Culture apparatus, method for producing cultures

Abstract

The present invention provides a culture apparatus and other devices that can improve culture efficiency using culture-promoting gases. [Solution] The culture apparatus 1 comprises a culture tank 2 for containing a liquid culture target C, the culture tank 2 having an upper space G containing a culture-promoting gas that promotes the cultivation of the culture target C formed above the liquid surface LL of the culture target C, and a stirring blade 3 for stirring the culture target C contained in the culture tank 2 by rotation, the stirring blade 3 comprising a plate-shaped body extending in a plate shape from its rotation axis 30 toward the outer circumference of the culture tank 2, and at least one opening provided in the plate-shaped body, and forming a flow of the culture target C that takes in the culture-promoting gas from the upper space G into the culture target C.

Description

[Technical Field]

[0001] This disclosure relates to culture devices, etc. [Background technology]

[0002] Patent Document 1 discloses a cell culture apparatus equipped with a propeller-type stirring blade. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2024-6374 [Overview of the project] [Problems that the invention aims to solve]

[0004] Aerated culture of aerobic bacteria and facultative anaerobic bacteria requires culture-promoting gases such as oxygen. When such aerated culture is performed using the culture apparatus described in Patent Document 1, much of the culture-promoting gas supplied to the culture medium through a sparger, etc., passes through the culture medium and escapes above the liquid surface without being used for the growth of the cultured organisms. Therefore, it is difficult to improve the culture efficiency.

[0005] This disclosure is made in view of these circumstances and aims to provide a culture device, etc., that can improve culture efficiency using culture-promoting gases. [Means for solving the problem]

[0006] To solve the above problems, a culture apparatus in one aspect of the present disclosure is a culture tank for containing a culture medium containing a target to be cultured, the culture tank having an upper space containing a culture-promoting gas that promotes the cultivation of the target to be cultured, which is formed above the liquid surface of the culture medium; and a stirring blade for stirring the culture medium contained in the culture tank by rotation, the stirring blade comprising a plate-shaped body extending in a plate shape from its axis of rotation toward the outer circumference of the culture tank, and at least one opening provided in the plate-shaped body, thereby forming a flow of culture medium that takes in the culture-promoting gas from the upper space into the culture medium.

[0007] As will be described in more detail later, the stirring blade according to this embodiment allows for the efficient intake of culture-promoting gases into the culture medium from the space above the stirring blade or the culture medium (gas phase).

[0008] Another aspect of the present disclosure is a method for producing a culture. This method involves introducing a culture medium containing the substance to be cultured into a culture tank, stirring the culture medium by rotating a stirring blade around a rotating shaft, the blade having a plate-shaped body extending outward from a rotating shaft in the culture tank and at least one opening provided in the plate-shaped body, and introducing a culture-promoting gas, which promotes the cultivation of the substance to be cultured, into the culture medium from an upper space formed above the liquid surface of the culture medium in the culture tank, through the rotation of the stirring blade.

[0009] Furthermore, any combination of the above components, as well as any representations thereof converted into methods, apparatus, systems, recording media, computer programs, etc., are also included in this disclosure. [Effects of the Invention]

[0010] According to this disclosure, it is possible to increase the culture efficiency using culture-promoting gases. [Brief explanation of the drawing]

[0011] [Figure 1] A schematic diagram of the culture apparatus is shown. [Figure 2] This is a schematic functional block diagram of the culture apparatus. [Figure 3] It is a flowchart showing an example of a process executed by the functional blocks of FIG. 2. [Figure 4] The stirring blade according to the first embodiment is shown. [Figure 5] The stirring blade according to the second embodiment is shown. [Figure 6] The stirring blade according to the third embodiment is shown. [Figure 7] The culture device according to the comparative example is shown. [Figure 8] The measurement results of the oxygen transfer volume coefficient when water is put in are shown. [Figure 9] The measurement results of the oxygen transfer volume coefficient when a high-viscosity aqueous solution is put in are shown. [Figure 10] The results of the second example are shown. [Figure 11] The results of the third example are shown. [Figure 12] The results of the fourth example are shown.

Mode for Carrying Out the Invention

[0012] Hereinafter, embodiments for implementing the present disclosure (hereinafter also referred to as embodiments) will be described in detail with reference to the drawings. In the description and / or the drawings, the same or equivalent components, members, processes, etc. are denoted by the same reference numerals, and redundant descriptions are omitted. The scales and shapes of the respective parts shown are set for the sake of simplicity of description and are not to be construed in a limited manner unless otherwise specified. The embodiments are illustrative and do not limit the scope of the present disclosure in any way. All features presented in the embodiments and combinations thereof are not necessarily essential to the present disclosure. The embodiments are presented, for convenience, decomposed into components for each function and / or each group of functions for realizing it. However, one component in the embodiments may actually be realized by a combination of a plurality of components as separate entities, or a plurality of components in the embodiments may actually be realized by one component as an integral entity. Also, a plurality of embodiments and variations may be disclosed in parallel, but any components of each embodiment and / or each variation may be combined in any manner as long as they do not inhibit each other's functions.

[0013] FIG. 1 schematically shows the configuration of a culture device 1 according to an embodiment of the present disclosure. In the example of this embodiment, the vertical direction (or longitudinal direction, height direction) in FIG. 1 coincides with the vertical direction, and the left-right direction (or transverse direction, width direction) in FIG. 1 coincides with the horizontal direction. Also, the axial direction in which the central axis of the culture tank 2 and / or the rotation axis 30 of the stirring blade 3 extends later coincides with the vertical direction, i.e., the vertical direction in FIG. 1. Further, the left-right direction, i.e., the horizontal direction in FIG. 1, is also referred to as the radial direction for defining the diameters of the culture tank 2 and the stirring blade 3. Note that the vertical direction, the vertical direction, and the axial direction in FIG. 1 may be different from each other. Similarly, the left-right direction, the horizontal direction, and the radial direction in FIG. 1 may be different from each other.

[0014] The culture apparatus 1 comprises a culture tank 2 that contains a culture medium C (also referred to as culture fluid) containing the organism to be cultured, and a stirring blade 3 that agitates the culture medium C in the culture tank 2 by rotation. The culture tank 2 comprises a cylindrical or circular tube-shaped straight body section 21 extending in the axial direction, and a bottom section 22 that is provided below and continuous with the straight body section 21. The capacity of the culture tank 2 is arbitrary, but for example, it is 3 liters (3L).

