Low energy consumption fermentation system and fermentation method

Abstract

The present disclosure provides a low energy consumption fermentation system and a fermentation method. The low energy consumption fermentation system includes a fermentation tank, a feeding tank, an aeration device, a stirring shaft, a fermentation broth feeding tank, at least one adding tank and an automatic control device. The feeding tank is coupled to the fermentation tank. The aeration device is disposed at a bottom of the fermentation tank. The stirring shaft is installed upright in the fermentation tank, and a plurality of stirring blades is disposed on the stirring shaft. The fermentation broth feeding tank is coupled to the fermentation tank. The addition tank is coupled to the fermentation tank. The automatic control device is coupled to the feeding tank, the aeration device, the stirring shaft, the fermentation broth feeding tank, and at least one adding tank.

Description

[Technical Field]

[0001] This disclosure relates to a low-energy fermentation system and a low-energy fermentation method. [Previous Technology]

[0002] The microorganisms used in aerobic fermentation technology are single-celled fungi, such as yeast or other strains suitable for aerobic fermentation. They are relatively easy to grow and harmless, and are widely used in the brewing industry. Yeast can break down macromolecules into smaller molecules that are easily metabolized and utilized by cells, and can also be used in cell culture and genetic engineering research. Related bioculture systems have developed rapidly in recent years and are widely used in various fields, gaining considerable popularity.

[0003] With the increasing market demand for various products, fermentation byproducts, including microbial cells and other related biomass, existing bio-fermentation tanks are being modified and applied. Bio-fermentation tanks use aerobic fermentation as the main process. The aeration equipment used is mainly installed at the bottom of the fermentation tank or in the space below the fermentation tank, so that oxygen or a mixture containing other oxygen can be delivered into the fermentation tank. This allows the yeast or other microbial cells contained in the bio-fermentation tank to perform cellular aerobic respiration. At the same time, the microbubbles generated by the oxygen delivered by the aeration equipment agitate the fluid and enhance the uniformity in the bio-fermentation tank.

[0004] Currently, aerobic fermentation processes require manual replenishment of the culture medium in the bio-fermentation tank at fixed intervals. Without real-time monitoring of the manufacturing process, unnecessary large-molecule proteins or other microbial cells can easily be generated in the bio-fermentation tank, causing contamination. [Summary of the Invention]

[0005] This disclosure provides a low-energy fermentation system, comprising a fermentation tank, a feed tank, an aeration device, a stirring shaft, a fermentation broth feed tank, at least one addition tank, and an automatic control device. The feed tank is coupled to the fermentation tank. The aeration device is disposed at the bottom of the fermentation tank. The stirring shaft is vertically inserted into the fermentation tank, and multiple stirring blades are disposed on the stirring shaft. The fermentation broth feed tank is coupled to the fermentation tank. At least one addition tank is coupled to the fermentation tank. The automatic control device is coupled to the feed tank, the aeration device, the stirring shaft, the fermentation broth feed tank, and at least one addition tank.

[0006] In some embodiments, the low-energy fermentation system further includes at least one sensor disposed on the fermentation tank, and the at least one sensor is coupled to an automatic control device.

[0007] In some embodiments, the low-energy fermentation system further includes an airflow meter coupled with an oxygenation device.

[0008] In some embodiments, the stirring blades on the stirring shaft are used to maintain a tip speed of 0.3 m / s to 5.8 m / s.

[0009] In some embodiments, the stirring blades include three pairs of stirring blades spaced apart on the stirring shaft, each pair of stirring blades being symmetrically arranged on the stirring shaft, with adjacent pairs of stirring blades spaced apart by a distance, the distance being in ratio of 1 / 4 to 1 / 5 to the diameter of the fermentation tank.

[0010] In some embodiments, the fermentation tank has a liquid level, and the ratio of the distance to the liquid level is 1 / 3 to 1 / 6.

