Method for increasing dissolved oxygen content of fermentation liquor and application

Abstract

The invention belongs to the technical field of microbial fermentation, and particularly relates to a method for increasing the dissolved oxygen content of fermentation liquor and application. According to the method for increasing the dissolved oxygen content of the fermentation liquor, the mode of supplementing an oxygen-containing raw material to the fermentation liquor is changed for the first time, the oxygen-containing raw material is introduced in a micro-bubble mode to increase the dissolved oxygen content in the fermentation liquor, and the characteristics that the micro-bubbles are low in rising speed, long in standing time, high in dissolving efficiency and large in gas-liquid contact surface in the fermentation liquor are utilized; the method has the characteristics of self-oxygenation, negative charge carrying, rich free radicals with strong oxidizing property and the like, and sufficient dissolved oxygen is provided for the microbial protein fermentation liquor, so that the concentration of mycoprotein in the fermentation liquor is improved, and the technical effects of high yield of microbial protein and energy conservation are finally realized.

Description

Technical Field

[0001] The invention belongs to the technical field of microbial fermentation, and specifically relates to a method for increasing the dissolved oxygen content of a fermentation liquid and its application. Background Art

[0002] Microbial protein is an ideal alternative protein prepared by microbial fermentation. The preparation of microbial protein can greatly improve the efficiency of protein production, reduce carbon emissions in the protein preparation process, and achieve the purpose of protecting the environment. However, in the current fermentation production process of microbial protein, there is a technical problem of high production cost. From a production perspective, one of the main ways to reduce production costs is to increase the weight of mycelium protein per unit volume of fermentation broth, and the weight of mycelium protein per unit volume of fermentation broth is the yield. However, the main factor restricting the yield of microbial protein is that the dissolved oxygen content in the fermentation production process cannot meet the full growth requirements of the protein mycelium, thereby limiting the concentration of the protein mycelium in the fermentation broth.

[0003] In most aerobic fermentations, oxygen supply is usually achieved by passing air into the fermentation liquid. At a certain critical cell concentration, the oxygen supply cannot meet the needs of cell growth, becoming a limiting matrix for cell growth, which in turn leads to low cell density and product concentration. Traditional methods to improve oxygen supply mainly include increasing the stirring rate, increasing the ventilation rate, and increasing the tank pressure. However, due to the low solubility of oxygen and mechanical and operational reasons, its operating range is limited, so conventional methods of increasing the dissolved oxygen in the fermentation liquid, such as increasing the stirring speed and increasing the ventilation volume, cannot meet the dissolved oxygen demand of high-density fermentation of microbial protein. Summary of the invention

[0004] The invention provides a method for increasing the dissolved oxygen content of a fermentation liquid and its application, thereby increasing the dissolved oxygen content and the concentration of bacterial protein in the fermentation liquid.

[0005] In order to solve the above technical problems, the following technical solutions are proposed:

[0006] The present invention provides a method for increasing the dissolved oxygen content of a fermentation liquid, comprising:

[0007] Inoculating microorganisms in a culture medium for fermentation culture, wherein the fermentation culture is at the peak of fermentation, and oxygen-containing raw materials are introduced into the fermentation equipment in the form of microbubbles;

[0008] When the fermentation culture is carried out to the 8th to 15th hour, the fermentation culture begins to enter the fermentation peak period, and the time of the fermentation peak period is from the 8th to 15th hour of the fermentation culture to the end of the fermentation culture.

[0009] Preferably, the oxygen-containing raw material includes a gaseous oxygen-containing raw material and a liquid oxygen-containing raw material; the gaseous oxygen-containing raw material includes one or more of oxygen, oxygen-enriched air and air; the liquid oxygen-containing raw material includes a hydrogen peroxide solution and / or sterilized edible water; the mass concentration of hydrogen peroxide in the hydrogen peroxide solution is 3% to 30%.

[0010] Preferably, the gaseous oxygen-containing raw material is sterilized before preparing microbubbles.

[0011] Preferably, the microbubble introduction rate is 1% to 2.5% / h of the fermentation liquid volume.

[0012] Preferably, the method for preparing the microbubbles comprises:

[0013] The oxygen-containing raw material is subjected to microbubble treatment to obtain microbubbles of the oxygen-containing raw material;

[0014] The microbubble treatment equipment comprises a microbubble generator; the diameter of the microbubbles generated by the microbubble generator is nanometer-level and / or micrometer-level.

[0015] Preferably, the microorganism comprises Fusarium brevicaulis or Fusarium venezuelae.

[0016] Preferably, the fermentation temperature is 27-29° C., and the fermentation time is 23-30 h.

[0017] The present invention provides a microbubble introduction device used in the method described in the above technical solution, comprising a gas raw material chamber, a liquid raw material chamber, a fermentation device, a microbubble device and an air filtration and sterilization system; the fermentation equipment is provided with a microporous distributor; the liquid raw material chamber is connected to the microbubble device; the gas raw material chamber is connected to the air filtration and sterilization system; the air filtration and sterilization system is connected to the microbubble device, and the microbubble device is connected to the fermentation equipment.

[0018] The present invention provides application of the method described in the above technical solution in increasing the yield of microbial protein and / or reducing the ventilation volume of fermentation culture.

[0019] The present invention provides a method for increasing the yield of microbial protein, comprising:

[0020] The microorganisms are inoculated into a culture medium for fermentation culture, and when the fermentation culture is at the peak of fermentation, oxygen-containing raw materials are introduced into the fermentation equipment in the form of microbubbles;

[0021] When the fermentation culture is carried out to the 8th to 15th hour, the fermentation culture begins to enter the fermentation peak period, and the time of the fermentation peak period is from the 8th to 15th hour of the fermentation culture to the end of the fermentation culture.

[0022] Beneficial effects of the present invention: The present invention provides a method for increasing the dissolved oxygen content of a fermentation liquid. The present invention is the first to change the way in which the fermentation liquid is supplemented with oxygen-containing raw materials, and introduce the oxygen-containing raw materials in the form of microbubbles to increase the dissolved oxygen content in the fermentation liquid. The microbubbles have the characteristics of slow rising speed, long residence time, high dissolution efficiency, large gas-liquid contact surface, self-oxygenation, negative charge, and rich in strong oxidizing free radicals in the fermentation liquid, so as to provide sufficient dissolved oxygen for the microbial protein fermentation liquid, thereby increasing the concentration of bacterial protein in the fermentation liquid, and finally achieving the technical effect of high yield of microbial protein, reducing the ventilation volume and the rotation speed during the fermentation process, and also having the technical effect of energy saving. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Flow chart for introducing microbubbles into the fermentation tank;

[0024] Figure 2 This is a schematic diagram of the structure of a device for introducing microbubbles into a fermentation tank. DETAILED DESCRIPTION

[0025] The present invention provides a method for increasing the dissolved oxygen content of a fermentation liquid, comprising:

[0026] Inoculating microorganisms in a culture medium for fermentation culture, wherein the fermentation culture is at the peak of fermentation, and oxygen-containing raw materials are introduced into the fermentation equipment in the form of microbubbles;

[0027] When the fermentation culture is carried out to the 8th to 15th hour, the fermentation culture begins to enter the fermentation peak period, and the time of the fermentation peak period is from the 8th to 15th hour of the fermentation culture to the end of the fermentation culture.

