A pleurotus geesterutii liquid strain culture solution and application thereof

Abstract

The application discloses a liquid culture medium of pleurotus geesterus and application thereof, and belongs to the technical field of edible mushroom cultivation. The liquid culture medium of the pleurotus geesterus comprises the following components in mass fraction: potato juice 60-80 parts, glucose 15-20 parts, corn cob water extract 10-20 parts, yeast extract powder 4-7 parts, lecithin 0.1-0.3 parts, green bean sprout juice 5-8 parts, amaranth water extract 10-20 parts, KH2PO4 0.75-1.5 parts, MgSO4 0.4-0.6 parts, VB1 0.0005 parts, and deionized water, which is supplemented to 1000 parts. The application adopts the synergistic cooperation of various natural extracts, constructs a microenvironment with amino acid and vitamin nutrition and antioxidant components, and the combination of "nutrition + protection" can significantly improve the growth vigor of the pleurotus geesterus mycelium and promote the mycelium growth, thereby providing an effective basis for the liquid culture of the pleurotus geesterus.

Description

Technical Field

[0001] This invention belongs to the field of edible fungi cultivation technology, and in particular relates to a liquid culture medium for Pleurotus ostreatus and its application. Background Technology

[0002] Oyster mushrooms are a rare edible fungus that combines high nutritional value with a unique seafood flavor. Their flesh is plump and tender, with a delicious taste. The protein content is significantly higher than common mushrooms such as button mushrooms and shiitake mushrooms, and they are rich in the eight essential amino acids and various vitamins, earning them the nickname "MSG mushroom." Oyster mushrooms have a delicate texture and low fiber content, and their peak fruiting period is concentrated from June to August, perfectly filling the gap in the market supply of other edible fungi during the hot season. This gives them a clear competitive advantage and a promising market prospect.

[0003] In the industrial production of edible fungi, liquid spawn technology is gradually becoming an important development direction to replace traditional solid spawn due to its advantages such as short production cycle, numerous mycelial development points, high inoculation efficiency, low cost, and ease of automation. Studies have shown that cultivation using liquid spawn can result in fruiting dates up to 40 days earlier than with solid spawn, and the increased mycelial germination points and better fluidity significantly improve biological efficiency. However, the core bottleneck of liquid spawn technology lies in the stability and controllability of spawn quality, a problem particularly prominent in the large-scale production of oyster mushrooms.

[0004] Although preliminary studies have explored the culture medium formulation (such as carbon and nitrogen sources and inorganic salt ratios) and culture conditions (such as temperature, pH, shaking speed, and aeration) of liquid spawn for *Pleurotus ostreatus*, in actual industrial propagation, liquid spawn generally suffers from slow mycelial biomass accumulation and low spawn viability. More critically, current liquid spawn propagation often exhibits uneven mycelial ball size, thin and aging mycelia, and low extracellular enzyme activity, resulting in a long recovery period after inoculation and slow substrate absorption, severely impacting cultivation efficiency and fruiting uniformity.

[0005] The reasons for the poor vitality and slow growth of oyster mushroom liquid spawn are multifaceted. First, oyster mushrooms are wood-rotting fungi, and their degradation and utilization of lignocellulose carbon sources depends on the secretion of a series of extracellular enzymes such as laccase and carboxymethyl cellulase (CMC enzyme). Under the conditions of liquid submerged fermentation, the shear force of the culture medium, dissolved oxygen level, and nutrient mass transfer efficiency all affect the synthesis and secretion of these enzymes, thus restricting the metabolic activity of the mycelium. Second, the physiological state of the liquid spawn is closely related to the fermentation process. The consumption of reducing sugars, the accumulation of soluble proteins, and the appearance of enzyme activity peaks follow specific temporal patterns. If the fermentation endpoint is not accurately determined, the culture can easily be terminated before the mycelium reaches its optimal physiological state, or the spawn may age and degenerate due to over-cultivation.

