA in the extractant regenerated by distillation.

[0123] As shown in Figure 3, in the system without an extractant circulation mechanism, IBA remained in the fermentation broth, resulting in an IBA recovery rate of only 75%. In contrast, in the system with an extractant circulation mechanism, IBA in the fermentation broth was transferred to the extractant throughout the fermentation period, resulting in an IBA recovery rate of up to 99%. From the above, it was revealed that by providing a circulation mechanism for the extractant, the transfer rate of the target product from the fermentation liquid to the extractant does not decrease, the concentration of the target product in the fermentation liquid can be kept low, and the yield of the target product can be kept high.

[0124] [Example 1] (Test to confirm the equalization of IBA concentration in an extractive fermentation apparatus equipped with multiple extractive fermentation tanks and intermediate tanks) Using a system equipped with multiple extractive fermentation tanks and an intermediate tank, and a system equipped with a single extractive fermentation tank and no intermediate tank, the changes in the IBA concentration in the extracted extractant and the circulation flow rate of the extractant were confirmed.

[0125] Specifically, as shown in Figure 4, in a system equipped with three 1-L extraction and fermentation tanks and an intermediate tank, extractive fermentation was carried out for 72 hours using 300 mL of saccharified solution (initial glucose concentration: 140 g / L), 300 mL of extractant (type of extractant: oleyl alcohol), and fermentation microorganisms (Corynebacterium genus bacteria). The changes in the IBA concentration in the extracted extractant and the circulation flow rate of the extractant were confirmed using a simulation model (calculated using Microsoft Office Excel 2016 in the same manner as in Reference Example 1). In addition, in a system equipped with one 3-L extractive fermenter and no intermediate tank, 900 mL of saccharified solution (initial glucose concentration 140 g / L), 900 mL of extractant (oleyl alcohol), and a fermenting microorganism (Corynebacterium sp.) were used to examine the changes in the IBA concentration in the extracted extractant and the circulation flow rate under the same conditions and procedures as in the system equipped with three 1-L extractive fermenters and an intermediate tank. The operating pattern for the system equipped with three 1-L extractive fermenters and an intermediate tank was as shown in Table 1 below. The results are shown in Figure 4. In Figure 4, the left graph shows the change over time in the IBA concentration in the extracted extractant (the IBA concentration in the extractant extracted from the intermediate tank in the system equipped with three 1-L extractive fermenters and an intermediate tank). The right graph shows the change over time in the flow rate of the extractant sent to the distillation column.

[0126] [Table 1]

[0127] As shown in Figure 4, in the system equipped with three 1-L extractive fermentation tanks and an intermediate tank, the fluctuation range of the IBA concentration in the extractant and the extractant flow rate sent to the distillation column was smaller than in the system equipped with one 3-L extractive fermentation tank and no intermediate tank. From the above, it has become clear that by providing multiple extractive fermentation tanks and intermediate tanks, it is possible to level out fluctuations over time in the concentration of the target product in the extractant and in the amount of extractant sent to the distillation column, thereby obtaining a target product with a stable concentration and stabilizing the distillation operation and the circulation amount of the extractant. [Industrial Applicability]

[0128] According to the continuous extraction and fermentation apparatus and the continuous extraction and fermentation method of the present embodiment, the target product can be efficiently recovered at a stable concentration. [Explanation of symbols]

[0129] 1... saccharification tank, 2, 4, 31... piping, 3... solid-liquid separation device, 5, 24, 25, 26, 54, 55, 56... valve, 10... extraction fermentation tank group, 11, 12, 13... extraction fermentation tank, 21, 22, 23... first piping, 30... intermediate tank, 40... distillation column, 41... preheater, 51, 52, 53, 54, 57... second piping, 60... control unit, 71, 72, 73, 74, 75, 76... concentration sensor, 80... second intermediate tank, 100, 200... continuous extraction fermentation device

