New strain of shiitake mushroom and method for cultivating shiitake mushroom

Abstract

To provide a method for cultivating shiitake mushrooms, which can distribute the generation of fruit bodies twice or more in relation to cultivation on a fungal bed of shiitake mushrooms, and can shorten the rest period after the completion of the first generation to less than half the usual period, and a new shiitake mushroom strain. [Solution] In the artificial cultivation of shiitake mushrooms, a seed fungus is inoculated into a culture medium, and mycelium is allowed to spread to form a fungal bed. The fungal bed that has completed maturation is placed in an indoor environment maintained at a predetermined temperature within the range of 26 to 31°C, the first produced fruiting body is harvested, and immediately after harvesting, the fungal bed is stimulated to produce fruiting bodies and the second produced fruiting bodies are harvested, or the fungal bed is left in the same indoor environment after harvesting maintained at a predetermined temperature within the range of 26 to 31°C for 1 to 10 days, after which the fungal bed is stimulated to produce fruiting bodies and the second produced fruiting bodies are harvested. The present invention also provides a new shiitake mushroom strain, KX-S056 (deposit number: NITE P-04117).

Description

[Technical field]

[0001] The present invention relates to a new strain of shiitake mushroom and a method for cultivating shiitake mushrooms by fungal bed cultivation. [Background technology]

[0002] Shiitake mushroom cultivation is a method in which a seed fungus is inoculated onto a fungal bed, an artificial medium made by mixing a base material such as sawdust with a nutrient source and adjusting the moisture, and then the mycelium is cultivated to form primordia, after which fruit bodies are produced and harvested. In Shiitake mushroom cultivation, a single mushroom bed is not used to grow fruit bodies (mushrooms) only once, but rather the grown fruit bodies are harvested from the mushroom bed and allowed to rest for a certain period of time, after which the mushroom bed is given a second germination stimulus to grow fruit bodies (mushrooms). This is usually repeated 2 to 6 times in this cultivation method.

[0003] In conventional methods for cultivating shiitake mushrooms on sawdust, after the first harvest, it was essential to perform rest management under certain temperature conditions to allow shoots (primordia formation) to form in preparation for the next generation, as described in Non-Patent Documents 1 and 2. This rest management is a management technique based on the idea from the time when log cultivation was carried out. Furthermore, Patent Document 1 discloses a mushroom cultivation method in which cultivation is terminated after the first emergence as a means of eliminating this rest management. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Revised edition of the latest mushroom cultivation techniques (Plant World), 2014, "The latest technology for mushroom cultivation using the Mori Sangyo method" (p138-146) [Non-Patent Document 2] Ibid., "The latest technology for cultivating shiitake mushrooms on a bed using the Kitaken method" (pp. 147-157) [Patent documents]

[0005] [Patent Document 1] JP 2020-130034 A Summary of the Invention [Problem to be solved by the invention]

[0006] As mentioned above, in the general Shiitake mushroom cultivation using sawdust beds, after each harvest, the sawdust beds are kept in a resting condition for at least 20 days in an environment with a temperature range of 20 to 23°C in order to form primordia for the next generation. After that, the sawdust beds are stimulated to produce fruit bodies and then harvested. This process has been repeated. This rest management requires temperature control for long periods during the blank period when fruit bodies (mushrooms) do not appear, which not only increases management costs but also reduces cultivation efficiency, which is problematic. However, rest management after each harvest has traditionally been considered an essential process to ensure good fruit body appearance in the next harvest, and the equipment, time, and expenses required for resting have been considered necessary in shiitake cultivation up until now. For this reason, shiitake have long been recognized as a mushroom that is difficult to cultivate in an industrial setting in a fully air-conditioned facility, compared to mushrooms such as enokitake and bunashimeji that can be grown in air-conditioned facilities.

[0007] It is possible to concentrate mushrooms in one burst in order to eliminate the need for rest management, but limiting it to one burst can lead to problems with stabilizing yield and quality. There are certain size restrictions (1.0-3.0 kg) on ​​the size of the mushroom beds required for industrial cultivation, and due to the morphological characteristics of shiitake mushrooms, each fruiting body is large, so in order to maintain quality, it is preferable to have them dispersed in two or more bursts rather than concentrated in one burst. However, in the case of shiitake mushrooms, unlike enokitake and nameko mushrooms, whose primordia are formed after the developmental process, primordia are formed as an extension of the cultivation process after the mycelium spreads, so it was extremely difficult to control the number of primordia formed. Therefore, it is not possible to adjust the number of buds by simply specifying the area of ​​the mushroom bed.

