Method for preparing organic selenium by using saussurea involucrata and application of organic selenium

Abstract

The invention discloses a method for preparing organic selenium from saussurea involucrata and application of the method, and belongs to the technical field of organic selenium preparation. The preparation method of the organic selenium provided by the invention comprises the following steps: the inoculation amount of saussurea involucrata is 2.5%, a sterile Na2SeO3 solution is added after culture is performed for 2 hours, the working concentration of Na2SeO3 is 25 mu g / mL, and culture is continued for 36 hours after uniform mixing; the organic selenium is successfully prepared by adopting the preparation method provided by the invention, the final total selenium content is 1356.60 + / -23.75 mu g / g, the selenium conversion rate is 19.94 + / -0.14%, the organic selenium content is 1177.74 + / -28.82 mu g / g, and the proportion is 86.81 + / -0.89%; the provided preparation method of the selenium-rich saussurea involucrata bacteria is simple and easy to operate, has low requirements on instruments and equipment and high conversion rate of organic selenium, and can be used for industrial production of organic selenium.

Description

Technical Field

[0001] This invention relates to the field of organic selenium preparation technology, and in particular to a method for preparing organic selenium using Saussurea involucrata and its application. Background Technology

[0002] Selenium was discovered in 1817 by the Swedish chemist... Jakob Berzelius first discovered it, primarily in the form of inorganic selenium (Se). 2- SeO4 2- SeO3 2- Organic selenium (such as selenoproteins) and zero-valent selenium (Se... 0 Selenium exists in the form of selenium. Studies have shown that selenium is one of the essential trace elements for the growth, development, and biological functions of organisms, and plays an important role in the central nervous system, endocrine system, and cardiovascular system.

[0003] Although selenium has many important physiological functions, such as antioxidation, anti-cancer effects, and immune regulation, the safe intake and potential toxicity ranges for selenium are relatively narrow. Selenium deficiency is defined as a selenium content in human plasma below 70 μg / L or a selenium content in hair below 0.2 μg / g. When the selenium content in the body is below 80 ng / mL, it usually causes selenium deficiency diseases, such as Keshan disease and Kashin-Beck disease. Keshan disease is caused by both selenium deficiency and a mutant strain of Coxsackie B virus, causing symptoms such as chest tightness, nausea, vomiting, and myocardial necrosis. Furthermore, studies have shown that selenium deficiency is also associated with diseases of the nervous and immune systems; insufficient selenium supply to the brain may lead to Alzheimer's disease. Similarly, excessive selenium can also be harmful to the human body. Both inorganic and organic selenium can have toxic effects on organisms. Selenium can replace sulfur in cysteine ​​and methionine, and it can also replace sulfur in the synthesis of thioglycolic acids and the reaction of selenite with thiol groups. Excessive replacement can lead to the loss of protein or enzyme function, thereby causing symptoms such as hair loss, skin diseases, and bad breath.

[0004] The human body primarily obtains selenium from various plant and animal products consumed daily. The development of selenium-enriched foods, especially those rich in organic selenium, provides a more effective way to supplement selenium nutrition. Selenium-enriched foods are mainly divided into naturally enriched and artificially enriched foods. Naturally enriched selenium foods refer to plant and animal products cultivated using selenium from natural resources, while artificially enriched selenium foods involve the addition of inorganic selenium, which is then converted into organic selenium-rich foods by plants, animals, or microorganisms. The human body's ability to absorb and utilize different forms of selenium varies. In animal products, selenium mainly exists as selenocysteine, which is easily digested and utilized by the body. In plant products, selenium is mainly absorbed and converted from SeO4 in the external environment. 2- and SeO32- To form selenomethionine and selenocysteine.

