Novel strain of shiitake mushroom and method for cultivating shiitake mushroom

Abstract

To provide a method for cultivating Lentinus edodes, which relates to mushroom bed cultivation of Lentinus edodes, can disperse the generation of a fruit body to two or more times, and can shorten a rest period after the completion of the first generation to a half or less of a usual period, and to provide a new strain of Lentinus edodes.SOLUTION: In artificial cultivation of Lentinus edodes, inoculating a culture medium with a spawn, spreading hyphae to form a mushroom bed, and placing the mushroom bed after completion of maturation in an indoor environment maintained at a predetermined temperature within a temperature range of 26 to 31 °C; The present invention provides a method for cultivating Lentinus edodes, comprising harvesting a first generated fruit body, stimulating a mushroom bed immediately after harvesting to generate a fruit body, and harvesting a second generated fruit body, or stimulating a mushroom bed after harvesting to generate a fruit body and harvesting a second generated fruit body after leaving the mushroom bed for 1 to 10 days in a room maintained at a predetermined temperature within a temperature range of 26 °C to 31 °C, and also provides a novel strain of Lentinus edodes KX-NITEP (accession number: NITEP 04117). S056.SELECTED DRAWING: Figure 1

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 cultivation method in which seed fungi are inoculated into a fungal bed, which is an artificial medium made by mixing a base material such as sawdust with nutrients and adjusting the moisture content, and then cultivating it to grow mycelium and form primordia, which are then allowed to produce fruiting bodies and be harvested. In Shiitake mushroom cultivation, a single mushroom bed is not used for a single production of fruiting bodies (mushrooms), but rather the grown fruiting bodies are harvested from the bed, allowed to rest for a certain period of time, and then stimulated to germinate again, causing a second production of fruiting bodies (mushrooms). This cultivation method is usually repeated 2 to 6 times.

[0003] In conventional Shiitake mushroom sawdust cultivation methods, after the first harvest, the sawdust beds must be left to rest under constant temperature conditions to allow bud formation (primordia formation) in preparation for the next generation, as described in Non-Patent Document 1 or Non-Patent Document 2. This rest management is a management technique based on the thinking that has been used since the days of log cultivation. 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 Techniques for Shiitake Mushroom Cultivation Using the Mori Sangyo Method" (pp. 138-146) [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] Japanese Patent Application Publication No. 2020-130034 Summary of the Invention [Problem to be solved by the invention]

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

[0007] To avoid the need for resting management, it is possible to concentrate mushrooms in one spawn, but limiting spawning to one spawn can cause 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 distribute spawning to two or more times rather than concentrating spawning in one spawn. However, unlike mushrooms such as Enokitake and Nameko, in which primordia are formed after developmental manipulation, shiitake mushrooms undergo primordium formation as an extension of the cultivation process after mycelium spread, making it extremely difficult to control the number of primordia formed. Therefore, it is not possible to adjust the number of buds simply by specifying the area of ​​the fungal 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 occurrence of fruit bodies to two or more times and shorten the rest period after the completion of the first occurrence to less than half of the usual period, and to provide a new shiitake mushroom strain that can be suitably used for this 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 shiitake mushroom 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 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 emerged, stimulating the fungal bed immediately after harvesting to produce fruiting bodies and harvesting the second fruiting bodies, or leaving the fungal bed in the same room 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 produce fruiting bodies and harvesting the second fruiting bodies. [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. [Effects of the Invention]

[0011] The inventors have succeeded in placing the cultured fungal bed in an indoor environment within a temperature range of 26 to 31°C, allowing fruiting body emergence and primordium formation to proceed simultaneously, thereby distributing fruiting body emergence over two or more occasions rather than concentrating it in one event, and shortening the rest period after the first emergence to less than half the usual period. As a result, the cultivation period can be significantly shortened, accelerating the cycle until harvest, increasing the annual turnover rate per facility and enabling efficient cultivation. This overturns the conventional wisdom about fungal bed cultivation, which has traditionally been considered difficult to cultivate in an air-conditioned facility due to the long-term cultivation period required. Furthermore, cultivation in summer and greenhouses is also possible.