[0008] The present invention has been made in consideration of the above-mentioned circumstances, and its object is to provide a new method for artificially cultivating shiitake mushrooms, which can distribute the generation of fruit bodies to two or more times and shorten the rest period after the end of the first generation to less than half the usual period, and to provide a new shiitake mushroom strain that can be suitably used for said method. [Means for solving the problem]

[0009] [1] A first aspect of the present invention is a new Lentinus edodes strain, KX-S056 (deposit number: NITE P-04117). [2] A second aspect of the present invention is a new Lentinula edodes strain according to the first aspect, which is capable of forming primordia and cultivating fruiting bodies in an environment of 28°C or higher.

[0010] [3] A third aspect of the present invention is a method for artificially cultivating shiitake mushrooms, comprising the steps of inoculating a culture medium with a seed fungus, allowing mycelium to spread and cultivating a fungal bed, placing the cultivated fungal bed in an indoor environment within a temperature range of 26 to 31°C, harvesting the first fruiting body that has developed, stimulating the fungal bed immediately after harvesting to cause fruiting bodies to develop and harvesting the second fruiting bodies that have developed, or leaving the bed in the same condition after harvesting in an indoor environment within a temperature range of 26 to 31°C for 1 to 10 days, stimulating the fungal bed to cause fruiting bodies to develop and harvesting the second fruiting bodies that have developed. [4] A fourth aspect of the present invention is a method for cultivating shiitake mushrooms according to the third aspect, characterized in that the mushroom bed is placed in an indoor environment within a temperature range of 26 to 31°C and cultured. Effect of the Invention

[0011] The inventors have succeeded in dispersing the occurrence of fruit bodies to two or more times by placing the cultured fungal bed in an indoor environment within a temperature range of 26 to 31°C, and simultaneously proceeding with the occurrence of fruit bodies and the formation of primordia, and in shortening the rest period after the end of the first occurrence to less than half the usual period. As a result, the cultivation period can be significantly shortened and the cycle until harvest can be accelerated, and the annual turnover rate per facility can be increased, enabling efficient cultivation. Therefore, it is possible to overturn the common sense of fungal bed cultivation, which has been considered difficult to cultivate in an air-conditioned facility factory because of the need for long-term cultivation. In addition, it is also possible to cultivate in the summer or in a greenhouse.

[0012] The present inventors have also succeeded in developing a new shiitake mushroom strain, KX-S056 (deposit number: NITE P-04117). The new shiitake mushroom strain, KX-S056, is characterized by being capable of forming primordia and cultivating fruit bodies in an environment of 28°C or higher. Therefore, it is expected that the new shiitake mushroom strain, KX-S056, can be cultivated in summer or in greenhouses in artificial cultivation of shiitake mushrooms, such as on logs or on fungal beds. Moreover, the new shiitake mushroom strain, KX-S056, can be suitably applied to the above-mentioned shiitake mushroom cultivation method proposed by the present inventors. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 is a diagram showing an example of a cultivation schedule when the shiitake mushroom cultivation method of the present invention is applied. [Diagram 2] FIG. 1 is a diagram showing an example of a cultivation schedule according to a conventional general shiitake mushroom cultivation method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] An example of an embodiment of the present invention will be described below, however, the present invention is not limited to the embodiment described below.

[0015] <The new shiitake mushroom strain of the present invention> The new shiitake mushroom strain (also referred to as the "new shiitake mushroom strain of the present invention") will be described as one example of an embodiment of the present invention.

[0016] The new shiitake mushroom strain of the present invention is the new shiitake mushroom strain KX-S056, which has been deposited at the Patent Microorganisms Depositary Center under Accession No. NITE P-04117. The new shiitake mushroom strain of the present invention has the characteristics of being high temperature resistant and capable of forming primordia in an environment of 28°C or higher (illumination intensity 50-500Lx, humidity 60-90%) and of cultivating fruiting bodies in the same environment. Therefore, not only can it be suitably applied to the cultivation method of the present invention described later, but it can also be easily cultivated in artificial cultivation of shiitake mushrooms, such as log cultivation or mushroom bed cultivation, in summer or in a greenhouse. In addition, the new shiitake mushroom strain of the present invention forms only strong buds (primordia) in high temperature ranges, limiting the number of buds (high temperature suppression), improving the problem of concentrated growth of the first stage, which has been a problem until now. Furthermore, as the mushrooms grow, an appropriate number of primordia are formed as needed and grow in a dispersed manner in the second stage, making it possible to harvest mushrooms with good shapes and uniform sizes.

