Edible fungus liquid state fermentation continuous feeding process based on regulation and control of respiration quotient

Abstract

The invention relates to the field of edible fungus fermentation preparation, in particular to an edible fungus liquid state fermentation continuous feeding process based on regulation and control of a respiration quotient. According to the method, physiological parameters in the continuous feeding fermentation process are monitored in real time, a scientific continuous feeding process is established, and the respiratory quotient range is regulated to be 0.75-1.05 according to different fermentation targets, so that the thallus amount and / or the thallus protein are / is produced through fermentation, and the thallus amount, the biological conversion rate and the protein content of edible fungi are also remarkably improved. The method is wide in technical operation means condition range, simple, convenient and feasible to operate, and easy to realize automatic and continuous operation; the continuous fermentation can save the time of repeated tank washing and sterilization, improves the production efficiency, is easier to control the fermentation parameters, has high sugar utilization rate, and is suitable for industrial production.

Description

Technical Field

[0001] The invention relates to the field of edible fungus fermentation preparation, and in particular to an edible fungus liquid fermentation continuous feeding process based on respiratory quotient regulation. Background Art

[0002] Edible fungi are an important biological resource. They are low in fat and energy, rich in polysaccharides, triterpenes, vitamins and other nutrients. They have certain effects on improving human immunity, preventing and treating various chronic diseases and anti-aging. The protein content is as high as about 40%, and they have the potential to be used as a substitute protein. There is huge potential for development and application.

[0003] However, the current production methods of edible fungi are mostly artificial cultivation, which has a long production cycle and low efficiency. The use of liquid fermentation technology to produce edible fungi can reduce the production cycle and cost, improve the efficiency of edible fungi production, and increase the content of substances such as bacterial protein and polysaccharides, thereby increasing nutritional value. Although liquid fermentation of edible fungi has a high conversion rate, there is still a need to further improve the fermentation rate and bacterial volume.

[0004] In recent years, continuous feeding fermentation technology has been frequently used in yeast, E. coli and other fermentation fields, and there have been many successful reports. Continuous feeding fermentation can increase the fermentation rate, reduce the fermentation cost, and enrich the target product by regulating the fermentation parameters. However, in the liquid fermentation of edible fungi, the application of continuous feeding fermentation technology is less.

[0005] Therefore, it is of great significance to the development and application of edible fungi to regulate the respiratory quotient during the fermentation process, control the continuous flow fermentation process, and improve the liquid fermentation rate, bacterial volume and protein content of edible fungi. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a continuous feeding process for liquid fermentation of edible fungi based on respiratory quotient regulation in view of the deficiencies of the prior art.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0008] A continuous feeding process for liquid fermentation of edible fungi based on respiratory quotient regulation, wherein cultured edible fungus seed liquid is inoculated into a fermentation medium for fermentation culture; when the reducing sugar content is lower than 2 g / L, the feeding medium is fed, and the rate of feeding the feeding medium is regulated according to physiological parameters monitored in real time, thereby regulating the respiratory quotient to a range of 0.75 to 1.05, thereby producing the target fermentation bacterial mass and / or bacterial protein.

[0009] Wherein, the edible fungus is a fungus of the genus Agaricus, preferably Agaricus bisporus.

[0010] In some embodiments of the present invention, the Agaricus bisporus is purchased from the China Agricultural Microbiological Culture Collection Center with a collection number of ACCC 52701.

[0011] Wherein, the edible fungus seed liquid is the seed liquid obtained through two seed cultures;

[0012] Specifically, the two seed cultures include primary seed culture and secondary seed culture; the seed culture medium formulas for the two cultures are: 10-20 g / L wheat flour, 2-5 g / L yeast extract, 20-50 g / L glucose, 0.01-1 g / L ferrous sulfate heptahydrate, 0.05-2.5 g / L potassium dihydrogen phosphate, 0.01-0.1 g / L vitamin B1, pH 4.5-6.5.

