Method for rapidly screening high-poly-selenium shiitake mushroom strains in batches and application of high-poly-selenium shiitake mushroom strains

Abstract

The invention provides a method for rapidly screening high-poly-selenium mushroom strains in batches and application, and belongs to the technical field of edible mushroom breeding and cultivation. Respectively inoculating the strains on a selenium-free basic culture medium to obtain pure mycelia as a mother strain of a subsequent experiment; a series of culture media containing different concentrations of selenium are designed by adopting a gradient incremental method, the selenium gathering characteristics of different strains can be comprehensively covered and distinguished, and the growth conditions and color changes of the strains under different selenium concentrations are further comprehensively analyzed and compared, so that the shiitake mushroom strain with the strongest selenium gathering capacity is screened out. According to the method disclosed by the invention, the shiitake mushroom strain with relatively strongest selenium gathering capacity can be screened out, and the upper limit of the concentration of exogenous selenium added in the production of the shiitake mushroom strain is determined, so that the yield and the quality are not influenced in the actual production of the shiitake mushroom strain, and meanwhile, the produced shiitake mushroom can reach the selenium element content standard required by the current national standard GB1903.22-2016 on the selenium-rich edible mushroom powder.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of Lentinula edodes solid strain screening, and particularly relates to a method for rapidly and batch screening of high-selenium Lentinula edodes strains and application thereof. BACKGROUND

[0002] Selenium is one of the trace elements necessary for maintaining normal physiological functions of the human body. Studies have shown that many chronic diseases such as Keshan disease, Kashin-Beck disease, type 2 diabetes, and thyroid nodules are related to selenium deficiency. Appropriate intake of selenium has many functions such as anti-tumor, anti-oxidation, and enhancement of human immunity. However, the selenium content in most natural foods is extremely low and far from meeting the normal needs of the human body, so it is necessary to scientifically and effectively supplement selenium. The development and research of selenium-rich foods have become one of the hotspots for improving the nutritional value and market competitiveness of agricultural products. As a kind of popular edible fungus, Lentinula edodes has attracted much attention due to its rich nutritional ingredients. In recent years, with the deepening of people's understanding of the health benefits of selenium, the research and production of selenium-rich Lentinula edodes have gradually become the focus of the industry.

[0003] As a kind of large fungus, the fruiting body of Lentinula edodes is edible and rich in nutrients. Under the condition of artificial addition of exogenous selenium, Lentinula edodes can absorb and convert inorganic selenium into organic selenium, not only improving the taste, but also improving the nutritional and health value, becoming an ideal selenium source supplement. There are two different selenium content standards for selenium-rich Lentinula edodes in China. One is directly used as a vegetable, with a selenium content requirement of 0.15-5 mg / kg, such as the current Shaanxi local standard DB61 / T556 and cooperative standard GHT1135. The other is used as a high-selenium food additive, with a selenium content requirement of 180-400 mg / kg (national standard GB1903.22). As a food additive, the latter has higher requirements for selenium content. The common Lentinula edodes strains have growth limitations in high-selenium concentration medium, such as growth inhibition, red mycelium, yield reduction, and even death. Therefore, it cannot meet the selenium content requirements. The main reason is that the Lentinula edodes strain cannot assimilate a large amount of exogenous selenium into Lentinula edodes organic selenium, and the strain cannot grow and differentiate normally in the presence of high-concentration exogenous selenium. In order to produce high-selenium edible fungus additives that meet the selenium content requirements of national standard GB1903.22, screening of high-selenium Lentinula edodes strains becomes the first important step in production.