[0017] (New strain breeding method) The novel shiitake mushroom strain of the present invention was obtained by the following crossbreeding method. First, we obtained monokaryotic mycelium LE16 strain (Kinox Corporation's strain name) from 20 spores by the spore dilution method from the fruiting body of a strain we own, which was produced by crossbreeding existing varieties. Similarly, we obtained monokaryotic mycelium No. 1650 (Kinox Corporation strain name) from 20 spores derived from the fruiting body of a strain owned by our company that was produced by crossbreeding an existing variety.

[0018] Next, the monokaryotic mycelium LE16 strain and the monokaryotic mycelium No. 1650 strain were subjected to Mon-Mon mating on PDA (Nissui Pharmaceutical Co., Ltd.) petri dish medium to cultivate 200 hybrid strains including the dikaryotic mycelium No. KX-S056. After repeating the selection tests several times using 200 of the hybrid strains in standard bed cultivation, we were able to select "New Shiitake Mushroom Strain KX-S056," which has strong resistance to high temperatures during growth.

[0019] (Mycological properties of the strain of Lentinula edodes KX-S056 deposited at the Institute of Microbiology) Next, the mycological properties of the shiitake mushroom strain KX-S056 deposited at the Institute of Microbiology are shown below.

[0020] (a) Growth state on malt extract agar medium (20°C) The colony diameter is 29.8 mm on the 10th day and 39.7 mm on the 14th day, and white aerial hyphae are produced. The hyphae are white and grow straight. The reverse side is uniform and does not change color.

[0021] (b) Growth on potato-glucose agar medium (20°C) The colony diameter is 30.1 mm on the 10th day and 40.4 mm on the 14th day, and produces white aerial hyphae. The hyphae are white and grow straight. The reverse side is uniform and does not change color.

[0022] (c) Growth on oatmeal agar medium (20°C) The colony diameter was 32.8 mm on the 10th day and 43.3 mm on the 14th day. The hyphae were white, dense, and linear. The reverse side was uniform and did not change color.

[0023] (d) Growth state in phenol oxidase assay medium (20°C) On the 10th day, the colony diameter was 16.8 mm, the browning radius was 26.3 mm, and on the 20th day, the colony diameter was 37.2 mm, the mycelium was white, and there were many aerial mycelium.

[0024] (e) Optimal culture growth temperature A 6 mm diameter seed was inoculated onto a PDA (Difco) plate medium and cultured at each temperature shown in Table 1. After 14 days, the diameter of each colony was measured, and the optimum growth temperature was found to be around 25°C. Furthermore, the daily growth rate at 30°C was almost twice as fast as that at 10°C.

[0025] [Table 1]

[0026] (f) Optimal growth pH After sterilizing 40 ml of PGY liquid medium, the pH was adjusted, and a 6 mm diameter agar medium (PDA) culture seed was inoculated and cultured at 20°C for 20 days. After harvesting the bacteria, the dry weight was measured for each pH. As a result, the optimal pH was around pH 5.0.

[0027] [Table 2] (g) Confrontation culture test Furthermore, the shiitake mushroom KX-S056 was examined for similarities and differences with other shiitake mushrooms that have high-temperature-producing properties by dual culture on PDA (Nissui Pharmaceutical Co., Ltd.) agar medium. The shiitake mushroom strains tested were the eight strains shown in Table 3 (including the control strain). The dikaryotic mycelium of the test strain was punched out with a 6 mm cork borer, and each was inoculated face-to-face in the center of a PDA plate medium (20 mm apart), and after culturing at 23°C for 15 days, it was judged whether or not a band appeared at the contact point of the two colonies. The results are shown in Table 3. As shown in Table 3, all test strains of KX-S056 showed a clear aversion to contact, making it clear that it is a new strain.

[0028] [Table 3]

[0029] (h) Hardness (hardness of the fungus cap) The hardness of the middle part of the calyx that developed was measured using a fruit hardness tester KM-1 type (Fujiwara Seisakusho Co., Ltd.) and a relative comparison was made with XR1 (7.70 N, a level 3 hardness) as the standard. The average measurement value of 20 pieces was 7.24 N, which corresponds to a level 2 (medium) hardness in the Variety Registration Examination Criteria Characteristics Table.

[0030] <Cultivation method of the present invention> A method for artificially cultivating shiitake mushrooms (also referred to as the "cultivation method of the present invention") will be described as one embodiment of the present invention.

