Edible mushroom culture medium and cultivation method

Abstract

The invention belongs to the technical field of edible mushroom cultivation, and particularly relates to an edible mushroom culture medium and a cultivation method. The formula of each liter of the edible mushroom culture medium comprises 180-220 g of potatoes, 10-20 g of glucose, 5-15 g of fructose, 2-5 g of peptone, 1-5 g of yeast extract powder, 0.8-1.2 g of monopotassium phosphate, 0.3-0.8 g of magnesium sulfate, 0.05-0.5 g of methionine, 0.4-1.4 g of ferric ammonium citrate and 50-500 mg of sodium selenite, by adding the glucose and the fructose, the culture medium is in a weak acid environment, the selenium tolerance can be improved, the methionine is used as an assimilation carrier of selenium, and the selenium tolerance can be improved. In a thallus metabolism process, selenium is promoted to replace sulfur in methionine to generate selenomethionine with higher biological activity, the tolerance of edible mushrooms to selenium is improved, and the ammonium ferric citrate promotes the growth of mushrooms and increases the selenium content.

Description

Technical Field

[0001] The invention belongs to the technical field of edible fungus cultivation, and particularly relates to an edible fungus culture medium and a cultivation method. Background Art

[0002] Selenium is a trace element with important biological functions, exhibiting health benefits such as antioxidant and immunomodulatory properties. Increasing the selenium content of edible fungi not only enhances their nutritional value but also meets the daily selenium needs of the general population. To enhance the selenium content of edible fungi, some approaches have attempted to improve selenium conversion by adding exogenous selenium sources (such as sodium selenate, potassium selenate, yeast selenium, and nano-selenium) to the culture medium or by adjusting the cultivation environment. However, because selenium absorption by edible fungi is influenced by multiple factors, such as culture medium pH, nutrient composition, temperature, and humidity, existing technologies for improving selenium conversion remain limited. Furthermore, the bioavailability of different selenium sources varies significantly. Therefore, precisely adjusting culture medium formulations to improve selenium absorption and conversion remains a key challenge that needs to be addressed. Summary of the Invention

[0003] In order to solve the above problems, the present invention provides an edible fungus culture medium and a cultivation method.

[0004] Disclosed is an edible fungus culture medium. The formula per liter of the edible fungus culture medium is: 180g-220g of potato, 10g-20g of glucose, 5g-15g of fructose, 2g-5g of peptone, 1g-5g of yeast extract powder, 0.8g-1.2g of potassium dihydrogen phosphate, 0.3g-0.8g of magnesium sulfate, 0.05g-0.5g of methionine, 0.4g-1.4g of ammonium ferric citrate, and 50mg-500mg of sodium selenite.

[0005] Preferably, the formula of the edible fungus culture medium per liter is: 200g potato, 15g glucose, 10g fructose, 3g peptone, 2g yeast extract powder, 1g potassium dihydrogen phosphate, 0.5g magnesium sulfate, 0.05g~0.5g methionine, 0.2g~3g ammonium ferric citrate, and 50mg~500mg selenium mother solution.

[0006] Preferably, the strain is inoculated into the edible fungus culture medium according to claim 1 to obtain a mother strain; Inoculating the bacterial mother strain onto the original seed culture medium to obtain the bacterial original strain; inoculating the bacterial stock into a culture medium to obtain a bacterial culture medium; The cultivated species is inoculated into a mushroom stick to cultivate edible fungi.

[0007] Preferably, the formula of the original seed culture medium is: 70%~80% of broad-leaved wood chips, 15%~20% of bran, 0.8%~1.2% of lime, 0.8%~1.2% of gypsum, 0.5%~2% of glucose, 0.2%~0.8% of ammonium ferric citrate, and 0.01%~0.05% of 5g / 50mL of selenium mother solution, totaling 100%.

