A fermentation method and application of selenium-rich pleurotus stipticus mycelium

Abstract

The present application relates to the technical field of edible mushroom mycelium fermentation and application, and provides a fermentation method and application of selenium-rich pachykytosmirus mycelium. The fermentation method of the selenium-rich pachykytosmirus mycelium comprises the following steps: sequentially culturing pachykytosmirus mother strains in PDA culture medium and liquid seed culture medium to obtain pachykytosmirus liquid strains; inoculating the pachykytosmirus liquid strains into sodium selenite culture medium for culture to obtain selenium-rich pachykytosmirus liquid; mixing corn powder, soybean powder, wheat powder, glucose, yeast powder and potato water, boiling for 4-5 min, filtering and taking the filtrate, mixing the filtrate with the selenium-rich pachykytosmirus liquid to obtain a selenium-rich liquid fermentation culture medium; sterilizing the selenium-rich liquid fermentation culture medium, inoculating the pachykytosmirus liquid strains for culture, and obtaining selenium-rich pachykytosmirus mycelium after fermentation. The selenium-rich pachykytosmirus mycelium can be used for preparing selenium-rich pachykytosmirus powder.

Description

Technical Field

[0001] This invention relates to the technical field of fermentation and application of edible fungi mycelium, specifically to the fermentation method and application of seafood mushroom mycelium. Background Technology

[0002] Selenium-enriched foods are an important source of selenium for the human body. Selenium intake mainly depends on the selenium content of food and the total amount of selenium-enriched foods consumed. Appropriate selenium supplementation can enhance immunity, delay aging, and has anti-inflammatory and anti-cancer effects. Currently, various selenium-enriched foods have been developed, such as selenium-enriched edible fungi, selenium-enriched rice, selenium-enriched tea, and selenium-enriched eggs.

[0003] Edible mushroom fruiting bodies have a long growth cycle and consume significant human and material resources, while mycelium has a relatively short growth cycle, requires less growth space, has a lower chance of contamination, and can yield intracellular or extracellular substances with the same efficacy as fruiting bodies. Edible mushroom mycelium exhibits significant selenium enrichment effects, and the resulting fermented mycelium powder is an important raw material for the health industry, applicable to the development of functional foods and health products.

[0004] Liquid fermentation is currently the main method for obtaining mycelium and active substances from edible fungi. Compared with solid fermentation and fruiting body culture, liquid fermentation allows for sufficient contact between the strain and the culture medium, controllable dissolved oxygen levels, and good mass transfer, enabling rapid and efficient acquisition of intracellular and extracellular substances from mycelium.

[0005] Selenium-enriched seafood mushroom powder contains abundant protein, polysaccharides, crude fiber, amino acids, trace elements, etc., and has the effects of improving immunity, anti-oxidation, lowering blood sugar, preventing tumors, and anti-cancer. Summary of the Invention

[0006] In view of this, the present invention provides a fermentation method and application of selenium-enriched seafood mushroom mycelium, which at least solves one problem existing in the prior art.

[0007] The present invention provides a fermentation method for selenium-enriched seafood mushroom mycelium, comprising the following steps:

[0008] The mother culture of seafood mushroom was cultured in PDA medium and then in liquid seed medium in sequence to obtain liquid spawn of seafood mushroom;

[0009] The seafood mushroom liquid spawn was inoculated into sodium selenite medium and cultured to obtain selenium-enriched seafood mushroom liquid;

[0010] Mix corn flour, soybean flour, wheat flour, glucose, yeast powder, and potato water, boil for 4-5 minutes, filter and collect the filtrate, mix the filtrate with the selenium-enriched seafood mushroom liquid to obtain a selenium-enriched liquid fermentation culture medium.

[0011] The selenium-enriched liquid fermentation medium was sterilized and inoculated with the seafood mushroom liquid spawn for cultivation. After fermentation, selenium-enriched seafood mushroom mycelium was obtained.

[0012] The sodium selenite culture medium is a culture medium containing sodium selenite, and the selenium concentration is 10 mg / L to 100 mg / L.