[0031] The cultivation method of the present invention is a method for artificially cultivating shiitake mushrooms, characterized in that a seed fungus is inoculated into a culture medium, mycelium is allowed to spread to form a fungal bed, the fungal bed that has completed maturation is placed in an indoor environment that is hotter than usual (26 to 31°C) to allow the generation of fruiting bodies and the formation of primordia to proceed simultaneously, the first fruiting body that has developed is harvested, and immediately after harvesting, the fungal bed is stimulated to develop fruiting bodies and the second fruiting bodies that have developed are harvested, or the fungal bed is left in the same indoor environment as after harvesting for 1 to 10 days at a temperature higher than usual, and then the fungal bed is stimulated to develop fruiting bodies and the second fruiting bodies that have developed are harvested. Each step will be described in detail below.

[0032] (Preparation of culture medium) The culture medium may be prepared by any of the conventionally known methods. For example, it is preferable to prepare a culture medium by mixing a nutrient source such as rice bran, bran or other cereal bran with a wood substrate such as sawdust, and then adding water to adjust the moisture content. In this case, examples of the wood substrate include crushed deciduous trees such as oak and chestnut. Examples of nutrient sources include cereal bran such as rice, wheat, and corn, as well as supplemental nutrient sources. The moisture content of the culture medium is preferably adjusted appropriately depending on the type of bacteria, and generally should be adjusted to a moisture content of, for example, 60 to 63%.

[0033] The culture medium prepared as described above is preferably filled into a container, and, if necessary, sterilized and cooled as required. In this case, the container into which the culture medium is filled may be a bottle, a bag, a box, or the like. The amount of culture medium filled in the container may be adjusted appropriately. The sterilization method may be any method, for example, a method of sterilizing the filled culture medium at high pressure at 121°C for 60 minutes, or at normal pressure at 98°C or higher for 4 hours or more, but is not limited to these methods. The cooling can be achieved by placing the culture medium, which has become hot due to sterilization, in a cooling chamber or the like and cooling it to an appropriate temperature (for example, 20° C. or lower). However, the method is not limited to this.

[0034] (Inoculation) The seed fungus to be inoculated in the cultivation method of the present invention is preferably a fungus species capable of forming primordia and cultivating fruit bodies in an environment of 28° C. or higher (illumination intensity 50-500 Lx, humidity 60-90%). Among them, it is particularly preferable to use the new Lentinula edodes strain of the present invention (new Lentinula edodes strain KX-S056), which is particularly excellent in resistance to high temperatures. In this way, by using as the seed fungus a fungus species capable of forming primordia and cultivating fruiting bodies in an environment of 28°C or higher, and storing the infested fungus bed in an environment at a higher temperature than usual, the generation or cultivation of fruiting bodies and the formation of primordia for the second generation can proceed simultaneously, so that after harvesting the first generated fruiting bodies, it is possible to harvest more than 30% of the medium mass of fruiting bodies (mushrooms) up to the second generation in a short period of time and terminate cultivation without the need for a long period of rest management as in the past. In addition, by storing in an environment at a higher temperature than usual, a certain number of primordia will no longer develop, so they will be able to be generated in a dispersed manner in two or more times without being concentrated in the first generation, and mushrooms with good shapes can be harvested efficiently.

[0035] The inoculation method may be to inoculate the surface or inoculation hole of the medium with the seed bacteria in a sterile room, or by other methods such as mixing the seed bacteria into the medium.

[0036] (culture) As for the culture, a conventionally known method may be appropriately adopted. For example, after inoculation of the seed fungus, the fungal bed can be stored in a culture room in the dark with the temperature, humidity, carbon dioxide concentration, and other conditions adjusted, allowing the mycelium to be cultivated and spread throughout the medium.

[0037] In this case, the temperature of the culture room (pre-culture) is preferably 15 to 28° C., and more preferably 20° C. or higher or 25° C. or lower. It is further preferable to maintain said temperature. The humidity in the culture room may be adjusted appropriately within the bounds of common technical knowledge. As a general guideline, it is preferable to set it to, for example, 55 to 85%, and more preferably, 65% or more or 75% or less. The carbon dioxide concentration in the culture chamber may also be adjusted appropriately within the bounds of common technical knowledge. As a general guideline, it is preferable to set it to, for example, 450 to 3500 PPm, and more preferably, 500 PPm or more or 3000 PPm or less. The culture period differs depending on the type of bacteria, and is preferably set appropriately, typically about 30 to 50 days.