[0028] The present invention inoculates the microorganism in a culture medium for fermentation culture. The present invention does not specifically limit the type and source of the microorganism, as long as the microorganism can grow and reproduce under aerobic conditions to produce microbial protein. As an embodiment, the microorganism may include Fusarium brevicaulis and / or Fusarium veneziae. In a specific embodiment of the present invention, the Fusarium brevicaulis may be Fusarium brevicaulis FXFB001, and the deposit number of Fusarium brevicaulis FXFB001 is CGMCC No.41066; the Fusarium veneziae may be Fusarium veneziae A3 / 5. As an embodiment, the microorganism of the present invention is first activated and cultured to obtain a single colony; the single colony is seed cultured to obtain a seed liquid; the seed liquid is inoculated into a fermentation medium for fermentation culture to obtain bacterial protein. The present invention does not specifically limit the parameters of the activation culture and seed culture, and conventional methods can be used. As an embodiment, the temperature of the fermentation culture of the present invention may be 27-29°C, and in a specific embodiment of the present invention, the temperature of the fermentation culture may be 27°C, 28°C or 29°C. The fermentation culture time can be 26 to 30 hours. In a specific embodiment of the present invention, the fermentation culture time can be 26, 27, 28, 29 or 30 hours. The fermentation culture of the present invention can include an initial fermentation period and a peak fermentation period; the initial fermentation period is from the start of fermentation to the 8th to 15th hour, and the peak fermentation period is from the 8th to 15th hour to the end of fermentation. For example, in a specific embodiment of the present invention, the initial fermentation period may be from the start of fermentation to the 12th hour (excluding the 12th hour), and the peak fermentation period may be from the 12th hour to the 26th hour of the fermentation culture; or, in a specific embodiment of the present invention, the initial fermentation period may be from the start of fermentation to the 13th hour (excluding the 13th hour), and the peak fermentation period may be from the 13th hour to the 30th hour of the fermentation culture; or, in a specific embodiment of the present invention, the initial fermentation period may be from the start of fermentation to the 10th hour (excluding the 10th hour), and the peak fermentation period may be from the 10th hour to the 29th hour of the fermentation culture; in a specific embodiment of the present invention, the initial fermentation period may be from the start of fermentation to the 14th hour (excluding the 14th hour), and the peak fermentation period may be from the 14th hour to the 29th hour of the fermentation culture.

[0029] As an embodiment, air can be introduced in the initial stage of fermentation of the present invention. The present invention has no special restrictions on the ventilation volume of the air and the tank pressure of the fermentation equipment, as long as the needs of microorganisms are met. The fermentation equipment of the present invention can be a fermentation tank. In the initial stage of fermentation, the ratio of the volume of fermentation liquid in the fermentation tank of the present invention to the ventilation volume per minute is 1: (0.5-0.6). For example, in the present invention, a fermentation tank with a volume of 50L, a volume of fermentation liquid of 30L, an air ventilation volume per minute of 15-18L, and an air ventilation volume per hour of 900-1080L. In a specific embodiment of the present invention, a fermentation tank with a volume of 50L, a volume of fermentation liquid of 30L, and an air ventilation volume of 1000L per hour. The tank pressure of the fermentation equipment in the initial stage of fermentation of the present invention can be 0.05MPa.

[0030] As the fermentation of the present invention proceeds, the microbial mycelium continues to grow and will enter the peak fermentation period from the initial fermentation period. After entering the peak fermentation period, the oxygen consumption gradually increases, glucose is continuously consumed, and the dissolved oxygen content in the fermentation liquid gradually decreases from the initial 100%. When entering the peak fermentation period and the dissolved oxygen content in the fermentation liquid is ≤30%, the present invention introduces the oxygen-containing raw material into the fermentation equipment in the form of microbubbles and simultaneously introduces air to supplement the oxygen content in the fermentation liquid; the oxygen content in the fermentation liquid during the peak fermentation period is 30% to 35%. During the peak fermentation period, when air is introduced, the ratio of the volume of the fermentation liquid in the fermenter of the present invention to the ventilation volume per minute is 1: (0.5 to 0.8), or can be 1: (0.55 to 0.73); during the peak fermentation period, when microbubbles are introduced, the introduction flow rate of the microbubbles is 1% to 2.5% / h of the volume of the fermentation liquid.

[0031] For example, in a specific embodiment of the present invention, the volume of the fermentation liquid is 30L, and the microbubble liquid is introduced at a rate of 1.7% / h of the volume of the fermentation liquid and air is introduced at the same time (i.e., ventilation); when air is introduced, the ventilation volume before feeding at the peak of fermentation is 1000L / h, and the ventilation volume is adjusted to 1200L / h after feeding, that is, the ratio of the volume of the fermentation liquid to the ventilation volume per minute is 1: (0.56-0.67); in a specific embodiment of the present invention, the volume of the fermentation liquid is 30L, and the microbubble liquid is introduced at a rate of 1% / h of the volume of the fermentation liquid and air is introduced at the same time (i.e., ventilation); when air is introduced, the ventilation volume before feeding at the peak of fermentation is 1000L / h, and the ventilation volume is adjusted to 1300L / h after feeding, and the ratio of the volume of the fermentation liquid to the ventilation volume per minute is 1: (0.56-0.67). 72); in a specific embodiment of the present invention, the volume of the fermentation liquid is 30L, and microbubble liquid is introduced at a rate of 2.3% / h of the volume of the fermentation liquid and air is introduced at the same time (i.e., ventilation); when air is introduced, the ventilation volume before feeding at the peak of fermentation is 1000L / h, and the ventilation volume is adjusted to 1000L / h after feeding, that is, the ratio of the volume of the fermentation liquid to the ventilation volume per minute is 1:0.56; in a specific embodiment of the present invention, the volume of the fermentation liquid is 30L, and microbubble liquid is introduced at a rate of 1.3% / h of the volume of the fermentation liquid and air is introduced at the same time (i.e., ventilation); when air is introduced, the ventilation volume before feeding at the peak of fermentation is 1000L / h, and the ventilation volume is adjusted to 1200L / h after feeding, that is, the ratio of the volume of the fermentation liquid to the ventilation volume per minute is 1:(0.56~0.67).

[0032] The present invention utilizes the automatic control system on the fermentation equipment to realize the interlocking control of the dissolved oxygen and microbubble feed amount, controls the oxygen content in the fermentation liquid to be ≥30% to 35%, and ensures that the bacteria in the fermentation liquid grow in the optimal dissolved oxygen environment. During the peak fermentation period of the present invention, when the ventilation volume and stirring conditions reach more than 50% of the maximum parameters and the dissolved oxygen content in the fermentation liquid is still lower than the process requirements, the oxygen-containing raw material is introduced into the fermentation tank in the form of microbubbles to increase the dissolved oxygen in the fermentation liquid, remove the dissolved oxygen restriction of the fermentation liquid, provide a favorable dissolved oxygen environment for the growth of microbial protein, increase the mycelial protein concentration, and thus increase the weight of mycelial protein per unit volume of fermentation liquid.