[0013] In the fermentation method of this invention, the mother spawn of *Mushroom concha* is first cultured in PDA medium and then in shake flasks to obtain liquid spawn of *Mushroom concha*. The obtained liquid spawn of *Mushroom concha* is then inoculated into sodium selenite medium for further culture to obtain selenium-enriched *Mushroom concha* liquid. At this time, the selenium-enriched *Mushroom concha* liquid is rich in organic selenium, which, as an exogenous selenium additive, is more conducive to the selenium-enriched fermentation of mycelium. The obtained selenium-enriched *Mushroom concha* liquid is mixed with filtrate prepared from corn flour, soybean flour, wheat flour, glucose, potato water, and yeast powder to obtain a selenium-enriched liquid fermentation medium. Finally, the liquid spawn of *Mushroom concha* is fermented using this selenium-enriched liquid fermentation medium to obtain selenium-enriched *Mushroom concha* mycelium.

[0014] The fermentation method of this invention uses corn, soybeans, and wheat as the main raw materials for selenium-enriched fermentation culture medium. These materials are safe and provide ample and diverse nutrients for mycelial fermentation, meeting the growth requirements of edible fungi mycelia and improving fermentation efficiency and quality. Simultaneously, they replace the addition of inorganic salts such as magnesium sulfate, reducing the health risks posed by chemicals and providing safer raw materials for the development of functional foods and health products. Using grains as fermentation raw materials has advantages such as wide availability, low price, reliable quality, and high yield. The cultivation process produces no wastewater or waste residue, saving water resources and achieving clean production, making it an economical and practical culture material.

[0015] The selenium-enriched seafood mushroom mycelium obtained by the fermentation method of the present invention is rich in polysaccharides and can be used to prepare selenium-enriched seafood mushroom powder. In other words, the present invention also provides the application of the selenium-enriched seafood mushroom mycelium in the preparation of selenium-enriched seafood mushroom powder.

[0016] Due to the adoption of the above technical solutions, the embodiments of the present invention have at least the following beneficial effects: the selenium-enriched liquid fermentation method solves the problem of long fermentation cycle of selenium-enriched solid fermentation, achieving the effect of obtaining a large amount of mycelium in a short time; the above fermentation method has easy-to-control conditions, low production cost, and is easy to carry out industrial production, with good selenium enrichment effect and high polysaccharide content in fermentation liquid; the use of selenium-enriched seafood mushroom mycelium and the liquid fermentation medium for cultivating it to prepare selenium-enriched seafood mushroom powder solves the problem of nutrient waste in liquid fermentation medium, reduces wastewater discharge, and improves the utilization rate of fermentation products. Attached Figure Description

[0017] Figure 1The graph shows the relationship between sodium selenite concentration and the mycelial biomass and selenium content of selenium-enriched seafood mushroom powder.

[0018] Figure 2 The graph shows the relationship between the amount of selenium-enriched bacterial solution added and the polysaccharide content and selenium content of the selenium-enriched seafood mushroom powder.

[0019] Figure 3 The graph shows the relationship between the inoculation amount of liquid spawn of *Varicaria stellatus* and the polysaccharide content and selenium content of the mycelium powder of *Varicaria stellatus*.

[0020] Figure 4 These are photographs of the fermentation results of the liquid fermentation medium in Examples 1, 14-18.

[0021] Figure 5 This is a graph showing the relationship between different liquid fermentation media and the mycelial biomass of selenium-enriched seafood mushrooms. Detailed Implementation

[0022] The following will provide a clear and complete description of the concept and technical effects of the present invention in conjunction with the embodiments and accompanying drawings, so as to fully illustrate the purpose, solution and effects of the present invention.

[0023] The present invention provides a fermentation method for selenium-enriched seafood mushroom mycelium, comprising the following steps:

[0024] The mother culture of seafood mushroom was cultured in PDA medium and then in liquid seed medium in sequence to obtain liquid spawn of seafood mushroom;

[0025] The seafood mushroom liquid spawn was inoculated into sodium selenite medium and cultured to obtain selenium-enriched seafood mushroom liquid;

[0026] Mix corn flour, soybean flour, wheat flour, glucose, yeast powder, and potato water, boil for 4-5 minutes, filter and collect the filtrate, mix the filtrate with the selenium-enriched seafood mushroom liquid to obtain a selenium-enriched liquid fermentation culture medium.