[0006] Therefore, building a stable and efficient liquid spawn preparation technology system has become an urgent need to break through the bottleneck of industrialized production of oyster mushrooms, and is of great significance to promoting the standardization and intelligent upgrading of the industry. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a liquid spawn culture medium for Pleurotus ostreatus and its application. This liquid spawn culture medium can significantly enhance the growth vitality of Pleurotus ostreatus mycelium and promote mycelial growth, providing a valid basis for the liquid spawn culture of Pleurotus ostreatus.

[0008] To achieve the above objectives, the present invention provides a liquid culture medium for *Pleurotus ostreatus*, comprising the following components in parts by weight: 60-80 parts potato juice, 15-20 parts glucose, 10-20 parts corn cob aqueous extract, 4-7 parts yeast extract, 0.1-0.3 parts lecithin, 5-8 parts mung bean sprout juice, 10-20 parts amaranth aqueous extract, 0.75-1.5 parts KH₂PO₄, 0.4-0.6 parts MgSO₄, 0.0005 parts VB₁, and deionized water to a total of 1000 parts.

[0009] Preferably, the liquid culture medium for *Pleurotus ostreatus* comprises the following components in parts by weight: 70 parts potato juice, 18 parts glucose, 15 parts corn cob water extract, 5.5 parts yeast extract, 0.2 parts lecithin, 7 parts mung bean sprout juice, 15 parts amaranth water extract, 1 part KH2PO4, 0.5 parts MgSO4, 0.0005 parts VB1, and deionized water to a total of 1000 parts.

[0010] Preferably, the pH value of the bacterial culture medium is 4.9 to 6.0.

[0011] The present invention also provides a method for culturing liquid mycelium based on the liquid culture medium of *Pleurotus ostreatus* described above, comprising the following steps: S1. Incubation of oyster mushroom on slant medium: Inoculate the oyster mushroom mother culture onto slant medium and culture at a constant temperature of 23℃~25℃ in the dark for 7~10 days to obtain activated mother culture; S2. Shake flask culture: Dispense the cooled liquid spawn culture solution of Pleurotus ostreatus into shake flasks, with the liquid volume being 20%~30% of the shake flask volume; cut the activated mother culture into small pieces and inoculate them into the shake flasks for constant temperature shaking culture; thus obtaining the shake flask liquid spawn. S3. Fermentation tank cultivation: Dispense the cooled oyster mushroom liquid spawn culture solution into the fermentation tank, and inoculate the primary seed liquid from the shake flask into the fermentation tank at an inoculation rate of 8%~12% (v / v); culture in the fermentation tank for 6~9 days to obtain liquid spawn.

[0012] Preferably, the conditions for the shaker culture in step S2 include: culture at a temperature of 23℃~25℃ for 5~7 days.

[0013] Preferably, the rotation speed of the shaker culture in step S2 is 150~180 r / min.

[0014] Preferably, the fermentation conditions in step S3 include: cultivation at a temperature of 23℃~25℃; an aeration rate of 0.5~1.0 vvm, a tank pressure of 0.03~0.06 MPa, and a stirring speed of 130~150 r / min.

[0015] The present invention also provides the application of the liquid culture medium of Pleurotus ostreatus as described above in improving the viability of Pleurotus ostreatus strains.

[0016] The present invention also provides the application of the liquid culture medium of Pleurotus ostreatus as described above in improving the mycelial growth of Pleurotus ostreatus.

[0017] This invention also provides the application of the liquid spawn cultured in the liquid spawn culture solution of *Pleurotus ostreatus* as described above in the cultivation of *Pleurotus ostreatus*, including the following steps: filling the cultivation substrate into the cultivation bag, sterilizing and cooling it, and then inoculating the cultivation bag with the liquid spawn; placing the inoculated cultivation bag in the cultivation room for 20-25 days, followed by 3-5 days of post-ripening, and then transferring it to the fruiting room for 7-11 days of cultivation.