[0005] Tibetan Kefir Grains (TKGs) are mainly distributed in the high-altitude areas of western my country. They were initially discovered in the cowhide bags used by herders to hold milk, where they undergo long-term natural fermentation to form 0.3–3.5 cm granules. TKGs are composed of proteins, polysaccharides, and a complex microbial community, resulting in a curled, hollow structure with low melting point, emulsifying properties, and the ability to alter food texture. The microbial composition of TKGs mainly consists of lactic acid bacteria, yeast, and acetic acid bacteria, with lactic acid bacteria and yeast being the dominant groups. These different groups interact to form a stable ecosystem. Multiple studies have shown that TKGs exhibit good antioxidant activity, reducing intracellular ROS production, inhibiting apoptosis, and lowering inflammatory cytokine levels, thus providing protection to the human body. Simultaneously, during fermentation, TKGs produce organic acids, acetaldehyde, CO2, and bacteriocins, substances with antibacterial effects, while also competing with pathogens for nutrients, making them a highly promising antibacterial agent. In addition, the intake of TKGs can regulate the gut microbiota in the human body, thereby preventing organ damage and disease by promoting the oxidation of substances such as fatty acids. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing organic selenium using Saussurea involucrata and its application, so as to provide a method for efficiently preparing organic selenium using Saussurea involucrata.

[0007] To achieve the above objectives, the present invention provides a method for preparing organic selenium using *Saussurea involucrata*, comprising the following steps:

[0008] Inoculate sterile pure milk with *Symplocos edulis*, then add sterile inorganic selenium solution, let it stand for incubation, collect the *Symplocos edulis* after incubation, wash it, and extract the organic selenium.

[0009] Preferably, the concentration of inorganic selenium after adding sterile inorganic selenium solution to sterile pure milk is 20–40 μg / mL.

[0010] Preferably, sterile pure milk is inoculated with Saussurea involucrata and cultured at 28°C for 2–4 hours before adding sterile inorganic selenium solution.

[0011] Preferably, the inoculation amount of *Syzygium spp.* is 1% to 2% of the total amount of aseptic pure milk to which aseptic inorganic selenium solution has been added.

[0012] Preferably, after adding sterile inorganic selenium solution, the mixture is incubated statically for 36–48 hours.

[0013] Preferably, the snow lotus fungus is collected by filtration.

[0014] Preferably, the washing is performed using sterile distilled water.

[0015] An organic selenium prepared using the method described above for preparing organic selenium from snow lotus fungus.

[0016] An application of an organic selenium source as described above in the preparation of organic selenium-containing foods.

[0017] The application of an organic selenium as described above in the preparation of organic selenium supplements.

[0018] Therefore, the present invention provides a method for preparing organic selenium using Saussurea involucrata and its application, the specific technical effects of which are as follows:

[0019] (1) The method for preparing organic selenium provided by the present invention is as follows: the inoculum amount of snow lotus is 2.5%, and after culturing for 2 hours, sterile Na2SeO3 solution is added. The working concentration of Na2SeO3 is 25 μg / mL. After mixing, the mixture is further cultured for 36 hours.

[0020] (2) Organic selenium was successfully prepared using the preparation method provided by the present invention. The final total selenium content was 1356.60±23.75μg / g, the selenium conversion rate was 19.94±0.14%, the organic selenium content was 1177.74±28.82μg / g, and the proportion was 86.81±0.89%.

[0021] (3) The organic selenium preparation method provided by the present invention is simple and easy to operate, has low requirements for instruments and equipment, and has a high organic selenium conversion rate, and can be used for the industrial production of organic selenium.

[0022] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is the selenium standard curve prepared in Example 2 of the present invention;

[0025] Figure 2 This illustrates the effect of different substrate concentrations on biomass and unit selenium enrichment in Example 2 of this invention.

[0026] Figure 3 This illustrates the effect of different substrate concentrations on the viable counts of lactic acid bacteria and yeast in Example 2 of the present invention.

[0027] Figure 4 This illustrates the effect of different substrate concentrations on the color of TKGs in Example 2 of this invention; where - represents white; + represents light red; ++ represents red; and +++ represents dark red.

[0028] Figure 5 This describes the effect of inoculation amount on the selenium enrichment effect of TKGs in Example 2 of the present invention.

[0029] Figure 6 This describes the effect of inorganic selenium addition time on the selenium enrichment effect of TKGs in Embodiment 2 of the present invention.

[0030] Figure 7 This describes the effect of cultivation time on the selenium enrichment effect of TKGs in Example 2 of the present invention. Detailed Implementation

[0031] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0032] To make the objectives, technical solutions, and advantages of this application clearer, more thorough, and more complete, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. The following detailed descriptions are all illustrations of embodiments, intended to provide further detailed explanation of the present invention. Unless otherwise specified, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0033] The instruments, equipment, reagents and materials used in the examples were all obtained commercially; the Na2SeO3 was of analytical grade with a purity of 99%; the Saussurea costatum was obtained from a laboratory strain bank; and the methods and steps not described in detail were all conventional techniques in the art.