[0013] Specifically, the conditions for the first-level seed culture are: the inoculum amount is 2 to 5 small pieces of bacteria from the flat plate for every 150 to 250 mL of the first-level culture medium, the culture temperature is 24 to 28°C, the stirring speed is 100 to 200 rpm, and the culture is 4 to 6 days; the conditions for the second-level seed culture are: 10 to 20% of the volume of the second-level seed culture medium, the culture temperature is 24 to 28°C, the stirring speed is 100 to 200 rpm, and the culture is 2 to 4 days.

[0014] The fermentation medium has a formula of: acidified molasses with a sugar content of 10 to 35 g / L, corn steep liquor 10 to 60 g / L, ammonium sulfate 1 to 10 g / L, ferrous sulfate heptahydrate 0.01 to 1 g / L, potassium dihydrogen phosphate 0.1 to 1 g / L, vitamin B1 0.01 to 0.1 g / L, and pH 4.5 to 6.5.

[0015] In some embodiments of the present invention, the fermentation medium has a formula of: acidified molasses (converted sugar content is 25-30 g / L), corn steep liquor 30 g / L, ammonium sulfate 5 g / L, ferrous sulfate heptahydrate 0.08 g / L, potassium dihydrogen phosphate 0.5 g / L, vitamin B1 0.02 g / L, pH = 5.5.

[0016] The fermentation culture conditions are as follows: temperature 25-28°C, pH 4.8-6.0, stirring speed 150-400rpm, ventilation volume 0.4-1.2vvm, dissolved oxygen controlled at more than 30%, and tank pressure 0.05-0.12Mpa.

[0017] In some embodiments of the present invention, the fermentation culture conditions are as follows: the temperature is controlled at 26°C, the pH is controlled at 5.5 with ammonia water, the stirring speed is 300rpm, the ventilation volume is 0.06vvm, the dissolved oxygen is controlled at more than 30%, and the pressure is 0.08Mpa.

[0018] Wherein, the physiological parameters include bacterial oxygen uptake rate and carbon dioxide release rate.

[0019] Specifically, the bacterial oxygen uptake rate and carbon dioxide release rate are calculated based on the oxygen concentration and carbon dioxide concentration measured by an exhaust gas analyzer.

[0020] Specifically, the calculation formula of the bacterial oxygen uptake rate is:

[0021]

[0022] Specifically, the calculation formula of the carbon dioxide release rate is:

[0023]

[0024] The meaning and unit of each parameter are as follows: (1) OUR: bacterial oxygen uptake rate, mmol / L / h, mol / h / m 3 ; (2) CER: carbon dioxide release rate, mmol / L / h, mol / h / m 3 ; (3) Fai: intake air flow rate under standard conditions, m 3 / h, standard state refers to the temperature of 0℃, 1.01×10 ^5 Air flow rate under Pa; (4) V: fermentation liquid volume, m 3 ; (5) 0.0224: The volume of 1 mol of gas under standard conditions, m 3 / moL; (6) 20.34%: intake oxygen concentration; (7) 79.02%: intake inert gas concentration; (8) 0.03%: intake carbon dioxide concentration; (9) C1: exhaust carbon dioxide concentration, %; (10) C2: exhaust oxygen concentration, %; (11) C3: fermentation broth oxygen concentration, mol / m 3 ; (12) C4: concentration of carbon dioxide in the fermentation broth, mol / m 3 ; (13) Fb: feeding speed: m 3 / h.

[0025] Furthermore, the respiratory quotient = carbon dioxide release rate / microorganism oxygen uptake rate, that is,

[0026] The feed culture medium has a formula of: acidified molasses with a sugar content of 10 to 35 g / L and 10 to 60 g / L corn steep liquor.

[0027] The acidified molasses is molasses that has been precipitated and then acidified and hydrolyzed with acid to obtain an acidified molasses with a reducing sugar concentration of 15 to 25 wt %;

[0028] Specifically, the acid used is any one or more of hydrochloric acid, sulfuric acid, nitric acid or phosphoric acid.