[0027] The selenium-enriched liquid fermentation medium was sterilized and inoculated with the seafood mushroom liquid spawn for cultivation. After fermentation, selenium-enriched seafood mushroom mycelium was obtained.

[0028] The sodium selenite culture medium is a culture medium containing sodium selenite, and the selenium concentration is 10 mg / L to 100 mg / L.

[0029] In some preferred embodiments, the selenium concentration of the sodium selenite culture medium is 10 mg / L to 20 mg / L. Most preferably, the selenium concentration of the sodium selenite culture medium is 20 mg / L.

[0030] In some preferred embodiments, the PDA culture medium is cultured at a temperature of 20-25℃ for 14-16 days. The preparation method of the PDA culture medium includes the following steps: Take 100-300g of peeled potato tubers, add 1000mL of water, cook until done, then filter to obtain a filtrate. Add 10-30g of glucose, 10-30g of agar, 0.2-1g of magnesium sulfate, 0.5-2g of dipotassium hydrogen phosphate, and 1-3g of yeast powder to the filtrate sequentially, heat until dissolved, and add water to 1000mL. Sterilize the obtained culture medium at 121-130℃ for 20-40 minutes, then cool to 40-50℃ and pour into petri dishes. Cool until solidified to obtain the PDA culture medium.

[0031] In some preferred embodiments, the liquid seed culture medium is cultured at a temperature of 20-25℃ for 5-7 days. The preparation method of the liquid seed culture medium includes the following steps: Take 100-300g of peeled potato tubers, add 1000mL of water, cook until tender, then filter to obtain a filtrate. Add 10-30g of glucose, 0.2-1g of magnesium sulfate, 0.5-2g of dipotassium hydrogen phosphate, and 1-3g of yeast powder to the filtrate sequentially, heat until dissolved, and add water to 1000mL. Sterilize the obtained culture medium at 121-130℃ for 20-40 minutes, then cool to 20-30℃ to obtain the liquid seed culture medium.

[0032] In some preferred embodiments, the inoculation of the *Viola yezoensis* liquid spawn into sodium selenite medium specifically involves: inoculating the *Viola yezoensis* liquid spawn into sodium selenite medium for shake-flask culture; homogenizing the culture after fermentation to obtain selenium-enriched *Viola yezoensis* broth; the culture temperature is 20-25℃; the culture time is 7-9 days; and the shaker speed is 140-160 r / min. The preparation method of the sodium selenite medium includes the following steps: taking 100-300g of peeled potato tubers, adding 1000mL of water, cooking, and then filtering to obtain the filtrate; adding 10-30g of glucose, 0.2-1g of magnesium sulfate, 0.5-2g of dipotassium hydrogen phosphate, 1-3g of yeast powder, and 10-100mg of sodium selenite to the filtrate sequentially; heating until dissolved; and adding water to 1000mL; sterilizing the obtained medium at 121-130℃ for 20-40min; and then cooling to 20-30℃ to obtain the sodium selenite medium.

[0033] In some preferred embodiments, the preparation method of the selenium-enriched liquid fermentation medium includes the following steps: Take 100-300g of peeled potato tubers, add 1000mL of water, cook until done, then filter to obtain filtrate. Add 10-30g of glucose, 1-2g of yeast powder, 5-10g of corn flour, 2.5-5g of soybean flour, and 5-10g of wheat flour to the filtrate in sequence, heat until dissolved, boil for 5 minutes, and add water to 1000mL. After filtration, mix with selenium-enriched seafood mushroom liquid, with the selenium-enriched seafood mushroom liquid accounting for 40%-50% of the total liquid fermentation medium volume. Sterilize the medium at 121-130℃ for 20-40 minutes, then cool to 20-30℃ to obtain the selenium-enriched liquid fermentation medium. The corn flour, soybean flour, and wheat flour are 100-mesh powders.