[0034] Example 1

[0035] The specific steps for activating TKGs (Teacinthia suspensa) are as follows:

[0036] TKGs stored at -20℃ were thawed at 4℃ and then filtered through a 2mm sieve to obtain *Symplocos edulis* granules. The surface of the granules was washed with sterile distilled water. Subsequently, the granules were inoculated into sterile milk in a laminar flow hood, sealed with sealing film, and incubated at 28℃. Fresh sterile milk was passed through a 2mm sieve every 24 hours for 7 consecutive days to activate the TKGs.

[0037] Example 2

[0038] The conditions for preparing organoselenium were optimized as follows:

[0039] S21. Material preparation.

[0040] Sterile Na2SeO3 solution: Accurately weigh 0.5g Na2SeO3 and dissolve it in 100mL of sterile distilled water to prepare a 5mg / mL Na2SeO3 solution. Dispense the solution into centrifuge tubes and sterilize at 95℃ for 15min.

[0041] Aseptic pure milk: Pure milk (purchased from a local supermarket) is dispensed into culture bottles, sealed with sealing film, and sterilized at 95°C for 15 minutes.

[0042] TKGs microbial particles: The activated TKGs from Example 1 were passed through a 2mm sieve and washed with sterile distilled water. Then, TKGs microbial particles with similar diameters and growth conditions were selected in a clean bench, weighed, and placed in sterile containers for later use.

[0043] S22. Prepare a selenium standard curve.

[0044] A 100 mg / L selenium standard solution was diluted with 20% hydrochloric acid to prepare selenium standard solutions with concentrations of 0, 2, 4, 6, 8, 12, 16, and 20 μg / L. 1.00 mL of each of the different concentrations of selenium standard solutions was taken, and the selenium content was determined using hydride atomic fluorescence spectrometry.

[0045] A selenium standard curve was established by fitting the selenium concentration as the x-axis and the fluorescence intensity as the y-axis, as shown below. Figure 1 As shown, the obtained regression equation is y = 131.31x - 32.40, and its R² value is within the range of 0-20 μg / L. 2 =0.9998, therefore, the fluorescence intensity measured by this instrument has a good linear relationship with the selenium concentration of the set series of standard solutions. When determining the selenium content in a sample, it can be measured by diluting to a range of 0–20 μg / L.

[0046] S23. Determine the optimal concentration of selenium-enriched substrate.

[0047] A certain amount of sterile Na₂SeO₃ solution was added to sterile pure milk to achieve Na₂SeO₃ concentrations of 5, 10, 15, 20, 25, 30, 35, and 40 μg / mL. Then, 2% (v / v) TKGs bacterial granules were inoculated into each granule and incubated at 28°C for 24 hours. After incubation, the granules were collected by passing them through a 2 mm sieve and washing them several times with distilled water to obtain selenium-enriched bacterial granules.

[0048] The color of the microbial cells is positively correlated with the selenium content. A high-selenium environment accelerates the production of elemental selenium, which is toxic to microorganisms, imparts a metallic taste to food, and ruins the flavor of fermented products. Therefore, the unit selenium enrichment, biomass, viable cell count, and color are used as evaluation indicators.

[0049] (1) The selenium-enriched bacterial particles obtained after washing were pre-frozen at -80℃ for 12 hours, then freeze-dried under vacuum until constant weight, and their mass was recorded as the biomass. The results are as follows: Figure 2 As shown, with the increase of selenium-enriched substrate concentration, the biomass of Se-TKGs showed a trend of first increasing and then decreasing. When the selenium-enriched substrate concentration was 25 μg / mL, the biomass of selenium was 0.1017 ± 0.0014 g. However, when the concentration was too high, inorganic selenium would have a toxic effect on microorganisms, thereby inhibiting their growth.

[0050] (2) Place the freeze-dried selenium-enriched microbial particles in a digestion vessel that has been soaked in 20% nitric acid overnight, add 5 mL of nitric acid and pre-digest at 110°C for 30 min, cool to room temperature and then add 1 mL of nitric acid and 1 mL of hydrogen peroxide, mix well and seal the lid for microwave digestion. The microwave digestion procedure is shown in Table 1.