[0015] The inner or side walls of the straight cylinder portion 21 have a circular cross-section when viewed from above (axially), and their diameter D represents the diameter of the culture tank 2. The cross-section of the straight cylinder portion 21 when viewed from above may be any non-circular shape. In this case, the diameter D of the culture tank 2 may be defined as the diameter of the inscribed circle of the cross-sectional shape of the straight cylinder portion 21, or as the diameter of the circumscribed circle of the said cross-sectional shape, or as the average or intermediate value of these.

[0016] An opening (not shown) is provided above the straight body section 21 (for example, in the upper space G described later) for introducing a culture medium C containing the target organism into the culture tank 2. Introducing the culture medium C into the culture tank 2 is not limited to introducing a culture medium C in which the target organism is suspended in a culture medium into the culture tank 2, but also includes introducing a culture medium into the culture tank 2, then introducing the target organism into the culture medium in the culture tank 2 to generate the culture medium C in the culture tank 2, or introducing the target organism into the culture tank 2, then introducing the culture medium into the culture tank 2 to generate the culture medium C in the culture tank 2. This culture medium inlet is closed by a lid (not shown) or the like while the culture medium C is being stirred by the stirring blade 3. The culture medium C may also be supplied into the culture tank 2 from a culture medium supply port such as a supply nozzle (not shown) that may be provided on the side wall of the straight body section 21 or the like.

[0017] The bottom 22 of the culture tank 2 is formed in a curved shape that bulges downward from the lower end of the straight cylinder 21. The lowest part of the culture tank 2 is formed at the center of the bottom 22 by the curved bulge. The bottom 22 may be formed in the shape of an inverted cone or an inverted frustocone, with the diameter decreasing downwards, or it may be formed in a planar shape with the axial direction as the normal direction.

[0018] An outlet (not shown) may be provided at the bottom of the culture tank 2 to discharge the culture medium C from the culture tank 2 to the culture apparatus 1. This outlet may be configured to be openable and closable by an outlet opening / closing mechanism such as a valve. For example, when the culture medium C is added to the culture tank 2 and stored, when the culture medium C is stirred by the stirring blade 3 to promote mixing and culturing, and when the concentration of the culture medium C is made uniform, a valve controlled to the closed state closes the outlet. Also, when the culture medium C, after mixing and culturing is substantially complete and the concentration has been made uniform, is discharged while being stirred by the stirring blade 3 as needed, a valve controlled to the open state opens the outlet. The culture medium C after culturing may be discharged from an opening in the upper part of the culture tank 2, where the lid is open. Alternatively, the culture medium C after culturing may be discharged to the outside of the culture tank 2 from a fluid outlet such as a discharge nozzle that may be provided on the side of the straight body section 21.

[0019] The horizontal boundary line between the roughly cylindrical straight section 21 and the curved bottom section 22 is also called the tangent line TL. The vertical distance L between the lowest part of the culture tank 2 (bottom section 22) and the surface or liquid level LL of the culture medium C inside the culture tank 2 is also expressed as the liquid level height or reference height in the operating liquid volume. The operating liquid volume is the liquid volume determined by the specifications of the culture apparatus 1. In the example of this embodiment, the liquid level height L along the axial direction of the culture medium C is greater than the tank diameter D along the radial direction of the culture tank 2, for example, the ratio L / D is 1.2 or more. Such a culture tank 2 is preferable for forming a flow of culture medium C that circulates largely along the vertical direction by the rotation of the stirring blade 3 (schematically shown by the solid arrow in Figure 1), as will be described later. Note that if the bottom section 22 is formed in a planar shape, the vertical distance L between the planar bottom section 22 (bottom plate) and the liquid level LL of the culture medium C can be interpreted as the liquid level height.

[0020] The culture target, which is introduced into the culture tank 2 and cultured while being stirred by the stirring blade 3, can be any aerobic bacteria or facultative anaerobic bacteria that are cultured aerobically. Examples of such bacteria include fungi, including yeasts and filamentous fungi, and other microorganisms, including actinomycetes and hydrogen bacteria, but are not limited to these. For example, the culture target may be any microorganism such as bacteria or any tissue of plants or animals such as cells, and it is preferable that the culture requires oxygen or any other culture-promoting gas. Culture means increasing the number of bacterial cells or microorganisms, but also includes the increase of bacterial cells or microorganisms associated with fermentation, accumulation, biological reactions, etc. Oxygen is a typical example of a culture-promoting gas, but hydrogen, carbon dioxide, mixed gas, synthesis gas, etc. may be used depending on the type of culture target. Note that the culture medium C, in which cells are the culture target, is also called a cell suspension.

[0021] As will be described later, the culture apparatus 1 (especially the stirring blade 3) according to this embodiment allows for efficient mixing of culture-promoting gas into the culture medium C (schematically shown by the white arrows in Figure 1). The viscosity of the culture medium C is arbitrary, but is preferably between 1 mPa·s and 200,000 mPa·s, more preferably between 2 mPa·s and 200,000 mPa·s, and even more preferably between 4 mPa·s and 200,000 mPa·s. The viscosity of the culture medium C increases as the amount of bacterial cells or other substances to be cultured increases. That is, the viscosity of the culture medium C increases (changes) as the concentration of the substances to be cultured increases with the progress of the culture. For example, as a culture medium C, it is preferable that the maximum viscosity reaches a high viscosity region between 500 mPa·s and 200,000 mPa·s as the culture progresses, and more preferably that it reaches a high viscosity region between 4,000 mPa·s and 200,000 mPa·s.

[0022] The stirring blade 3 is rotatably mounted around a rotation axis 30 that substantially coincides with the vertical central axis of the culture tank 2. Although not shown in the illustration, a rotational drive unit such as an electric motor that generates rotational power, and a rotational power conversion unit such as a transmission or reduction gear that converts the rotational power to a desired rotational speed (or rotational velocity) or torque may be provided above the rotation axis 30. Note that the rotational drive unit is not limited to an electric motor, but may also be a fluid machine or a heat engine. A lower bearing (not shown) may be provided below the rotation axis 30. The rotational speed of the stirring blade 3 is arbitrary, but for example, it is between 100 rpm and 1200 rpm. The stirring power by the stirring blade 3 is expressed as rotational power relative to the operating liquid volume of the culture tank 2, and is 0.1 kW / m 3 and 50kW / m 3 Preferably, it is between 0.1 kW / m 3 and 3.0kW / m 3 It is more preferable to be between 0.5 kW / m 3 and 3.0kW / m 3 It is more preferable that it be between these two values. The detailed configuration of the stirring blade 3 will be described later.