[0038] After the mycelium has spread, the medium is aged in the culture chamber or in a separate aging chamber at a temperature of 20 to 31°C, preferably at least 25°C or not more than 30°C, and more preferably at said temperature, under intermittent light culture at 100 to 300 Lx for a further 40 to 60 days, preferably at least 45 days or not more than 55 days, and the culture is preferably completed within a total of 90 days. The humidity and carbon dioxide concentration during ripening may be adjusted in the same manner as in the above-mentioned pre-culture.

[0039] As described below, when a fungus with excellent high-temperature resistance, such as the new shiitake mushroom strain of the present invention (new shiitake mushroom strain KX-S056) is used as a seed fungus, the fungus bed can be placed in an indoor environment maintained at a higher temperature than the above, for example, a specified temperature of 26 to 31°C, or in an indoor temperature environment that varies in the temperature range of 15 to 35°C, for cultivation and maturation. By culturing and maturing in an environment with a higher temperature than usual, strict temperature control is no longer necessary, making it possible to culture and maturate in a vinyl greenhouse, etc. Also, the effect of suppressing the high temperature of the primordia can be obtained.

[0040] (Generation operation) Once the cultivation is complete, the culture bed is removed from the bag or other container and stored in a growth room in an indoor environment maintained at a specified temperature within the range of 26 to 31°C while controlling the moisture (by watering, etc.), or it is preferable to store the culture bed in an indoor environment of 15 to 35°C while controlling the moisture (by watering, etc.). By storing the mushroom bed in such an environment, it is possible to simultaneously develop the first fruiting body and form the primordia for the second and subsequent generations, and it is also possible to kill a certain percentage of the primordia that are weak to high temperatures, so it is possible to spread out the generation of fruiting bodies over two or more times. As a result, even if the resting period after the end of the first generation is shortened to less than half the usual period, it is possible to adequately harvest the second and subsequent generations of fruiting bodies. In addition, since normal shiitake mushroom fungi do not develop (grow) or germinate (form primordia) at such high temperatures, it is preferable to use fungi having high temperature resistance as described above.

[0041] When storing in an indoor environment where a specified temperature is maintained, the temperature is preferably 26 to 31°C, more preferably 27°C or higher or 30°C or lower, and even more preferably 28°C or higher or 29°C or lower. On the other hand, when storing in an indoor environment of 15 to 35°C, i.e., when storing in an indoor environment where the temperature fluctuates within that range, the temperature should be in the range of 15 to 35°C, but even if the daytime temperature is 35°C, it is preferable that the nighttime temperature be reduced to 25°C.

[0042] In this case, the illuminance in the room is preferably 100 to 1000 Lx. The humidity in the growth chamber may be appropriately adjusted within the bounds of common technical knowledge. As a general guideline, it is preferable to set it to, for example, 60 to 95%, and more preferably, 70% or more or 85% or less. The carbon dioxide concentration in the growth chamber may be adjusted appropriately within the bounds of common technical knowledge. As a general guideline, it is preferable to set it to, for example, 400 to 3000 PPm, and more preferably, 800 PPm or more or 2500 PPm or less. The moisture regulation during this period may be carried out appropriately based on common technical knowledge. For example, it is preferable to continuously sprinkle water 2 to 4 times a day.

[0043] The period of the above-mentioned generation operation, i.e., the period during which the cultured mushroom bed is stored in a high-temperature indoor environment, can be estimated to be about 3 to 7 days as a rough guide.

[0044] (Harvesting of the first crop) As a rough guide, after starting the above-mentioned growth procedure, bud cutting can be confirmed around 3 to 5 days later, and the first fruiting body (mushroom) can be harvested around 1 to 2 days later, and they can be harvested over a period of 3 to 4 days.

[0045] (Post-harvest management) After harvesting the first fruiting body, the fungal bed can be immediately stimulated to cause fruiting bodies to develop and the second fruiting bodies can be harvested, or the fungal bed can be left in the same cultivation room for 1 to 10 days in an indoor environment maintained at a specified temperature within the temperature range of 26 to 31°C, and then the fungal bed can be stimulated to cause fruiting bodies to develop and the second fruiting bodies can be harvested.