[0033] As an embodiment, the oxygen-containing raw material of the present invention may include a gaseous oxygen-containing raw material and a liquid oxygen-containing raw material. The gaseous oxygen-containing raw material of the present invention includes one or more of oxygen, oxygen-enriched air and air; the gaseous oxygen-containing raw material may be sterilized before preparing microbubbles. The present invention does not specifically limit the sterilization method, and a conventional method may be used. In a specific embodiment of the present invention, the sterilization may be performed using an air filtration sterilization system, which is a sterilization system commonly used in the fermentation industry. The air filtration sterilization system is composed of an oil-water filter, an air prefilter and an air fine filter; the gaseous oxygen-containing raw material is sterilized by passing through an oil-water filter, an air prefilter and an air fine filter in sequence. As an embodiment, the oxygen-enriched air of the present invention may be air with an oxygen concentration of ≥21% and <100%. The oxygen is industrial grade or medical grade. As an embodiment, the liquid oxygen-containing raw material of the present invention may include a hydrogen peroxide solution and / or sterilized edible water. The mass concentration of hydrogen peroxide in the hydrogen peroxide solution of the present invention can be 3% to 30%, or 3% to 10%; in a specific embodiment of the present invention, the mass concentration of hydrogen peroxide in the hydrogen peroxide solution can be 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%. The hydrogen peroxide solution with a mass concentration of more than 3% itself has a disinfecting effect, and the hydrogen peroxide solution does not need to undergo a sterilization process and can be prepared at room temperature. The present invention uses a hydrogen peroxide solution with a mass concentration of more than 3% as a liquid source for the microbubble device, which can sterilize the microbubble device to avoid bacterial contamination of the fermentation liquid, and can also be decomposed into oxygen and water in the fermentation liquid to provide oxygen for the fermentation liquid again. The method for preparing the hydrogen peroxide solution of the present invention is: mixing commercially available hydrogen peroxide and water. The water of the present invention can be edible water or deionized water. The commercially available hydrogen peroxide is food grade or pharmaceutical grade or analytical grade. The mass concentration of hydrogen peroxide in the commercially available hydrogen peroxide can be 30% or 50%. The sterilized edible water described in the present invention can be sterilized tap water or deionized water; the present invention does not specifically limit the sterilization method, and a conventional method can be used. In a specific embodiment of the present invention, the sterilization method can be heating sterilization. The gaseous oxygen-containing raw material and the liquid oxygen-containing raw material described in the present invention can be used alone to pass into the fermentation equipment in the form of microbubbles, or can be used in combination to pass into the fermentation equipment in the form of microbubbles. In a specific embodiment of the present invention, the present invention uses the oxygen and hydrogen peroxide solution in combination, and both the oxygen and the hydrogen peroxide solution are passed into the microbubble equipment to prepare the microbubble liquid, and then passed into the fermentation equipment. The introduction of air in the form of microbubbles reduces the amount of air introduced, which has the technical effect of energy saving.

[0034] As an embodiment, the present invention introduces oxygen-containing raw materials into fermentation equipment in the form of microbubbles. The microbubbles of the present invention are prepared by a microbubble device. The present invention does not specifically limit the model and source of the microbubble device, as long as the microbubble generator can produce microbubbles with a diameter of nanometer or micrometer. The diameter of the microbubbles used in the present invention is micrometer and nanometer, and the bubbles are very small, and there is no need to mechanically stir and break the bubbles, which can save stirring power to a large extent. And because the microbubbles rise slowly in the fermentation liquid, have a long residence time, high dissolution efficiency, and a large gas-liquid contact surface, and have the characteristics of self-oxygenation, negative charge, and rich in strong oxidizing free radicals, sufficient dissolved oxygen is provided for the microbial protein fermentation liquid, and the improvement of oxygen utilization can reduce ventilation and save electricity. Therefore, whether in terms of oxygen utilization or cost, the present invention has obvious advantages in the form of microbubbles. In a specific embodiment of the present invention, the microbubble generator is an NBQ microbubble generator, and the manufacturer is Shandong Weijing Chemical Technology Co., Ltd. The flow rate of the microbubbles of the present invention can be 1% to 2.5% of the volume of the fermentation liquid / h; in a specific embodiment of the present invention, the flow rate of the microbubbles can be 0.3, 0.4, 0.5, 0.6 or 0.7L / h. The present invention connects the discharge pipe of the microbubble device to the bottom of the fermentation tank, and the generated microbubbles are passed into the fermentation tank after passing through the microporous distributor inside the fermentation tank. The gas supply mode in the fermentation culture is changed by the combination of the microporous distributor and the microbubble device, which can fully, directly, quickly and efficiently supplement the dissolved oxygen of the fermentation liquid, reduce the ventilation volume, the speed and energy consumption of the motor, reduce the power consumption of the motor, and improve the utilization rate of the equipment. In a specific embodiment of the present invention, the maximum load of the stirring motor is reached when the maximum speed of the fermentation tank with a volume of 50L is 750rpm, and when the speed in the embodiment of the present invention is 340-400rpm, the dissolved oxygen demand of microbial fermentation can be met, which is only 45.3% to 53.3% of the maximum speed of 750rpm. The low speed setting can achieve the technical effect of reducing energy consumption, protecting the motor, and reducing the power consumption of the motor. In the embodiment of the present invention, the maximum ventilation volume of the fermentation tank with a volume of 50L is 2500L / h, while the maximum ventilation volume in the embodiment of the present invention is 1000L / h to 1300L / h, which is only 40% to 52% of the maximum ventilation volume, saving a large amount of air consumption, and having the technical effect of energy saving.

[0035] The technical solution of the present invention can utilize the fermentation equipment to detect the dissolved oxygen content in the fermentation liquid in real time online, thereby realizing the interlocking control of the dissolved oxygen content and the feed amount of microbubbles, ensuring that the bacteria in the fermentation liquid grow in the optimal dissolved oxygen environment, and reducing the raw material consumption and the power consumption of the microbubble equipment. In a specific embodiment of the present invention, the dissolved oxygen electrode in the fermentation tank can detect the dissolved oxygen content in the fermentation liquid online.

[0036] As the peak of fermentation progresses, glucose in the fermentation broth is continuously consumed. When the glucose content of the fermentation broth during the peak of fermentation of the present invention is ≤5g / L, the feed liquid is added for feeding. The ingredients of the feed liquid include glucose and complex vitamins; the glucose concentration in the feed liquid can be 300g / L; the concentration of complex vitamins in the feed liquid can be 0.1mg / L. The preparation method of the complex vitamin of the present invention comprises: mixing vitamin B1, vitamin B12, vitamin B2, vitamin B3, vitamin B5, vitamin B6, vitamin B9, vitamin C and vitamin H / D-biotin in a mass ratio. The present invention has no special restrictions on the parameters of the mixing, as long as the mixing is uniform. The flow rate of the feed liquid of the present invention is to supplement 0.4-0.6mL of feed liquid per liter of fermentation broth per hour. In a specific embodiment of the present invention, the flow rate of the feed liquid is 0.4mL of feed liquid, 0.5mL of feed liquid or 0.6mL of feed liquid per liter of fermentation broth per hour. The glucose content in the fermentation broth after feeding can be 2-5 g / L. In a specific embodiment of the present invention, the glucose content in the fermentation broth after feeding can be 2, 3, 4 or 5 g / L. The feeding solution of the present invention can be added until the fermentation culture is completed.