[0023] The stirring power of the stirring blade 3 may be controlled according to the viscosity change of the culture medium C. As schematically shown in Figure 2, the culture apparatus 1 comprises a rotary drive control unit 82 and a measuring unit 81 for measuring viscosity changes. In this embodiment, the culture apparatus 1 comprises an electric motor as the rotary drive unit 83, an inverter as the rotary drive control unit 82, and a turbidimeter as the measuring unit 81. As the culture of the culture target progresses, the viscosity and turbidity increase as the concentration of the culture target in the culture medium C increases. That is, since viscosity and turbidity are correlated, the viscosity of the culture medium C can be indirectly measured by measuring the turbidity of the culture medium C using the turbidimeter. Alternatively, the viscosity change of the culture medium C may be measured directly with a viscometer.

[0024] The inverter controls the motor based on the rotational speed command value from the control panel 84, but it can be switched to viscosity control by operation from the control panel 84. As shown in Figure 3, in step S10, it is determined whether the command from the control panel 84 is for viscosity control or not. If it is viscosity control, the process proceeds to step S20; otherwise, viscosity control is terminated. In step S20, the turbidimeter (measuring unit 81) measures the turbidity of the culture medium C and calculates and acquires the viscosity change. In step S30, the rotational drive control unit 82 calculates the commanded rotational speed of the motor according to the viscosity change. When the viscosity of the culture medium C increases, the commanded rotational speed is increased, and when the viscosity of the culture medium C decreases, the commanded rotational speed is decreased. In step S40, the commanded torque is calculated from the difference between the commanded rotational speed and the actual motor rotational speed, and a torque current corresponding to the commanded torque is output to the motor.

[0025] As described above, by controlling the stirring power of the stirring blade 3 in accordance with the viscosity change of the culture medium C, the culture growth rate can be controlled in accordance with the viscosity change of the culture medium C. In particular, in culture medium C where the maximum viscosity reaches a high viscosity region between 500 mPa·s and 200,000 mPa·s, or between 4,000 mPa·s and 200,000 mPa·s, the rotational speed of the stirring blade 3 tends to decrease and the culture efficiency tends to decrease due to the increase in load torque accompanying the increase in viscosity of the culture medium C. In the case of general stirring blades such as turbine blades and propeller blades, the increase in load torque accompanying the increase in viscosity leads to shutdown of operation or partial stirring of the culture medium C. However, the stirring blade 3, which will be described in detail later, is equipped with a plate-shaped body that extends in a plate shape from the rotation shaft 30 toward the outer circumference of the culture tank 2, and at least one opening provided in the plate-shaped body, so that continuous stirring is possible even when the load torque increases due to the increase in viscosity of the culture medium C, allowing cultivation to continue and the culture growth rate to be maintained. Furthermore, in bacterial culture using such a stirring blade 3, it is more preferable to control the stirring power of the stirring blade 3 in accordance with the change in viscosity of the culture medium C.

[0026] Therefore, in such a bacterial cell culture using the stirring blade 3, it is preferable to apply control of the stirring power of the stirring blade 3 according to the change in the viscosity of the culture solution C. Although the effects when the culture solution C has a high viscosity have been described above, depending on the type of bacterial cells, the viscosity may be low, and it is necessary to rotate the stirring blade 3 at a low rotational speed. By controlling the stirring power of the stirring blade 3 according to the change in the viscosity of the culture solution C, when the viscosity of the culture solution C is low due to the characteristics of the bacterial cells, the rotational speed of the stirring blade 3 can be decreased, and an optimal shear force according to the type of bacterial cells can be applied to the culture solution C.

[0027] In FIG. 1, in the vicinity of the inner peripheral wall of the straight barrel portion 21 in the culture tank 2, there is provided a baffle 4 that extends substantially along the axial direction over most of the liquid surface height L and projects substantially in the radial direction toward the central axis of the culture tank 2 (or the rotation axis 30 of the stirring blade 3). As in the illustrated example, a plurality of baffles 4 may be provided along the circumferential direction around the rotation axis 30. In this case, the plurality of baffles 4 are preferably arranged at equal intervals in the circumferential direction. For example, when N baffles 4 (N is a natural number of 2 or more) are provided, these are arranged at equal intervals at every 360 / N° angle centered on the rotation axis 30 in the axial view (top view in FIG. 1).

[0028] Since the culture solution C rotated in the circumferential direction by the stirring blade 3 hits the baffle 4, also called a baffle plate, an axial flow is generated, preventing the culture solution C from rotating in the same manner as the stirring blade 3 due to inertia. Note that the baffle 4 must not interfere with the rotation of the stirring blade 3 and is arranged in the radial range on the outer peripheral side of its rotation region.

[0029] In promoting the generation of the circulation flow (solid arrows) of the culture solution C described later and / or the intake of the culture promoting gas into the culture solution C (white arrows), the width d along the direction orthogonal to the axial direction of each baffle 4, the diameter D of the culture tank 2, and the number n of the baffles 4 B The relationship with is 0.1 ≦ (d / D) 1.2 n B ≦ 0.35 is preferable, and 0.25 ≦ (d / D) 1.2 n BIt is more preferable that the value be ≤0.35. Note that the width direction of each baffle 4 does not need to coincide with the radial direction of the culture tank 2 (left-right direction in Figure 1), as schematically shown in Figure 1; it may be in a direction intersecting the radial direction (but perpendicular to the axial direction).

[0030] The culture apparatus 1 may further include all or part of the culture medium supply unit 5, the culture-promoting gas supply unit 6, and the temperature control unit 7.

[0031] The culture medium supply unit 5 is a tube capable of supplying culture media, such as liquid or solid media, required for culturing the target organism into the culture tank 2. The culture medium supply unit 5 can supply any amount of culture medium to any location in any manner within the culture tank 2, but it is preferable to supply the culture medium downward (or diagonally downward, leftward, or rightward) in the lower region of the culture tank 2 or the straight body section 21, as shown in the illustrated example. The culture medium supplied in this manner to the lower region of the culture tank 2 or the straight body section 21 is efficiently mixed with the target organism, such as aerobic bacteria, while riding on the circulating flow indicated by the solid arrows in Figure 1 (furthermore, as will be described later, it is efficiently mixed with the culture-promoting gas indicated by the white arrows in Figure 1 near the center of the liquid level LL).

[0032] The placement or piping of the tubular culture medium supply unit 5 within the culture tank 2 is arbitrary, but it is preferable to utilize the intermediate region between the region where the stirring blade 3 rotates radially inward and the region where the baffles 4 are provided radially outward, as shown in the illustrated example. The intermediate region is the region located in the axial direction of the stirring blade 3, between the circumference of the region where the stirring blade 3 rotates and the circumference connecting the ends of the multiple baffles 4. The culture medium supply unit 5 may supply the required amount of culture medium all at once when starting the culture of the target organism, or it may supply it gradually to replenish the amount of culture medium consumed as the culture progresses.