[0008] Preferably, the culture medium formula is: 70% to 80% broadleaf wood chips, 15% to 20% bran, 0.8% to 1.2% lime, 0.8% to 1.2% gypsum, 0.5% to 1% glucose, 0.2% to 0.8% ammonium ferric citrate, 0.1% to 0.3% of 5g / 50mL selenium mother solution, totaling 100%.

[0009] Preferably, the mushroom stick formula is: 70% to 80% broadleaf wood chips, 15% to 20% bran, 0.8% to 1.2% lime, 0.8% to 1.2% gypsum, 0.8% to 1.2% glucose, and 0.8% to 1.2% ammonium ferric citrate, totaling 100%.

[0010] Preferably, the mushroom stick size is 17cm~18cm×58cm~60cm, and the bag weight is 2.6kg~3.1kg.

[0011] Preferably, the preparation method of the mushroom stick is normal pressure sterilization, weighing the raw materials in the mushroom stick formula and mixing them to obtain a matrix formula, adding 50 mg / kg~300 mg / kg of sodium selenite to the matrix formula, and sterilizing at 100°C for 20h~24h to obtain a mushroom stick.

[0012] Preferably, during the cultivation, the mycelium management temperature is 22° C. to 25° C. and the humidity is 55% to 60%.

[0013] Preferably, during the cultivation, the mushroom production management temperature is 15°C to 25°C and the humidity is 85% to 90%.

[0014] The present invention aims to provide a method for cultivating selenium-enriched edible fungi. This method improves selenium conversion efficiency by optimizing the mycelial culture medium and cultivation substrate formulations. This method increases the selenium content of edible fungi by adjusting the culture medium formulation, utilizing a plate culture method, and cultivating conditions. Specifically, by adding glucose and fructose (fermentable sugars) to the culture medium, the naturally occurring weakly acidic environment during mycelial growth and metabolism enhances the edible fungi's tolerance to and conversion of selenium, ultimately increasing the selenium content of the fungi.

[0015] Compared with the prior art, the present invention is beneficial in that: The present invention creates a weakly acidic culture medium by adding glucose and fructose, which helps improve selenium tolerance. Methionine is also added to the culture medium, using it as a selenium assimilation carrier. During bacterial metabolism, selenium (Se) replaces sulfur (S) in methionine to produce the more biologically active selenomethionine (SeMet), thereby reducing the toxicity of sodium selenite and improving edible fungi's tolerance to selenium. Appropriate concentrations of ammonium ferric citrate can effectively promote the growth of shiitake mushrooms and increase their selenium content.

[0016] The present invention adds fermentable sugars (glucose and fructose) in a specific proportion to naturally form and maintain a weakly acidic environment during the growth and metabolism of edible fungi, which can effectively improve the tolerance of edible fungi (especially shiitake mushrooms and oyster mushrooms) to selenium (especially in the form of sodium selenite), overcome the inhibitory effect of high selenium concentration on mycelial growth (such as Figure 1 B / E vs. C / F; methionine (Met) is added to the culture medium. Methionine, acting as a selenium assimilation carrier, promotes the efficient replacement of sulfur (S) in methionine by selenium (Se) during bacterial metabolism, resulting in the production of selenomethionine (SeMet), a highly bioactive, primary organic selenium form. This process significantly reduces the cytotoxicity of inorganic selenium sources such as sodium selenite and is a key mechanism for improving mycelial tolerance and conversion efficiency to selenium. Within an appropriate concentration range (0.2 g / L–3 g / L mycelial culture medium; 0.2%–0.8% stock / cultivar; 0.2%–0.8% production substrate), ammonium ferric citrate significantly promotes mycelial growth and increases fruiting body biomass (Tables 1 and 2), while synergistically increasing the total selenium content and organic selenium ratio in the fruiting bodies (Table 2). This mechanism of action may involve iron supplementation and the integrative effects of citrate, which reduce selenium toxicity or enhance selenium bioavailability. This triple synergy enhances selenium content in edible fungi.