[0011] In some embodiments, the oxygenation device includes a plurality of pores, and the diameter of each pore is from 0.5 micrometers to 10 micrometers.

[0012] This disclosure also provides a low-energy fermentation method, which includes the following steps: Aerobic microbial cells are transported to a fermentation tank via the feed trough of the low-energy fermentation system as described above, so that the aerobic microbial cells mix with the culture medium fluid in the fermentation tank. Sterile gas is supplied to the fermentation tank via an aeration device. The aerobic microbial cells, sterile gas, and culture medium fluid in the fermentation tank are stirred by a stirring shaft. The tip speed of each stirring blade on the stirring shaft is maintained at 0.3 m / s to 5.8 m / s.

[0013] In some embodiments, the flow rate of sterile gas supplied to the fermentation tank by the oxygenation device is 0.5 L / min to 5 L / min.

[0014] In some embodiments, supplying sterile gas to the fermentation tank via an oxygenation device includes maintaining the dissolved oxygen level in the fermentation tank at 35% to 45% by an automatic control device.

[0015] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only, and are intended to provide further explanation of the claimed content of this disclosure.

Implementation Method

[0016] Embodiments of the present disclosure will now be described in detail, examples of which are illustrated in the accompanying drawings. Where possible, the same reference numerals are used in the drawings and description to refer to the same or similar parts.

[0017] The following plurality of embodiments are described and disclosed in detail with reference to the accompanying drawings. For clarity, many practical details will be described in the following description. However, it should be understood that these practical details are not intended to limit the scope of this disclosure. That is, these practical details are not essential in some embodiments of this disclosure. In addition, for the sake of simplicity, some known structures and elements will be shown schematically in the drawings.

[0018] As used herein, “about,” “approximately,” “essentially,” or “substantially” includes the value and the average value within an acceptable range of deviations from a particular value as determined by one of ordinary skill in the art, taking into account the measurement in question and a particular number of errors associated with the measurement (i.e., limitations of the measurement system). For example, “about” may mean within one or more standard deviations of the value, or, for example, within ±30%, ±20%, ±15%, ±10%, ±5%. Furthermore, as used herein, “about,” “approximately,” “essentially,” or “substantially” may be used to select a more acceptable range of deviations or standard deviations depending on the nature of the measurement, the coating, or other properties, and may not apply to all properties with a single standard deviation.

[0019] Although the methods disclosed herein are described below using a series of operations or steps, the order in which these operations or steps are shown should not be construed as a limitation of this disclosure. For example, some operations or steps may be performed in a different order and / or simultaneously with other steps. Furthermore, it is not necessary to perform all the illustrated operations, steps, and / or features to achieve the implementation of this disclosure. In addition, each operation or step described herein may include several sub-steps or actions.

[0020] This disclosure provides a low-energy fermentation system for continuous, large-scale aerobic fermentation production of microbial cells. This system avoids unnecessary contamination caused by the production of large molecular proteins or other microbial cells, and compared to traditional fermentation systems, the low-energy fermentation system disclosed herein can save at least 65% of energy. Figure 1 is a schematic diagram of a low-energy fermentation system according to various embodiments of this disclosure. Referring to Figure 1, the low-energy fermentation system 10 includes a fermentation tank 110, a feed tank 120, an oxygenation device 130, a stirring shaft 140, a fermentation broth feed tank 150, at least one addition tank 162, 164, 166, and an automatic control device 170. Specifically, the feed tank 120 is coupled to the fermentation tank 110. The oxygenation device 130 is disposed at the bottom of the fermentation tank 110. The stirring shaft 140 is vertically inserted into the fermentation tank 110, and a plurality of stirring blades 142 are disposed on the stirring shaft 140. Fermentation broth feed tank 150 is coupled to fermentation tank 110. At least one addition tank 162, 164, 166 is coupled to fermentation tank 110. Automatic control device 170 is coupled to feed tank 120, aeration device 130, stirring shaft 140, fermentation broth feed tank 150, and at least one addition tank 162, 164, 166. In some embodiments, automatic control device 170 includes artificial intelligence (AI).