[0046] It is possible to stimulate the mushroom bed immediately after harvesting the first batch to produce fruit bodies, but from the standpoint of increasing the yield of the second batch of fruit bodies and harvesting better quality fruit bodies, it is preferable to leave the mushroom bed in the same cultivation room for 1 to 10 days in an indoor environment maintained at a specified temperature within the temperature range of 26 to 31°C and then stimulate the mushroom bed. In this case, the humidity in the growth room is preferably 75 to 85%, the carbon dioxide concentration is preferably 500 to 2500 PPm, and the illuminance is preferably 200 to 800 Lx. The storage period is preferably 3 days, and more preferably 5 days.

[0047] Methods for stimulating the culture bed include physical stimuli such as temperature, vibration, cutting of the hyphae, and even oxygen deprivation, but submersion in water is the most effective method because it can apply these physical stimuli in a complex manner. The term "soaking" refers to a process in which the culture bed is soaked in water, for example, in water at a temperature of 14 to 18°C ​​for about 6 to 18 hours.

[0048] After soaking, the mushroom bed is returned to the growth room and stored under the above conditions, and the second batch of fruiting bodies will grow and can be harvested.

[0049] (Harvesting of the second batch) The second generation of fruiting bodies (mushrooms) can be harvested 7 to 10 days after stimulation as described above.

[0050] (Subsequent post-harvest management and harvesting) After harvesting the second fruiting bodies, the shiitake mushroom cultivation may be terminated as is, or, if necessary, the mushroom bed may be immediately stimulated to cause fruiting bodies to occur and the second fruiting bodies to be harvested, similar to the management after harvesting the first fruiting bodies, or the mushroom bed may be left in the same cultivation room for 1 to 10 days in an indoor environment maintained at a specified temperature within the temperature range of 26 to 31°C, and then the mushroom bed may be stimulated to cause fruiting bodies to occur and the third fruiting bodies may be harvested. Post-harvest management and harvesting can be repeated thereafter if necessary. Furthermore, with the new shiitake mushroom strain of the present invention, approximately 70% of the lifetime production can be harvested with the first two occurrences. Therefore, when considering economic efficiency when harvesting from the third occurrence onwards, stopping at the second occurrence and increasing the turnover rate of the facility will increase the annual production volume per facility area and make production more efficient.

[0051] <Explanation of terms, etc.> In the present invention and this specification, when it is written "α to β" (α and β are arbitrary numbers), unless otherwise specified, it includes the meaning of "α or more and β or less", as well as "preferably larger than α" or "preferably smaller than β". In addition, when it is stated that "α or more" or "α≦" (α is any number), it also means "preferably greater than α" unless otherwise specified, and when it is stated that "β or less" or "≦β" (β is any number), it also means "preferably smaller than β" unless otherwise specified. EXAMPLES

[0052] An example of the present invention will be described below, however, the present invention is not limited to the example described below.

[0053] <Example 1> Fresh bran (National Feed Wholesale Cooperative), rice bran and Neovitas HM (Kinox Corporation) were added to the broadleaf sawdust as nutritional sources at a mass ratio of 5:3:2, at 10% per total mass of culture medium (1.2 kg) (60 g of fresh bran, 36 g of rice bran and 24 g of Neovitas HM were added per bag for a total of 120 g), and the moisture content was then adjusted to approximately 61% by mass to prepare the culture medium. Using a filling machine, a polypropylene cultivation bag with a filter (ST45-20: F-Tech Co., Ltd.) was filled with 1.2 kg of the prepared culture medium (net mass), and an inoculation hole with a diameter of about 20 mm reaching the bottom was provided in the center of the culture medium, and the bag mouth was temporarily sealed. It was then sterilized in a high-pressure sterilizer according to the usual method and cooled. Cooling was performed in a clean room to prevent recontamination by return air during cooling.

[0054] Thereafter, in the same clean room, shiitake mushroom seed culture (KX-S056) was aseptically inoculated onto the front surface of the culture medium, including the inoculation hole, to initiate culture. The cultivation was carried out in a dark state for 25 days until mycelium spread, with the temperature of the cultivation room kept constant at 23°C, humidity at 65-75%, and carbon dioxide concentration at 800-2500 PPm. After the spread was complete, the temperature of the cultivation room was kept at 23°C, humidity at 65-75%, and carbon dioxide concentration at 800-2500 PPm, and the light intensity was changed to 300 Lx only during the day, and the cultivation (maturation) was carried out for another 61 days. After a total of 86 days of cultivation, the bags were removed and the cultivation operation was carried out.