[0029] in,

[0030] When the fermentation target is bacterial protein, the respiratory quotient is regulated in the range of 0.75 to 0.85;

[0031] When the fermentation target is the amount of bacteria, the respiratory quotient is regulated to range from 0.95 to 1.05;

[0032] When the fermentation target is the amount of bacteria and bacterial protein, in the early stage of the fed-batch culture medium, i.e. 24 to 48 hours, the respiratory quotient is regulated to be in the range of 0.95 to 1.05; in the later stage of the fed-batch culture medium, i.e. 36 to 60 hours (when the amount of bacteria increases and is stable), the respiratory quotient is regulated to be in the range of 0.75 to 0.85.

[0033] The use of the bacterial protein prepared by the above-mentioned edible fungus liquid fermentation continuous feeding process in the preparation of microbial feed, edible fungus flavoring, or fermentation nitrogen source is also within the scope of protection of the present invention.

[0034] Beneficial effects:

[0035] (1) The present invention provides a continuous feeding process for liquid fermentation of edible fungi based on respiratory quotient regulation, which can improve the production efficiency, fungal mass and protein yield of edible fungi; by real-time monitoring and regulation of the respiratory quotient during the fermentation process, the conversion rate and growth rate of edible fungi can be improved, the cost can be reduced, and the decline of edible fungi can be alleviated; at the same time, the present invention can flexibly adjust the range of the respiratory quotient according to different product requirements, achieve different industrial production goals, and realize the automation and refined control of feeding during the fermentation process.

[0036] (2) The technical operation means of the present invention have a wide range of conditions, are simple and feasible to operate, and are easy to realize automated and continuous operation; the use of continuous fermentation can save time for repeated tank washing and sterilization, improve production efficiency, and make it easier to control fermentation parameters, with high sugar utilization rate, which is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The present invention will be further described in detail below with reference to the accompanying drawings, and the above and / or other advantages of the present invention will become more clear.

[0038] Figure 1 To regulate the effect of respiratory quotient on bacterial cell mass in continuous fed-batch fermentation.

[0039] Figure 2 This is a physical picture of the bacterial extract. DETAILED DESCRIPTION

[0040] The present invention will be further described in detail below in conjunction with specific implementations, and the above and / or other advantages of the present invention will become more clear.

[0041] The experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0042] In the following examples, the Agaricus bisporus was purchased from the China Agricultural Microbiological Culture Collection Center with a collection number of ACCC 52701.

[0043] Example 1: Effect of regulating the respiratory quotient on bacterial mass and protein content in continuous fed-batch fermentation

[0044] 1. Fermentation raw material treatment: Remove the residue and precipitate from molasses, add concentrated sulfuric acid to acidify to pH 2.0, and hydrolyze it into acidified molasses with a reducing sugar content of 20 wt%. Sterilize the acidified molasses and corn syrup solution at 115°C for 20 minutes.

[0045] 2. Bacteria activation and seed culture

[0046] (1) Activation of the fungus: Cut a small piece from the slant or plate of Agaricus bisporus ACCC 52701 stored at low temperature and inoculate it into the center of a PDA plate. Incubate it in a 24-28°C incubator for 3-7 days until the mycelium has grown all over the plate.

[0047] The formula of PDA culture medium is: 500 g / L potato cubes boiled juice, 30 g / L glucose and 20 g / L agar, pH = 5.0, sterilized at 121°C for 20 min.

[0048] (2) Primary seed culture: Take 2 to 5 small pieces of mycelium from the plate and place them in 150 mL of primary seed culture medium. The culture temperature is 26°C and the stirring speed is 180 rpm. Cultivate for 4 to 6 days to obtain the primary seed solution.