[0021] In some embodiments, the fermentation tank 110 has an internal space, adopts an upright cylindrical structure with a capacity of 5 liters to 1000 liters, and has a diameter D. In some embodiments, the low-energy fermentation system 10 further includes a heat preservation component 210 covering the fermentation tank 110 for temperature control of the fermentation tank 110.

[0022] The feed trough 120 is used to transport aerobic microbial cells to the fermentation tank 110. In some embodiments, a valve 380 may be added between the feed trough 120 and the fermentation tank 110 to control the amount of aerobic microbial cells entering the fermentation tank 110.

[0023] In some embodiments, the aeration device 130 includes an aeration base (not shown) and an aeration disc structure (not shown) above it, wherein the aeration disc structure includes an air chamber formed by a combination of a protective ring (not shown), a multi-layered sintered stacked hollow structure (not shown), and a membrane (not shown) with a plurality of pores. For example, the aeration disc structure is evenly distributed with a plurality of pores, and the average pore diameter of each pore can be from 0.5 µm to 10 µm. An aeration disc structure with an appropriate pore size can be selected according to the gas flow rate. An appropriate pore size and spacing distribution can prevent microbubbles from rapidly agglomerating into larger bubbles, thereby allowing the gas to be evenly distributed in the mixed fluid of aerobic microbial cells and culture medium fluid in the form of microbubbles. Furthermore, the aeration disc structure can provide microbubbles with a size of about 0.5 µm to about 10 µm, so that the mixed fluid in the fermentation tank 110 can be in full contact with the gas. Within the aforementioned aperture size range, the size of the microbubbles can be improved by adjusting the total flow rate and pressure of the introduced gas. Microbubbles can improve the solubility of oxygen. Appropriately sized microbubbles can make the gas evenly distributed in the mixed fluid of aerobic microbial cells and culture medium fluid, thereby increasing the dissolved oxygen content of the mixed fluid and enhancing the uniformity in the fermentation tank 110.

[0024] Furthermore, the dissolved oxygen (DO) in the fermentation tank 110 has a significant impact on microbial growth and product formation. During fermentation, an adequate supply of sterile air is necessary for the microorganisms to multiply and accumulate the required metabolic products. Because during fermentation, as the microorganisms rapidly grow into the logarithmic growth phase, their oxygen consumption increases significantly. If the air supply is stopped at this point, the oxygen in the mixed liquid in the fermentation tank 110 will be quickly depleted by the microorganisms. Generally, oxygen is not easily soluble in water. Under one atmosphere of pressure and 25°C, the concentration of dissolved oxygen in water is approximately 0.25 mg / L. However, under the same conditions, the low-energy fermentation system 10 disclosed herein can significantly increase the concentration of dissolved oxygen in water to 15 mg / L.

[0025] In some embodiments, the low-energy fermentation system 10 further includes an airflow meter 220, a gas filter 230, and a gas compressor 240. Specifically, the airflow meter 220 is coupled to the oxygenation device 130, the gas filter 230 is coupled to the airflow meter 220, and the gas compressor 240 is coupled to the gas filter 230. The airflow meter 220 is used to detect changes in the gas flow direction and continuously measure the flow of substances over a certain period of time. The purpose of the gas filter 230 is to filter bacteria in the gas and remove unwanted or unnecessary excess gas to obtain sterile gas. In some embodiments, a valve 310 may be added between the airflow meter 220 and the oxygenation device 130 to block or open the gas flow, change the flow rate, control the flow direction, regulate the downstream pressure, and release pressure when the system pressure exceeds or falls below a predetermined range.