[0033] The culture-promoting gas supply unit 6 is a sparger or similar tube capable of supplying a culture-promoting gas such as oxygen to the culture-promoting gas supply unit 6 located below (on the other side) in the axial direction from the stirring blade 3 within the culture tank 2. In the illustrated example, the tubular tip 61 from which the culture-promoting gas is actually released from the culture-promoting gas supply unit 6 is positioned to extend radially (left-right) within the bottom region of the bottom 22 below the stirring blade 3. Since the radial length of the tip 61 is approximately the same as or slightly larger than the diameter R of the rotation range of the stirring blade 3, the culture-promoting gas released upward from the tip 61 is immediately stirred by the stirring blade 3, allowing the culture-promoting gas to be efficiently dispersed in the culture medium C.

[0034] The arrangement or piping of the tubular culture-promoting gas supply unit 6 within the culture tank 2 is arbitrary, but it is preferable to utilize the area below the stirring blade, as shown in the illustrated example. Furthermore, as previously mentioned, the bottom region within the bottom 22 below the stirring blade 3 is also efficiently utilized to accommodate the tip 61. The culture-promoting gas supply unit 6 may continuously supply a substantially constant amount of culture-promoting gas during the cultivation of the culture target, or the amount of culture-promoting gas supplied may be changed according to the progress of cultivation. The amount and manner of supplying culture-promoting gas by the culture-promoting gas supply unit 6 are arbitrary, but for example, it is preferable to supply a culture-promoting gas such as air at a rate of 0.1 to 20 VVM per volume of the culture tank 2 (e.g., 3 L), preferably at a rate of 0.1 to 10 VVM, and more preferably at a rate of 0.1 to 3.7 VVM. Here, VVM stands for gas volume per liquid volume per minute, and is a unit that indicates the volume of culture-promoting gas supplied per minute per liter of culture medium C. While air is a common example of a culture-promoting gas, it is not limited to air; for example, oxygen or oxygen-containing gas mixtures can also be used.

[0035] As will be described later, in this embodiment, since culture-promoting gas can be introduced into the culture medium C from the upper space G (gas phase) above the liquid surface LL, if a sufficient amount of culture-promoting gas is present in the upper space G, the culture-promoting gas supply unit 6 does not need to be provided.

[0036] Here, the upper space G is the space (gas phase) that is formed above the liquid level LL after the culture medium C is added to the culture tank 2 to the operating volume. This upper space G can store culture-promoting gas to accelerate the cultivation of the target organism (or culture-promoting gas accumulates naturally). The culture tank 2 may be provided with a relief valve to release the culture-promoting gas accumulated in the upper space G. The upper space G may be sealed when it has accumulated the amount of culture-promoting gas necessary for culturing the target organism C.

[0037] Alternatively, during the cultivation of the culture target (or during stirring by the stirring blade 3), the necessary amount of culture-promoting gas may be supplied into the upper space G from a culture-promoting gas supply pipe (not shown) or the like. Furthermore, if the aforementioned culture-promoting gas supply unit 6 is provided, at least a portion of the culture-promoting gas supplied to the bottom 22 of the culture tank 2 may be released from the liquid surface LL into the upper space G. Therefore, it can be interpreted that the culture-promoting gas supply unit 6 performs at least a part of the function of the culture-promoting gas supply pipe or the like in this case.

[0038] The temperature control unit 7, for example, covers the outer surface of the culture tank 2 in an annular shape and adjusts (heats and / or cools) the culture medium C inside the culture tank 2 to an appropriate temperature. The temperature control unit 7 can maintain the culture medium C at any temperature while it is being stirred by the stirring blade 3, but it is preferable to maintain it between 20°C and 55°C, and more preferably between 25°C and 35°C, in order to increase the growth rate of bacterial cells, etc.

[0039] Next, the detailed configuration of the stirring blade 3 will be described. Figures 4 to 6 show three different exemplary embodiments of the stirring blade 3. As will be described in detail later, these stirring blades 3 are stirring the culture medium C contained in the culture tank 2 by rotation, and are common in that they include a plate-shaped body that extends in a plate shape from its rotation axis 30 toward the outer circumference of the culture tank 2 (left and right sides in Figure 1), and at least one opening provided in the plate-shaped body.

[0040] Figure 4 shows the stirring blade 3 (shown in Figure 1) according to the first embodiment. The upper part of Figure 4 schematically shows the stirring blade 3 in an axial view (upward view in Figure 1, etc.), and the lower part of Figure 4 schematically shows the stirring blade 3 in a radial view (front view in Figure 1, etc.). In the example of Figure 4, four (or more) stirring blades 3 are provided around the rotation axis 30. Here, it is preferable that the multiple stirring blades 3 are provided symmetrically around the rotation axis 30, and in the axial view of the upper part of Figure 4, they are arranged at equal intervals (point symmetry) at angles of 360 / 4 = 90° around the rotation axis 30. In the front view of the lower part of Figure 4, two stirring blades 3 with substantially the same configuration are arranged symmetrically on the left and right sides of the rotation axis 30. Note that the number of stirring blades 3 is not limited to four, but may be two, six, or any number. If the number of stirring blades 3 is odd, only one stirring blade 3 will appear in the front view or cross-sectional view as shown in the lower part of Figure 4.

[0041] The stirring blade 3 shown in Figure 4 comprises a plate-shaped body 31 that extends in a plate shape from the rotation axis 30 toward the outer circumference of the culture tank 2 (left and right sides in Figure 4), and a plurality of openings 32 provided in the plate-shaped body 31 (two in the example in Figure 4).

[0042] The plate-shaped body 31 is preferably rectangular in shape, as illustrated in Figure 4, with two sides (left and right) along the axial direction (up and down) and two sides (top and bottom) along the radial direction (left and right). However, the shape of the plate-shaped body 31 is arbitrary and can be determined by straight or curved lines extending in any direction. For example, the lower edge of the plate-shaped body 31 may be curved or bent to match the curved bottom 22 of the culture tank 2 (Figure 1).

[0043] The maximum radial width (left-right direction) W of the plate-shaped body 31 determines the width W of the stirring blade 3. Here, in order to promote the generation of the circulating flow of the culture medium C (solid arrow in Figure 1) and / or the uptake of culture-promoting gas into the culture medium C (white arrow in Figure 1), the ratio W / D of the width W of the stirring blade 3 in the direction perpendicular to the axial direction to the diameter D of the culture tank 2 is preferably between 0.2 and 0.35, and more preferably between 0.25 and 0.3. Similarly, the diameter R (=2W) of the rotation range of one stirring blade 3 is preferably between 0.4 and 0.7, and more preferably between 0.5 and 0.6.