[0051] Table 1 Microwave Digestion Procedure

[0052] step Set temperature (°C) Heating time (min) Isothermal time (min) 1 120 6 1 2 150 3 5 3 180 5 10

[0053] After microwave digestion is complete, the digestion vessel is opened to release pressure and transferred to a 160℃ electric furnace for acid removal until approximately 1 mL of clear liquid remains in the digestion vessel. After cooling to room temperature, 5 mL of 50% hydrochloric acid solution is added, and reduction is carried out at 110℃ for 30 min. After cooling, the solution is transferred to a 50 mL volumetric flask, diluted to volume with sterile distilled water, and mixed thoroughly. The sample is then diluted to a concentration of 0–20 μg / L and detected using hydride atomic fluorescence spectrometry. The result is substituted into the selenium standard curve prepared in step S22 to obtain the selenium concentration ρ. The same method is used to detect the sample without added selenium-enriched bacterial particles (blank control), and the result is recorded as ρ0. The amount of selenium per unit volume in the prepared selenium-enriched bacterial particles is calculated using Formula I:

[0054]

[0055] Where X represents the selenium content in the selenium-enriched bacterial granules (μg / g); ρ represents the selenium concentration in the sample (μg / L); ρ0 represents the selenium concentration in the blank (μg / L); V represents the total volume of the sample after final volume adjustment (mL); and m represents the mass of the sample after freeze-drying (g).

[0056] The results are as follows Figure 2 As shown, the concentration of selenium-enriched substrate increases, and the unit selenium enrichment of the bacterial particles increases, indicating that TKGs have a high adsorption and absorption capacity for sodium selenite.

[0057] Methods for counting viable bacteria: Under aseptic conditions and at 4°C, grind the bacterial particles. Add 1g of the ground powder to 9mL of sterile physiological saline and vortex for 1min. Continuously dilute the suspension in 10-fold serial dilutions and inoculate 100μL into MRS and YPD media, repeating each dilution three times. Incubate the MRS-inoculated particles anaerobically at 37°C for 24h, then count the lactic acid bacteria. Incubate the YPD-inoculated particles at 28°C for 48h, then count the yeast colonies on the media. Select dilution plates with colony counts between 30-300 for counting. Calculate lg CFU / g using Formula II.

[0058]

[0059] MRS medium: Dissolve the broth medium in distilled water according to the instructions, add 2% agar, and autoclave at 121°C for 15 minutes.

[0060] YPD medium: Dissolve 1% yeast extract, 2% glucose, 2% peptone and 2% agar in distilled water and autoclave at 121°C for 15 min.

[0061] The results are as follows Figure 3 As shown, with increasing selenium-enriched substrate concentration, the viable count of lactic acid bacteria initially increased and then decreased, while the viable count of yeast initially plateaued and then decreased. When the selenium-enriched substrate concentration was 25 μg / mL, the viable counts of lactic acid bacteria and yeast were 6.66 ± 0.04 lg CFU / g and 6.69 ± 0.0140 lg CFU / g, respectively. When the concentration exceeded 25 μg / mL, the viable count trend plateaued with increasing concentration, indicating that within the 25-40 μg / mL range, the inorganic selenium effect slowed microbial growth, a result consistent with the biomass trend.

[0062] Bacterial color identification: The color of the selenium-enriched bacterial granules, which were vacuum freeze-dried to constant weight in step S23 (1), was evaluated.

[0063] The results are as follows Figure 4 As shown in Table 2, the red color of the bacteria deepened with increasing concentration of selenium-enriched substrate. When the concentration exceeded 25 μg / mL, the color of the bacteria deepened and the fermentation broth had an off-odor.

[0064] Table 2. Comparison of bacterial particle colors at different selenium-enriched substrate concentrations.

[0065] Selenium-enriched substrate concentration (μg / mL) 0 10 15 20 25 30 35 40 Mycelium color - + + + + ++ ++ +++

[0066] Where - represents white; + represents light red; ++ represents red; and +++ represents dark red.

[0067] In summary, a substrate concentration of 25 μg / mL is the critical concentration value for TKGs to achieve optimal properties in terms of biomass, unit selenium enrichment, and viable bacterial count. Therefore, the final selenium-enriched substrate concentration was determined to be 25 μg / mL.