Claims

1. a group of extraction fermentation tanks, each of which has two or more tanks arranged in parallel, each tank containing a saccharified solution and microorganisms in a lower phase and an extractant in an upper phase, and which are configured to ferment the saccharified solution with the microorganisms to produce a fermentation solution containing a target product and extract the target product into the extractant simultaneously; A first pipe configured to extract a part or all of the extractant from each of the two or more extractive fermentation tanks; an intermediate tank configured to mix the extractants extracted from each of the two or more extractive fermentation tanks and level out fluctuations in the concentration of the target product; a distillation column configured to separate and purify the target product from the extractant, the concentration of which has been equalized and which has been withdrawn from the intermediate tank; A second pipe configured to return the extractant recovered by separating the target product in the distillation column to the two or more extractive fermentation tanks; a control unit that controls the supply of the saccharified solution to the extractive fermentation tank, the withdrawal of the extractant from the extractive fermentation tank, and the supply of the extractant regenerated in the distillation column so as to start at a predetermined time interval for each of two or more extractive fermentation tanks; A continuous extractive fermentation apparatus comprising:

2. 2. The continuous extraction and fermentation apparatus according to claim 1, wherein the control unit is configured to perform real-time detection of the concentration of the target product contained in the extractant in the extractive-fermentation tank, and to control the flow rate of the extractant extracted from the extractive-fermentation tank, the supply rate of the extractant regenerated in the distillation column, and the operating conditions of the distillation column based on the real-time detected concentration of the target product contained in the extractant.

3. 3. The continuous extraction and fermentation apparatus according to claim 2, wherein the control unit is further configured to: detect the concentration of the target product contained in the fermentation liquor in the extractive fermentation tank in real time; calculate a transfer rate of the target product from the fermentation liquor to the extractant; and control, based on the transfer rate of the target product, a flow rate of the extractant extracted from the extractive fermentation tank, a supply amount of the extractant regenerated in the distillation column, and operating conditions of the distillation column.

4. The continuous extraction and fermentation apparatus according to any one of claims 1 to 3, wherein the target product is one or more compounds selected from the group consisting of alcohols, ketones, and organic acids.

5. The continuous extraction and fermentation apparatus according to any one of claims 1 to 4, wherein the target product is one or more compounds selected from the group consisting of normal butanol, isobutanol, ethanol, and acetone.

6. The continuous extraction and fermentation apparatus according to any one of claims 1 to 5, wherein the extractant is one or more selected from the group consisting of alcohols, alkanes, and fatty acids, each having a specific gravity of 0.6 to 0.

9.

7. The continuous extractive fermentation apparatus according to any one of claims 1 to 6, wherein the extractant is oleyl alcohol.

8. The continuous extractive fermentation apparatus according to any one of claims 1 to 7, wherein the volume ratio of the fermentation liquid to the extractant in the extractive fermentation tank is 1:0.5 to 1:

2.

9. a parallel extractive fermentation step in which extractive fermentation is carried out in parallel in two or more extractive fermentation tanks at a predetermined time interval, in which the saccharified solution is fermented with microorganisms in a lower phase to produce a target product and the produced target product is extracted and transferred to an extractant in an upper phase in the same tank; A leveling step in which a part or all of the extractant containing the target product is extracted from each of the two or more extraction fermentation tanks and mixed to level out fluctuations in the concentration of the target product; a separation and purification step of separating and purifying the target product from the extractant having a leveled concentration by distillation; a circulation step of circulating the extractant from which the target product has been separated and regenerated to two or more of the extractive fermentation tanks; A continuous extractive fermentation method comprising:

10. 10. The continuous extraction and fermentation method according to claim 9, further comprising a control step of detecting the concentration of the target product contained in the extractant in the extractive fermentation tank in real time, and controlling, based on the concentration of the target product contained in the extractant detected in real time, the flow rate of the extractant withdrawn from the extractive fermentation tank, the amount of the extractant from which the target product has been separated and regenerated that is supplied to the two or more extractive fermentation tanks, and the conditions for the separation and purification.

11. 11. The continuous extraction and fermentation method according to claim 10, wherein the control step further comprises: detecting the concentration of the target product contained in the fermentation liquor in the extractive fermentation tank in real time; calculating a transfer rate of the target product from the fermentation liquor to the extractant; and controlling, based on the transfer rate of the target product, the flow rate of the extractant withdrawn from the extractive fermentation tank, the amount of the extractant from which the target product has been separated and regenerated that is supplied to the two or more extractive fermentation tanks, and the conditions for the separation and purification.

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