Stirring device for microbial mycoprotein high-density fermentation system and application

Abstract

The invention relates to a stirring device for a microbial mycoprotein high-density fermentation system and application, and belongs to the technical field of microbial fermentation. Different from conventional double-layer paddle radial flow stirring in a traditional microbial reactor, the spiral ribbon stirring paddle is designed on the basis of the inclined blade paddle, axial flow can be provided on the basis of radial flow, a uniform three-dimensional mixed flow field is formed, meanwhile, three-dimensional distributed turbulent kinetic energy formed in a bottom dead zone by matching with a bent connecting body can be achieved, and the stirring efficiency is improved. Radial and axial mixing kinetic energy is provided for a bottom dead zone, so that the mixing effect of a mixing flow field is further improved, the overall mixing performance of a bioreactor system is improved, the formation of a mixing dead zone at the bottom of a fermentation tank in a high-density fermentation process is avoided, and thalli are prevented from sinking to the bottom of the tank body; and the bottlenecks of non-uniform material mixing, non-uniform gas distribution and the like of the traditional Rushton blade in the high-density fermentation process of the mycoprotein are improved.

Description

Technical Field

[0001] The invention relates to a stirring device for a microbial protein high-density fermentation system and application thereof, belonging to the technical field of microbial fermentation. Background Art

[0002] With the rapid development of biotechnology, high-density microbial fermentation has been widely used in many industrial fields, especially in the production of microbial protein, biopharmaceuticals, food additives, enzyme preparations and biofuels. As an important biological product, bacterial protein has a wide market demand and huge economic value. The production of microbial protein usually relies on large-scale fermentation processes, especially the use of high-density fermentation technology to improve production efficiency and reduce costs.

[0003] During the high-density fermentation of microorganisms, the concentration of microorganisms in the fermentation tank is usually high, which leads to an increase in the viscosity of the fermentation broth and accelerated oxygen consumption. Oxygen solubility and mass transfer efficiency become one of the key factors affecting the fermentation effect. In addition, the high-density fermentation process often involves feeding operations, which requires a liquid-liquid (nutrient matrix and fermentation broth) mixing effect that is as uniform as possible to achieve efficient growth of the strain. However, the agitator design in traditional fermenters usually cannot meet the special requirements of high-density fermentation for oxygen transfer and material mixing. There are characteristics such as large power consumption of the fermenter agitator paddle, the bacteria sinking to the bottom of the tank, and uneven gas-liquid mixing, which limits the efficient production of bacterial protein.

[0004] In addition, the agitator paddles in the prior art can only form a single radial flow or axial flow. The radial distribution of the turbulent kinetic energy of the blades leads to uneven distribution of the gas content and insufficient liquid-mass mixing. The gas accumulates only at the lower blades and does not form a uniform distribution in the tank. At the same time, a single radial flow field can only form a smaller circulation at different blade positions, and the radial flow agitator paddle will form a mass transfer barrier between the two layers of blades, hindering the mixing of materials. The flow field formed in this way is relatively limited and not three-dimensional enough. In the fermentation equipment, some dead zones that are difficult to act on often appear at the bottom, which will inevitably lead to insufficient mixing in the fermentation system and affect the output effect.

[0005] Therefore, there is an urgent need to design a new type of stirring paddle that can effectively overcome the above problems during high-density microbial fermentation, improve the efficiency of oxygen and material transfer, optimize fermentation conditions, and thereby increase the yield and quality of bacterial protein. Summary of the invention

[0006] In order to solve the above problems, the present invention provides a stirring device for a microbial protein high-density fermentation system, comprising:

[0007] A central stirring shaft, wherein a plurality of pitched blades are connected to the side of the central stirring shaft;

[0008] A hub connected to the bottom of the central stirring shaft;

[0009] Two secondary shafts are located on both sides of the central stirring shaft and are arranged parallel to the central stirring shaft;

[0010] Two spiral ribbon stirring paddles are located on both sides of the central stirring shaft, one end of each spiral ribbon stirring paddle is connected to the top of a secondary shaft, and the other end is connected to the bottom of another secondary shaft;

[0011] Bending connectors, each of which includes a balancing portion connecting the two sides of the hub and a bending portion connecting the balancing portion and the secondary shaft, wherein the bending portion is a V-shaped cylinder with an angle, and the vertex of the angle is arranged downward;

[0012] When the central stirring shaft and the hub are driven to rotate, the pitched-blade paddle, the secondary shaft, the spiral agitator paddle and the bent connector will rotate synchronously around the central stirring shaft and the hub. The radial flow provided by the rotation of the pitched-blade paddle is combined with the axial flow provided by the rotation of the spiral agitator paddle to form a uniform mixed flow field. When the bent connector rotates, a three-dimensionally distributed turbulent kinetic energy will be formed in the dead zone at the bottom of the fermentation system, thereby further strengthening the bottom flow field of the mixed flow field.