[0018] Compared with the prior art, the present invention has the following advantages and technical effects: 1. This invention uses glucose, potato juice, and corn cob water extract simultaneously. Mycelia preferentially utilize glucose and potato juice to achieve rapid germination and biomass accumulation. As glucose is consumed, mycelia are induced to secrete extracellular enzymes to decompose the complex polysaccharides in the corn cob water extract, thereby maintaining long-term metabolic activity and preventing aging due to carbon source depletion.

[0019] 2. The yeast extract of the present invention provides easily absorbed organic nitrogen for the oyster mushroom strain, which can rapidly increase mycelial protein; at the same time, the lignocellulose present in the corn cob water extract can induce mycelial synthesis and secretion of lignin-degrading enzymes. These two components work synergistically, which can better balance mycelial growth rate and extracellular enzyme activity than a single nitrogen source.

[0020] 3. This invention uses potato juice, mung bean sprout juice, corn cob water extract, and amaranth water extract. The mung bean sprout juice and amaranth extract contain various amino acids and antioxidants, which provide nitrogen and nutrients to the fungal strain, enhancing its vitality. Furthermore, the two have a synergistic antioxidant effect, delaying mycelial aging and improving the strain's stress resistance. The various plant-derived secondary metabolites and trace elements complement each other, providing multiple growth-promoting signaling substances that stimulate the growth of *Pleurotus ostreatus* mycelium and enhance the germination ability of the strain after inoculation. Meanwhile, KH2PO4, MgSO4, and VB1 precisely supplement key inorganic ions and growth factors, providing coenzymes and activators for metabolic reactions. This composite formula results in denser, more uniform mycelial balls and a shorter recovery period after inoculation. Detailed Implementation

[0021] This invention provides a liquid culture medium for *Pleurotus ostreatus*, comprising the following components by weight: 60-80 parts potato juice, 15-20 parts glucose, 10-20 parts corn cob aqueous extract, 4-7 parts yeast extract, 0.1-0.3 parts lecithin, 5-8 parts mung bean sprout juice, 10-20 parts amaranth aqueous extract, 0.75-1.5 parts KH₂PO₄, 0.4-0.6 parts MgSO₄, 0.0005 parts VB₁, and deionized water to a total of 1000 parts.

[0022] In this invention, the liquid spawn culture medium of *Pleurotus ostreatus* preferably comprises the following components in parts by weight: 70 parts potato juice, 18 parts glucose, 15 parts corn cob aqueous extract, 5.5 parts yeast extract, 0.2 parts lecithin, 7 parts mung bean sprout juice, 15 parts amaranth aqueous extract, 1 part KH₂PO₄, 0.5 parts MgSO₄, 0.0005 parts VB₁, and deionized water to a total of 1000 parts. The pH value of the spawn culture medium is preferably 4.9-6.0.

[0023] In this invention, the preferred method for preparing the potato juice includes the following steps: taking fresh, unrotten, and unsprouted potatoes, cutting them into 0.5-1 cm cubes, adding 5 times their weight of water and bringing to a boil, then reducing to a simmer and continuing to cook for 25 minutes. Turning off the heat and letting it stand for 3-5 minutes, while still hot, filtering to remove the potato cubes and collecting the supernatant. The potato juice provides a carbon source for the liquid mycelium of *Pleurotus ostreatus*.

[0024] The present invention does not have any special restrictions on the glucose used, and commercially available glucose can be used; the glucose provides a fast-acting carbon source for the liquid spawn of Pleurotus ostreatus.

[0025] In this invention, the preferred method for preparing the corn cob aqueous extract includes the following steps: taking two intact, non-rotten or moldy corn cobs, crushing them to 1 cm, adding 2500 mL of water and boiling, then simmering over low heat for 30 minutes, turning off the heat and letting stand for 3-5 minutes, filtering while hot to remove the corn cobs, and collecting the supernatant. The corn cob aqueous extract can provide a slow-release carbon source for liquid microorganisms, and can also induce mycelial synthesis and secretion of lignin-degrading enzymes, thereby increasing the extracellular enzyme activity of the mycelia.