[0017] The culture medium of this invention ensures that strains with high viability, high selenium tolerance, and efficient selenium conversion are used in final production. During the fruiting body production (cultivation) phase, the optimal selenium addition concentration is determined (for example, 100 mg / kg of sodium selenite is beneficial for growth and yield, while 500 mg / kg results in a fruiting body selenium content of up to 587.46 mg / kg). This method achieves efficient selenium enrichment and conversion from strain to product.

[0018] This invention has developed a multi-component, synergistic selenium-enriched culture medium formulation system, encompassing weakly acidic induction (specific sugars), targeted conversion of selenoamino acids (methionine addition), and a key growth-promoting factor (ammonium ferric citrate). This system has been systematically integrated into the entire process of tertiary fungus strain preparation and fruiting body production. This method significantly improves the tolerance and conversion efficiency of edible fungi to inorganic selenium (sodium selenite), successfully achieving ultra-high selenium enrichment (>500mg / kg) in the fruiting bodies, primarily in highly bioactive organic selenium (selenomethionine), while ensuring mycelial growth rate and fruiting body yield. This technology provides a reliable solution for the efficient production of high-quality selenium-enriched edible fungi products. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Figure 2 shows the mycelial growth of selenium-enriched Lentinus edodes and Pleurotus ostreatus on different culture media. A and D show the mycelial growth of Lentinus edodes and Pleurotus ostreatus on the culture medium of formula 1, respectively; B and E show the mycelial growth of Lentinus edodes and Pleurotus ostreatus on the culture medium of formula 2, respectively; C and F show the mycelial growth of Lentinus edodes and Pleurotus ostreatus on the culture medium of formula 3, respectively. DETAILED DESCRIPTION

[0020] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited by the specific embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. The experimental methods described in the embodiments of the present invention are all conventional methods unless otherwise specified.

[0021] Example 1 Mycelial growth of selenium-rich edible fungi The present invention provides a method for cultivating selenium-rich edible fungi, which comprises the following specific steps: 1. Prepare a selenium mother solution: Dissolve the selenium source, sodium selenite, in sterile water to prepare a 5g / 50mL selenium mother solution. Using sodium selenate as a selenium source can also achieve similar results.

[0022] 2. Make edible fungus culture medium Recipe 1 culture medium (comprehensive PDA medium): 200 g potato, 10 g glucose, 10 g sucrose, 2 g peptone, 1.0 g potassium dihydrogen phosphate, 0.5 g magnesium sulfate, and water to 1000 mL.

[0023] Recipe 2 culture medium: 200 g potato, 10 g glucose, 10 g sucrose, 2 g peptone, 1.0 g potassium dihydrogen phosphate, 0.5 g magnesium sulfate, 0.5 mL of 5 g / 50 mL selenium mother solution, and make up to 1000 mL with water.

[0024] Formula 3 culture medium: 200 g potato, 15 g glucose, 10 g fructose, 3 g peptone, 2 g yeast extract powder, 1 g potassium dihydrogen phosphate, 0.5 g magnesium sulfate, 0.1 g methionine, 1 g ammonium ferric citrate, 0.5 mL of 5 g / 50 mL selenium mother solution, and make up to 1000 mL with water.

[0025] To prepare Formulation 1, Formulation 2, and Formulation 3, follow the above recipes: weigh 200g of potato slices, add to 1000mL of water, simmer for 15 minutes, and filter. Weigh the remaining reagents and dissolve them in the filtrate, then add water to 1000mL. Sterilize by autoclaving at 121°C for 30 minutes. Pour 20mL of medium into each 90mm Petri dish and allow to solidify and cool before use.

[0026] 3. Vaccination The pre-activated Lentinus edodes and Pleurotus ostreatus spawn were punched with a 5mm hole puncher and inoculated into the center of the plates of Formula 1 culture medium, Formula 2 culture medium and Formula 3 culture medium respectively.