[0044] Furthermore, the maximum axial height (vertical direction) H of the plate-shaped body 31 determines the height H of the stirring blade 3. Here, in order to promote the generation of a circulating flow of the culture medium C and / or the uptake of culture-promoting gas into the culture medium C, the ratio H / L of the height H of the stirring blade 3 along the axial direction to the liquid surface height L of the culture medium C is preferably between 0.78 and 0.98, and more preferably between 0.78 and 0.88.

[0045] In the example shown in Figure 4, two openings 32 (321, 322) are provided in one stirring blade 3 or plate-shaped body 31. However, the number of openings 32 is arbitrary; there may be one or three or more. Preferably, each opening 32 is rectangular in shape, defined by two sides (left and right) along the axial direction (up and down) and two sides (top and bottom) along the radial direction (left and right). However, the shape of each opening 32 is arbitrary; for example, it may be circular, elliptical, triangular, or other polygonal shape, and can be defined by straight or curved lines extending in any direction. Furthermore, the shapes of multiple openings 32 may be the same (however, their dimensions may differ), as in the example in Figure 4, or they may be different.

[0046] The arrangement of the multiple openings 32 in the plate-shaped body 31 is arbitrary, but it is preferable that they be aligned along the axial direction (up and down) and / or the radial direction (left and right). In the example of Figure 4, the openings 32 include at least one inner opening 321 provided on the rotation axis 30 side (radially inward) and at least one outer opening 322 provided on the outer circumference side (radially outward) of the culture tank 2 (Figure 1). The inner opening 321 and the outer opening 322 are provided in overlapping axial ranges. Preferably, as in the example of Figure 4, the inner opening 321 and the outer opening 322 are arranged radially side by side in substantially the same axial range.

[0047] The number of radially aligned openings 32 can be three or more. Furthermore, as shown in the example in Figure 6 described later, multiple openings 32 may be arranged axially within overlapping radial ranges. Additionally, multiple openings 32 may be arranged in both axial and radial directions. This arrangement of one or more openings 32 in a grid or mesh-like two-dimensional configuration on the plate-shaped body 31 facilitates the formation of a desired circulation flow (solid arrow in Figure 1) of the culture medium C. In particular, as shown in the embodiments described later, by optimizing the shape and arrangement of the openings 32 according to the type of culture target and the viscosity of the culture medium C, a desired circulation flow can be formed for any culture target in the culture medium C.

[0048] In the example shown in Figure 4, all the openings 32 are positioned on the upper side (one side) of the plate-shaped body 31 in order to form a desired circulating flow for the culture medium C containing a specific target organism. For example, all the openings 32 are positioned within 70% of the upper edge of the plate-shaped body 31, with the height H of the stirring blade 3 (or plate-shaped body 31) being 100% (i.e., no openings 32 are provided within 30% of the lower edge of the plate-shaped body 31). In such a stirring blade 3, the lower part where no openings 32 are provided is a plate-shaped paddle section 33 that strongly scrapes the culture medium C, while the upper part is an intake section 34 that takes in the culture medium C through concentrated lattice-shaped or other openings 32.

[0049] The lower paddle section 33 generates a flow of culture medium C mainly in the axial downward and radially outward directions as the stirring blade 3 rotates. These flows strike the inner circumferential wall of the culture tank 2 (Figure 1), generating a flow of culture medium C FO that rises along the inner circumferential wall (solid arrows in Figures 1 and 2). Meanwhile, the upper intake section 34 takes in the culture medium C that has risen in the radially outward region into the opening 32. Here, since the area of ​​the inner opening 321 is larger than the area of ​​the outer opening 322 (for example, the width and / or height of the inner opening 321 is larger than the width and / or height of the outer opening 322), the culture medium C is strongly drawn towards the inner opening 321. As a result, a flow of culture medium C FI that descends along the rotation axis 30 in the radially inward region is generated (solid arrows in Figures 1 and 2). Note that the areas of the inner opening 321 and the outer opening 322 may be substantially the same, or the latter may be larger than the former. Even in this case, the stirring blade 3 still collects the strong upward flow FO on the radially outward side, and the culture medium C is drawn inward on the radial side.

[0050] As described above, in this embodiment, the rotation of the stirring blade 3 generates an inner flow FI of the culture medium C along the axial direction from the upper side (one side) to the lower side (the other side) on the rotation axis 30 side (radially inward), and an outer flow FO of the culture medium C along the axial direction from the lower side (the other side) to the upper side (one side) on the outer circumference side of the culture tank 2 (radially outward). The stirring blade 3 according to this embodiment, illustrated in Figures 4 to 6, is suitable for the purpose of forming a large circulating flow within the culture tank 2, as schematically shown in Figure 1, through the downward flow FI on the radially inward side and the upward flow FO on the radially outward side.

[0051] As schematically shown in Figure 1, the large circulating flow of the culture medium C generates a strong downward flow (which can also be called the starting point of FI) in the center of the liquid surface LL (near the rotation axis 30). This downward flow not only strongly pulls the culture medium C downward, but also strongly draws culture-promoting gas into the culture medium C from the upper space G (gas phase) above the liquid surface LL (white arrow in Figure 1). Thus, according to the stirring blade 3 of this embodiment, culture-promoting gas can be efficiently taken into the culture medium C from the stirring blade 3 or the upper space G above (on one side) the culture medium C, thereby significantly increasing the efficiency of aerobic culture and other methods that require culture-promoting gas.

[0052] Figure 5 shows the stirring blade 3 according to the second embodiment. Components similar to those in the first embodiment in Figure 4 are denoted by the same reference numerals and redundant explanations are omitted. The stirring blade 3 shown in Figure 5 comprises a plate-shaped body 31 that extends in a plate shape from the rotation axis 30 toward the outer circumference of the culture tank 2 (left and right sides in Figure 5), and a single opening 32 provided in the plate-shaped body 31.

[0053] The opening 32 is preferably rectangular, as illustrated in Figure 5, with two sides (left and right) aligned axially (up and down) and two sides (top and bottom) aligned radially (left and right). However, the shape of the opening 32 is arbitrary and may be circular, elliptical, triangular, or other polygonal, and can be defined by straight or curved lines extending in any direction.

[0054] The arrangement of the openings 32 in the plate-shaped body 31 is arbitrary, but it is preferable that they be located in the central region in the axial direction, as shown in Figure 5. For example, the openings 32 are arranged symmetrically with respect to the radial center line O of the plate-shaped body 31.