[0026] In some embodiments, the stirring blades 142 on the stirring shaft 140 include at least one pair of stirring blades 142, and the at least one pair of stirring blades 142 are symmetrically arranged on the stirring shaft 140. In some embodiments, the stirring blades 142 on the stirring shaft 140 include three pairs of stirring blades 142 spaced apart on the stirring shaft 140, each pair of stirring blades 142 being symmetrically arranged on the stirring shaft 140, and adjacent pairs of stirring blades 142 being spaced apart by a distance 143, the ratio of the distance 143 to the diameter D of the fermentation tank 110 being 1 / 4 to 1 / 5, as shown in Figure 1. The number of stirring blades 142 on the stirring shaft 140 can be designed according to the volume of the fermentation tank 110, and this disclosure is not limited thereto. The stirring shaft 140 and multiple stirring blades 142 mounted on it are positioned above the aeration device 130. The rotation of these stirring blades 142 stirs the fluid within the bio-fermentation tank 110, generating eddies. These eddies can cause the microbubbles generated by the aeration device 130 to be evenly distributed in the mixture of aerobic microbial cells and culture medium fluid within the fermentation tank 110. The combination of the stirring shaft 140 and the multiple stirring blades 142 with the aeration device 130 not only enhances uniformity and transport quality but also further increases the dissolved oxygen content within the bio-fermentation tank 110.

[0027] It is worth noting that when this low-energy fermentation system 10 is operating, the stirrers 142 on the stirring shaft 140 are used to maintain a tip speed of 0.3 m / s to 5.8 m / s. It should be noted that the "tip speed" referred to here is the speed of the tip (the end furthest from the stirring shaft 140) of each stirrer 142 when it rotates. When the tip speed of each stirrer 142 is maintained within the above range, the power consumption of the low-energy fermentation system 10 can be significantly reduced.

[0028] The relationship between the distance 143 between adjacent pairs of agitators 142 and the fluid height in the bio-fermentation tank 110 affects the flow pattern and mixing. In some embodiments, the fermentation tank 110 has a liquid level height H, and the ratio of the distance 143 between adjacent pairs of agitators 142 to the liquid level height H is 1 / 3 to 1 / 6. In one embodiment, considering that the volume of the fermentation tank 110 is in the range of minimum (5L) and maximum (500L), it is necessary to maintain good axial flow and sufficient mixing, and the ratio of the distance 143 between adjacent pairs of agitators 142 to the liquid level height H is preferably 1 / 4.

[0029] In some embodiments, a valve 350 and a pump 280 may be added between the fermentation broth feed tank 150 and the fermentation tank 110 to continuously add the nutrients required by the aerobic microbial cells to the fermentation tank 110, so that the nutrients can be automatically supplied to the fermentation tank 110 under predetermined time conditions, thereby promoting the growth and yield of aerobic microbial cells and realizing the automation of continuous feeding.

[0030] For example, the fermentation broth feed tank 150 includes YPG culture medium, YAG culture medium, or a combination thereof. Specifically, the YPG culture medium includes yeast extract, peptone, and glycerol, with a molar ratio of 1:1:1 to 1:2:2. Specifically, the YAG culture medium includes yeast extract, ammonium sulfate, and glycerol, with a molar ratio of 1:1:1 to 1:2:30.

[0031] In some embodiments, the number of addition tanks coupled to the fermentation tank 110 can be multiple. For example, the addition tanks include an antifoaming agent addition tank 162, an acidic solution addition tank 164 and an alkaline solution addition tank 166, which are independently coupled to the fermentation tank 110.

[0032] Furthermore, a valve 320 and a pump 250 can be added between the defoamer addition tank 162 and the fermentation tank 110 to suppress the foam generated by the mixed liquid in the fermentation tank 110.

[0033] Similarly, a valve 330 and a pump 260 can be added between the acid solution addition tank 164 and the fermentation tank 110 to control the acid-base (pH) value of the mixed liquid in the fermentation tank 110.

[0034] Similarly, a valve 340 and a pump 270 can be added between the alkaline solution addition tank 166 and the fermentation tank 110 to control the acid-base (pH) value of the mixed liquid in the fermentation tank 110.