[0027] 4. Cultivation The inoculated culture medium plate was placed in a constant temperature incubator at 23±2°C and cultured for 5-7 days.

[0028] like Figure 1 As shown, A and D are the mycelial growth conditions of Lentinus edodes and Pleurotus ostreatus inoculated on the culture medium of formula 1; B and E are the mycelial growth conditions of Lentinus edodes and Pleurotus ostreatus inoculated on the culture medium of formula 2; C and F are the mycelial growth conditions of Lentinus edodes and Pleurotus ostreatus inoculated on the culture medium of formula 3 with a sodium selenite concentration of 50 mg / L.

[0029] Table 1 Growth of Lentinus edodes and Pleurotus ostreatus mycelium under different recipes Note: ++++ indicates that the mycelium grows vigorously and densely, ++ indicates that the mycelium grows densely, and + indicates that the mycelium grows sparsely; different lowercase letters indicate significant differences (P<0.05).

[0030] Depend on Figure 1 As shown in Table 1, with Formula 3, the mycelium growth rate of Lentinus edodes and Pleurotus ostreatus was fast and the mycelium growth was the most vigorous, indicating that the addition of methionine and ammonium ferric citrate had a significant growth-promoting effect on both mushrooms.

[0031] Example 2 Selenium-enriched shiitake mushroom cultivation and production 1. Production of first-grade mushroom seeds (mother seeds) The slant culture medium formula, i.e., formula 3 culture medium: 200 g potato, 15 g glucose, 10 g fructose, 3 g peptone, 2 g yeast extract powder, 1 g potassium dihydrogen phosphate, 0.5 g magnesium sulfate, 0.1 g methionine, 1 g ammonium ferric citrate, 0.5 mL of 5 g / 50 mL selenium mother solution, and water to make up to 1000 mL.

[0032] Prepare a slant culture medium according to the above recipe, inoculate the independently bred Lentinus edodes strain "Anxiang No. 3" (CGMCC 23884) onto the culture medium, and culture it in a constant temperature incubator at 23±2°C. Wait until the mycelium fills the test tube to obtain the Lentinus edodes mother culture for later use.

[0033] 2. Production of secondary species (original species) of shiitake mushrooms The stock culture medium formula is: 78% broadleaf wood chips, 18% bran, 1% lime, 1% gypsum, 1.15% glucose, 0.8% ammonium ferric citrate, and 0.05% 5g / 50mL selenium mother solution, totaling 100%. The water content of the stock culture medium is 60%-65%.

[0034] Prepare the stock culture medium according to the above formula, inoculate the mother culture of Lentinus edodes onto the stock culture medium, and culture it in a culture room at 23±2°C. When the mycelium fills the bag, the Lentinus edodes stock culture is obtained and set aside.

[0035] 3. Production of third-grade mushroom varieties (cultivated varieties) Cultivation medium formula: 78% broadleaf wood chips, 18% bran, 1% lime, 1% gypsum, 1% glucose, 0.7% ammonium ferric citrate, 0.3% 5g / 50mL selenium mother solution, totaling 100%. The moisture content of the cultivation medium is 60%-65%.

[0036] Prepare the cultivation medium according to the above formula, inoculate the original shiitake mushroom seeds onto the cultivation medium, and culture in a culture room at 23±2°C until the mycelium fills the bag to obtain the cultivation seeds for later use.

[0037] 4. Selenium-enriched shiitake mushroom production (1) Matrix formula Hardwood wood chips 78%, bran 18%, lime 1%, gypsum 1%, glucose 1%, ammonium ferric citrate 1%, total 100%.

[0038] Add 1 mL to 5 mL of 5 g / 20 mL selenium mother solution to 2.5 kg of the matrix formula, with a water content of 60% to 65%.