[0034] The potato water is the filtrate obtained by boiling potatoes in water and then filtering it. In some preferred embodiments, the potato water is prepared by taking 1 cm... 3 Peel potato tubers of various sizes, add water and boil until tender. Filter through 8 layers of gauze to obtain the filtrate, which is potato water.

[0035] In some preferred embodiments, the inoculation amount of the seafood mushroom liquid spawn is 10%-14%.

[0036] In some preferred embodiments, the amount of selenium-enriched seafood mushroom broth added to the selenium-enriched liquid fermentation medium is 44%.

[0037] After fermentation, the seafood mushroom mycelium obtained is homogenized together with the selenium-enriched liquid fermentation medium, and then freeze-dried or spray-dried to obtain selenium-enriched seafood mushroom powder.

[0038] The following are some typical examples.

[0039] In the following examples and comparative examples, the PDA culture medium was prepared according to the following steps: 200g of peeled potato tubers were taken, 1000mL of water was added, the tubers were cooked, filtered, and the filtrate was obtained; 20g of glucose, 20g of agar, 1g of magnesium sulfate, 2g of dipotassium hydrogen phosphate and 2g of yeast powder were added to the filtrate in sequence, heated until dissolved, and water was added to 1000mL; the mixture was sterilized at 121℃ for 20min, cooled to 45℃ and poured into petri dishes, and cooled until solidified to obtain the PDA culture medium.

[0040] In the following examples and comparative examples, the liquid seed culture medium was prepared according to the following steps: 200g of peeled potato tubers were taken, 1000mL of water was added, the tubers were cooked, and then filtered to obtain the filtrate; 20g of glucose, 1g of magnesium sulfate, 2g of dipotassium hydrogen phosphate and 2g of yeast powder were added to the filtrate in sequence, the mixture was heated until dissolved, and water was added to 1000mL; the obtained culture solution was sterilized at 121℃ for 20min, and then cooled to 20℃ to obtain the liquid seed culture medium.

[0041] Example 1

[0042] Cultivate selenium-enriched seafood mushroom mycelium according to the following steps:

[0043] (1) Cultivation of liquid spawn of seafood mushroom: The mother spawn of seafood mushroom was cultured in PDA medium and liquid seed medium in sequence to obtain liquid spawn of seafood mushroom;

[0044] (2) Preparation of selenium-enriched seafood mushroom liquid: Sodium selenite culture medium was prepared, and the seafood mushroom liquid spawn obtained in step (1) was inoculated into sodium selenite culture medium at an inoculation amount of 8% for shake flask culture. After the culture was completed, homogenization was performed to obtain selenium-enriched seafood mushroom liquid.

[0045] (3) Preparation of selenium-enriched liquid fermentation medium: Mix corn flour, soybean flour, wheat flour, glucose, yeast powder and potato water, boil for 4 min-5 min, filter and take the filtrate, and then mix the filtrate with the selenium-enriched seafood mushroom liquid at a volume ratio of 56:44 to obtain selenium-enriched liquid fermentation medium.

[0046] (4) Liquid fermentation of selenium-enriched seafood mushroom mycelium: Sterilize and cool the selenium-enriched liquid fermentation medium prepared in step (3), then inoculate the seafood mushroom liquid inoculum in step (1) and carry out shake flask culture. After the fermentation is completed, selenium-enriched seafood mushroom mycelium is obtained.