[0037] like Figure 2 As shown, the present invention provides a microbubble introduction device used in the method described in the above technical solution, comprising a gas raw material chamber 4, a liquid raw material chamber 5, a fermentation device 1, a microbubble device 2 and an air filtration and sterilization system 3; the fermentation device 1 is provided with a microporous distributor; as an optional embodiment, the gas raw material chamber 4 comprises a gas oxygen-containing raw material storage tank; the liquid raw material chamber 5 comprises a liquid oxygen-containing raw material storage tank; the fermentation device 1 may comprise a fermentation tank. The air filtration and sterilization system 3 comprises an oil-water separator, an air pre-filter and an air fine filter. As an optional embodiment, the 5 liquid oxygen-containing raw material storage tanks of the present invention are connected to the 2 microbubble devices; the gas oxygen-containing raw material storage tanks are connected to the oil-water separator, the oil-water separator is connected to the air pre-filter, the air pre-filter is connected to the air fine filter; the air fine filter is connected to the microbubble device; the gas raw material in the oxygen-rich gas storage tank is sterilized in turn through the oil-water separator, the air pre-filter and the air fine filter, and the sterilized gas raw material enters the microbubble device. In the present invention, the liquid oxygen-containing raw material and the sterilized gaseous oxygen-containing raw material are simultaneously introduced into the microbubble device, the liquid raw material and the gaseous raw material are prepared into a microbubble liquid, and then the microbubble device is connected to the fermentation device, and the microbubbles generated by the microbubble device are introduced into the fermentation device after passing through the microporous distributor provided in the fermentation device.

[0038] The present invention provides the application of the method described in the above technical solution in increasing the yield of microbial protein and / or reducing the ventilation volume of fermentation culture. The results of the embodiments of the present invention show that the application of the method of the present invention can significantly increase the yield of microbial protein and reduce the air ventilation volume.

[0039] The present invention provides a method for increasing the yield of microbial protein, comprising:

[0040] The microorganisms are inoculated into a culture medium for fermentation culture, and when the fermentation culture is at the peak of fermentation, oxygen-containing raw materials are introduced into the fermentation equipment in the form of microbubbles;

[0041] When the fermentation culture is carried out to the 8th to 15th hour, the fermentation culture begins to enter the fermentation peak period, and the time of the fermentation peak period is from the 8th to 15th hour of the fermentation culture to the end of the fermentation culture.

[0042] The types of microorganisms, fermentation culture time and temperature, parameters of the peak fermentation period, and parameters of microbubbles of the present invention have been discussed above and will not be repeated here.

[0043] In most aerobic fermentations in the prior art, oxygen supply is usually achieved by passing air through the fermentation liquid. At a certain critical cell concentration, the oxygen supply cannot meet the needs of cell growth, becoming a limiting matrix for cell growth, which leads to low cell density and product concentration. The traditional method of improving oxygen supply mainly increases the stirring rate, increases the ventilation rate, increases the tank pressure, etc., consumes a lot of electricity and has a high cost. However, due to the low solubility of oxygen and mechanical and operational reasons, its operating range is limited, so the conventional method of increasing the dissolved oxygen in the fermentation liquid, such as increasing the stirring rate, increasing the ventilation volume, etc., cannot meet the dissolved oxygen demand of microbial protein. In addition, it has been reported in the prior art that the method of passing oxygen or the method of adding hydrogen peroxide solution is used to increase the dissolved oxygen in the fermentation liquid. However, these two methods have a low utilization rate of oxygen, a limited degree of improving the dissolved oxygen in the fermentation liquid, and a high cost, and have not been widely promoted and used in the fermentation industry so far.

[0044] The present invention changes the way in which the fermentation liquid is supplemented with oxygen-containing raw materials, uses oxygen-containing raw materials to prepare microbubbles, and changes the gas supply mode of the oxygen-containing raw materials through a microporous distributor and a microbubble device at the same time, and uses the advantages of large oxygen content of the oxygen-containing raw materials, slow rising speed of microbubbles in water, long residence time, high dissolution efficiency, large gas-liquid contact surface, self-oxygenation, negative charge, and rich in strong oxidizing free radicals to provide sufficient dissolved oxygen for microbial protein fermentation liquid. After the microbubbles are introduced, the present invention uses the dissolved oxygen electrode in the fermentation tank to detect the dissolved oxygen content in the fermentation liquid online and the feed amount of the microbubbles to achieve interlocking control, ensuring that the bacteria in the fermentation liquid grow in the optimal dissolved oxygen environment.

[0045] In order to further illustrate the present invention, the technical solution provided by the present invention is described in detail below in conjunction with the accompanying drawings and embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0046] 1. The culture medium used in Examples 1 to 3 and Comparative Examples 1 to 2 is composed as follows:

[0047] a. The activation medium components are: 30g glucose, 25g yeast extract powder, 1g potassium dihydrogen phosphate, 0.2g magnesium sulfate heptahydrate and 0.01g calcium chloride, 20g agar, add water to 1000mL, pH is 5.5-6.1, and sterilize at 121℃ for 30min.

[0048] b. The components of the seed culture medium are: 30 g glucose, 25 g yeast extract powder, 1 g potassium dihydrogen phosphate, 0.2 g magnesium sulfate heptahydrate and 0.01 g calcium chloride. Add water to 1000 mL, pH 5.5-6.1, and sterilize at 121°C for 30 min.

[0049] c. The fermentation medium components are: glucose 25g / L, citric acid 1g / L, potassium dihydrogen phosphate 1g / L, ammonium sulfate 5g / L, magnesium sulfate heptahydrate 0.2g / L, calcium chloride 0.01g / L, manganese sulfate monohydrate 1.7mg / L, ferrous sulfate heptahydrate 5mg / L, zinc chloride 1.7mg / L, cobalt chloride 2mg / L and multivitamin 0.1mg / L. Prepare 27L in total, pH 5.5-6.1, sterilize at 121℃ for 30min.

[0050] The multivitamin consists of the following components in equal mass ratios: vitamin B1, vitamin B12, vitamin B2, vitamin B3, vitamin B5, vitamin B6, vitamin B9, vitamin C and vitamin H / D-biotin.

[0051] 2. The feeding solution consists of glucose and multivitamins. The concentration of glucose in the feeding solution is 300 g / L, and the concentration of multivitamins in the feeding solution is 0.1 mg / L.

[0052] 3. The strain used in Examples 1 to 3 and Comparative Examples 1 to 2 is Fusarium brevicaulis FXFB001, the preservation number of Fusarium brevicaulis FXFB001 is CGMCC No.41066, which has been deposited in the General Microbiological Center of the China National Microbiological Culture Collection Administration, see Chinese patent document CN202410044012.8-Application of Fusarium brevicaulis in the production of mycelial protein.

[0053] The strain used in Example 4 is Fusarium venenatum A 3 / 5 strain, Fusarium venenatum A 3 / 5, numbered IMI 145425, ATCC 20334.