[0055] In the example shown in Figure 5, the openings 32 (which may be divided into multiple openings) are provided on the plate-shaped body 31, biased towards the radially inward direction, in order to form a desired circulating flow for the culture medium C containing a specific target organism. For example, all the openings 32 are provided within 70% of the inner edge of the plate-shaped body 31 (the edge in contact with the rotation axis 30), with the width W of the stirring blade 3 (or plate-shaped body 31) being 100% (i.e., no openings 32 are provided within 30% of the outer edge of the plate-shaped body 31). With such a stirring blade 3, a strong inward downward flow FI can be generated by the openings 32 concentrated radially inward.

[0056] Figure 6 shows the stirring blade 3 according to the third embodiment. Components similar to those in the first embodiment in Figure 4 and the second embodiment in Figure 5 are denoted by the same reference numerals and redundant explanations are omitted. The stirring blade 3 shown in Figure 6 comprises a plate-shaped body 31 that extends in a plate shape from the rotation axis 30 toward the outer circumference of the culture tank 2 (left and right sides in Figure 6), and a plurality of openings 32 provided in the plate-shaped body 31.

[0057] In the example shown in Figure 6, two openings 32 (323, 324) are provided in one stirring blade 3 or plate-shaped body 31. However, the number of openings 32 is arbitrary; there may be one or three or more. Preferably, each opening 32 is rectangular in shape, defined by two sides (left and right) along the axial direction (up and down) and two sides (top and bottom) along the radial direction (left and right). However, the shape of each opening 32 is arbitrary; for example, it may be circular, elliptical, triangular, or other polygonal shape, and can be defined by straight or curved lines extending in any direction. Furthermore, the shapes of multiple openings 32 may be the same (however, their dimensions may differ), as in the example shown in Figure 6, or they may be different.

[0058] In the example shown in Figure 6, the opening 32 comprises at least one upper opening 323 (upper opening) provided on the upper side (one side) along the axial direction of the plate-shaped body 31, and at least one lower opening 324 (downward opening) provided on the lower side (the other side). The upper opening 323 and the lower opening 324 are provided in overlapping radial ranges (overlapping ranges in an axial view). Preferably, as in the example shown in Figure 6, the upper opening 323 and the lower opening 324 are arranged side by side in the axial direction within substantially the same radial range. The number of openings 32 arranged in the axial direction in this manner may be three or more.

[0059] In the example shown in Figure 6, all the openings 32 are positioned radially inward on the plate-shaped body 31 in order to form a desired circulating flow for the culture medium C containing a specific target organism. For example, all the openings 32 are positioned within 70% of the inner edge of the plate-shaped body 31 (the edge in contact with the rotation axis 30), with the width W of the stirring blade 3 (or plate-shaped body 31) being 100% (i.e., no openings 32 are positioned within 30% of the outer edge of the plate-shaped body 31). With such a stirring blade 3, a strong inward downward flow FI can be generated by the openings 32 concentrated radially inward.

[0060] Furthermore, in the stirring blade 3 illustrated in Figure 6, there is no opening 32 in the approximately central region in the axial direction of the plate-shaped body 31, and it is instead a plate-shaped paddle section 35 that strongly scrapes the culture medium C. Above the paddle section 35, an upper intake section 36 is configured to take in the culture medium C through an upper opening 323, such as a rectangular or grid shape, and below the paddle section 35, a lower intake section 37 is configured to take in the culture medium C through a lower opening 324, such as a rectangular or grid shape. The axial arrangement and length of the paddle section 35, the upper intake section 36, and the lower intake section 37 are optimized to form a desired circulating flow.

[0061] The paddle section 35, located approximately in the axial center, generates a flow of culture medium C mainly in the axial downward direction and radially outward direction as the stirring blade 3 rotates. This axially downward flow is taken into the lower opening 324 by the lower intake section 37 and then strikes the curved bottom 22 of the culture tank 2 (Figure 1), generating a flow of culture medium C FO that rises from the bottom 22 along the inner circumferential wall. In addition, the radially outward flow generated by the paddle section 35 strikes the inner circumferential wall of the culture tank 2, generating a flow of culture medium C FO that rises along the inner circumferential wall.

[0062] On the other hand, the upper intake section 36 takes in the culture medium C that has risen in the radially outer region into the upper opening 323 which is positioned radially inward. As a result, a flow FI of the culture medium C descends along the rotation axis 30 in the radially inward region. Note that the area and height of the upper opening 323 and the lower opening 324 may be substantially the same, or the former may be larger than the latter, or the latter may be larger than the former.

[0063] Next, examples of the method for producing the culture according to this embodiment are shown.

[0064] In the first embodiment, the oxygen transfer capacity coefficient (kLa) of oxygen, a typical culture-promoting gas, was measured under substantially the same operating conditions for the culture apparatus 1 according to this embodiment shown in Figure 1 and the culture apparatus 10 according to the comparative example shown in Figure 7. The oxygen transfer capacity coefficient is a representative indicator of the efficiency of aerobic culture using oxygen as the culture-promoting gas (the larger the oxygen transfer capacity coefficient, the higher the efficiency of aerobic culture).

[0065] The culture apparatus 10 shown in Figure 7 differs from the culture apparatus 1 shown in Figure 1 only in its stirring blade. Specifically, the stirring blade 8 of the culture apparatus 10 shown in Figure 7 is a typical two-stage upper and lower disk turbine blade. With this stirring blade 8, large circulation flow of the culture medium C and the uptake of oxygen (culture promoting gas) from the upper space G into the culture medium C are less likely to occur, as shown in Figure 1. For this reason, as shown below, a significantly lower oxygen transfer capacity coefficient was observed compared to the stirring blade 3 according to this embodiment.

[0066] For each of the culture devices 1 and 10, the oxygen transfer capacity coefficient was measured using a DO sensor according to the following procedure. (1) Add water or an aqueous solution of a specified viscosity to the 3L culture tank 2. (2) Set the stirring blades 3 and 8 to a predetermined rotation speed. (3) Rotate the impellers 3 and 8 at the rotational speed set in (2), and purge the liquid introduced in (1) with N2 gas while stirring, reducing the dissolved oxygen concentration to 1 mg / L or less. (4) The supply of N2 gas is stopped, and while supplying a predetermined amount of air into the liquid through a culture-promoting gas supply unit 6 such as a sparger, the stirring blades 3 and 8 are rotated at a predetermined rotational speed to start stirring the liquid. (5) Record the change in dissolved oxygen concentration over time from the start of (4) until saturation occurs. (6) To calculate the saturated dissolved oxygen concentration, measure the temperature after the completion of (5).