[0013] Furthermore, the balancing part is a horizontally arranged cylinder, and a smooth transition surface is provided at a connection between the balancing part and the hub, and at a connection between the balancing part and the bending part.

[0014] Furthermore, the bending portion is a hollow V-shaped cylinder, the bending angle of which is 10° to 80°, and the diameter of the V-shaped cylinder is 1 / 5-1 / 2 of the hub diameter.

[0015] Furthermore, the plurality of pitched-blade paddles are distributed at different height levels of the central stirring shaft, and the pitched-blade paddles at each height level are distributed on the same horizontal plane in a centrally symmetrical manner with the central stirring shaft as the center.

[0016] Furthermore, adjacent pitch-blade propellers at each altitude level are spaced 30° to 120° apart, and each pitch-blade propeller is tilted and has an angle of 30° to 90° with the horizontal plane.

[0017] Furthermore, the spiral ribbon stirring paddle is a spiral-shaped arc-shaped thin plate.

[0018] Furthermore, the twist of the spiral ribbon stirring paddle is 40° to 80°, and the pitch is 40 to 100 mm.

[0019] Furthermore, the central stirring shaft is a hollow cylinder, and the central stirring shaft is installed on the central axis of the fermentation system.

[0020] Furthermore, a plurality of threaded holes are provided on the side of the central stirring shaft.

[0021] The present invention also provides application of the stirring device in a yeast cell protein fermentation system or a fungal cell protein fermentation system.

[0022] Beneficial effects of the present invention:

[0023] Different from the conventional double-layer blade radial flow stirring in traditional microbial reactors, the present invention designs a spiral ribbon stirring paddle based on the inclined blade paddle, which helps to provide axial flow on the basis of radial flow to form a uniform three-dimensional mixing flow field. At the same time, it can also cooperate with the three-dimensional distribution of turbulent kinetic energy formed by the bent connector in the bottom dead zone, that is, provide radial and axial mixing kinetic energy for the bottom dead zone, further enhance the mixing effect of the mixing flow field, improve the overall mixing performance of the bioreactor system, avoid the formation of a mixing dead zone at the bottom of the fermentation tank during high-density fermentation and avoid the bacteria from sinking to the bottom of the tank, and improve the bottlenecks of uneven material mixing and uneven gas distribution of traditional Rushton blades in the high-density fermentation of bacterial protein; further, after the overall mixing performance of the fermentation system is improved, it can effectively promote the ability of microorganisms to utilize substrates and absorb oxygen, so as to help the growth of strains in the high-density fermentation of microbial protein, which not only effectively reduces the production cost, but also has significant effect advantages in the application of high-density fermentation of microbial protein. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a three-dimensional schematic diagram of the overall structure of a stirring device in one embodiment of the present invention.

[0025] Figure 2 It is a front view of the overall structure of the stirring device in one embodiment of the present invention.

[0026] Figure 3 It is a top view of the overall structure of the stirring device in one embodiment of the present invention.

[0027] Figure 4 This is a CFD simulation comparison diagram of the gas holdup distribution of the stirring impeller of the present invention and the traditional bioreactor.

[0028] Figure 5 This is a CFD simulation comparison diagram of the flow field characteristic distribution of the stirring paddle of the present invention and the traditional bioreactor.

[0029] Figure 6 This is a CFD simulation comparison diagram of the turbulent kinetic energy distribution of the stirring paddle of the present invention and the traditional bioreactor.

[0030] Figure 7 It is a line graph comparing the effects of the stirring paddle of the present invention and the traditional bioreactor in bacterial protein production, as well as actual effect photos.

[0031] In the figure, 1, central stirring shaft; 2, inclined blade paddle; 3, secondary shaft; 4, hub; 5, ribbon stirring paddle; 6, bent connector; 61, balancing part; 62, bending part. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] In the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] In the present invention, the "first" and "second" are only used to distinguish similar components / parts with different positions or different characteristics, and have no other limiting meanings; the "upper" refers to the direction of each component away from the ground, and the "lower" refers to the direction of each component away from the ground.