[0054] 4. Equipment used in the following examples and comparative examples

[0055] The microbubble equipment is: NBQ microbubble generator (pilot model), produced by Shandong Weijing Chemical Technology Co., Ltd.;

[0056] The air pre-filter and air fine filter are manufactured by Shanghai Filter Co., Ltd., and their models are GS-B2-1 and GS-PTFE-05 respectively;

[0057] Oil-water filter model MJF, manufacturer: Xinxiang Matt Filtration Equipment Co., Ltd.;

[0058] The hydrogen peroxide solution was 30% hydrogen peroxide solution from Sinopharm Group, analytical grade;

[0059] Oxygen-enriched gas is industrial oxygen produced by local enterprises;

[0060] The fermentation tank is a 50L general fermentation tank, produced by Shanghai Guoqiang Biochemical Engineering Equipment Co., Ltd.

[0061] 5. The detection methods of mycelial protein biomass and mycelial yield in the following examples and comparative examples are as follows:

[0062] The inactivated fermentation liquid is cooled to below 40°C, and a volume of y L is measured and filtered using a plate and frame filter with a filter cloth of 800 mesh and a filtration pressure of 0.4 MPa to obtain x kg of mycelium protein. Then the mycelium protein biomass = x / y×100%.

[0063] The detection methods of the bacterial yields in the following examples and comparative examples are as follows:

[0064] The mycelial protein x (kg) obtained by plate and frame filtration, the total amount of glucose a (kg) reserved is weighed, and the remaining glucose b (kg) not used is subtracted, then the mycelial yield = x / (ab) × 100%.

[0065] 6. The steps of adding hydrogen peroxide solution in the following examples and comparative examples are as follows:

[0066] Oxygen is used as the gas source and hydrogen peroxide solution is used as the liquid source;

[0067] The oxygen is sterilized through a filtration system including an oil-water filter, an air pre-filter and an air fine filter and then connected to the microbubble device; the hydrogen peroxide solution is stored in a storage tank connected to the hydrogen peroxide solution, and the hydrogen peroxide solution storage tank is connected to the microbubble device.

[0068] After the hydrogen peroxide solution and oxygen are prepared into microbubbles by the microbubble device, the discharge hose of the microbubble device is connected to the bottom of the fermentation tank and introduced into the fermentation tank through the microporous distributor at the bottom of the fermentation tank. Figure 1 The schematic diagram of the structure of the device for introducing microbubbles into the fermentation tank is shown in Figure 2 .

[0069] When the fermentation cycle of the microbial protein bacteria starts from 10 to 14 hours and ends at the end of fermentation (about 30 hours), the fermentation culture is at its peak and the dissolved oxygen content in the fermentation liquid is lower than the process requirement, oxygen and hydrogen peroxide solution are introduced into the fermentation tank in the form of microbubbles. The automatic control system on the device achieves interlocking control through the online detection results of the dissolved oxygen electrode and the feed amount of oxygen and hydrogen peroxide, and adjusts the flow rate of the microbubble liquid entering the fermentation tank to ensure that the bacteria in the fermentation liquid grow in the optimal dissolved oxygen environment.

[0070] Example 1

[0071] 1. Activate strains and prepare seed solution

[0072] The low-temperature frozen Fusarium brevicaulis FXFB001 was inoculated into the slant activation medium for activation and cultured at 28°C for 30 hours. The activated Fusarium brevicaulis FXFB001 was selected and inoculated into a 250mL three-concave conical flask containing 50mL seed culture medium, and cultured at 28°C and 200rpm for 24 hours to obtain the seed liquid of Fusarium brevicaulis FXFB001.

[0073] 2. Fermentation

[0074] The seed liquid obtained in the previous step was inoculated into a 50L fermentation tank at an inoculation rate of 5% of the culture medium volume. The fermentation medium in the fermentation tank was 30L (27L prepared fermentation medium + condensed water produced by 3L steam sterilized culture medium). The fermentation temperature was 28°C. During the fermentation process, ammonia water was added to control the pH of the fermentation system to 6.0.

[0075] The fermentation culture of Fusarium brevis FXFB001 consists of the initial fermentation period and the peak fermentation period. The initial fermentation period of this batch is 0 to 12 hours of the fermentation culture (excluding the 12th hour). 。 The ventilation volume at the initial stage of fermentation is 1000L / h, and the tank pressure is 0.05MPa. In the initial stage of fermentation, since the glucose content in the fermentation liquid is greater than 5%, no liquid replenishment is required. As the mycelium grows, the oxygen consumption at the initial stage of fermentation gradually increases, and the dissolved oxygen gradually decreases from the initial 100% to 30%.

[0076] As the mycelium of Fusarium brevis FXFB001 grows, the fermentation enters the peak period from the initial stage of fermentation. The peak period of fermentation in this embodiment is from the 12th hour of fermentation (including the 12th hour) to the end of the fermentation culture.

[0077] During the peak period of fermentation, feed and set the speed to couple dissolved oxygen. The specific feeding is: when the glucose content in the fermentation liquid is ≤5g / L, start adding feed liquid at a rate of 0.5mL / L / h for feeding. 0.5mL / L / h means 0.5mL per liter of fermentation liquid per hour (the same below), and the tank pressure is 0.05MPa. After feeding, the glucose content in the fermentation liquid is controlled to be 2-5g / L, and feeding is carried out until the end of fermentation. The fermentation culture is 26h in total.

[0078] When the fermentation peak period comes, the speed coupling dissolved oxygen is set immediately, the speed does not exceed 375rpm (50% of the maximum parameter of the speed; the maximum parameter of the speed is 750rpm, the same below), and the dissolved oxygen content is 30%. After the dissolved oxygen is less than 30%, microbubble liquid is introduced at the same time as the air, the tank pressure is 0.05MPa, the amount of air introduced is 1000L / h before feeding at the peak of fermentation, and the ventilation volume is adjusted to 1200L / h after feeding (48% of the maximum parameter of ventilation volume; the maximum parameter of ventilation volume is 2500L / h, the same below); microbubble liquid is introduced at a rate of 1.7% / h of the volume of the fermentation liquid, and the dissolved oxygen content during the peak of fermentation is controlled to be greater than or equal to 30%. The microbubble liquid is prepared from industrial oxygen and a hydrogen peroxide solution with a concentration of 5%. After the fermentation culture is completed, the fermentation liquid of Fusarium brevis FXFB001 is obtained.

[0079] 3. Finished product preparation

[0080] a. Inactivation: The obtained Fusarium brevis FXFB001 fermentation liquid was kept at 60° C. for 20 min using a microbial fermentation tank.

[0081] b. Filtration: The fermented liquid after inactivation was cooled to 40°C and filtered using a plate-frame filter cloth of 800 mesh and a filtration pressure of 0.4 MPa to obtain mycelial protein. The mycelial protein biomass was detected to be 59 g / L, and the mycelial yield calculated on a wet basis of mycelial protein was 120%.

[0082] Energy consumption: Example 1 The conventional air consumption during the entire fermentation process is 28800L; the power consumption for fermentation stirring is 13KW; the power consumption of the microbubble equipment is 1.4kw, the oxygen consumption is 1L, and the consumption of 5% hydrogen peroxide solution is 7L.