[0012] The present inventors also succeeded in developing a new shiitake mushroom strain, KX-S056 (deposit number: NITE P-04117). This new shiitake mushroom strain, KX-S056, is characterized by its ability to form primordia and develop fruiting bodies in an environment of 28°C or higher. Therefore, it is expected that shiitake mushrooms can be cultivated artificially, such as on logs or fungal beds, even in summer or in greenhouses. Furthermore, this strain can be suitably applied to the above-mentioned shiitake mushroom cultivation method proposed by the present inventors. [Brief explanation of the drawings]

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

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

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

[0016] The new Lentinus edodes strain of the present invention is the new Lentinus edodes strain KX-S056, which has been deposited at the International Patent Microorganisms Depositary Center under accession number NITE P-04117. The new shiitake mushroom strain of the present invention is characterized by its high temperature tolerance and the ability to form primordia in an environment of 28°C or higher (illumination of 50-500Lx, humidity of 60-90%), and to develop fruiting bodies in the same environment. Therefore, it can be suitably applied to the cultivation method of the present invention described later, and can also be easily cultivated in artificial cultivation of shiitake mushrooms, such as log cultivation or fungal bed cultivation, in summer or in greenhouse cultivation. Furthermore, the new Shiitake mushroom strain of the present invention only produces strong buds (primordia) in high-temperature ranges, limiting the number of buds (high-temperature suppression), thereby improving the problem of concentrated first-stage growth. Furthermore, as the mushrooms continue to grow, an appropriate number of primordia are formed as needed, and the second-stage growth occurs in a dispersed manner, making it possible to harvest mushrooms with good shape and uniform size.

[0017] (New strain breeding method) The new strain of shiitake mushroom of the present invention was obtained by the following mating method. First, we obtained monokaryotic mycelium strain LE16 (Kinox Corporation strain name) from 20 spores using the spore dilution method from the fruiting body of a strain we own, which was created 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, which was produced by crossbreeding existing varieties.

[0018] Next, the monokaryotic mycelium LE16 strain and the monokaryotic mycelium No. 1650 strain were hybridized on PDA (Nissui Pharmaceutical Co., Ltd.) petri dish medium to produce 200 hybrid strains, including the dikaryotic mycelium No. KX-S056 strain. After repeating several selection tests using 200 of these hybrid strains in bed cultivation according to standard methods, we were able to select a new shiitake strain, KX-S056, which has strong resistance to high temperatures during growth.

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

[0020] (a) Growth status 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 discolor.

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

[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, and the hyphae were white, dense, and linear. The reverse side was uniform and not discolored.

[0023] (d) Growth status in phenoloxidase assay medium (20°C) On the 10th day, the colony diameter was 16.8 mm and the browning radius was 26.3 mm. On the 20th day, the colony diameter was 37.2 mm, and the mycelium was white with many aerial mycelia.

[0024] (e) Optimal culture growth temperature A 6mm 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 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 dry weight of the bacteria was measured at each pH. The optimum pH was found to be around pH 5.0.

[0027] [Table 2] (g) Confrontation culture test Furthermore, the similarities and differences between the shiitake mushroom KX-S056 and other shiitake mushrooms with thermogenic properties were investigated by dual culture on PDA (Nissui Pharmaceutical Co., Ltd.) agar medium. The shiitake strains tested were the eight strains shown in Table 3 (including the control strain). Dikaryotic mycelia of the test strain were punched out with a 6 mm cork borer, and each was inoculated face-to-face into the center of a PDA plate (20 mm apart). After culturing at 23°C for 15 days, it was determined whether a band appeared at the contact point between 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 fungal cap) The hardness of the middle part of the cap of the fruiting body was measured using a fruit hardness tester KM-1 type (Fujiwara Seisakusho Co., Ltd.) and compared with the XR1 (7.70 N, level 3 hardness) as the standard. The average of 20 measurements was 7.24 N, which corresponds to level 2 (medium) hardness in the Variety Registration Examination Standard 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 now be described as an example of an 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 culture medium is inoculated with a seed culture medium, mycelium is allowed to spread, and a fungal bed is formed. After the fungal bed has matured, it is placed in a room environment that is warmer than usual (26 to 31°C) to allow the development of fruiting bodies and the formation of primordia to proceed simultaneously. The first fruiting body is harvested, and immediately after harvest, the fungal bed is stimulated to develop fruiting bodies and the second fruiting bodies are harvested; alternatively, after harvest, the fungal bed is left in a room environment that is warmer than usual for 1 to 10 days, and then the fungal bed is stimulated to develop fruiting bodies and the second fruiting bodies are harvested. Each step will be described in detail below.