[0035] like Figure 1-Figure 3 As shown, the present invention provides a stirring device for a microbial protein high-density fermentation system, comprising:

[0036] A central stirring shaft 1, wherein the central stirring shaft 1 is a hollow cylinder, and the central stirring shaft 1 is sleeved and installed on the central axis of a fermentation system (e.g., a fermentation tank); a plurality of inclined blade paddles 2 and a plurality of threaded holes are connected to the side of the central stirring shaft 1; the plurality of inclined blade paddles 2 are distributed at different height levels of the central stirring shaft 1, and the inclined blade paddles 2 at each height level are centrally symmetrically distributed on the same horizontal plane with the central stirring shaft 1 as the center; preferably, adjacent inclined blade paddles 2 at each height level are spaced 30° to 120° apart, and each inclined blade paddle 2 is tilted and has an angle of 30° to 90° with the horizontal plane;

[0037] A hub 4 connected to the bottom of the central stirring shaft 1;

[0038] Two secondary shafts 3 are located on both sides of the central stirring shaft 1 and are arranged parallel to the central stirring shaft 1;

[0039] Two spiral stirring paddles 5 are located on both sides of the central stirring shaft 1, one end of each spiral stirring paddle 5 is connected to the top of a secondary shaft, and the other end is connected to the bottom of another secondary shaft 3; the spiral stirring paddle 5 is a spiral arc-shaped thin plate, preferably, the torsion of the spiral stirring paddle 5 is 40° to 80°, and the pitch is 40 to 100 mm; Figure 3 As shown, in a top-down perspective, the two spiral ribbon stirring blades 5 can be combined to form an approximately circular shape;

[0040] The bending connectors 6 each include a balancing portion 61 connecting the two sides of the hub 4 and a bending portion 62 connecting the balancing portion 61 and the secondary shaft 3. The bending portion 62 is a V-shaped cylinder with an angle, and the vertex of the angle is set downward.

[0041] The fermentation system described in the present invention can be a fermentation tank, preferably a cylindrical fermentation tank. Preferably, the height of the central stirring shaft and the two secondary shafts is 1 / 8-8 / 8 of the overall height of the fermentation tank body, and the inner diameter size is determined according to the size of different equipment. The central stirring shaft 1 has a threaded hole on the side, which is convenient for fixing to the fermentation tank body through fasteners and other accessories. Taking a 5L fermentation tank as an example, preferably, the height of the two vertical profiles is 90mm, the height of the central stirring paddle 1 is 70mm, the length of the inclined blade paddle 2 is 15mm, the width is 7mm, and the thickness is 1mm; the diameter of the central stirring paddle 1 is 68mm, and the width of the ribbon stirring paddle 5 is 3.7mm and the thickness is 1mm.

[0042] When the central stirring shaft 1 and the hub 4 are driven to rotate, the pitched blade paddle 2, the secondary shaft 3, the ribbon stirring paddle 5 and the bent connector 6 will rotate synchronously around the central stirring shaft 1 and the hub 4. Since the pitched blade paddle 2 and the ribbon stirring paddle 5 can provide radial and axial kinetic energy respectively, the radial flow provided by the rotation of the pitched blade paddle 2 and the axial flow provided by the rotation of the ribbon stirring paddle 5 are combined to form a uniform mixed flow field; and when the bent connector 6 rotates, a richer three-dimensional distribution of turbulent kinetic energy will be formed in the dead zone at the bottom of the fermentation system, which promotes the uniform mixing of gas and liquid, and can increase the vector velocity of the fluid, which is helpful to further enhance the mixing of the liquid quality at the bottom of the fermentation tank, thereby forming a more three-dimensional enhanced mixing flow field in multiple directions (different from the ordinary flow field formed by the traditional stirring paddle in a single direction), which can overcome the problem of the mixing dead zone at the bottom of the fermentation system during the high-density fermentation of microorganisms and avoid the bacteria from sinking to the bottom of the tank body (this is a common problem in traditional fermentation tanks).

[0043] In addition to being able to form three-dimensionally distributed turbulent kinetic energy, the bent connector 6 itself also has a basic supporting function for the secondary shaft 4 and the spiral ribbon stirring paddle 5. At the same time, it can also share part of the pressure for the hub when the overall stirring device rotates, preventing the hub from being squeezed and deformed due to excessive load, thereby increasing the life of the stirring device.

[0044] Furthermore, the balancing part 61 is a horizontally arranged cylinder, and the connection between the balancing part 61 and the hub 4 and the connection between the balancing part 61 and the bending part 62 are both provided with smooth transition surfaces, which are helpful to reduce the resistance during rotation and are more conducive to forming three-dimensionally distributed turbulent kinetic energy. The bending part 62 is a hollow V-shaped cylinder, preferably, the angle of the bending angle is 10° to 80°, and the diameter of the V-shaped cylinder is 1 / 5-1 / 2 of the hub diameter.