[0004] The existing methods for screening high-selenium agaricus bisporus strains are as follows: 1) The selenium-enriching capacity of a strain is evaluated by measuring the mycelium length or the propagation speed. For example, a method for screening selenium-enriched agaricus bisporus solid strains and a device are disclosed in a Chinese patent (application number 202110228399.9). The method selects three agaricus bisporus varieties, sets two groups of culture media to which inorganic selenium (Na2SeO3) and organic selenium are added at a gradient concentration of 25-90 mg / kg, measures the mycelium length after inoculation and cultivation by using a vernier caliper, records and compares the growth speed of the mycelium in the culture media, and analyzes and compares to obtain the conclusion that the addition of 60 mg / kg of organic selenium is the best concentration and type of exogenous selenium, and a strain with the fastest growth is screened from the three varieties. Although this method can reflect the stress resistance and growth speed of the strain, it cannot directly determine the ability of the strain to assimilate exogenous selenium into organic selenium, which means that even if a strain with a fast growth speed is screened, the selenium-enriching effect of the strain is not ideal. 2) The selenium-enriching capacity of a strain is evaluated by extracting and detecting the selenium protein content in the fruiting body of the strain. For example, Wei et al. reported a protoplast mutagenesis breeding technology for selenium-enriched agaricus bisporus strains (Wei et al., Protoplast mutagenesis breeding technology for selenium-enriched agaricus bisporus strains, Edible Fungi, 2004, 26(2): 12). The protoplasts of agaricus bisporus are prepared, and then the protoplasts are subjected to ultraviolet mutagenesis. The mutagenized strains are inoculated into culture media containing different concentrations of selenium, and the agaricus bisporus is cultivated to the fruiting body stage. Then, the selenium protein content in the fruiting bodies of different strains is measured to determine the selenium-enriching capacity of the mutagenized strains, and a strain with a strong selenium-enriching capacity is obtained. Although this method is accurate, it is complicated, time-consuming, and not suitable for large-scale screening. In addition, the experimental conditions are high, and professional detection equipment and technical personnel are required, which increases the cost and difficulty of screening. In view of the limitations of the above methods, there is an urgent need for an efficient, intuitive and rapid screening method. Research on the selenium metabolism mechanism of microorganisms shows that the color change of mycelium can directly reflect the selenium metabolism state. When the assimilation capacity of a strain is insufficient, excessive selenium will be dissimilated and reduced to red nano-selenium particles. This phenomenon provides a theoretical basis for developing a new screening method. However, there is no report on the use of this principle to screen high-selenium agaricus bisporus strains. SUMMARY

[0005] In view of the technical status that the existing methods for screening selenium-enriched agaricus bisporus strains are complicated, time-consuming, high in cost and not suitable for large-scale screening, cannot directly and rapidly determine and screen agaricus bisporus strains with high selenium assimilation capacity, and have a low screening accuracy, the present application aims to provide a method for rapidly and batch screening high-selenium agaricus bisporus and applications thereof.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solutions: The present application provides a method for rapidly and batch screening high-selenium agaricus bisporus strains, comprising: Step 1, inoculating candidate agaricus bisporus strains into a basic culture medium for cultivation to obtain seed bank strains; Step 2, inoculate the seed bank strain to the initial screening selenium-containing medium plate, and invert culture until the mycelium grows, and the strain with non-red mycelium is reserved, and the selenium content of the initial screening selenium-containing medium is 40 mg / L; Step 3, inoculate the strain with non-red mycelium in step 2 to the screening medium with increasing selenium content, and continue to culture for multiple rounds, and the strain with non-red mycelium obtained by screening is the target strain, i.e. high selenium-accumulating Lentinula edodes strain; The screening medium with increasing content is the screening medium with the increasing gradient of 20 mg / L per time.

[0007] In step 1, the basic medium is composed of 200 g of potato, 20 g of glucose, 20 g of agar, 3 g of MgSO4, 0.5 g of KH2PO4, 5.0 g of proteose peptone, and 1000 mL of water.

[0008] Further, the candidate Lentinula edodes strain is more than two different Lentinula edodes strains with strong stress resistance, fast growth and high yield.

[0009] In step 2, the initial screening selenium-containing medium is the basic medium added with a selenium source, and the selenium content is obtained by selenium content, and the selenium source is sodium selenite or potassium selenite.

[0010] In step 2, the temperature of the inverted culture is 25-30℃, and the inverted culture time is 1-3 weeks.

[0011] In step 3, the selenium content of the screening medium is 60-100 mg / L, and the culture temperature is 25-30℃.

[0012] The above-mentioned method for rapidly and batch screening high selenium-accumulating Lentinula edodes strain further comprises a selenium tolerance capacity prediction step of the target strain, specifically comprising: inoculating the target strain to screening medium 2 with a selenium content higher than that of the screening medium, inverting culture until the mycelium is formed, and observing the color of the mycelium, when the color of the mycelium is red, the selenium content of the screening medium is the highest selenium tolerance concentration of the target strain.

[0013] The selenium content of the screening medium 2 is 120-200 mg / L.