[0083] Example 2

[0084] 1. Activate strains and prepare seed solution

[0085] Same as Example 1.

[0086] 2. Fermentation

[0087] The seed liquid obtained in the previous step was inoculated into a 50L fermenter at an inoculation rate of 5% of the culture medium volume. The fermentation medium in the fermenter was 30L (27L of prepared fermentation medium + condensed water produced by 3L of steam sterilization medium). The fermentation temperature was 28°C. During the fermentation process, ammonia water was added to control the pH of the fermentation system to 6.0.

[0088] The fermentation culture of Fusarium brevis FXFB001 consists of the initial fermentation period and the peak fermentation period. The initial fermentation period of this batch is 0 to 13 hours of the fermentation culture (excluding the 13th hour). 。 The ventilation volume at the initial stage of fermentation is 1000L / h, and the tank pressure is 0.05MPa. In the initial stage of fermentation, since the glucose content in the fermentation liquid is greater than 5%, no liquid replenishment is required. As the mycelium grows, the oxygen consumption at the initial stage of fermentation gradually increases, and the dissolved oxygen gradually decreases from the initial 100% to 30%.

[0089] As the mycelium of Fusarium brevis FXFB001 grows, it enters the peak period of fermentation from the initial stage of fermentation.

[0090] The peak fermentation period of this embodiment is from the 13th hour of fermentation (including the 13th hour) to the end of fermentation culture. During the peak fermentation period, feed supplement and set the rotation speed to couple dissolved oxygen. Feed supplement is specifically: when the glucose content in the fermentation liquid is ≤5g / L, start adding feed liquid at a rate of 0.5mL / L / h for feeding. 0.5mL / L / h means 0.5mL of feed per liter of fermentation liquid per hour (the same below), the tank pressure is 0.05MPa, and the glucose content in the fermentation liquid is controlled to be 2-5g / L after feeding. Feed supplement until the end of fermentation, the fermentation culture is 30h in total.

[0091] When the fermentation peak period comes, the speed coupling dissolved oxygen is set immediately, the speed does not exceed 400rpm (53% of the maximum parameter of the speed, the maximum parameter of the speed is 750rpm), and the dissolved oxygen content is 30%. After the dissolved oxygen is less than 30%, microbubble liquid is introduced while introducing air, and the tank pressure is 0.05MPa; during the fermentation peak period, the ventilation volume before feeding is 1000L / h, and the ventilation volume is adjusted to 1300L / h after feeding (52% of the maximum parameter of the ventilation volume, the maximum parameter of the ventilation volume is 2500L / h), and microbubble liquid is introduced at a rate of 1% / h of the volume of the fermentation liquid. The microbubble liquid is prepared by industrial oxygen and a hydrogen peroxide solution with a concentration of 7%. The dissolved oxygen content during the fermentation peak period is controlled to be greater than or equal to 30%. After the fermentation culture is completed, the fermentation liquid of Fusarium brevis FXFB001 is obtained.

[0092] 3. Finished product preparation

[0093] a. Inactivation: Same as Example 1.

[0094] b. Filtration: Same as Example 1. The mycelium protein biomass was detected to be 66 g / L, and the mycelium yield calculated on a wet basis of mycelium protein was 126%.

[0095] Energy consumption: Example 2 The conventional air consumption during the entire fermentation process is 35100L; the power consumption for fermentation stirring is 15.3KW; the power consumption of the microbubble equipment is 1.7kw, the oxygen consumption is 0.73L, and the 7% hydrogen peroxide solution consumption is 5.1L.

[0096] Example 3

[0097] 1. Activate strains and prepare seed solution

[0098] The low-temperature frozen Fusarium brevicaulis FXFB001 was inoculated into a slant activation culture medium for activation and cultured at 28°C for 30 h. The activated Fusarium brevicaulis FXFB001 was picked out and inoculated into a 250mL three-concave conical flask containing 50mL of seed culture medium, and cultured at 28°C and 200rpm for 24 h to obtain the seed solution of Fusarium brevicaulis FXFB001.

[0099] 2. Fermentation

[0100] The seed liquid obtained in the previous step was inoculated into a 50L fermenter at an inoculation rate of 5% of the culture medium volume. The fermentation medium in the fermenter was 30L (27L of prepared fermentation medium + condensed water produced by 3L of steam sterilization medium). The fermentation temperature was 28°C. During the fermentation process, ammonia water was added to control the pH of the fermentation system to 6.0.

[0101] The fermentation culture of Fusarium brevis FXFB001 consists of the initial fermentation period and the peak fermentation period. The initial fermentation period of this batch is 0 to 10 hours (excluding the 10th hour) of the fermentation culture. The air volume in the initial fermentation period is 1000L / h, and the tank pressure is 0.05MPa. In the initial fermentation period, since the glucose content in the fermentation liquid is greater than 5%, no liquid replenishment is required. With the growth of mycelium, the oxygen consumption in the initial fermentation period gradually increases, and the dissolved oxygen gradually decreases from the initial 100% to 30%.

[0102] As the mycelium of Fusarium brevis FXFB001 grows, the fermentation enters the peak period from the initial fermentation stage. The peak period of fermentation in this embodiment is from the 10th hour of fermentation (including the 10th hour) to the end of the fermentation culture.

[0103] Feeding and setting the speed coupling dissolved oxygen during the peak fermentation period. Feeding is specifically: when the glucose content in the fermentation liquid is ≤5g / L at the peak of fermentation, feed liquid is added at a rate of 0.5mL / L / h. 0.5mL / L / h means 0.5mL per liter of fermentation liquid per hour (the same below). After feeding, the glucose content in the fermentation liquid is controlled to be 2-5g / L. Feeding is carried out until the end of fermentation, and the fermentation culture is cultured for a total of 29h.

[0104] When the fermentation peak comes, the speed is immediately set to couple the dissolved oxygen, the speed does not exceed 340rpm (the maximum speed is 750rpm, 340rpm is 45% of the maximum speed parameter), and the dissolved oxygen content is 30%. Dissolved oxygen is less than 30% ， Microbubble liquid is introduced at the same time as air is introduced, and the tank pressure is 0.05MPa; the ventilation volume before feeding at the peak of fermentation is 1000L / h, and the ventilation volume after feeding is still 1000L / h (40% of the maximum parameter of ventilation volume), and microbubble liquid is introduced at a rate of 2.3% / h of the volume of the fermentation liquid, and the microbubble liquid is prepared by industrial oxygen and a hydrogen peroxide solution with a concentration of 9%. The dissolved oxygen content during the peak of fermentation is controlled to be greater than or equal to 30%. After the fermentation culture is completed, the fermentation liquid of Fusarium brevis FXFB001 is obtained.

[0105] 3. Finished product preparation

[0106] a. Inactivation: Same as Example 1.

[0107] b. Filtration: Same as Example 1. The mycelium protein biomass was detected to be 55 g / L, and the mycelium yield calculated on a wet basis of mycelium protein was 109%.

[0108] Energy consumption: The conventional air consumption during the whole fermentation process of Example 3 is 29000L; the power consumption for fermentation stirring is 13.6KW; the power consumption of the microbubble equipment is 1.9kw, the oxygen consumption is 1.9L, and the 9% hydrogen peroxide solution consumption is 13.3L.