[0045] The stirring device of the present invention can be processed and formed by 3D printing. This technology not only saves materials, optimizes weight reduction, simplifies the manufacturing process, and quickly forms, but also can meet the size requirements of different fermentation tank systems.

[0046] The following are several examples to illustrate the application of the stirring device in a yeast cell protein fermentation system or a fungal cell protein fermentation system.

[0047] Example 1: CFD simulation comparison between the present invention and conventional Rushton impeller

[0048] The high-density fermentation system for microbial protein and the stirring device of the present invention are established in 3D-Paddle (Paddle3D). The flow field characteristics and engineering parameters in the three-dimensional space of the fermentation system can be obtained by CFD method, including velocity field, substance concentration field, shear field, turbulence intensity, power consumption, etc. The results show that when the rotation speed is 400rpm, the stirring device of the present invention can improve the gas dispersion performance. The cross-sectional diagram shows that the gas holdup of the present invention within this range is significantly higher than that of the traditional Rushton stirring paddle (CK), and the oxygen supply conditions are significantly improved ( Figure 4 ).

[0049] The stirring device of the present invention forms a mixed axial flow + radial flow three-dimensional space flow field, and the entire tank body forms a larger circulation. The larger space circulation will be beneficial to the macroscopic mixing of materials, while the traditional Rushton stirring paddle is a typical radial flow field, which can only form a smaller circulation at different blade positions, and the radial flow stirring paddle will form a mass transfer barrier between the two layers of blades, hindering the mixing of materials (such as Figure 5 shown).

[0050] In addition, it can be clearly observed that the turbulent kinetic energy of the Rushton blade is distributed radially, which is the main reason why the impeller causes uneven distribution of gas holdup and insufficient liquid-mass mixing. The structure of the present invention makes the turbulent kinetic energy present a three-dimensional distribution in space, promotes uniform mixing of gas and liquid, and significantly improves the limitations of traditional blades (such as Figure 6 shown).

[0051] Therefore, the stirring device designed in the present invention is a novel stirring blade that can improve the gas content, mixing capacity and other performances of the fermentation system, and is beneficial to the high-density fermentation of microorganisms such as yeast.

[0052] Example 2: Practical application of the present invention in high-density fermentation of microbial protein

[0053] First, Aspergillus oryzae stored at -80℃ was activated on PDA solid culture medium, and then the colonies were picked and cultured in seed culture medium (dextrin 20g / L, peptone 5g / L, yeast powder 1g / L, NaNO3 1g / L, KH2PO4 0.5g / L, MgSO4·7H200.5g / L, FeSO4·7H20 0.01g / L) for 24h.

[0054] Then, 20% of the transfer volume was transferred into a 5-L fermentation tank filled with 3-L fermentation medium (dextrin 60 g / L, yeast powder 3 g / L, corn steep liquor dry powder 6 g / L, K2HPO4 0.98 g / L, KH2PO4 0.75 g / L, MgSO4·7H2O 0.1 g / L, anhydrous CaCl2 0.075, trace element solution 1 mL). The culture medium was cultured at 400 rpm, 30 °C, and 2 vvm with 1 mL / L of trace element solution (FeSO4·7H20 3 g / L, CuSO4·5H2O 0.4 g / L, MnSO4·H2O 1 g / L, H3BO3 1 g / L, Na2MoO4·2H2O 1 g / L, CoCl2·6H2O 0.3 g / L, and ZnSO4·7H2O, fixed to 1 L). Feeding was started after 6 h of cultivation.

[0055] Comparative experiment approach:

[0056] On the one hand, in the 5L fermentation tank (Rushton blade, CK fermentation tank) sold by Dibier Company, Aspergillus oryzae fermentation was carried out. At the end of the fermentation, the mycelium concentration reached 13.0g / L, and its protein content reached 43.8%. The fermentation process required the addition of 206.4g / L of yeast powder (such as Figure 7 AB).

[0057] On the other hand, the same bacterial protein fermentation was carried out in a 5L Dibier fermenter (3D-Paddle, TS fermenter) equipped with a stirring device of the present invention. At the end of the fermentation, the mycelium concentration could reach 18.5 g / L, and the protein content could reach 46.7%. During the fermentation process, 103.36 g / L of yeast powder and 60.96 g / L of (NH4)2SO4 were added. Compared with the CK fermenter, the supplementary organic nitrogen source was reduced by 50% (such as Figure 7 CD).