[0014] The method for producing high selenium-accumulating Lentinula edodes obtained by the method uses the high selenium-accumulating Lentinula edodes strain as the strain to inoculate the base material, and cultures to obtain high selenium-accumulating Lentinula edodes.

[0015] The selenium content of the base material is 75-150 mg / kg, and the base material is composed of 80% of sawdust, 18% of bran, 1% of gypsum and 1% of light calcium carbonate; and the culture condition is constant temperature culture at 26-30℃.

[0016] Compared with the prior art, the present application has the following beneficial effects: The present application provides a method for quickly batch screening high selenium-accumulating Lentinula edodes, for the first time proposes a combination strategy of "grading screening + color index + gradient increase", and screens high selenium-accumulating strains by observing the color change of Lentinula edodes strains on culture media with different selenium concentrations. The method is intuitive and easy to operate, and can quickly, intuitively and accurately identify Lentinula edodes strains with strong selenium assimilation ability and high selenium accumulation. Through multiple screenings by gradually increasing the selenium concentration, the strain with the strongest assimilation ability and the highest selenium concentration can be accurately found, effectively solving the problem of low screening accuracy in existing methods and improving the accuracy and reliability of screening. Compared with traditional screening methods based on growth rate, reproduction rate or selenium protein content, the present method is more efficient, can directly judge the selenium assimilation ability of the strain in a short time (through the color change of the colony or the lichen), and greatly saves the screening time and cost.

[0017] Further, by additionally testing the tolerance of the target strain to a higher selenium concentration (120-200 mg / L), the screened high selenium-accumulating Lentinula edodes strain has a high selenium tolerance concentration (200 mg / L), has important application value in commercial production, can significantly improve the selenium content and nutritional value of Lentinula edodes, and can be directly applied to the commercial production of Lentinula edodes to improve the selenium content and nutritional value of Lentinula edodes and meet the market demand for healthy food.

[0018] The screening method adopted by the present application has universality based on the principle of color change, and can be used not only for screening selenium-rich Lentinula edodes, but also for screening other selenium-rich microorganisms (such as selenium-rich yeast, selenium-rich Pleurotus ostreatus, Hericium erinaceus, Tricholoma matsutake, and all edible fungi and microorganisms), and has wide application prospects and value.

[0019] The target strain screened by the present application can be directly used for selenium-rich Lentinula edodes cultivation, shortening the research and development to industrialization cycle, and the high selenium-accumulating Lentinula edodes strain obtained by the above screening method has strong selenium assimilation ability and a high selenium tolerance concentration (120-200 mg / L), which has important application value in commercial production and can significantly improve the selenium content and nutritional value of Lentinula edodes. Inoculating the high selenium-accumulating Lentinula edodes strain into the substrate for cultivation can obtain high selenium-accumulating Lentinula edodes with a selenium content of 300-400 mg / kg, which not only has higher nutritional value, but also has better market prospects and economic benefits. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 Figure 1 is a schematic diagram of the strain inoculation method of the present application, wherein 1 is Japan 238, 2 is 808, 3 is L-241, 4 is Shengxiang 215, 5 is 130, 6 is 912, 7 is 168, 8 is Anxiang No. 1, 9 is 9608, 10 is Qingke 212, 11 is 908, and 12 is Qihex No. 9. Figure 2 Color presented by 12 strains of the method of the present application after cultivation in 40 mg / L medium; wherein 1 is Japan 238, 2 is 808, 3 is L-241, 4 is Shenxiang 215, 5 is 130, 6 is 912, 7 is 168, 8 is Anxiang No. 1, 9 is 9608, 10 is Qingke 212, 11 is 908, and 12 is Qihexi No. 9; Figure 3 Color presented by strains 9608 and Anxiang No. 1 of the method of the present application after cultivation in 80 mg / L medium, wherein 1 and 2 are 9608, and 3 and 4 are Anxiang No. 1; Figure 4 Color presented by strain 9608 of the method of the present application after cultivation in 180 mg / L medium. DETAILED DESCRIPTION

[0021] In order to make the personnel in the technical field better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the personnel in the field without creative labor should belong to the scope of protection of the present application.

[0022] It should be noted that the terms "first", "second", and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not have to be limited to the clearly listed steps or units, but can include other steps or units not clearly listed or inherent to the process, method, product or device.