[0047] In step (1), the PDA medium is cultured at 22℃ for 15 days. In step (1), the liquid seed medium is cultured at 22℃ for 7 days. In step (2), the seafood mushroom liquid spawn is inoculated into sodium selenite medium for shake-flask culture at 22℃ for 7 days, with a shaker speed of 150 r / min. The preparation method of the sodium selenite medium includes the following steps: Take 200g of peeled potato tubers, add 1000mL of water, cook, and then filter to obtain the filtrate. Add 20g of glucose, 1g of magnesium sulfate, 2g of dipotassium hydrogen phosphate, 2g of yeast powder and 20mg of sodium selenite to the filtrate in sequence, heat until dissolved, and add water to 1000mL. Sterilize the obtained culture solution at 121℃ for 20min, and then cool to 20℃ to obtain the sodium selenite medium. In step (3), the preparation method of selenium-enriched liquid fermentation culture medium includes the following steps: Take 200g of peeled potato tubers, add 1000mL of water and cook until done, then filter to obtain filtrate, which is potato water. Add 20g of glucose, 2g of yeast powder, 5g of corn flour, 2.5g of soybean flour and 5g of wheat flour to the potato water in sequence, heat to boiling, stir and maintain for 5 minutes, and add water to 1000mL. After filtration, mix with selenium-enriched seafood mushroom liquid. The selenium-enriched seafood mushroom liquid accounts for 44% of the total liquid volume of the culture medium. Sterilize the obtained culture medium at 121℃ for 20 minutes, and then cool to 20℃ to obtain selenium-enriched liquid fermentation culture medium. The corn flour, soybean flour and wheat flour are powders with a particle size of 100 mesh. Each conical flask (250mL) is sealed with 100mL of selenium-enriched liquid fermentation culture medium. The specific cultivation method of step (4) includes the following steps: In a clean bench, the seafood mushroom spawn is inoculated into a selenium-enriched fermentation medium and cultured at 22°C and 150 r / min for 7 days to obtain selenium-enriched seafood mushroom mycelium.

[0048] After the fermentation of the seafood mushroom mycelium obtained in this embodiment is completed, it is homogenized together with the selenium-enriched liquid fermentation culture medium and then freeze-dried to obtain selenium-enriched seafood mushroom powder.

[0049] Examples 2-5

[0050] The steps for cultivating selenium-enriched seafood mushroom mycelium in Examples 2-5 are the same as in Example 1, except that the concentration of sodium selenite in the sodium selenite culture medium in step (2) is different. Specifically, the concentrations of sodium selenite in the sodium selenite culture medium in Examples 2-5 are 10 mg / L, 30 mg / L, 40 mg / L, and 50 mg / L, respectively. The preparation method includes the following steps: Take 200g of peeled potato tubers, add 1000mL of water, cook, and then filter to obtain the filtrate. Add 20g of glucose, 1g of magnesium sulfate, 2g of dipotassium hydrogen phosphate, 2g of yeast powder, and different weights (10mg, 30mg, 40mg, 50mg) of sodium selenite to the filtrate in sequence, heat until dissolved, and add water to 1000mL. Sterilize the obtained culture solution at 121℃ for 20min, and then cool to 20℃ to obtain the sodium selenite culture medium.

[0051] After the fermentation of the seafood mushroom mycelium obtained in Examples 2-5 is completed, it is homogenized together with the selenium-enriched liquid fermentation culture medium and then freeze-dried to obtain selenium-enriched seafood mushroom powder.

[0052] Examples 6-9

[0053] The steps for cultivating selenium-enriched seafood mushroom mycelium in Examples 6-9 are the same as in Example 1, except that the ratio of the filtrate to the selenium-enriched seafood mushroom mycelium solution in step (3) is different. Specifically, the volume ratios of the filtrate to the selenium-enriched seafood mushroom mycelium solution in steps (3) of Examples 6-9 are 62:38, 60:40, 58:42, and 54:46, respectively.

[0054] After the fermentation of the seafood mushroom mycelium obtained in Examples 6-9 is completed, it is homogenized together with the selenium-enriched liquid fermentation culture medium and then freeze-dried to obtain selenium-enriched seafood mushroom powder.

[0055] Examples 10-13

[0056] The steps for cultivating selenium-enriched seafood mushroom mycelium in Examples 10-13 are the same as in Example 1, except for the inoculation amount in step (2). Specifically, the inoculation amounts in step (2) of Examples 10-13 are 6%, 10%, 12%, and 14%, respectively.

[0057] After the fermentation of the seafood mushroom mycelium obtained in Examples 10-13 is completed, it is homogenized together with the selenium-enriched liquid fermentation culture medium and then freeze-dried to obtain selenium-enriched seafood mushroom powder.