[0035] In some embodiments, the low-energy fermentation system 10 may further include at least one sensor disposed on the fermentation tank 110, and the at least one sensor is coupled to an automatic control device 170. In some embodiments, the number of sensors may be multiple, for example, the sensors include a dissolved oxygen sensor 410, a temperature sensor 420, and a pH sensor 430. These sensors are used to detect whether the mixed solution in the fermentation tank 110 is maintained within a predetermined range.

[0036] As shown in Figure 1, the automatic control device 170 is coupled to the feed tank 120, the oxygenation device 130, the stirring shaft 140, the fermentation broth feed tank 150, the defoamer addition tank 162, the acid solution addition tank 164, and the alkaline solution addition tank 166. More specifically, the automatic control device 170 is electrically connected to pumps 250, 260, 270, and 280, the airflow meter 220, the stirring shaft 140, the dissolved oxygen sensor 410, the temperature sensor 420, and the pH sensor 430.

[0037] Referring again to Figure 1, the low-energy fermentation system 10 may further include a sterilization steam pipe 180 and an exhaust pipe 190, each disposed at the top of the fermentation tank 110. In some embodiments, a valve 360 ​​may be added to the sterilization steam pipe 180 to control whether high-temperature steam can enter the fermentation tank 110 from the sterilization steam pipe 180. In some embodiments, a valve 370 may be added to the exhaust pipe 190 to control whether gas can be discharged from the exhaust pipe 190, and simultaneously control the pressure inside the fermentation tank 110. In some embodiments, the low-energy fermentation system 10 further includes an outlet 290 for discharging a mixed solution of microorganisms and culture medium fluid.

[0038] This disclosure also provides a low-energy fermentation method for continuous large-scale aerobic fermentation production of microbial cells. This method not only reduces the energy consumption of the aforementioned fermentation system but also reduces production costs. Figure 2 is a flowchart of various embodiments of the low-energy fermentation method according to this disclosure. The low-energy fermentation method 50 includes at least steps 510, 520, 530, and 540. Step 510 is a sterilization step. Specifically, referring to Figures 1 and 2, the sterilization step includes introducing high-temperature steam into the fermentation tank 110 for 30 to 60 minutes, wherein the temperature of the high-temperature steam is 110°C to 130°C. More specifically, at one atmosphere of pressure, valve 360 ​​is opened, and high-temperature steam at a temperature of 110°C to 130°C is continuously introduced into the fermentation tank 110 from the sterilization steam pipe 180 for sterilization. After sterilization is completed, valve 370 is opened, and the sterilized high-temperature steam is discharged from fermentation tank 110 through exhaust pipe 190.

[0039] Step 520 involves using the feed tank 120 of the low-energy fermentation system 10 to transport aerobic microbial cells to the fermentation tank 110, so that the aerobic microbial cells are mixed with the culture medium fluid in the fermentation tank.

[0040] Step 530 involves supplying sterile gas to the fermentation tank 110 via the aeration device 130. Specifically, the gas compressor 240 is turned on, and gas (e.g., air) is filtered through the gas filter 230 to obtain sterile gas. The flow rate is then controlled by the automatic control device 170 via the airflow meter 220, thereby continuously supplying sterile gas to the fermentation tank 110. The sterile gas enters the pores on the aeration device 130 at the bottom of the fermentation tank 110 and generates fine, dense microbubbles within the fermentation tank 110. These microbubbles are evenly distributed in the mixed solution of aerobic microbial cells and culture medium fluid to enhance the uniformity within the fermentation tank 110.

[0041] In some embodiments, the flow rate of sterile gas supplied to the fermentation tank 110 via the oxygenation device 130 is 0.5 L / min to 5 L / min. The gas flow rate can be adjusted as needed, and this disclosure is not limited thereto. It should be noted that in this system, the rotation of the gas compressor 240 and the stirring shaft 140 is the main source of energy consumption. Therefore, the higher the required gas flow rate in the fermentation tank 110, the more energy is consumed. Conversely, the lower the gas flow rate used in the fermentation tank 110, the more energy is saved.