[0023] The present application will be described in further detail below in combination with the drawings: Embodiment 1 (1) Establishment and preservation of seed bank: 12 normal production strains of Lentinula edodes were purchased from all over the country, and their number designation and strain characteristics are listed in Table 1.

[0024] Table 1: Collection and characteristics of production strains of Lentinula edodes

[0025] (2) Preparation of seed culture and screening medium: Basal culture medium: Weigh 200 g of potatoes, cut them into pieces, and boil them for 30 minutes. Filter the supernatant and add 20 g of glucose, 20 g of agar, 3 g of MgSO4, 0.5 g of KH2PO4, 5.0 g of peptone, and 1000 mL of water.

[0026] Screening medium: Based on the basal medium, different amounts of sodium selenite (Na2SeO3) were added to prepare the screening medium, where the selenium content (measured in selenium) was set to 40, 60, 80, and 100 mg / L, respectively.

[0027] The above culture media were sterilized and stored in Erlenmeyer flasks respectively. They were melted in advance before use and poured into plates. The plates were used after solidification.

[0028] (3) The 12 shiitake mushroom strains listed in Table 1 were transferred to the slant of the basal culture medium test tube respectively, and cultured in a 25°C incubator until the mycelium covered the entire slant. After the culture was completed, the test tube was stored in a 4°C environment and used as a seed bank strain.

[0029] (4) Preliminary screening The 12 seed bank strains were inoculated onto screening culture medium plates with a selenium content of 40 mg / L, with 4 strains inoculated on each plate. The specific inoculation layout is shown in the attached Figure 1 This layout helps to systematically observe and compare the growth of different strains under the same environmental conditions, ensuring the standardization and repeatability of the experiment. It also allows each strain to have a relatively independent and fixed growth space, reducing mutual interference between strains.

[0030] The inoculated plate was incubated upside down at 25°C for 2 weeks and observed after the bacterial lawn grew. Figure 2 As shown in the figure, strains 9608 and Anxiang No. 1 were found to have thick, lush, and stable mosses, and were retained. The remaining strains all turned varying shades of red. In an environment with a selenium concentration of 40 mg / L, a red moss generally indicates that the strain is selenium-sensitive, disrupting its intracellular physiological and biochemical processes and leading to abnormal mycelial growth. A thick, lush moss that does not turn red indicates that the strain has good selenium tolerance and can grow normally under certain selenium concentrations. Therefore, based on this observation, strains 9608 and Anxiang No. 1, which performed well, were retained, while the remaining selenium-sensitive strains were eliminated.

[0031] (5) Further screening The 9608 and Anxiang No. 1 strains that were initially screened were inoculated on 60 mg / L, 80 mg / L and 100 mg / L culture plates for further screening. The inoculated plates were also incubated inverted at 25°C for 2 weeks. The results were observed after the fungus lawns grew.Figure 3 , 9608 and Anxi No. 1 present color after culture in 80 mg / L medium, wherein the strain with white color of mycelium is 9608, and the strain with light red color of mycelium is Anxi No. 1. When the selenium concentration reaches 80 mg / L, the color of mycelium of Anxi No. 1 strain becomes red, while the color of mycelium of 9608 strain remains basically unchanged, which indicates that the physiological and biochemical processes in the cells of Anxi No. 1 strain are greatly affected by selenium at a concentration of 80 mg / L, resulting in abnormal mycelial growth (color change to red); while the 9608 strain can still maintain a relatively normal growth state at this concentration, and has stronger tolerance to selenium, so the 9608 strain is finally selected as the target strain.

[0032] (6) Upper limit of selenium tolerance When the selenium concentration is 100 mg / L, the color of the mycelium of strain 9608 remains basically unchanged, indicating that this concentration is not the upper limit of selenium tolerance of the target strain, and the selenium concentration needs to be further increased to determine the tolerance limit.

[0033] Strain 9608 was inoculated into selenium-containing medium with selenium content of 120 mg / L-200 mg / L (concentration gradient interval of 20 mg / L), respectively, and the mycelium was grown for 10 days at 25°C in an inverted culture. It was found that, referring to the attached Figure 4 When the selenium concentration reaches 180 mg / L, the color of the mycelium of strain 9608 becomes pink, and the size of the mycelium remains basically unchanged; while at a selenium content of 200 mg / L, the color of the mycelium is dark red, and the mycelium becomes small and thin, and the growth is inhibited, which indicates that the selenium concentration of 200 mg / L has seriously affected the normal growth of strain 9608. Therefore, it can be concluded that the upper limit of selenium tolerance of the strain is 170-180 mg / L. In production practice, the inorganic selenium content in the base material should be controlled not higher than 180 mg / kg to ensure the normal growth of the strain and the quality of the selenium-enriched product.