[0058] Examples 14-18

[0059] The steps for cultivating selenium-enriched seafood mushroom mycelium in Examples 14-18 are the same as in Example 1, except that the proportions of rice flour, corn flour, soybean flour, and wheat flour added in step (3) are different. Specifically, the amounts of corn flour, soybean flour, wheat flour, rice flour, glucose, yeast powder, and potato added in Examples 14-18 are shown in the table below.

[0060] Table 1. Liquid fermentation medium formulation

[0061]

[0062] After the fermentation of the seafood mushroom mycelium obtained in Examples 14-18 is completed, it is homogenized together with the selenium-enriched liquid fermentation culture medium and then freeze-dried to obtain selenium-enriched seafood mushroom powder.

[0063] Comparative Example 1

[0064] Cultivate seafood mushroom mycelium according to the following steps:

[0065] (1) Cultivation of liquid spawn of seafood mushroom: The mother spawn of seafood mushroom was cultured in PDA medium and liquid seed medium in sequence to obtain liquid spawn of seafood mushroom;

[0066] (2) Preparation of ordinary seafood mushroom liquid: Prepare ordinary culture medium without sodium selenite, and inoculate the seafood mushroom liquid spawn obtained in step (1) into the ordinary culture medium at an inoculation amount of 8% for shake flask culture. After the culture is completed, homogenize the culture medium to obtain ordinary seafood mushroom liquid.

[0067] (3) Preparation of ordinary liquid fermentation culture medium: Mix corn flour, soybean flour, wheat flour, glucose, yeast powder and potato water, boil for 4 min-5 min, filter and take the filtrate, and mix the filtrate with the ordinary seafood mushroom liquid at a volume ratio of 56:44 to obtain ordinary liquid fermentation culture medium.

[0068] (4) Liquid fermentation of common seafood mushroom mycelium: Sterilize and cool the common liquid fermentation culture medium prepared in step (3), then inoculate the seafood mushroom liquid inoculum in step (1) and carry out shake flask culture. After the fermentation is completed, common seafood mushroom mycelium is obtained.

[0069] In step (1), the PDA medium is cultured at 22℃ for 15 days. In step (1), the liquid seed medium is cultured at 22℃ for 7 days. In step (2), the seafood mushroom liquid spawn is inoculated into a normal medium for shake-flask culture at 22℃ for 7 days, with a shaker speed of 150 r / min. The preparation method of the normal medium includes the following steps: Take 200g of peeled potato tubers, add 1000mL of water, cook, then filter to obtain filtrate. Add 20g of glucose, 1g of magnesium sulfate, 2g of dipotassium hydrogen phosphate and 2g of yeast powder to the filtrate in sequence, heat until dissolved, and add water to 1000mL. Sterilize the obtained culture solution at 121℃ for 20min, and then cool to 20℃ to obtain the normal medium. In step (3), the preparation method of ordinary liquid fermentation culture medium includes the following steps: Take 200g of peeled potato tubers, add 1000mL of water and cook until done, then filter to obtain filtrate. Add 20g of glucose, 2g of yeast powder, 5g of corn flour, 2.5g of soybean flour and 5g of wheat flour to the filtrate in sequence, heat to boiling, stir and maintain for 5min, and add water to 1000mL. After filtration, mix with ordinary seafood mushroom liquid, the ordinary seafood mushroom liquid accounts for 44% of the total liquid volume of the culture medium. Sterilize the obtained culture medium at 121℃ for 20min, and then cool to 20℃ to obtain ordinary liquid fermentation culture medium. The corn flour, soybean flour and wheat flour are powders with a particle size of 100 mesh. Each conical flask (250mL) is sealed with 100mL of ordinary liquid fermentation culture medium. The specific cultivation method of step (4) includes the following steps: In a clean bench, the seafood mushroom spawn is inoculated into a common fermentation medium and cultured at 22°C and 150 r / min for 7 days to obtain common seafood mushroom mycelium.

[0070] After the fermentation of Comparative Example 1, the mycelium of the seafood mushroom obtained is homogenized together with the ordinary liquid fermentation culture medium, and then freeze-dried to obtain ordinary seafood mushroom powder.