[0026] The present invention does not impose any special restrictions on the yeast extract powder, and conventional commercially available yeast extract powder can be used; the yeast extract powder provides a fast-acting nitrogen source for the strain and improves the mycelial growth rate.

[0027] The present invention does not impose any special restrictions on the lecithin used, and commercially available lecithin can be used; the lecithin can enhance mycelial vitality and stress resistance, prevent mycelial balls from sticking together and clumping, and improve the uniformity and survival rate of mycelial balls.

[0028] In this invention, the preferred method for preparing mung bean sprout juice includes the following steps: grinding and pulverizing 200g of mung bean sprouts, filtering, and adjusting the volume to 1000mL to obtain mung bean sprout juice; the mung bean sprout juice contains serine, alanine, ascorbic acid, and other substances, which can significantly delay strain degradation, increase mycelial biomass and growth rate, and enhance antioxidant enzyme activity.

[0029] In this invention, the preferred method for preparing the amaranth aqueous extract includes the following steps: washing 50g of fresh, unrotten amaranth, adding 1000mL of water, boiling, then simmering for 2-3 minutes, filtering to remove the amaranth, and adjusting the volume to 1000mL to obtain the amaranth aqueous extract. The amaranth aqueous extract contains various active substances; it can reduce oxidative stress in liquid culture, decrease reactive oxygen species damage to mycelia, and enhance mycelial stress resistance.

[0030] This invention does not impose any special restrictions on KH2PO4 and MgSO4; commercially available materials can be used.

[0031] This invention does not impose any special restrictions on the VB1 mentioned above; any commercially available VB1 can be used.

[0032] The present invention also provides a method for culturing liquid mycelium based on the liquid culture medium of *Pleurotus ostreatus* described above, comprising the following steps: S1. Incubation of oyster mushroom on slant medium: Inoculate the oyster mushroom mother culture onto slant medium and culture at a constant temperature of 23℃~25℃ in the dark for 7~10 days to obtain activated mother culture; S2. Shake flask culture: Dispense the cooled liquid spawn culture solution of Pleurotus ostreatus into shake flasks, with the liquid volume being 20%~30% of the shake flask volume; cut the activated mother culture into small pieces and inoculate them into the shake flasks for constant temperature shaking culture; thus obtaining the shake flask liquid spawn. S3. Fermentation tank cultivation: Dispense the cooled oyster mushroom liquid spawn culture solution into the fermentation tank, and inoculate the primary seed liquid from the shake flask into the fermentation tank at an inoculation rate of 8%~12% (v / v); culture in the fermentation tank for 6~9 days to obtain liquid spawn.

[0033] In this invention, the conditions for the shaker culture in step S2 preferably include: culture at a temperature of 23℃~25℃ for 5~7 days; and the rotation speed of the shaker culture is preferably 150~180 r / min.

[0034] In this invention, the preferred conditions for fermentation in step S3 include: cultivation at a temperature of 23°C to 25°C; the preferred aeration rate of the fermentation tank is 0.5 to 1.0 vvm, more preferably 0.65 vvm; the preferred tank pressure is 0.03 to 0.06 MPa; and the preferred stirring speed is 130 to 150 r / min.

[0035] The present invention also provides the application of the liquid culture medium of Pleurotus ostreatus as described above in improving the viability of Pleurotus ostreatus strains.

[0036] The present invention also provides the application of the liquid culture medium of Pleurotus ostreatus as described above in promoting the mycelial growth of Pleurotus ostreatus.