[0049] Secondary seed culture: Pour the primary seed solution into 1.5 L of secondary seed culture medium at a volume of 10-20% v / v, culture at 26° C., stirring at 180 rpm, and culture for 3 days to obtain the secondary seed solution.

[0050] Among them, the formula of the first and second level seed culture medium is: wheat flour 15g / L, yeast extract 3g / L, glucose 30g / L, ferrous sulfate heptahydrate 0.08g / L, potassium dihydrogen phosphate 0.5g / L, vitamin B1 0.05g / L, pH=5.0.

[0051] 3. Continuous fed-batch fermentation to regulate respiratory quotient

[0052] The cultured secondary seed liquid was inoculated into a 50L fermentation tank containing 35L fermentation medium at an inoculation rate of 15% v / v for fermentation culture. The temperature during the fermentation process was controlled at 26°C, the pH was controlled at 5.5 with ammonia water, the stirring speed was 300rpm, the ventilation volume was 0.06vvm, the dissolved oxygen was controlled at more than 30%, and the pressure was 0.08Mpa. When the reducing sugar concentration dropped to 2g / L, fed-batch continuous fermentation was started, and the feed medium was added. The specific regulation was divided into experimental groups 1 to 3, with batch fed-batch fermentation as the control.

[0053] (1) Experimental group 1: Keep RQ at about 0.8. When RQ < 0.75, increase the feed medium flow acceleration. When RQ > 0.85, reduce the feed medium flow acceleration. During the entire regulation process, the feed medium flow acceleration was 2-4% fermentation volume / h. The fermentation lasted for 55 hours. After the fermentation was completed, the fermentation liquid was collected and centrifuged at 12000 rpm and 10°C for 10 minutes in a tubular centrifuge to collect the bacterial cells, which were then washed once with deionized water and collected after centrifugation.

[0054] (2) Experimental Group 2: Keep RQ at about 1.0. When RQ < 0.95, increase the feed medium flow acceleration. When RQ > 1.05, reduce the feed medium flow acceleration. During the entire regulation process, the feed medium flow acceleration was 3-6% fermentation volume / h. The fermentation lasted for 55 hours. After the fermentation was completed, the fermentation liquid was collected and centrifuged at 12,000 rpm and 10°C for 10 minutes in a tubular centrifuge to collect the bacterial cells, which were then washed once with deionized water and collected after centrifugation.

[0055] (3) Experimental Group 3: Maintain RQ at about 1.2. When RQ < 1.15, increase the feed medium flow acceleration. When RQ > 1.25, reduce the feed medium flow acceleration. During the entire regulation process, the feed medium flow acceleration was 2-4% fermentation volume / h. The fermentation lasted for 55 hours. After the fermentation was completed, the fermentation liquid was collected and centrifuged at 12,000 rpm and 10°C for 10 minutes in a tubular centrifuge to collect the bacterial cells, which were then washed once with deionized water and collected after centrifugation.

[0056] (4) Control group: The cultured secondary seed liquid was inoculated into a 50L fermentation tank filled with 35L fermentation medium at an inoculum volume of 15% v / v for fermentation culture. The temperature during the fermentation process was controlled at 26°C, the pH was controlled at 5.5 with ammonia water, the stirring speed was 300rpm, the ventilation volume was 0.06vvm, the dissolved oxygen was controlled at more than 30%, and the pressure was 0.08Mpa. When the reducing sugar concentration dropped to 2g / L, batch feeding was started. Specifically, when the reducing sugar content was lower than 2g / L, 30% of the total volume of the fermentation liquid was discharged, and an equal volume of feed medium was added. The above feeding process was repeated for a total of 2 times, and the fermentation lasted for a total of 55h. After the fermentation was completed, the fermentation liquid was collected and centrifuged for 10min at 12000rpm and 10°C in a tubular centrifuge to collect the bacterial cells, which were then washed once with deionized water and collected after centrifugation.