[0071] For the above examples and comparative examples, the mycelial biomass was calculated using the following method:

[0072] Take 100 mL of the fermentation broth from step (4), filter it, obtain mycelia, rinse them several times with distilled water, collect the mycelia, dry them at 60℃, weigh them accurately, and record the dry weight of the mycelia. The mycelial biomass is calculated using the following formula:

[0073]

[0074] In the formula, m is the dry weight of mycelium in g; V is the volume of fermentation broth in L.

[0075] For the above examples and comparative examples, the polysaccharides in the bacterial powder were extracted using an ultrasonic-assisted dilute alkali extraction and alcohol precipitation method, and the polysaccharide content in the bacterial powder was determined using the phenol-sulfuric acid method. The polysaccharide content was calculated using the following formula:

[0076]

[0077] In the formula: C1 is the measured polysaccharide concentration, μg / mL; D is the dilution factor; C 原 The concentration of the polysaccharide solution is in mg / mL.

[0078] The polysaccharide selenium content of the above-mentioned embodiments and comparative examples was determined according to the method in national standard GB 5009.93-2017.

[0079] The mycelial biomass and selenium content of the mycelial powder in Comparative Examples 1 and Examples 1-5 are as follows: Figure 1 As shown, sodium selenite concentration significantly affects the biomass of *Varicaria stellatus* mycelium. With increasing sodium selenite concentration, the biomass decreases sharply. The mycelial biomass obtained from culturing with 20 mg / L sodium selenite was 5.86 ± 0.02 g / L, while at 30 mg / L it was only 1.82 ± 0.10 g / L, a decrease of 68.94%. Simultaneously, sodium selenite concentration affects the selenium content of the mycelial powder. With increasing sodium selenite concentration, the selenium content in the mycelial powder continuously increases. This may be due to the *Varicaria stellatus* mycelium failing to convert the excess sodium selenite in the culture medium, resulting in a higher residual inorganic selenium in the selenium-enriched mycelial powder. The biomass of Comparative Example 1 was 5.61 ± 0.04 g / L. In summary, the optimal sodium selenite concentration for culturing selenium-enriched *Varicaria stellatus* mycelium is 20 mg / L.

[0080] The polysaccharide content and selenium content of the mycelium powder in Examples 1, 6-9 are as follows: Figure 2 As shown, the polysaccharide content in the fermentation broth exhibited a trend of first increasing and then decreasing, with an overall range of 8.82-9.18 mg / mL. The polysaccharide content reached its maximum when the selenium-enriched bacterial solution was added at 44%. The high polysaccharide content in the fermentation broth is due to its composition, which includes both intracellular and extracellular polysaccharides, with a higher proportion of extracellular polysaccharides. With increasing selenium-enriched bacterial solution addition, the selenium content in the polysaccharides showed an upward trend, with an overall range of 198.02-276.34 mg / kg. This indicates that under suitable selenium concentrations, increasing the amount of selenium-enriched bacterial solution added promotes the enrichment of selenium in the mycelium of *Viola yedoensis*, leading to the synthesis of more selenium polysaccharides.

[0081] The content of polysaccharides and selenium in the mycelial powder of Examples 1, 10-13 are as follows: Figure 3As shown, when the inoculum amount is in the range of 6%-8%, the polysaccharide content and selenium content of the fermentation broth increase with the increase of concentration. When the inoculum amount is higher than 10%, the polysaccharide content and selenium content in the polysaccharide in the bacterial solution decrease significantly. The optimal inoculum amount is 8%. Under this condition, the polysaccharide content of the fermentation broth is 16.56±0.25mg / mL and the selenium content of the polysaccharide is 327±9.5mg / kg.

[0082] The fermentation results of the liquid fermentation medium in Examples 1, 14-18 are as follows: Figure 4 As shown, the fermentation broth is generally yellow, the mycelial balls are light yellow, and the mycelium has a strong ability to climb the walls; the mycelial balls in Example 1 are small but very dense and uniform; the mycelial balls in Example 16 are larger in volume but have a lower density. The mycelial biomass of Examples 1, 14-18 is as follows: Figure 5 As shown, in Example 1, the amount of corn flour added was 5%, soybean flour was 2.5%, and wheat flour was 5%. This amount of addition was more suitable for the growth of seafood mushroom mycelium, and the biomass was 9.28±0.01g / L, which was significantly higher than the biomass of other formulations.