[0034] Through the above systematic experimental steps and observation and analysis, the 9608 strain with high tolerance to selenium is successfully screened, and the upper limit of its selenium tolerance is determined, which provides an important theoretical basis and practical guidance for the production of selenium-enriched shiitake mushrooms.

[0035] (7) Production verification of high selenium aggregation ability of strain 9608 The production cultivation medium was composed of 80% sawdust, 18% bran, 1% gypsum and 1% light calcium carbonate. According to the results of strain screening and selenium tolerance experiment, the selenium content of the production medium was set to 75, 100 and 150 mg / kg, i.e. 75 g, 100 g or 150 g of sodium selenite was added per ton of dry medium, while the production strain 808 of the enterprise was used as a control to compare the growth and selenium accumulation ability of the screened strain 9608 and the control strain 808 under different selenium concentrations.

[0036] In the three groups of cultivation media with different selenium contents, strains 808 and 9608 were inoculated respectively, and the medium preparation, sterilization, inoculation, cultivation and management were carried out according to the conventional method of shiitake mushroom production. During the growth of shiitake mushrooms, the growth rate, color change, primordium differentiation and fruiting body development of the two strains were observed, and after the shiitake mushrooms were harvested, the selenium content of the shiitake mushrooms was detected, and the observation results and determination results are shown in Table 2.

[0037] Table 2: Growth and development of the screened strain 9608 under different selenium content conditions

[0038] Analysis of the growth of the control strain 808 No selenium condition: The growth and development of strain 808 were normal, the mycelium was milky white, the growth amount was full of the bag, the fruiting body development was normal, the cap diameter was 4-6 cm, and the selenium content of the fruiting body was not detected, which indicated that strain 808 could grow normally in the normal selenium-free environment, meeting the basic requirements of shiitake mushroom production.

[0039] Low selenium condition (75 mg / kg): When the selenium content of the medium was 75 mg / kg, the mycelium of strain 808 turned pale red, the growth was greatly inhibited, and the growth amount was greatly reduced; the fruiting body development was severely disturbed, the differentiation was delayed, the yield was reduced, the cap diameter was smaller, and part of the fruiting bodies grew abnormally, and the selenium content of the fruiting body was 48 mg / kg. This indicated that strain 808 was sensitive to selenium, and its growth and development would be significantly affected under relatively low selenium concentration.

[0040] High selenium condition (100 mg / kg): When the selenium content was 100 mg / kg, the mycelium of strain 808 was more severely inhibited, and it was difficult to develop into normal fruiting bodies, and individual differentiated fruiting bodies were all abnormal, further indicating that strain 808 had poor tolerance to high concentration of selenium and could not grow and develop normally in high selenium environment.

[0041] Analysis of the growth of the screened strain 9608 The observation of the growth and development of strain 9608 shows that under the condition of different selenium contents in the base material, the mycelium of 9608 is milky yellow, no color change occurs, the mycelium grows plump, and grows into a full bag, which shows that strain 9608 has good tolerance to different concentrations of selenium, and the presence of selenium does not have a significant inhibitory effect on the mycelial growth; the fruit body develops normally, and the fruit bodies developed under the condition of containing selenium and not containing selenium have the same size and shape, and the cap diameter is 4-6 cm (4-5.5 cm when the selenium content is 150 mg / kg). This shows that strain 9608 can maintain normal fruit body development under high-selenium environment and is not affected by the concentration of selenium; the selenium content of the fruit body of strain 9608 is also increased accordingly, and when the selenium content in the base material is 75, 100 and 150 mg / kg, the selenium content of the fruit body is 218, 324 mg / kg and 420 mg / kg, respectively, all of which meet the national standard requirements (national standard GB 1903.22) for high-selenium shiitake mushrooms. Subsequent production verification shows that when the selenium content in the base material is 150 mg / kg, the selenium content of shiitake mushrooms can be increased to 442 mg / kg.