[0057] The formula of the fermentation medium is: acidified molasses (converted sugar content is 25-30 g / L), corn steep liquor 30 g / L, ammonium sulfate 5 g / L, ferrous sulfate heptahydrate 0.08 g / L, potassium dihydrogen phosphate 0.5 g / L, vitamin B1 0.02 g / L, pH=5.5.

[0058] The formula of the feed medium is: 30 g / L acidified molasses and 35 g / L corn steep liquor.

[0059] 4. Fermentation results

[0060] During the fermentation process of the continuous fed-batch fermentation test groups 1 to 3 and the batch fed-batch fermentation control group, the oxygen uptake rate OUR, carbon dioxide release rate CER, and respiratory quotient RQ (RQ = CER / OUR) of the bacteria were detected in real time by tail gas analyzer at regular intervals. At the same time, samples were taken at regular intervals, and the reducing sugar concentration was determined by DNS method, the bacterial mass (dry weight) was determined by drying and weighing, and the protein content was determined by Kjeldahl nitrogen analyzer.

[0061] Sugar concentration, bacterial count and RQ results are as follows Figure 1 As shown, in the batch fed fermentation of the control group, without adjusting the RQ, the fermentation RQ of Agaricus bisporus was basically below 0.8, the highest bacterial volume was close to 18 g / L, but it fluctuated significantly, and the sugar-bacteria conversion rate was 61.2%; in the continuous fed fermentation, when the RQ was adjusted at about 0.8 (experimental group 1), the bacterial volume was low, and the sugar-bacteria conversion rate was 64.4%; when the RQ value was adjusted at about 1.0 (experimental group 2), the bacterial volume kept rising steadily and then tended to a flat state, the bacterial volume could reach 22.14 g / L, and the sugar-bacteria conversion rate was 68.5%; when the RQ was adjusted at about 1.2 (experimental group 3), the bacterial volume showed a state of first increasing and then decreasing, and the sugar-bacteria conversion rate was 65.5%.

[0062] The results of protein content are shown in Table 1. Before 26 hours, the fermentation was in the stage of culture without adding feed medium. When the fermentation reached 26 hours, the difference in protein content was not obvious. At this time, the reducing sugar content was lower than 2 g / L. Feed medium was added. It can be found that the protein content of both the control group and experimental groups 1 to 3 gradually increased. Among them, the increase in experimental group 1 was the most obvious. Finally, when the fermentation reached the end point of fermentation, the protein content reached 49.7%.

[0063] Table 1 Effect of different RQ conditions on protein content

[0064] Fermentation time Comparison Experimental Group 1 Experimental Group 2 Experimental Group 3 26h 45.5％ 45.8％ 45.6％ 45.75％ 42h 47.2％ 49.4％ 48.5％ 48％ 55h 47.8％ 49.7％ 48.6％ 48.2％

[0065] In summary, when the fermentation target is the amount of bacterial cells, the best value is to adjust the RQ value to around 1.0; when the fermentation target is bacterial protein, the best value is to adjust the RQ value to around 0.8.

[0066] Example 2 Effect of regulating respiratory quotient at different stages of continuous fed-batch fermentation

[0067] The fermentation raw material treatment, strain activation and seed culture process are the same as in Example 1.

[0068] The cultured secondary seed liquid was inoculated into a 50L fermentation tank containing 35L fermentation medium at an inoculation rate of 15% v / v for fermentation culture. The temperature during the fermentation process was controlled at 26°C, the pH was controlled at 5.5 with ammonia water, the stirring speed was 300rpm, the ventilation volume was 0.06vvm, the dissolved oxygen was controlled at more than 30%, and the pressure was 0.08Mpa. When the reducing sugar concentration dropped to 2g / L, continuous feeding fermentation was started, and the feed medium was added to keep RQ at about 1.0. When RQ < 0.95, the feed medium flow acceleration was increased. When RQ > 1.05, the feed medium flow acceleration was reduced. When the fermentation was 36h, the feed medium flow rate was reduced to stabilize RQ at about 0.8. The fermentation lasted for 60h. After the fermentation was completed, the fermentation liquid was collected and centrifuged for 10min at 12000rpm and 10°C using a tubular centrifuge to collect the bacteria, which were washed once with deionized water and collected after centrifugation. Fed-batch fermentation was used as a control.