[0067] Figure 8 shows the measurement results of the oxygen transfer capacity coefficient when water (viscosity: 1 mPa·s) is added in (1) for each Pv, which is the stirring power per unit volume (settable by the rotational speed in (2) above). For all measured Pv values, it was confirmed that the stirring blade 3 according to this embodiment can achieve a significantly larger oxygen transfer capacity coefficient compared to the stirring blade 8 according to the comparative example (it can maintain a high concentration of dissolved oxygen in the culture medium C). As mentioned above, with the stirring blade 3 according to this embodiment, oxygen (culture promoting gas) is taken up from the upper space G into the culture medium C through the large circulation flow of the culture medium C as shown in Figure 1.

[0068] Figure 9 shows the measured oxygen transfer capacity coefficient for each Pv when a high-viscosity aqueous solution (viscosity: 4600 mPa·s) is added in (1). Similar to the case of low-viscosity water in Figure 8, it was confirmed that for all measured Pv values, the stirring blade 3 according to this embodiment can achieve a significantly larger oxygen transfer capacity coefficient compared to the stirring blade 8 according to the comparative example (it can maintain a high concentration of dissolved oxygen in the culture medium C). Here, the difference in oxygen transfer capacity coefficient between the stirring blade 3 according to this embodiment and the stirring blade 8 according to the comparative example was about 6-7 times in Figure 8 for low-viscosity water, while it was about 10-11 times in Figure 9 for high-viscosity aqueous solution. Therefore, it can be said that the stirring blade 3 according to this embodiment is particularly effective for stirring high-viscosity culture medium C (of course, it also has an advantage over the comparative example when stirring low-viscosity culture medium C).

[0069] It is expected that the viscosity of the culture medium C will increase as the culture progresses in the culture apparatus 1. As is clear from comparing Figures 8 and 9 with respect to the stirring blade 3 according to this embodiment, the oxygen transfer capacity coefficient for each Pv value decreases as the viscosity of the culture medium C increases. To compensate for this decrease in the oxygen transfer capacity coefficient due to the increase in the viscosity of the culture medium C, the rotation speed of the stirring blade 3 may be adaptively increased to increase Pv (i.e., increase the oxygen transfer capacity coefficient) as the culture progresses in the culture apparatus 1, that is, according to the progress of the culture. The progress of the culture can be determined based on arbitrary parameters such as the elapsed time since the start of the culture, the cumulative amount of culture medium supplied, the cumulative amount of culture-promoting gas supplied, the viscosity of the culture medium C, and the temperature of the culture medium C, and an appropriate threshold may be set to trigger changes in rotation speed, etc. In addition, the amount of oxygen supplied by the culture-promoting gas supply unit 6 may be increased according to the progress of the culture. In addition to or instead of improving the oxygen transfer capacity coefficient as described above, the amount of culture medium supplied by the culture medium supply unit 5 may be increased, or the temperature of the culture medium C may be changed by the temperature control unit 7, in order to promote the culture itself.

[0070] In the second embodiment, a type of facultative anaerobic bacterium, yeast (Saccharomyces cerevisiae), was cultured using the stirring blade 3 according to the first embodiment shown in Figure 4 and the stirring blade 8 according to the comparative example shown in Figure 7. Specifically, six baffles 4 (arranged at equal intervals of 60° angles around the rotation axis 30) and four stirring blades 3 and 8 (arranged at equal intervals of 90° angles around the rotation axis 30) were installed in a 3L culture tank 2. Air was then released into the culture medium C from a sparger acting as a culture-promoting gas supply unit 6, and fed-batch culture was performed for 5 days while the stirring blades 3 and 8 were rotated at 100-1200 rpm. The amount of air supplied was varied for four conditions: 0.1 VVM, 2 VVM, 3.7 VVM, and 10 VVM. The amount of fed-batch medium supplied was adaptively adjusted according to the measurement results of the amount of glucose remaining in the culture medium C. Furthermore, to assess the progress of the fed-batch culture, culture medium C was periodically sampled, dried, and weighed. The dry cell weight concentration, based on the resulting dry cell weight, was used as an evaluation item.

[0071] Figure 10 shows the results of the second embodiment. It was confirmed that the stirring blade 3 (Figure 4) according to this embodiment achieved significantly superior oxygen transfer capacity coefficient (kLa) and dry cell weight compared to the stirring blade 8 of the comparative example. In particular, the dry cell weight concentration (g / L) per 1 L of cell suspension as culture medium C using the stirring blade 3 according to this embodiment was approximately three times that of the stirring blade 8 of the comparative example, confirming that this embodiment is extremely effective for fed-batch culture of yeast (Saccharomyces cerevisiae). Furthermore, with the stirring blade 3, no change in dry cell weight concentration was observed even when the air supply was increased above 3.7 VVM; this is because the dry cell weight concentration reached the theoretical saturation state. Therefore, in the air supply range of 0.1 to 3.7 VVM, the stirring blade 3 can significantly increase the dry cell weight concentration compared to the stirring blade 8, resulting in better cell growth efficiency. Furthermore, the results from the second embodiment indicate that, at least in the range of air supply up to 20 VVM, the stirring blade 3 can achieve a higher dry cell weight concentration than the stirring blade 8.

[0072] In the third embodiment, Aspergillus Oryzae, a type of aerobic fungus, was cultured using the stirring blade 3 according to the second embodiment shown in Figure 5 and the stirring blade 8 according to the comparative example shown in Figure 7. Specifically, six baffles 4 (arranged at equal intervals of 60° angles around the rotation axis 30) and four stirring blades 3 and 8 (arranged at equal intervals of 90° angles around the rotation axis 30) were installed in a 3L culture tank 2. Air was then released into the culture medium C at approximately 2 VVM from a sparger acting as a culture-promoting gas supply unit 6, the temperature was maintained at approximately 30°C by a temperature control unit 7, and the stirring blades 3 and 8 were rotated at 100-1200 rpm for 5 days while fed-batch culture was performed. The amount of fed-batch medium supplied was adaptively adjusted according to the measurement results of the amount of glucose remaining in the culture medium C. Furthermore, to assess the progress of the fed-batch culture, culture medium C was periodically sampled, dried, and weighed. The dry cell weight concentration, based on the resulting dry cell weight, was used as an evaluation item.

[0073] Figure 11 shows the results of the third embodiment. It was confirmed that the stirring blade 3 (Figure 5) according to this embodiment achieved significantly better oxygen transfer capacity coefficient (kLa) and dry cell weight compared to the stirring blade 8 of the comparative example. In particular, the dry cell weight concentration (g / L) per 1 L of cell suspension as culture medium C using the stirring blade 3 according to this embodiment was approximately twice that of the stirring blade 8 of the comparative example, confirming that this embodiment is extremely effective for fed-batch culture of Aspergillus Oryzae.