[0055] After removing the bags, the cultivation bed was watered twice a day, and in order to confirm cultivation in the high temperature range, the environmental temperature was set at five constant levels of 26°C, 28°C, 30°C, 31°C, and 32°C. The carbon dioxide concentration was 800-2,000 PPm, and light of approximately 500 Lx was irradiated only during the daytime. Growth was controlled at an environmental humidity range of 70-95%, and the first cultivation was harvested.

[0056] After the first batch was harvested, the mushroom bed was left in the growth room for 7 days, watered twice a day, and kept at a temperature range of 26-32°C, with a humidity of 80-95% and a carbon dioxide concentration of 800-2000ppm.Then, the mushroom bed was submerged in water (water temperature 16°C) for 16 hours, the mushroom bed was returned to the shelf, and a second batch was harvested.

[0057] The results are shown in Table 4. At 26°C, the yield per mushroom bed was 291.9g in total up to the second production, the total number of fruit bodies produced was 27.4, and the rate of abnormalities was 5.9%. At 28°C, the total yield per mushroom bed was 258.9g up to the second batch, the total number of fruit bodies produced was 22.5, and the rate of abnormal fruit bodies was 11.1%. Similarly, in the 30℃ group, the total yield was 203.2g, the number of pieces was 23.4, and the rate of abnormalities was 30.9%. In the 31℃ group, the total yield was 182.4g, the number of pieces was 16.7, and the rate of abnormalities was 29.0%. Furthermore, in the constant temperature area of ​​32°C, no mushrooms were observed to emerge due to the adverse effects of high temperatures.

[0058] [Table 4]

[0059] <Comparative Example 1> In Example 1, except that the seed fungus used for inoculation was changed to a commercially available variety capable of growing at 30°C shown in Table 5, the cultivation period was limited to 86 days under the same management as in Example 1, and the same growth operation was carried out. Growth management after the bag breaking treatment was the same as in Example 1, and after the harvest of the first growth was completed, it was left to stand for 7 days in the same way, and then the second growth was managed by the same water soaking treatment.

[0060] [Table 5]

[0061] In addition, no mushrooms grew on No. 706 when it was cultivated on a mushroom bed for 86 days.

[0062] As shown in Table 5, even when using a commercially available variety that can develop at 30°C, by placing the cultured mushroom bed in an indoor environment maintained at a specified temperature within the range of 26 to 31°C, it was confirmed that the development of fruit bodies can be dispersed into two periods and the rest period after the first development can be shortened to less than half the usual period. However, compared to the shiitake mushroom spawn (KX-S056), commercially available varieties that can grow at 30°C tend to be inferior in terms of shiitake yield and rate of abnormalities at higher temperatures, and a decrease in the amount of mushrooms grown was observed in the second growth.

[0063] In the above examples, the culture bed after cultivation is placed in an indoor environment maintained at a predetermined temperature within the temperature range of 26 to 31°C, thereby allowing the development of fruiting bodies and the formation of primordia to proceed simultaneously. Based on past experience and common technical knowledge, if the emergence of fruiting bodies and the formation of primordia proceed simultaneously when placed in an indoor environment maintained at a constant temperature of 31°C, it is likely that the emergence of fruiting bodies and the formation of primordia will also proceed simultaneously in an indoor environment where the temperature fluctuates between 15 and 35°C, for example, an indoor environment where the temperature is 25°C in the morning and evening but rises to 35°C during the day. The same can be said about temperature conditions during post-harvest management.

[0064] <Example 2> In order to confirm the formation of primordia at high temperature, the culture temperature was changed to constant temperatures of 26°C and 29°C from the initial culture stage, but the culture period was limited to 86 days under the same conditions as in Example 1. The cultivation operations consisted of watering the mushroom bed twice a day, setting the ambient temperature at a constant 20°C, keeping the carbon dioxide concentration at 800-2,000 PPm, and irradiating light at approximately 500 Lx during daytime hours only. Growth was controlled at an ambient humidity range of 70-95%, and only the first crop was harvested. As shown in Table 6, no significant difference was observed in the developmental status even when cultured at a constant high temperature of 29°C, and it was confirmed that the formation of the primordia that serve as the source of mushroom development was occurring normally, just as in culture at an initial culture temperature of 23°C.

[0065] [Table 6]

[0066] <Comparative Example 2> In Example 2, except that the seed bacteria used for inoculation was changed to Kitaken H73, the cultivation period was limited to 86 days under the same management as in Example 2, and the same generation operation was performed. Growth management was also performed at 20°C, and only the initial generation was managed.

[0067] [Table 7]

[0068] Note that No. 706 was excluded from the test because it does not produce mushrooms.