[0068] During the cultivation of S24 and TKGs, microorganisms such as lactic acid bacteria and yeast can biotransform inorganic selenium. Therefore, single-factor experiments were conducted using unit selenium enrichment amount and selenium conversion rate as evaluation indicators to reflect the selenium enrichment effect of TKGs, and three levels were selected for subsequent experiments.

[0069] The method for determining the unit selenium enrichment is the same as in step S23. The selenium element conversion rate is calculated according to formula III:

[0070]

[0071] Where Y represents the selenium conversion rate in the sample; X represents the unit selenium enrichment amount; M represents the amount of selenium added to the sample, in micrograms (μg); and m represents the mass (g) of the sample after freeze-drying.

[0072] (1) Effect of TKGs inoculum amount on the selenium enrichment effect of TKGs. 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, and 4% (w / v) of TKGs bacterial granules were inoculated into sterile milk containing 25 μg / mL Na2SeO3, and cultured at 28℃ for 24 h. After culture, the bacterial granules were collected through a 2 mm sieve and washed several times with distilled water.

[0073] The results are as follows Figure 5 As shown, when the inoculum size of TKGs increased to 2%, the selenium conversion rate began to increase slowly. This indicates that at this stage, excessively high inoculum sizes led to competition among the microbial communities in the TKGs, reducing the available nutrients and inhibiting their conversion of inorganic selenium. Therefore, orthogonal experiments were subsequently conducted with inoculum sizes of 1.0%, 1.5%, and 2.0%.

[0074] (2) Effect of inorganic selenium addition time on the selenium enrichment effect of TKGs.

[0075] 1% (v / v) of TKGs bacterial granules were inoculated into sterile milk and cultured at 28℃ for 2 h, 4 h, 6 h, 8 h, 10 h, and 12 h, respectively. Sterile Na₂SeO₃ solution was then added to adjust the substrate concentration to 25 μg / mL, and the culture was continued for 24 h. After the culture was completed, the bacterial granules were collected through a 2 mm sieve and washed several times with distilled water. The selenium enrichment per unit area and selenium conversion rate were determined.

[0076] The results are as follows Figure 6As shown, with the progression of selenium addition time, both the unit selenium content and selenium conversion rate of the bacteria exhibited a trend of first rapidly increasing and then slowly decreasing. For TKGs with an inoculum size of 1%, adding Na2SeO3 after 2 to 4 hours of cultivation resulted in better selenium enrichment of the bacteria compared to other time points. Adding inorganic selenium at the 4th hour resulted in the highest unit selenium content and selenium conversion rate, at 1668.37±20.56 μg / g and 13.53±0.26%, respectively. These results indicate that TKGs can better adapt to the selenium environment after culturing in aseptic milk for 2 to 4 hours. Therefore, subsequent orthogonal experiments were conducted with inorganic selenium addition times at 2 hours, 4 hours, and 6 hours of cultivation.

[0077] (4) The effect of incubation time on the selenium enrichment effect of TKGs.

[0078] 1% (v / v) TKGs bacterial granules were inoculated into sterile milk containing 25 μg / mL Na2SeO3 and incubated statically at 28℃ for 6, 12, 18, 24, 30, 36, 42, 48, 54, and 60 h, respectively. After incubation, the bacterial granules were collected through a 2 mm sieve and washed several times with distilled water. The unit selenium enrichment and selenium conversion rate were then determined.

[0079] The results are as follows Figure 7 As shown, with the increase of culture time, the unit selenium enrichment and selenium conversion rate of Se-TKGs showed a trend of first increasing and then decreasing. Especially after fermentation culture for 42 hours, the unit selenium enrichment and selenium conversion rate of Se-TKGs tended to level off. When fermentation reached 60 hours, both the unit selenium enrichment and selenium conversion rate began to decrease. Therefore, orthogonal experiments were subsequently conducted at three levels of culture time: 36 hours, 42 hours, and 48 hours.

[0080] (5) Orthogonal experiment. Inoculum size (A): 1.0%, 1.5%, 2.0%; selenium addition time (B): 2h, 4h, 6h; culture time (C): 36h, 42h, 48h. Based on L9(3 4 The experimental design was carried out using the table. The factors and levels are shown in Table 3. The experimental results and analysis of variance are shown in Tables 4 and 5.

[0081] Table 3. Factor Level Table for Orthogonal Experiment

[0082]

[0083] Table 4 Results of the orthogonal experiment

[0084]

[0085] In the table, yi represents the selenium conversion rate in the i-th repeated experiment.