[0037] The present invention also provides the application of the liquid spawn culture medium of Pleurotus ostreatus as described above in the cultivation of Pleurotus ostreatus, including the following steps: filling the cultivation substrate into the cultivation bag, sterilizing and cooling it, and then inoculating the cultivation bag with liquid spawn; placing the inoculated cultivation bag in the cultivation room for 20-25 days, then allowing it to ripen for 3-5 days, and then transferring it to the fruiting room for 7-11 days.

[0038] In this invention, inoculating the liquid spawn into the cultivation substrate can significantly shorten the mycelium growth cycle and fruiting time. The mycelium can fill the bag in as little as 22 days, and the first flush of mushrooms can be harvested after 9 days of cultivation in the fruiting room.

[0039] To further illustrate the present invention, the following detailed description, in conjunction with embodiments, of a liquid culture medium for *Pleurotus ostreatus* and its applications, should not be construed as limiting the scope of protection of the present invention.

[0040] Example 1 Liquid culture medium for Pleurotus ostreatus and its preparation method.

[0041] 1. Ingredients: 70 parts potato juice, 18 parts glucose, 15 parts corn cob water extract, 5.5 parts yeast extract, 0.2 parts lecithin, 7 parts mung bean sprout juice, 15 parts amaranth water extract, 1 part KH2PO4, 0.5 parts MgSO4, 0.0005 parts VB1, and deionized water to make up to 1000 parts.

[0042] 2. Preparation method.

[0043] 1) Raw material preparation: Potato juice: Take fresh potatoes that are not rotten or sprouted, cut them into 0.5-1cm cubes, add 5 times the weight of water and bring to a boil. After boiling, turn to low heat and continue to simmer for 25 minutes. Turn off the heat and let it stand for 3-5 minutes. Filter while hot to remove the potato cubes and take the supernatant. Corn cob water extract: Take 2 whole corn cobs that are not rotten or moldy, crush them to 1cm, add 2500mL of water and boil, then simmer for 30 minutes. Turn off the heat and let stand for 3-5 minutes. Filter while hot to remove the corn cobs and take the supernatant. Mung bean sprout juice: Grind 200g of mung bean sprouts into powder, filter, and bring the volume to 1000mL to obtain mung bean sprout juice; Amaranth water extract: Wash 50g of fresh, non-rotten amaranth, add 1000mL of water, bring to a boil, then simmer for 2-3 minutes. Filter to remove the amaranth and bring the volume to 1000mL to obtain the amaranth water extract. Glucose, yeast extract, KH2PO4, and MgSO4 were dissolved in warm water until completely dissolved and set aside; Vitamin B1 was dissolved in a small amount of sterile water and set aside. 2) Add deionized water to a container, then pour in the prepared potato juice, corn cob water extract, amaranth water extract, and mung bean sprout juice in sequence, stir and mix well, and then heat. 3) Add the dissolved glucose, yeast extract, VB1, KH2PO4, MgSO4 and lecithin to the solution obtained in step 2) in sequence; boil until boiling.

[0044] Example 2 Liquid culture medium for Pleurotus ostreatus and its preparation method.

[0045] 1. Ingredients: 60 parts potato juice, 20 parts glucose, 10 parts corn cob water extract, 7 parts yeast extract powder, 0.1 parts lecithin, 5 parts mung bean sprout juice, 10 parts amaranth water extract, 1 part KH2PO4, 0.5 parts MgSO4, 0.0005 parts VB1, and deionized water to make up to 1000 parts.

[0046] 2. Preparation method: The preparation method is the same as the specific implementation method in Example 1.

[0047] Example 3 Liquid culture medium for Pleurotus ostreatus and its preparation method.

[0048] 1. Ingredients: 80 parts potato juice, 15 parts glucose, 20 parts corn cob water extract, 4 parts yeast extract powder, 0.1 parts lecithin, 8 parts mung bean sprout juice, 20 parts amaranth water extract, 1 part KH2PO4, 0.5 parts MgSO4, 0.0005 parts VB1, and deionized water to make up to 1000 parts.