[0039] (2) Making mushroom sticks Weigh all raw materials and auxiliary materials according to the above recipe and mechanically mix them. Use high-density polyethylene (HDPE) with a thickness of 0.006 cm and a size of (17 cm-18 cm) x (58 cm-60 cm). Use a bagging machine to fill the bags, with a weight of 2.6 kg to 3.1 kg (average 2.85 kg). Sterilize at normal pressure until the internal temperature reaches 100°C and maintain for 20 to 24 hours to obtain bacterial sticks. In this example, the temperature was maintained for 20 hours. Move the bacterial sticks to the inoculation area and wait until the internal temperature drops below 28°C before inoculation.

[0040] (3) Vaccination Before inoculation, disinfect the surface of the culture medium. Inoculation should be performed in a sterile environment. Use a sterilized punch to evenly punch holes 2-3 cm deep and 1-1.5 cm in diameter on the surface of the mushroom sticks. Make four holes per stick. Immediately inoculate the culture medium into the holes to prevent any foreign bacteria from entering. Immediately place the bag over the stick and tie it shut.

[0041] (4) Training and management After inoculation of shiitake mushrooms, the mycelium management temperature is controlled at 22°C to 25°C, the humidity is controlled at 55% to 60%, and the culture is carried out in darkness or low light with regular ventilation until the mycelium has grown all over the mushroom sticks and has completed color change. The fruiting management temperature is controlled at 15°C to 25°C, the humidity is controlled at 85% to 90%, and scattered light and ventilation are increased to promote the formation of primordia and the development of fruiting bodies, which are then harvested in a timely manner. In this embodiment, the mycelium management temperature is controlled at 25°C and the humidity is controlled at 55%, and the fruiting management temperature is controlled at 20°C and the humidity is controlled at 85%.

[0042] Effect verification Analysis of Lentinus edodes fruiting body yield and selenium content To 2.5 kg of substrate, 1 mL to 5 mL of a 5 g / 20 mL selenium mother solution were added. As shown in Table 2, increasing sodium selenite concentration in the substrate resulted in the highest mycelial growth rate and yield, and the lowest contamination rate, at a selenium concentration of 100 mg / kg. This indicates that an appropriate selenium concentration can promote mycelial growth, increase yield, and enhance stress resistance. In this experiment, the highest selenium content in the fruiting bodies, at 587.46 mg / kg, was achieved when the sodium selenite concentration was 500 mg / kg.

[0043] Table 2 Effects of different selenium concentrations on the growth of Lentinus edodes Note: The selenium mother solution was 5 g / 20 mL. The corresponding selenium concentrations of adding 1 mL, 2 mL, 3 mL, 4 mL, and 5 mL were 100 mg / kg, 200 mg / kg, 300 mg / kg, 400 mg / kg, and 500 mg / kg, respectively. Different lowercase letters indicate significant differences (P<0.05).

[0044] Table 3 shows the effects of varying amounts of ammonium ferric citrate on shiitake mushroom growth at a selenium concentration of 100 mg / kg. The amount of ammonium ferric citrate added had a moderate impact on shiitake mushroom yield, selenium content, and organic selenium content. Appropriate concentrations of ammonium ferric citrate promoted the growth of selenium-enriched shiitake mushrooms.

[0045] Table 3 Effects of ammonium ferric citrate addition on the growth of Lentinus edodes Note: Different lowercase letters indicate significant differences (P<0.05).

[0046] When the goal is to produce high-yield selenium-rich shiitake mushrooms, the recommended addition amount of sodium selenite is 100 mg / kg and the addition amount of ammonium ferric citrate is 0.5%~1%; when the goal is to produce ultra-high-selenium shiitake mushrooms, the recommended addition amount of sodium selenite is 500 mg / kg and the addition amount of ammonium ferric citrate is 1%~1.5%.

[0047] The present invention achieves the following through the ternary synergistic system of methionine, FAC and weakly acidic environment: ① At a concentration of 100 mg / kg sodium selenite, the yield increased by 14.4% (reaching 0.963 kg / kg) against the trend, while the pollution rate decreased; ②At an ultra-high selenium concentration of 500mg / kg, the selenium content in the fruiting body exceeded 587.46mg / kg, and the organic selenium conversion rate was >85%; ③ Appropriate concentration of ammonium ferric citrate can improve the yield and selenium tolerance of Lentinus edodes; ④ The contamination rate was controlled below 3.06% in the selenium concentration range of 100mg / kg~500mg / kg.