[0086] Table 5. Analysis of Variance of Orthogonal Experiment Results

[0087]

[0088]

[0089] Table 5 shows that the inoculum size and selenium addition time both have a highly significant impact on the selenium conversion rate of Se-TKGs, while the culture time has no significant effect on the selenium conversion rate of Se-TKGs. The order of influence of each factor on the selenium conversion rate of Se-TKGs is A>B>C, i.e., inoculum size>selenium addition time>culture time.

[0090] As shown in Table 4, the optimal combination obtained from the experiment is A3B1C1, which means the inoculum amount is 2.0%, the selenium addition time is 2h, and the culture time is 36h.

[0091] Inoculate 2.5% activated *Saussurea involucrata* into 150 mL of sterile pure milk. After culturing at 28°C for 2 h, add sterile Na₂SeO₃ solution to make the Na₂SeO₃ concentration 25 μg / mL. Mix well and continue culturing at 28°C for 36 h. Collect selenium-enriched bacterial particles by sieving. Wash three times with sterile distilled water. Determine the organic selenium content using the following method: Add 50% hydrochloric acid to the prepared selenium-enriched bacterial particles, sonicate for 45 min, boil in a water bath for 30 min, centrifuge at 8000 rpm for 20 min, and collect 1 mL of the supernatant. Then, obtain the inorganic selenium content X₂ using the method in step S23 (2), and calculate the organic selenium content using formula IV.

[0092] X1 = X - X2 (Equation IV),

[0093] Where X1 represents the organic selenium content (μg / g); X2 represents the inorganic selenium content (μg / g); and X represents the unit selenium enrichment amount.

[0094] The conversion effect is shown in Table 6. The final total selenium content was 1356.60±23.75μg / g, the selenium conversion rate was 19.94±0.14%, and the organic selenium content was 1177.74±28.82μg / g, accounting for 86.81±0.89%.

[0095] Table 6. Statistical table of transformation effect of *Saussurea involucrata* under optimal conditions.

[0096]

[0097] Therefore, the method for preparing organic selenium using *Saussurea involucrata* provided by this invention is as follows: the inoculum amount of *Saussurea involucrata* is 2.5%, and after culturing for 2 hours, sterile Na2SeO3 solution is added. The working concentration of Na2SeO3 is 25 μg / mL. After mixing, the mixture is further cultured for 36 hours. Organic selenium was successfully prepared using the method provided by this invention. The final total selenium content was 1356.60±23.75 μg / g, the selenium conversion rate was 19.94±0.14%, and the organic selenium content was 1177.74±28.82 μg / g, accounting for 86.81±0.89%. The provided method for preparing organic selenium is simple and easy to operate, has low requirements for instruments and equipment, and has a high organic selenium conversion rate. It can be used for the industrial production of organic selenium.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing organic selenium using a snow fungus, characterized in that, The method comprises the following steps: The method comprises the following steps:

2. The method for preparing organic selenium with Ophiocordyceps sinensis according to claim 1, characterized in that: The concentration of inorganic selenium in the sterile inorganic selenium solution added into the sterile pure milk is 20-40 μg / mL.

3. The method for preparing organic selenium with Ophiocordyceps sinensis according to claim 1, characterized in that: The sterile inorganic selenium solution is added into the sterile pure milk inoculated with the snow lotus bacteria after the inoculated milk is cultured at 28°C for 2-4 h.

4. The method for preparing organic selenium with Ophiocordyceps sinensis according to claim 1, characterized in that: The inoculation amount of the snow lotus bacteria is 1%-2% of the total amount of the sterile pure milk added with the sterile inorganic selenium solution.

5. The method for preparing organic selenium with Ophiocordyceps sinensis according to claim 1, characterized in that: The culture is static for 36-48 h after the sterile inorganic selenium solution is added.

6. The method for preparing organic selenium with Ophiocordyceps sinensis according to claim 1, characterized in that: The snow lotus bacteria are collected by filtration.

7. The method for preparing organic selenium with Ophiocordyceps sinensis according to claim 1, characterized in that: The washing is performed by using sterile distilled water.

8. Organic selenium prepared by the method of claim 1-7.

9. Use of the organic selenium of claim 8 in the preparation of organic selenium food.

10. Use of the organic selenium of claim 8 in the preparation of organic selenium supplement.

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