[0109] Example 4

[0110] 1. Preparation of Culture Medium

[0111] a. Activation medium components: 25 g glucose, 25 g yeast extract, 0.8 g potassium dihydrogen phosphate, 0.2 g magnesium sulfate heptahydrate and 0.05 g calcium acetate, 20 g agar, add water to 1000 mL, pH 5.5-6.1, sterilize at 121°C for 30 min.

[0112] b. Seed culture medium components: 25 g glucose, 25 g yeast extract, 0.8 g potassium dihydrogen phosphate, 0.2 g magnesium sulfate heptahydrate and 0.05 g calcium acetate, add water to 1000 mL, pH 5.5-6.1, sterilize at 121°C for 30 min.

[0113] c. Fermentation medium components: 25g / L glucose, 1g / L phosphoric acid, 1g / L potassium sulfate, 0.2g / L magnesium sulfate heptahydrate, 0.1g / L calcium acetate, 1.7mg / L manganese sulfate monohydrate, 5mg / L ferrous sulfate heptahydrate, 1.7mg / L zinc chloride, 2mg / L cobalt chloride and 0.1mg / L multivitamin. Prepare 27L in total, pH 5.5-6.1, sterilize at 121℃ for 30min;

[0114] The multivitamin consists of the following components in equal mass ratios: vitamin B1, vitamin B12, vitamin B2, vitamin B3, vitamin B5, vitamin B6, vitamin B9, vitamin C and vitamin H / D-biotin.

[0115] 2. Activate strains and prepare seed solution

[0116] The low-temperature frozen Fusarium veneziae A 3 / 5 strain was inoculated into a slant activation medium for activation and cultured at 28°C for 36 hours. The activated strain was picked out and inoculated into a 250mL three-concave conical flask containing 50mL of seed culture medium, and cultured at 28°C and 200rpm for 28 hours to obtain the seed solution of Fusarium veneziae.

[0117] 3. Fermentation

[0118] The seed liquid obtained in the previous step was inoculated into a 50L fermenter at an inoculation rate of 5% of the culture medium volume. The fermentation medium in the fermenter was 30L (27L of prepared fermentation medium + condensed water produced by 3L of steam sterilization medium). The fermentation temperature was 28°C. During the fermentation process, ammonia water was added to control the pH of the fermentation system to 6.0.

[0119] The fermentation culture of Venezia Fusarium A 3 / 5 consists of the initial fermentation period and the peak fermentation period. The initial fermentation period of this batch is 0 to 14 hours (excluding the 14th hour) of the fermentation culture. The air volume in the initial fermentation period is 1000L / h, and the tank pressure is 0.05MPa. In the initial fermentation period, since the glucose content in the fermentation liquid is greater than 5%, no liquid replenishment is required. With the growth of mycelium, the oxygen consumption in the initial fermentation period gradually increases, and the dissolved oxygen gradually decreases from the initial 100% to 30%.

[0120] As the mycelium of Fusarium veneziae A3 / 5 grows, the fermentation enters the peak period from the initial stage of fermentation. The peak period of fermentation in this embodiment is from the 14th hour of fermentation (including the 14th hour) to the end of the fermentation culture.

[0121] Feeding and setting the speed coupling dissolved oxygen during the peak fermentation period. Feeding is specifically: when the glucose content in the fermentation liquid is ≤5g / L at the peak of fermentation, feed liquid is added at a rate of 0.5mL / L / h. 0.5mL / L / h means 0.5mL of feed per liter of fermentation liquid per hour (the same below), and the tank pressure is 0.05MPa. After feeding, the glucose content in the fermentation liquid is controlled to be 2-5g / L. Feeding is carried out until the end of fermentation, and the fermentation culture is 29h in total.

[0122] When the fermentation peak period comes, the speed is immediately set to couple the dissolved oxygen, that is, the speed is 375rpm (the maximum speed is 750rpm, and 375rpm is 50% of the maximum speed parameter), and the dissolved oxygen content is 30%. When the dissolved oxygen is less than 30%, microbubble liquid is introduced while introducing air, and the tank pressure is 0.05MPa; the ventilation volume before feeding at the peak of fermentation is 1000L / h, and the ventilation volume is adjusted to 1200L / h (48% of the maximum ventilation parameter) after feeding, and microbubble liquid is introduced at a rate of 1.3% / h of the volume of the fermentation liquid. The microbubble liquid is prepared from industrial oxygen and a hydrogen peroxide solution with a concentration of 6%. The dissolved oxygen content during the peak of fermentation is controlled to be greater than or equal to 30%. The fermentation culture is completed to obtain the Venice Fusarium A3 / 5 fermentation liquid.

[0123] 4. Finished product preparation

[0124] a. Inactivation: Same as Example 1.

[0125] b. Filtration: Same as Example 1. The mycelial protein biomass was detected to be 63 g / L, and the mycelial yield calculated on a wet basis of mycelial protein (wet basis, i.e., the ratio of the weight of the protein mycelial obtained after filtration to the weight of the consumed glucose) was 123%.

[0126] Energy consumption: Example 4 The conventional air consumption during the entire fermentation process is 32000L; the power consumption for fermentation stirring is 14.5KW; the power consumption of the microbubble equipment is 1.5kw, the industrial oxygen consumption is 0.86L, and the 6% hydrogen peroxide solution consumption is 6L.

[0127] Comparative Example 1

[0128] 1. Activate strains and prepare seed solution

[0129] Same as Example 1.

[0130] 2. Fermentation

[0131] The seed liquid obtained in the previous step was inoculated into a 50L fermenter at a volume ratio of 5% of the culture medium, and the fermentation medium in the fermenter was 30L; the fermentation temperature was 28°C, and during the fermentation process, ammonia water was added to control the pH of the fermentation system to 6.0.

[0132] The fermentation culture of Fusarium brevis FXFB001 consists of the initial fermentation period and the peak fermentation period. The initial fermentation period of this batch is 0 to 14 hours (excluding the 14th hour) of the fermentation culture. The air volume at the initial fermentation period is 1000L / h, and the tank pressure is 0.05MPa. In the initial fermentation period, since the glucose content in the fermentation liquid is greater than 5%, no liquid supplementation is required.

[0133] The peak period of fermentation is from the 14th hour of fermentation (including the 14th hour) to the end of fermentation culture.

[0134] After about 14 hours, when the glucose content in the fermentation liquid is ≤5g / L during the peak period of fermentation, the feeding liquid is added at a rate of 0.5mL / L / h for feeding, and the ventilation volume is adjusted to 2500L / h (100% of the maximum parameter of the ventilation volume), and the tank pressure is 0.05MPa; during the peak period of fermentation, the speed is set to couple the dissolved oxygen, that is, the speed is 750rpm (100% of the maximum parameter of the speed), and the dissolved oxygen content is 30%. When the dissolved oxygen in the solution is lower than 30%, the speed is no longer increased, and the culture is continued until 30 hours to end the fermentation, and the fermentation liquid of Fusarium brevis FXFB001 is obtained.

[0135] 3. Finished product preparation

[0136] a. Inactivation: Same as Example 1.