[0083] The above description is merely a preferred embodiment of the present invention. The present invention is not limited to the above-described embodiments. Any embodiment that achieves the technical effects of the present invention using the same means should fall within the protection scope of the present invention. Within the protection scope of the present invention, various modifications and variations can be made to the technical solutions and / or implementation methods.

Claims

1. A fermentation method for selenium-enriched seafood mushroom mycelium, comprising the following steps: The mother culture of seafood mushroom was cultured in PDA medium and then in liquid seed medium in sequence to obtain liquid spawn of seafood mushroom; The seafood mushroom liquid spawn was inoculated into sodium selenite medium and cultured to obtain selenium-enriched seafood mushroom liquid; Mix corn flour, soybean flour, wheat flour, glucose, yeast powder, and potato water, boil for 4-5 minutes, filter and collect the filtrate, mix the filtrate with the selenium-enriched seafood mushroom liquid to obtain a selenium-enriched liquid fermentation culture medium. The selenium-enriched liquid fermentation medium was sterilized and inoculated with the seafood mushroom liquid spawn for cultivation. After fermentation, selenium-enriched seafood mushroom mycelium was obtained. The sodium selenite culture medium is a culture medium containing sodium selenite, and the selenium concentration is 10 mg / L to 20 mg / L. The preparation method of the sodium selenite culture medium includes the following steps: Take 100-300 g of peeled potato tubers, add 1000 mL of water, cook until done, then filter to obtain filtrate. Add 10-30 g of glucose, 0.2-1 g of magnesium sulfate, 0.5-2 g of dipotassium hydrogen phosphate, 1-3 g of yeast powder and 10-20 mg of sodium selenite to the filtrate in sequence, heat until dissolved, and add water to 1000 mL. Sterilize the obtained culture medium at 121-130℃ for 20-40 min, and then cool to 20-30℃ to obtain sodium selenite culture medium. The preparation method of the selenium-enriched liquid fermentation medium includes the following steps: Take 100-300 g of peeled potato tubers, add 1000 mL of water, cook until done, then filter to obtain filtrate. Add 10-30 g of glucose, 1-2 g of yeast powder, 5-10 g of corn flour, 2.5-5 g of soybean flour, and 5-10 g of wheat flour to the filtrate in sequence, heat until dissolved, boil for 5 min, and add water to 1000 mL. After filtration, mix with selenium-enriched seafood mushroom liquid, with the selenium-enriched seafood mushroom liquid accounting for 40%-50% of the total liquid fermentation medium volume. Sterilize the medium at 121-130℃ for 20-40 min, and then cool to 20-30℃ to obtain the selenium-enriched liquid fermentation medium.

2. The method according to claim 1, characterized in that, The selenium concentration in the sodium selenite culture medium is 20 mg / L.

3. The method according to claim 1, characterized in that, The specific steps of inoculating the liquid spawn of *Varicaria spp.* into sodium selenite medium are as follows: the liquid spawn of *Varicaria spp.* is inoculated into sodium selenite medium for shake-flask culture, and after fermentation, homogenization is performed to obtain selenium-enriched *Varicaria spp.* The culture temperature is 20-25℃, the culture time is 7-9 days, and the shaker speed is 140-160 r / min.

4. The method according to claim 1, characterized in that, The inoculation amount of the seafood mushroom liquid spawn is 10%-14%.

5. The method according to claim 1, characterized in that, The amount of selenium-enriched seafood mushroom mycelium solution added to the selenium-enriched liquid fermentation culture medium is 44%.

6. The selenium-enriched seafood mushroom mycelium obtained by the method according to any one of claims 1 to 5.

7. The application of the selenium-enriched seafood mushroom mycelium according to claim 6 in the preparation of selenium-enriched seafood mushroom powder.

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