[0069] During the fermentation process, samples were taken every 4 hours and the protein content was determined by a Kjeldahl nitrogen analyzer. It was found that by regulating RQ in stages, both the bacterial mass and protein content could be increased. The results are shown in Table 2. First, bacterial mass regulation was performed. When the fermentation reached 36 hours, although the control group had been fed in batches, the bacterial mass rose to 17.4 g / L and remained stable for a period of time, the bacterial mass of the experimental group was still significantly higher than that of the control group. After that, protein regulation was performed. After the fermentation was completed, the bacterial mass of the experimental group was determined to be 20.8 g / L, and the protein content reached 50.6%, which was significantly higher than that of the control group.

[0070] Table 2 Experimental results of continuous fed-batch fermentation with staged regulation of respiratory quotient

[0071]

[0072] Example 3: Bacteria digestibility test

[0073] The fungi collected from the experimental group 1 in Example 1 were dried at 65°C to obtain edible fungi powder, and the monogastric animal SDS bionic digestion system (SDS-II type) was used to test the digestibility of the edible fungi powder on a medium and large pig model. The specific determination process was completed by Dongguan Pan Asia Pacific Biotechnology Co., Ltd.

[0074] The parameters for simulated digestion in the stomach stage were as follows: temperature 39°C, buffer flow rate 120 mL / min, digestion time 4 h, washing solution 1500 mL / time, 40 min each time, 3 times in total. The parameters for simulated digestion in the small intestine stage were as follows: temperature 39°C, buffer flow rate 120 mL / min, digestion time in the front part of the small intestine 16 h, washing solution 1500 mL / time, 40 min each time, 6 times in total. The determination of dry matter and crude protein content was carried out according to the methods of GB / T 6435-2006 and GB / T6432-94, respectively.

[0075] The calculation results of the cell digestibility are shown in Table 3. It can be seen that the monogastric dry matter digestibility of edible fungus cell powder is 58.95%, and the protein digestibility is 76.96%. Due to its low cost, high nutritional value and excellent aroma, it can be considered as a substitute for microbial feed such as yeast powder.

[0076] Table 3 In vitro bionic digestibility of edible fungus powder (single stomach)

[0077]

[0078] Example 4: Preparation of bacterial extract

[0079] Take 5 kg of bacteria collected from test group 1 in Example 1, crush them manually, and grind them with a colloid mill at a volume ratio of 1:5 (bacteria: pure water). Use a 50L tank for enzymatic hydrolysis, adjust the pH to 5.0, heat to 55°C, add 5mL cellulase (Novozymes), 5g glucanase (Nanyang Pangbo), 5g pectinase (Nanyang Pangbo), 5g glycoproteinase, stir evenly, and enzymolyze at 300rpm for 12h. No pH adjustment is required when the pH is 4.5-5.0, heat to 70°C, add 5g nuclease P1, and enzymolyze for 6 hours. Adjust the pH to 8.0 with sodium hydroxide, cool to 50°C, add 5g alkaline protease and 5g trypsin, and enzymolyze for 12h. Then centrifuge with a tubular centrifuge, pass the liquid through a microfiltration membrane, and use a rotary evaporator to concentrate to a solid content of more than 20g / L, then spray dry with a spray dryer to obtain a bacterial extract (such as Figure 2 As shown). According to the test, the protein content of the bacterial extract can reach 58%, which is rich in various essential amino acids and flavor amino acids and can be used as a seasoning additive or a nitrogen source for fermentation.

[0080] The present invention provides a thought and method for a continuous feeding process of liquid fermentation of edible fungi based on respiratory quotient regulation. There are many methods and ways to implement the technical solution. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention. All components not specified in this embodiment can be implemented by existing technologies.