[0137] b. Filtration: Same as Example 1. The mycelium protein biomass was detected to be 35 g / L, and the mycelium yield calculated on a wet basis of mycelium protein was 100%.

[0138] Energy consumption: In comparative example 1, the air consumption during the whole fermentation process is 54000L, and the power consumption for stirring is 23KW.

[0139] Comparative Example 2

[0140] 1. Activate strains and prepare seed solution

[0141] Same as Example 1.

[0142] 2. Fermentation

[0143] The seed liquid obtained in the previous step was inoculated into a 50L fermenter at a volume ratio of 5% of the culture medium, and the fermentation medium in the fermenter was 30L; the fermentation temperature was 28°C, and during the fermentation process, ammonia water was added to control the pH of the fermentation system to 6.0.

[0144] The fermentation culture of Fusarium brevis FXFB001 consists of the initial fermentation period and the peak fermentation period. The initial fermentation period of this batch is 0 to 11 hours (excluding the 11th hour) of the fermentation culture. The air volume at the initial fermentation period is 1000L / h, and the tank pressure is 0.05MPa. In the initial fermentation period, since the glucose content in the fermentation liquid is greater than 5%, no liquid supplementation is required.

[0145] The peak period of fermentation is from the 11th hour of fermentation (including the 11th hour) to the end of fermentation culture. About 11 hours later, when the glucose content in the fermentation liquid during the peak period of fermentation is ≤5g / L, the feeding liquid is added at a rate of 0.5mL / L / h for feeding. After feeding, the glucose content in the fermentation liquid is controlled at 2-5g / L, and the ventilation volume is adjusted to 2300L / h (92% of the maximum parameter of the ventilation volume), and the tank pressure is 0.05MPa. During the peak period of fermentation, the speed is set to couple the dissolved oxygen, that is, the speed is 700rpm (93% of the maximum parameter of the speed), and the dissolved oxygen content is 30%. When the dissolved oxygen in the solution is lower than 30%, the speed is no longer increased, and a 7% concentration of hydrogen peroxide liquid is added at a rate of 1% / h of the volume of the fermentation liquid while ventilation, and the culture is continued until 27 hours to end the fermentation, and the short-handled Fusarium FXFB001 fermentation liquid is obtained.

[0146] 3. Finished product preparation

[0147] a. Inactivation: Same as Example 1.

[0148] b. Filtration: Same as Example 1. The mycelium protein biomass was detected to be 41 g / L, and the mycelium yield calculated on a wet basis of mycelium protein was 104%.

[0149] Energy consumption: In comparative example 2, the air consumption during the whole fermentation process was 47800 L; the power consumption for stirring was 20.38 KW; and the consumption of 7% concentration hydrogen peroxide liquid was 4.8 L.

[0150] Comparison Table 1 of mycelium protein biomass, bacterial yield, and various energy consumptions of the above embodiments and comparative examples: It can be seen that the technical solution of the present invention has high mycelium protein biomass, high bacterial yield, and low air and electricity consumption.

[0151] Table 1 Comparison of mycelial protein biomass, mycelial yield, and various energy consumption of Examples 1 to 4 and Comparative Examples 1 to 2

[0152]

[0153] Taking the data of Comparative Example 1 as the benchmark, the increase and decrease of the corresponding data of other embodiments and Comparative Example 2 are shown in Table 2 below.

[0154] Table 2 Comparison results of Examples 1 to 4 and Comparative Examples 1 to 2

[0155]

[0156] Note: B / A = (comparative data of air usage) / (comparative data of mycelial protein biomass).

[0157] According to Table 2, the technical solution of the present invention not only increases the yield, but also saves energy, improves the overall mycelium protein production efficiency by more than 50%, reduces electricity consumption by more than 25%, and reduces gas consumption per unit of mycelium protein by more than 60%.

[0158] In summary, the technical solution of the present invention increases the yield of mycelium, while reducing unit costs such as working hours and energy consumption, and improving equipment utilization. The present invention is simple and easy to implement, and is convenient for large-scale production of microbial protein, meeting the national industrial requirements for sustainable development. The technical solution of the present invention can not only increase the yield, but also save energy, and improve the overall mycelium protein production efficiency by more than 50%. The residence time of the gas in the fermentation tank can also be increased through the microbubble method, and the gas consumption per unit mycelium protein can be reduced by more than 60%, thereby achieving energy-saving effects.

[0159] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for increasing the dissolved oxygen content of a fermentation broth, characterized in that: include: The microorganisms are inoculated into a culture medium for fermentation culture, and when the fermentation culture is at the peak of fermentation, oxygen-containing raw materials are introduced into the fermentation equipment in the form of microbubbles; When the fermentation culture is carried out to the 8th to 15th hour, the fermentation culture begins to enter the fermentation peak period, and the time of the fermentation peak period is from the 8th to 15th hour of the fermentation culture to the end of the fermentation culture.

2. The method according to claim 1, characterized in that: The oxygen-containing raw material includes a gaseous oxygen-containing raw material and a liquid oxygen-containing raw material; the gaseous oxygen-containing raw material includes one or more of oxygen, oxygen-enriched air and air; the liquid oxygen-containing raw material includes a hydrogen peroxide solution and / or sterilized edible water; the mass concentration of hydrogen peroxide in the hydrogen peroxide solution is 3% to 30%.

3. The method according to claim 2, characterized in that: The gaseous oxygen-containing raw material is sterilized before preparing microbubbles.

4. The method according to claim 1, characterized in that: The microbubble introduction rate is 1% to 2.5% / h of the fermentation liquid volume.

5. The method according to claim 1, characterized in that: The method for preparing the microbubbles comprises: The oxygen-containing raw material is subjected to microbubble treatment to obtain microbubbles of the oxygen-containing raw material; The microbubble treatment equipment comprises a microbubble generator; the diameter of the microbubbles generated by the microbubble generator is nanometer-level and / or micrometer-level.

6. The method according to claim 1, characterized in that: The microorganisms include Fusarium brevis and / or Fusarium venezuelae.

7. The method according to claim 1, characterized in that: The fermentation temperature is 27-29° C., and the fermentation time is 23-30 hours.

8. The microbubble introduction device used in the method according to any one of claims 1 to 7, characterized in that: It includes a gas raw material chamber, a liquid raw material chamber, a fermentation device, a microbubble device and an air filtration and sterilization system; the fermentation device is provided with a microporous distributor; the liquid raw material chamber is connected to the microbubble device; the gas raw material chamber is connected to the air filtration and sterilization system; the air filtration and sterilization system is connected to the microbubble device, and the microbubble device is connected to the fermentation equipment.

9. Use of the method according to any one of claims 1 to 7 in increasing the yield of microbial protein and / or reducing the ventilation volume of fermentation culture.

10. A method for increasing the yield of microbial protein, characterized in that: include: The microorganisms are inoculated into a culture medium for fermentation culture, and when the fermentation culture is at the peak of fermentation, oxygen-containing raw materials are introduced into the fermentation equipment in the form of microbubbles; When the fermentation culture is carried out to the 8th to 15th hour, the fermentation culture begins to enter the fermentation peak period, and the time of the fermentation peak period is from the 8th to 15th hour of the fermentation culture to the end of the fermentation culture.

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