[0069] As shown in Table 7, for existing commercially available varieties, the yield decreased and the rate of abnormalities increased sharply when cultured at a constant temperature of 29°C, confirming that high temperatures are detrimental to the formation of primordia during culture.

[0070] <Consideration> From the above examples and the results of tests conducted by the inventors thus far, it has been confirmed that by using a high-temperature-resistant shiitake mushroom species and placing the cultured mushroom bed in an indoor environment maintained at a specified temperature within the temperature range of 26 to 31°C, or by placing the cultured mushroom bed in an indoor environment of 15 to 35°C, it is possible to prevent the generation of fruit bodies from concentrating in one go and spread it out over two or more goes, and also to shorten the rest period after the end of the first go-round to less than half the usual period. In this way, the mushrooms do not grow in a concentrated initial growth pattern, but rather grow in a dispersed manner, allowing for efficient harvesting of well-formed shiitake mushrooms. In addition, the rest period after the first growth is completed can be shortened to less than half the usual period, which results in a significant reduction in the number of days for cultivation, enabling shiitake mushrooms to be grown and harvested efficiently in a short period of time. Therefore, for example, even with a small mushroom bed, by distributing the growth in two stages and allowing the first and second growths to occur almost continuously, it is possible to avoid the deterioration of quality that would result from concentrated growth.In addition, the rest period required after harvesting can be reduced by more than half or even to zero, which means that the growth period until the second growth can be generated can be significantly reduced to around 17 days, making it possible to realize a fully air-conditioned industrial cultivation system for shiitake mushroom bed cultivation.

[0071] In addition, when the new strain according to the present invention is used and cultivation is terminated at the second occurrence, it is possible to shorten the growth period by about 46 days compared to the normal cultivation method in which two resting periods are followed until the third occurrence. In the case of the second occurrence, cultivation can be completed in a total of 107 days, including the 90 days of cultivation. This is the same number of days as the total cultivation days, including cultivation and growth, for enokitake mushrooms, which took 55 days, nameko mushrooms, which took 75 days, and Bunashimeji mushrooms, which took 110 days, which are mushrooms that have been cultivated in factory-grown air-conditioned facilities, so it can be said that cultivation in a full-scale air-conditioned facility is possible.

[0072] By placing the cultivated mushroom bed in an indoor environment maintained at a specified temperature within the range of 26 to 31°C, or by placing the cultivated mushroom bed in an indoor environment of 15 to 35°C, the occurrence of fruit bodies can be dispersed into two periods and the rest period after the end of the first occurrence can be shortened to less than half of the usual period.The mechanism behind this can be considered as follows. That is, by placing the cultured bed in an indoor environment maintained at a predetermined temperature within the temperature range of 26 to 31°C, or by placing the cultured bed in an indoor environment of 15 to 35°C, the first fruiting body grows and at the same time, buds (primordia) for the second and subsequent generations are formed, so that it is considered that it is not necessary to provide a long rest period for the formation of primordia for the second and subsequent generations after the first generation harvest. In addition, since it is placed in a high temperature environment, a certain proportion of primordia die, and the formation of primordia for the first generation is suppressed (high temperature suppression) and the number of growth is also limited, so that it is considered that the generation of fruiting bodies can be dispersed in two times without being concentrated in the first generation. Such frequent repetition of the life and death of primordia is presumed to be a characteristic of high-temperature resistant bacteria.

Claims

1. New shiitake mushroom strain KX-S056 (deposit number: NITE P-04117).

2. 2. The new shiitake mushroom strain according to claim 1, which is capable of forming primordia and cultivating fruiting bodies in an environment of 28°C or higher.

3. A method for artificially cultivating shiitake mushrooms using the new shiitake mushroom strain according to claim 1 or 2, comprising the steps of inoculating a culture medium with a seed fungus, allowing the mycelium to spread and cultivating a fungal bed, placing the cultivated fungal bed in an indoor environment within a temperature range of 26 to 31°C, harvesting the first fruiting body that has developed, stimulating the fungal bed immediately after harvesting to cause fruiting bodies to develop and harvesting the second fruiting bodies that have developed, or leaving the bed in the same condition after harvesting in an indoor environment within a temperature range of 26 to 31°C for 1 to 10 days, stimulating the fungal bed to cause fruiting bodies to develop and harvesting the second fruiting bodies that have developed.

4. 4. The method for cultivating shiitake mushrooms according to claim 3, characterized in that the mushroom bed is placed in an indoor environment within a temperature range of 26 to 31° C.

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