[0042] It can be seen that, through comparison with the control strain 808, the mycelium and fruit body of strain 9608 obtained by the screening method of the present application grow and develop well under high-selenium conditions, and the selenium content of the fruit body is greatly increased, meeting the current national standard GB 1903.22-2016 for the selenium content of high-selenium edible fungus additives (selenium content 180-400 mg / kg). This result verifies the effectiveness of the method of the present application, and provides an excellent strain selection for the production of selenium-rich shiitake mushrooms, which helps to improve the production efficiency and product quality of selenium-rich shiitake mushrooms and promote the development of the selenium-rich edible fungus industry. At the same time, it also provides a reference and reference for the screening and production of other selenium-rich microorganisms. The method of the present application for rapidly and batch screening of high-selenium shiitake mushroom strains is simple, fast, effective and intuitive, and can be used for actual production, which has important guiding significance for production practice.

[0043] The above content only illustrates the technical idea of the present application and cannot limit the protection scope of the present application. Any modification made according to the technical idea of the present application on the basis of the technical solution falls within the protection scope of the claims of the present application.

Claims

1. A method for rapid batch screening of high-selenium shiitake mushroom strains, characterized in that: include: Step 1: inoculating candidate shiitake mushroom strains into a basic culture medium to obtain seed bank strains; Step 2: Inoculate the seed bank strains onto a primary screening selenium-containing medium plate, invert and culture until a bacterial lawn grows, and retain the strains whose bacterial lawn does not turn red, wherein the primary screening selenium-containing medium has a selenium content of 40 mg / L; Step 3, inoculating the strain whose bacterial lawn does not turn red in step 2 into a screening culture medium with increasing selenium content, continuing to culture for multiple rounds, and screening the strain whose bacterial lawn does not turn red as the target strain, i.e., a high-selenium shiitake mushroom strain; The selenium content of the screening culture medium with a content gradient increase is increased by 20 mg / L each time.

2. The method for rapid batch screening of high-selenium shiitake mushroom strains according to claim 1, characterized in that: In step 1, the basal culture medium consists of 200 g potatoes, 20 g glucose, 20 g agar, 3 g MgSO4, 0.5 g KH2PO4, 5.0 g peptone, and 1000 mL water.

3. The method for rapid batch screening of high-selenium shiitake mushroom strains according to claim 1, characterized in that: In step 2, the primary screening selenium-containing culture medium is a basal culture medium with a selenium source added thereto, the selenium content is obtained in terms of selenium, and the selenium source is sodium selenite or potassium selenite.

4. The method for rapid batch screening of high-selenium shiitake mushroom strains according to claim 1, characterized in that: In step 2, the inverted culture temperature is 25°C to 30°C, and the inverted culture time is 1 to 3 weeks.

5. The method for rapid batch screening of high-selenium shiitake mushroom strains according to claim 1, characterized in that: In step 3, the selenium content of the screening culture medium is 60-100 mg / L, and the culture temperature is 25°C-30°C.

6. A method for rapid batch screening of high-selenium shiitake mushroom strains according to any one of claims 1 to 5, characterized in that: The method also includes a step of predicting the selenium tolerance of the target strain, specifically including: inoculating the target strain onto a screening culture medium 2 having a higher selenium content than the screening culture medium, inverting the culture medium until a bacterial moss is formed, observing the color of the bacterial moss, and when the color of the bacterial moss turns red, the selenium content of the screening culture medium is the highest selenium tolerance concentration of the target strain.

7. A method for rapid batch screening of high-selenium shiitake mushroom strains according to claim 6, characterized in that: The selenium content of the screening medium 2 is 120 mg / L-200 mg / L.

8. Use of the method for rapid batch screening of high-selenium shiitake mushroom strains according to any one of claims 1 to 7 in screening selenium-rich microorganisms.

9. A method for producing high-selenium shiitake mushrooms using a high-selenium shiitake mushroom strain obtained by the method according to any one of claims 1 to 7, characterized in that: A high-selenium shiitake mushroom strain is used as a bacterial inoculation base material and cultured to obtain the high-selenium shiitake mushroom.

10. The method according to claim 9, characterized in that The selenium content of the base material is 75 mg / kg to 150 mg / kg, and the base material composition is 80% sawdust, 18% bran, 1% gypsum, and 1% light calcium carbonate; the culture condition is a constant temperature culture at 26°C to 30°C.

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