Claims

1. A continuous feeding process for liquid fermentation of edible fungi based on respiratory quotient regulation, characterized in that: The cultured edible fungus seed liquid is inoculated into the fermentation medium for fermentation culture. When the reducing sugar content is lower than 2g / L, the feeding medium is fed and the rate of the feeding medium is regulated according to the physiological parameters monitored in real time, and then the respiratory quotient is regulated to the range of 0.75 to 1.05, so as to produce the target fermentation bacterial mass and / or bacterial protein.

2. The continuous feeding process for liquid fermentation of edible fungi according to claim 1, characterized in that: The edible fungus is a fungus of the genus Agaricus, preferably Agaricus bisporus.

3. The continuous feeding process for liquid fermentation of edible fungi according to claim 1, characterized in that: The edible fungus seed liquid is a seed liquid obtained through two seed cultures; wherein the seed culture medium formulas of the two seed cultures are: 10-20 g / L wheat flour, 2-5 g / L yeast extract, 20-50 g / L glucose, 0.01-1 g / L ferrous sulfate heptahydrate, 0.05-2.5 g / L potassium dihydrogen phosphate, 0.01-0.1 g / L vitamin B1, and pH 4.5-6.

5.

4. The continuous feeding process for liquid fermentation of edible fungi according to claim 1, characterized in that: The fermentation medium has a formula of: acidified molasses with a sugar content of 10-35 g / L, 10-60 g / L corn steep liquor, 1-10 g / L ammonium sulfate, 0.01-1 g / L ferrous sulfate heptahydrate, 0.1-1 g / L potassium dihydrogen phosphate, 0.01-0.1 g / L vitamin B1, and a pH of 4.5-6.

5.

5. The continuous feeding process for liquid fermentation of edible fungi according to claim 1, characterized in that: The fermentation culture has the following conditions: temperature 25-28°C, pH 4.8-6.0, stirring speed 150-400rpm, ventilation volume 0.4-1.2vvm, dissolved oxygen controlled at more than 30%, and tank pressure 0.05-0.12Mpa.

6. The continuous feeding process for liquid fermentation of edible fungi according to claim 1, characterized in that: The physiological parameters include bacterial oxygen uptake rate and carbon dioxide release rate; the respiratory quotient = carbon dioxide release rate / bacterial oxygen uptake rate.

7. The continuous feeding process for liquid fermentation of edible fungi according to claim 1, characterized in that: The feed culture medium has a formula of: acidified molasses with a sugar content of 10 to 35 g / L and 10 to 60 g / L corn steep liquor.

8. The continuous feeding process for liquid fermentation of edible fungi according to any one of claims 4 or 7, characterized in that The acidified molasses is molasses with residues removed and precipitated, and then acidified and hydrolyzed with acid to obtain acidified molasses with a reducing sugar concentration of 15-25wt%, wherein the acid used is any one or more of hydrochloric acid, sulfuric acid, nitric acid or phosphoric acid.

9. The continuous feeding process for liquid fermentation of edible fungi according to claim 1, characterized in that: When the fermentation target is bacterial protein, the respiratory quotient is regulated in the range of 0.75 to 0.85; When the fermentation target is the amount of bacteria, the respiratory quotient is regulated to range from 0.95 to 1.05; When the fermentation target is the amount of bacteria and bacterial protein, in the early stage of the fed-batch culture medium, i.e. 24-48 hours, the respiratory quotient is regulated to be in the range of 0.95-1.05; in the late stage of the fed-batch culture medium, i.e. 36-60 hours, the respiratory quotient is regulated to be in the range of 0.75-0.

85.

10. Use of the bacterial protein obtained by the continuous feeding process of liquid fermentation of edible fungi according to any one of claims 1 to 9 in the preparation of microbial feed, edible fungi seasoning, or fermentation nitrogen source.

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