[0049] 2. Preparation method: The preparation method is the same as the specific implementation method in Example 1.

[0050] Comparative Example 1 Liquid culture medium for Pleurotus ostreatus and its preparation method.

[0051] 1. Ingredients: 70 parts potato juice, 18 parts glucose, 5.5 parts yeast extract, 0.2 parts lecithin, 1 part KH2PO4, 0.5 parts MgSO4, 0.0005 parts VB1, and deionized water to make up to 1000 parts.

[0052] 2. Preparation method: The preparation method is the same as the specific implementation method in Example 1.

[0053] Comparative Example 2 1. Ingredients: 70 parts potato juice, 18 parts glucose, 15 parts corn cob water extract, 5.5 parts yeast extract, 0.2 parts lecithin, 1 part KH2PO4, 0.5 parts MgSO4, 0.0005 parts VB1, and deionized water to make up to 1000 parts.

[0054] 2. Preparation method: The preparation method is the same as the specific implementation method in Example 1.

[0055] Example 4 Liquid spawn was prepared using the liquid spawn culture solutions of Examples 1-3 and Comparative Examples 1 and 2. During the culture process, the morphology of mycelial balls was observed, and whether there was clumping or odor was noted. Under aseptic conditions, a small amount of the shaken liquid spawn of *Pleurotus ostreatus* was taken and mixed with sterile physiological saline to prepare a temporary slide. The mycelial morphology was observed using an optical microscope with low and high magnification objectives at multiple points of view.

[0056] S1. Incubation of oyster mushroom on slant medium: Inoculate the oyster mushroom mother culture onto slant medium and culture at a constant temperature of 23℃~25℃ in the dark for 7~10 days to obtain activated mother culture; S2. Shake Flask Culture: The cooled liquid spawn culture solution of *Pleurotus ostreatus* was dispensed into shake flasks, with the volume being 20%–30% of the flask volume. The activated mother culture was cut into small pieces and inoculated into the shake flasks for constant temperature shaking culture. The culture was maintained at 23℃–25℃ for 6 days at a shaking speed of 165 r / min. The resulting liquid spawn was obtained. S3. Fermentation tank cultivation: The cooled liquid spawn culture of *Pleurotus ostreatus* is dispensed into the fermentation tank, and the primary seed liquid from the shake flask is inoculated into the fermentation tank at an inoculation rate of 8%~12% (v / v); the fermentation tank is incubated at a temperature of 23℃~25℃ for 8 days; the aeration rate of the fermentation tank is 0.65vvm; the tank pressure is preferably 0.05MPa, and the stirring speed is preferably 140r / min to obtain liquid spawn.

[0057] The results showed that the mycelial balls in Examples 1-3 were fine, uniform, and free of clumps; the culture medium was clear and odorless; the mycelia of *Pleurotus ostreatus* were robust, with clear cell wall outlines and vigorous branching; no large number of tiny, mobile, dot-like bacteria were visible in the field of view; and there were no short, thick, heteromorphic mold mycelia, sporangia, or spore heads. In contrast, the mycelial balls in Comparative Examples 1 and 2 were of varying sizes and showed slight clumps; the mycelia were thin and weak, with many breaks, indicating mycelial aging and autolysis, and the strain viability was poor.

[0058] Example 5 The liquid culture medium of Example 1 was used to cultivate oyster mushrooms.

[0059] The cultivation substrate is placed into cultivation bags, sterilized and cooled, and then liquid spawn is inoculated into the cultivation bags. The weight of the cultivation substrate in the cultivation bag is 1.8 kg; the inoculation amount of spawn is 100 g; the inoculated cultivation bags are placed in the cultivation room for 20-25 days, after which they are allowed to ripen for 3-5 days, and then transferred to the fruiting room for 7-11 days.