[0048] It should be noted that when the claims of the present invention involve numerical ranges, it should be understood that the two endpoints of each numerical range and any numerical value between the two endpoints can be selected. In order to avoid redundancy, the present invention describes preferred embodiments.

[0049] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0050] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. An edible fungus culture medium, characterized in that The formula of the edible fungus culture medium per liter is: 180g~220g of potatoes, 10g~20g of glucose, 5g~15g of fructose, 2g~5g of peptone, 1g~5g of yeast extract powder, 0.8g~1.2g of potassium dihydrogen phosphate, 0.3g~0.8g of magnesium sulfate, 0.05g~0.5g of methionine, 0.4g~1.4g of ammonium ferric citrate, and 50mg~500mg of sodium selenite.

2. The edible fungus culture medium according to claim 1, characterized in that The formula of the edible fungus culture medium per liter is: 200g of potato, 15g of glucose, 10g of fructose, 3g of peptone, 2g of yeast extract powder, 1g of potassium dihydrogen phosphate, 0.5g of magnesium sulfate, 0.05g-0.5g of methionine, 0.2g-3g of ammonium ferric citrate, and 50mg-500mg of selenium mother solution.

3. A method for cultivating edible fungi, characterized in that: inoculating the bacterial strain onto the edible fungus culture medium according to claim 1 to obtain a mother fungus strain; Inoculating the bacterial mother strain onto the original seed culture medium to obtain the bacterial original strain; inoculating the bacterial stock into a culture medium to obtain a bacterial culture medium; The cultivated species is inoculated into a mushroom stick to cultivate edible fungi.

4. The cultivation method according to claim 3, wherein The formula of the original seed culture medium is: 70%~80% of broad-leaved wood chips, 15%~20% of bran, 0.8%~1.2% of lime, 0.8%~1.2% of gypsum, 0.5%~2% of glucose, 0.2%~0.8% of ammonium ferric citrate, 0.01%~0.05% of 5g / 50mL of selenium mother solution, totaling 100%.

5. The cultivation method according to claim 3, wherein The culture medium formula for the cultivated species is: 70%~80% broad-leaved wood chips, 15%~20% bran, 0.8%~1.2% lime, 0.8%~1.2% gypsum, 0.5%~1% glucose, 0.2%~0.8% ammonium ferric citrate, 0.1%~0.3% of 5g / 50mL selenium mother solution, totaling 100%.

6. The cultivation method according to claim 3, wherein The formula of the mushroom stick is: 70%~80% of broad-leaved wood chips, 15%~20% of bran, 0.8%~1.2% of lime, 0.8%~1.2% of gypsum, 0.8%~1.2% of glucose, and 0.8%~1.2% of ammonium ferric citrate, totaling 100%.

7. The cultivation method according to claim 6, characterized in that The specifications of the mushroom sticks are 17cm~18cm×58cm~60cm, and the bag weight is 2.6kg~3.1kg.

8. The cultivation method according to claim 6, wherein The preparation method of the mushroom sticks is sterilization at normal pressure, weighing various raw materials in the mushroom stick formula and mixing them evenly to obtain a matrix formula, adding 50 mg / kg to 300 mg / kg of sodium selenite to the matrix formula, and sterilizing at 100° C. for 20 h to 24 h to obtain the mushroom sticks.

9. The cultivation method according to claim 3, wherein During the cultivation, the mycelium management temperature is 22° C. to 25° C. and the humidity is 55% to 60%.

10. The cultivation method according to claim 3, wherein During the cultivation, the mushroom production management temperature is 15°C to 25°C and the humidity is 85% to 90%.

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