[0042] In some embodiments, the aforementioned sterile gas includes oxygen, and the oxygen content accounts for 15% to 25% of the sterile gas content.

[0043] Step 540 involves stirring the aerobic microbial cells, sterile gas, and culture medium fluid within the fermentation tank 110 using the stirring shaft 140, wherein the tip speed of each stirring blade 142 on the stirring shaft 140 is maintained at 0.3 m / s to 5.8 m / s. Specifically, the tip speed of the stirring blades 142 on the stirring shaft 140 is preset to fall within the above range by the automatic control device 170, and then the stirring shaft 140 stirs the fermentation tank 110 to generate eddies. The eddies can drive the microbubbles generated by the oxygenation device 130, distributing them evenly in the mixed solution within the fermentation tank 110, which not only enhances uniformity and transport quality but also increases the dissolved oxygen content within the fermentation tank 110.

[0044] In some embodiments, the dissolved oxygen level in the fermentation tank 110 is maintained at 35% to 45% by the automatic control device 170. For example, when the dissolved oxygen sensor 410, which is electrically connected to the automatic control device 170, detects that the dissolved oxygen level in the fermentation tank 110 is not within the desired range, the automatic control device 170 will control the airflow meter 220 to continue to introduce sterile gas into the fermentation tank 110, thereby automating the control of the dissolved oxygen level in the fermentation tank 110.

[0045] In some embodiments, the pH of the fermentation tank 110 is maintained at 4.5 to 6.0 by the automatic control device 170. For example, when the pH sensor 430, which is electrically connected to the automatic control device 170, detects that the pH in the fermentation tank 110 is not within the desired range, the automatic control device 170 will control the pumps 260 and / or 270 to automatically add acidic or alkaline solutions to the fermentation tank 110, thereby automating the control of the pH in the fermentation tank 110.

[0046] In some embodiments, when the automatic control device 170 detects that foam is generated violently in the fermentation tank 110, the automatic control device 170 will control the pump 250 to automatically add defoamer to the fermentation tank 110 to suppress the foam in the fermentation tank 110, thereby avoiding excessive foam from affecting and potentially contaminating the mixed solution of aerobic microbial cells and culture medium fluid in the fermentation tank 110.

[0047] In some embodiments, step 540 further includes maintaining the temperature of the fermentation tank 110 at 20°C to 40°C. This temperature range is the optimal growth temperature for aerobic microbial cells.

[0048] The following detailed embodiments are provided to enable those skilled in the art to better understand the present disclosure. The provision of detailed embodiments is not intended to limit the scope of the present disclosure to the description of the embodiments.

[0049] In order to compare the power consumption of the conventional fermentation system and the low-energy fermentation system disclosed herein, power consumption data of Examples 1 to 3 and Comparative Examples 1 to 3 in this experimental example will be collected and statistically analyzed.

[0050] In this experimental example, Comparative Examples 1 to 3 used a conventional fermentation system, with its stirring speed controlled at 3.665 m / s (equivalent to 1000 rpm), and continuously produced aerobic microbial cells for 120 hours. Examples 1 to 3 used the low-energy fermentation system disclosed herein, with its stirring speed controlled at 1.099 m / s (equivalent to 300 rpm), and continuously produced aerobic microbial cells for 120 hours. The production hours and power consumption of Comparative Examples 1 to 3 and Examples 1 to 3 are shown in Table 1 below.

[0051] Table 1 Production hours (hours) Electricity consumption (watts) Comparative Example 1 120 6179 Comparative Example 2 120 6495 Comparative Example 3 120 6521 Example 1 120 848 Example 2 120 890 Example 3 120 885

[0052] As can be seen from Table 1 above, the electricity consumption of the traditional fermentation system is at least 7 times that of the low-energy fermentation system disclosed herein. In other words, using the low-energy fermentation system disclosed herein can save at least 7 times the energy consumption.