[0058] In addition, it can be clearly observed during the fermentation process that the TS fermenter has better effects on material mixing and gas distribution.

[0059] As described in the review, based on the characteristics of high-density fermentation process, such as large power consumption of the fermentation tank stirring paddle, the sinking of the bacteria to the bottom of the tank body, and uneven gas-liquid mixing, the present invention creatively combines the inclined blade paddle 2, the spiral ribbon stirring paddle 5, the hub 4, and the bent connector 6, which helps to provide axial flow on the basis of radial flow and provide radial and axial mixing kinetic energy for the liquid-liquid and gas-liquid mixing dead zone at the bottom of the fermentation tank, so that the entire stirring system is more three-dimensional and avoids the mixing dead zone at the bottom of the fermentation tank during high-density fermentation, overcomes the bottlenecks of uneven material mixing and uneven gas distribution of traditional Rushton blades in the high-density fermentation process of bacterial protein, improves the gas content, mixing ability and other properties of the biological reaction system, and realizes the improvement of the high-density fermentation performance of microbial bacterial protein.

[0060] The above embodiments show that the present invention can not only solve the problems described in the background technology such as uneven gas content distribution, insufficient liquid-mass mixing, gas accumulation only at the lower blade, only a small circulation, and the formation of a mass transfer barrier between the two layers of blades that hinders the mixing of materials, but also can solve the problems of oxygen transfer efficiency, nutrient transfer limitations, heat accumulation and heat dissipation in high-density fermentation processes.

[0061] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A stirring device for a high-density fermentation system of microbial protein, characterized in that: include: A central stirring shaft, wherein a plurality of pitched blades are connected to the side of the central stirring shaft; A hub connected to the bottom of the central stirring shaft; Two secondary shafts are located on both sides of the central stirring shaft and are arranged parallel to the central stirring shaft; Two spiral ribbon stirring paddles are located on both sides of the central stirring shaft, one end of each spiral ribbon stirring paddle is connected to the top of a secondary shaft, and the other end is connected to the bottom of another secondary shaft; Bending connectors, each of which includes a balancing portion connecting the two sides of the hub and a bending portion connecting the balancing portion and the secondary shaft, wherein the bending portion is a V-shaped cylinder with an angle, and the vertex of the angle is arranged downward; When the central stirring shaft and the hub are driven to rotate, the pitched-blade paddle, the secondary shaft, the spiral agitator paddle and the bent connector will rotate synchronously around the central stirring shaft and the hub. The radial flow provided by the rotation of the pitched-blade paddle is combined with the axial flow provided by the rotation of the spiral agitator paddle to form a uniform mixed flow field. When the bent connector rotates, a three-dimensionally distributed turbulent kinetic energy will be formed in the dead zone at the bottom of the fermentation system, thereby further strengthening the bottom flow field of the mixed flow field.

2. The stirring device according to claim 1, characterized in that: The balancing part is a horizontally arranged cylinder, and a smooth transition surface is provided at a connection between the balancing part and the hub, and at a connection between the balancing part and the bending part.

3. The stirring device according to claim 2, characterized in that: The bending portion is a hollow V-shaped cylinder, the bending angle of which is 10° to 80°, and the diameter of the V-shaped cylinder is 1 / 5-1 / 2 of the hub diameter.

4. The stirring device according to claim 1, characterized in that: The plurality of pitched-blade paddles are distributed at different height levels of the central stirring shaft, and the pitched-blade paddles at each height level are distributed on the same horizontal plane in a centrally symmetrical manner with the central stirring shaft as the center.

5. The stirring device according to claim 4, characterized in that: The interval between adjacent pitch-blade propellers at each altitude level is 30° to 120°, and each pitch-blade propeller is inclined and the angle with the horizontal plane is 30° to 90°.

6. The stirring device according to claim 1, characterized in that: The spiral ribbon stirring paddle is a spiral arc-shaped thin plate.

7. The stirring device according to claim 6, characterized in that: The torsion of the spiral ribbon stirring paddle is 40° to 80°, and the pitch is 40 to 100 mm.

8. The stirring device according to claim 1, characterized in that: The central stirring shaft is a hollow cylinder, and the central stirring shaft is installed on the central shaft of the fermentation system.

9. The stirring device according to claim 8, characterized in that: A plurality of threaded holes are arranged on the side of the central stirring shaft.

10. Use of the stirring device according to any one of claims 1 to 9 in a yeast cell protein fermentation system or a fungal cell protein fermentation system.

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