[0074] In the fourth embodiment, Monascus purpureus, a type of ascomycete, was cultured using the stirring blade 3 according to the third embodiment shown in Figure 6 and the stirring blade 8 according to the comparative example shown in Figure 7. Specifically, six baffles 4 (arranged at equal intervals of 60° angles around the rotation axis 30) and four stirring blades 3 and 8 (arranged at equal intervals of 90° angles around the rotation axis 30) were installed in a 3L culture tank 2. Air was then released into the culture medium C at approximately 2 VVM from a sparger acting as a culture-promoting gas supply unit 6, and fed-batch culture was performed for 5 days while the stirring blades 3 and 8 were rotated at 100-1200 rpm. The amount of fed-batch culture medium supplied was adaptively adjusted according to the measurement results of the amount of glucose remaining in the culture medium C. In addition, in order to grasp the progress of the fed-batch culture, the culture medium C was periodically sampled, dried, and weighed, and the dry cell weight concentration based on the obtained dry cell weight was used as an evaluation item.

[0075] Figure 12 shows the results of the fourth embodiment. It was confirmed that the stirring blade 3 (Figure 6) according to this embodiment achieved a significantly better dry cell weight compared to the stirring blade 8 in the comparative example. In particular, the dry cell weight concentration (g / L) per 1 L of cell suspension as culture medium C using the stirring blade 3 according to this embodiment was approximately twice that of the stirring blade 8 in the comparative example, confirming that this embodiment is extremely effective for fed-batch culture of Monascus purpureus.

[0076] The present disclosure has been described above based on embodiments. Various modifications are possible for each component and each combination of processes in the exemplary embodiments, and it will be obvious to those skilled in the art that such modifications are included in the scope of the present disclosure.

[0077] The configuration, operation, and function of each device and method described in the embodiments can be realized by hardware resources or software resources, or by the cooperation of hardware resources and software resources. Hardware resources include, for example, processors, ROMs, RAMs, and various integrated circuits. Software resources include, for example, operating systems and application programs. [Explanation of Symbols]

[0078] 1 Culture apparatus, 2 Culture tank, 3 Stirring blade, 4 Baffle, 5 Medium supply unit, 6 Culture-promoting gas supply unit, 7 Temperature control unit, 21 Straight body, 22 Bottom, 30 Rotating shaft, 31 Plate-shaped body, 32 Opening, 33 Paddle unit, 34 Intake unit, 35 Paddle unit, 36 Upper intake unit, 37 Lower intake unit, 321 Inner opening, 322 Outer opening, 323 Upper opening, 324 Lower opening.

Claims

1. A culture tank for containing a culture medium containing a target organism, A culture tank comprising an upper space containing a culture-promoting gas that promotes the cultivation of the target organism, which is formed above the liquid surface of the culture medium, A stirring blade for rotating and stirring the culture medium contained in the culture tank, A plate-shaped body extending in a plate-like manner from the axis of rotation toward the outer circumference of the culture tank, The plate-shaped body comprises at least one opening, A stirring blade that forms a flow of the culture medium, taking in the culture-promoting gas from the upper space into the culture medium, A culture device equipped with the following features.

2. The culture apparatus according to claim 1, wherein a plurality of the stirring blades are arranged symmetrically around the rotation axis.

3. The culture apparatus according to claim 2, wherein in the radial direction perpendicular to the axial direction of the rotation axis, the ratio of the width of the stirring blade to the diameter of the culture tank is between 0.4 and 0.

7.

4. In the culture tank, at least one baffle is provided on the outer circumference side of the stirring blade, Let D be the diameter of the culture tank, d be the width of the baffle, and n be the number of baffles. Ｂ In that case, 0.1≦(d / D) 1.2 n Ｂ ≦0.35 Satisfying the relationship, The culture apparatus according to claim 3.

5. The culture apparatus according to any one of claims 1 to 4, wherein the opening is provided on the plate-shaped body, biased toward the upper side.

6. The culture apparatus according to claim 5, wherein the opening is rectangular in shape, with sides aligned along the axial direction of the rotation axis.

7. The culture apparatus according to claim 6, wherein the opening is provided within a range of 70% from the upper edge of the plate-shaped body, with the height of the plate-shaped body being 100%.

8. The culture apparatus according to claim 7, wherein the ratio H / L of the height H of the stirring blade along the axial direction to the liquid level L of the culture medium in the operating liquid volume is between 0.78 and 0.

98.

9. The culture apparatus according to any one of claims 1 to 4, wherein the rotation of the stirring blade generates an internal flow of the culture material from top to bottom on the side of the rotating shaft, and an external flow of the culture medium from bottom to top on the outer circumference of the culture tank.

10. The culture apparatus according to any one of claims 1 to 4, further comprising a culture promoting gas supply unit for supplying the culture promoting gas below the stirring blade within the culture tank.

11. A rotational drive unit that rotates the aforementioned stirring blade, A rotation drive control unit that controls the rotation drive unit, A measuring unit for measuring the viscosity change of the culture medium, Equipped with, The rotational drive control unit changes the rotational power of the rotational drive unit and the stirring power of the stirring blade in accordance with the change in viscosity of the culture medium measured by the measuring unit. A culture apparatus according to any one of claims 1 to 4.

12. The process involves placing the culture medium containing the target organism into the culture vessel, The culture medium is stirred by rotating a stirring blade, which comprises a plate-shaped body extending outward from the rotating shaft in the culture tank and at least one opening provided in the plate-shaped body, around the rotating shaft. In the culture tank, a culture-promoting gas that promotes the cultivation of the target organism is introduced into the culture medium from the upper space formed above the liquid surface of the culture medium through the rotation of the stirring blade, A method for producing cultures that perform this process.

13. The viscosity of the culture medium changes as the culture progresses. The maximum viscosity of the culture medium reaches between 500 mPa·s and 200,000 mPa·s. A method for producing a culture according to claim 12.

14. The method for producing a culture according to claim 13, wherein the culture target is an aerobic bacterium or a facultative anaerobic bacterium.

15. The method for producing a culture according to claim 13, wherein the stirring power by the stirring blade is changed in accordance with the change in viscosity of the culture medium.

16. The stirring power from the aforementioned impeller is 0.1 kW / m 3 and 50kW / m 3 A method for producing a culture according to claim 15, wherein the culture is varied between the following ranges.

17. A method for producing a culture according to any one of claims 13 to 16, wherein the temperature of the culture medium during stirring by the stirring blade is maintained between 20°C and 55°C.

18. A method for producing a culture according to any one of claims 13 to 16, wherein the culture promoting gas is supplied into the culture medium from a culture promoting gas supply unit located below the stirring blade in the culture tank at a ratio of 0.1 to 20 VVM relative to the volume of the culture tank.

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