[0053] In some embodiments, the dry cell weight (DCW) of yeast cells obtained by the low-energy fermentation method 50 is not much different from that of yeast cells obtained by the conventional high-speed stirring fermentation method. The final dry weight of the culture obtained by both methods is 95 g ± 5 g.

[0054] Although this disclosure has been described in considerable detail with reference to certain embodiments, other embodiments may also be possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the embodiments included herein.

[0055] It will be apparent to those skilled in the art that various modifications and changes can be made to the structure of this disclosure without departing from the scope or spirit of this disclosure. In view of the foregoing, this disclosure is intended to cover modifications and changes to this disclosure that fall within the scope of the appended patent applications. [Simplified Explanation of the Diagram]

[0056] This disclosure can be more fully understood by reading the following detailed description of the embodiments and referring to the accompanying drawings. Figure 1 is a schematic diagram of a low-energy fermentation system according to various embodiments of this disclosure. Figure 2 is a flowchart of a low-energy fermentation method according to various embodiments of this disclosure. [Biomaterial Storage]

[0058] Domestic storage information (please note in order of storage institution, date, and number): None. International storage information (please note in order of storage country, institution, date, and number): None.

Claims

1. A low-energy fermentation system, comprising: One fermentation tank; A feed trough is coupled to the fermentation tank; An oxygenation device is installed at the bottom of the fermentation tank; a stirring shaft is vertically installed in the fermentation tank, and multiple stirring blades are installed on the stirring shaft; a fermentation liquid feed trough is coupled to the fermentation tank. At least one addition tank is coupled to the fermentation tank; And an automatic control device coupled to the feed trough, the oxygenation device, the stirring shaft, the fermentation broth feed trough and the at least one addition trough.

2. The low-energy fermentation system as described in claim 1 further includes at least one sensor disposed on the fermentation tank, and the at least one sensor being coupled to the automatic control device.

3. The low-energy fermentation system as described in claim 1 further includes an airflow meter coupled to the aeration device.

4. The low-energy fermentation system as claimed in claim 1, wherein the agitators on the agitator shaft are used to maintain a tip speed of 0.3 m / s to 5.8 m / s.

5. The low-energy fermentation system as claimed in claim 1, wherein the stirring blades comprise three pairs of stirring blades spaced apart on the stirring shaft, each pair of stirring blades being symmetrically arranged on the stirring shaft, adjacent pairs of stirring blades being spaced apart by a distance, and the distance being in proportion to a diameter of the fermentation tank being 1 / 4 to 1 / 5.

6. The low-energy fermentation system as claimed in claim 5, wherein the fermentation tank has a liquid level, and the distance to the liquid level is in a ratio of 1 / 3 to 1 / 6.

7. The low-energy fermentation system as claimed in claim 1, wherein the aeration device includes a plurality of pores, and each pore has a diameter of 0.5 micrometers to 10 micrometers.

8. A low-energy fermentation method, comprising: An aerobic microbial cell is fed into the fermentation tank via the feed trough of the low-energy fermentation system described in any one of claims 1 to 7, such that the aerobic microbial cell is mixed with a culture medium fluid in the fermentation tank; a sterile gas is supplied to the fermentation tank via the aeration device; and the aerobic microbial cell, the sterile gas, and the culture medium fluid in the fermentation tank are stirred by the stirring shaft, wherein the tip speed of each of the stirring blades on the stirring shaft is maintained at 0.3 m / s to 5.8 m / s.

9. The low-energy fermentation method as described in claim 8, wherein the flow rate of the sterile gas supplied to the fermentation tank via the aeration device is from 0.5 L / min to 5 L / min.

10. The low-energy fermentation method as claimed in claim 8, wherein supplying the sterile gas to the fermentation tank via the aeration device includes maintaining a dissolved oxygen level of 35% to 45% in the fermentation tank by means of the automatic control device.

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