[0060] The results showed that the mycelium could fill the bag in as little as 22 days, and the first flush of mushrooms could be harvested after 9 days of cultivation in the fruiting room. The harvested oyster mushrooms were pure in color, without yellowing or darkening, with fan-shaped or nearly round caps that were thick and plump. The leaves and stems showed no serious mechanical damage and were free from pests and diseases.

[0061] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A liquid culture medium for Pleurotus ostreatus, characterized in that, The product comprises the following components by weight: 60-80 parts potato juice, 15-20 parts glucose, 10-20 parts corn cob water extract, 4-7 parts yeast extract, 0.1-0.3 parts lecithin, 5-8 parts mung bean sprout juice, 10-20 parts amaranth water extract, 0.75-1.5 parts KH2PO4, 0.4-0.6 parts MgSO4, 0.0005 parts VB1, and deionized water to a total of 1000 parts.

2. The liquid culture medium for *Pleurotus ostreatus* according to claim 1, characterized in that, The liquid culture medium for *Pleurotus ostreatus* comprises the following components by weight: 70 parts potato juice, 18 parts glucose, 15 parts corn cob water extract, 5.5 parts yeast extract, 0.2 parts lecithin, 7 parts mung bean sprout juice, 15 parts amaranth water extract, 1 part KH2PO4, 0.5 parts MgSO4, 0.0005 parts VB1, and deionized water to a total of 1000 parts.

3. The liquid culture medium for *Pleurotus ostreatus* according to claim 1, characterized in that, The pH value of the bacterial culture medium is 4.9~6.

0.

4. A method for culturing liquid mycelium based on the liquid culture medium of *Pleurotus ostreatus* according to claim 1, characterized in that, Includes the following steps: S1. Incubation of oyster mushroom on slant medium: Inoculate the oyster mushroom mother culture onto slant medium and culture at a constant temperature of 23℃~25℃ in the dark for 7~10 days to obtain activated mother culture; S2. Shake flask culture: Dispense the cooled liquid spawn culture solution of Pleurotus ostreatus into shake flasks, with the liquid volume being 20%~30% of the shake flask volume; cut the activated mother culture into small pieces and inoculate them into the shake flasks for constant temperature shaking culture; thus obtaining the shake flask liquid spawn. S3. Fermentation tank cultivation: Dispense the cooled oyster mushroom liquid spawn culture solution into the fermentation tank, and inoculate the primary seed liquid from the shake flask into the fermentation tank at an inoculation rate of 8%~12% (v / v); culture in the fermentation tank for 6~9 days to obtain liquid spawn.

5. The method for culturing liquid bacterial strains according to claim 4, characterized in that, The conditions for shaking culture in step S2 include: culture at a temperature of 23℃~25℃ for 5~7 days.

6. The method for culturing liquid bacterial strains according to claim 4, characterized in that, The shaking speed for the shaker culture in step S2 is 150~180 r / min.

7. The method for culturing liquid bacterial strains according to claim 4, characterized in that, The conditions for fermentation in step S3 include: cultivation at a temperature of 23℃~25℃; the aeration rate of the fermentation tank is 0.5~1.0 vvm, the tank pressure is 0.03~0.06 MPa, and the stirring speed is 130~150 r / min.

8. The application of the liquid culture medium of *Pleurotus ostreatus* as described in any one of claims 1 to 3 in improving the viability of *Pleurotus ostreatus* spores.

9. The application of the liquid culture medium of Pleurotus ostreatus as described in any one of claims 1 to 3 in improving the mycelial growth of Pleurotus ostreatus.

10. The application of the liquid spawn cultured in the liquid culture medium of *Pleurotus ostreatus* as described in any one of claims 1 to 3 in the cultivation of *Pleurotus ostreatus*, characterized in that, The process includes the following steps: filling cultivation substrate into cultivation bags, sterilizing and cooling them, then inoculating the cultivation bags with liquid spawn; placing the inoculated cultivation bags in a cultivation room for 20-25 days, allowing them to ripen for 3-5 days, and then transferring them to a fruiting room for 7-11 days of cultivation.