[0032] (Preparation of culture medium) The culture medium may be prepared by any conventionally known method. For example, it is preferable to prepare a culture medium by mixing a nutrient source such as rice bran, wheat bran or other grain 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 sawtooth oak. Examples of nutrient sources include grain bran such as rice, wheat, and corn, as well as supplementary nutrient sources. The moisture content of the culture medium is preferably adjusted appropriately depending on the bacterial species, and as a general guideline, it is sufficient to adjust the moisture content to, for example, 60 to 63%.

[0033] The culture medium prepared as described above is preferably filled into a container, and if necessary, sterilized as required and allowed to cool. 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 as appropriate. Sterilization may be performed by any method, including, but not limited to, maintaining the filled culture medium at 121°C under high pressure for 60 minutes or at 98°C or higher under normal pressure for 4 hours or more. The cooling can be achieved by placing the culture medium, which has been heated by sterilization, in a cooling chamber or the like and cooling it to an appropriate temperature (for example, 20° C. or less), although the method is not limited to this.

[0034] (Inoculation) The seed culture to be inoculated in the cultivation method of the present invention is preferably a fungus species that can form primordia and develop fruiting bodies in an environment of 28°C or higher (illumination of 50 to 500 Lx, humidity of 60 to 90%). Among these, it is particularly preferable to use the new Lentinula edodes strain of the present invention (new Lentinula edodes strain KX-S056), which has excellent high-temperature resistance. In this way, by using as starter a fungus species that can form primordia and develop fruiting bodies in an environment of 28°C or higher, and storing the infested fungal bed in a higher-than-normal environment, the development and development of fruiting bodies and the formation of primordia for second development can proceed simultaneously. Therefore, after harvesting the first fruiting bodies, it is possible to harvest more than 30% of the medium mass of fruiting bodies (mushrooms) up to the second development in a short period of time, and complete cultivation, without the need for the long-term rest management required in the past. Furthermore, by storing the fungus in a higher-than-normal environment, a certain number of primordia will no longer develop, so development can be dispersed over two or more times rather than concentrated in the first development, allowing for the efficient harvest of well-shaped mushrooms.

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

[0036] (culture) Regarding the culture, a conventionally known method may be appropriately adopted. For example, after inoculation of the seed culture, the fungal bed can be stored in a dark culture room under controlled conditions such as temperature, humidity, and carbon dioxide concentration, 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 this temperature. The humidity in the culture room may be adjusted appropriately within the bounds of common technical knowledge, and as a general guideline, it is preferably set 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 bacterial species, and is preferably set appropriately, typically about 30 to 50 days.

[0038] After the mycelium has spread, the mixture is kept in the culture chamber or in a separate aging chamber at a temperature of 20 to 31°C, preferably 25°C or higher or 30°C or lower, and more preferably maintained at that temperature, under intermittent light conditions of 100 to 300 Lx, for a further 40 to 60 days, preferably 45 days or more or 55 days or less, for aging, 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 early culture.

[0039] As will be described later, when a fungus with excellent high-temperature resistance, such as the new shiitake strain of the present invention (new shiitake strain KX-S056) is used as the inoculum, the fungus bed can be placed in an indoor environment maintained at a temperature even higher than that described above, for example, a predetermined temperature of 26 to 31°C, or in an indoor temperature environment that varies in the temperature range of 15 to 35°C, and the fungus bed can be used for cultivation and aging. By culturing and aging in such a higher-temperature environment than usual, strict temperature control is no longer necessary, making it possible to culture and aging in a 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 fungal bed is removed from the bag or other container and stored in a growth room in an indoor environment where the cultivated fungal bed is maintained at a predetermined temperature within the range of 26 to 31°C while adjusting the moisture (by watering, etc.), or it is preferable to store the fungal bed in an indoor environment of 15 to 35°C while adjusting the moisture (by watering, etc.). By storing the fungal bed in this environment, the development of the first fruiting body and the formation of primordia for the second and subsequent generations can proceed simultaneously, and a certain percentage of primordia that are sensitive to high temperatures can be killed, so the fruiting of the first generation can be dispersed over two or more generations. As a result, even if the resting period after the first generation is shortened to less than half the usual period, it is possible to harvest a sufficient number of fruiting bodies from the second generation onwards. In addition, since normal shiitake fungi do not develop (grow) or germinate (form primordia) at such high temperatures, it is preferable to use fungi that are resistant to high temperatures 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 in the range 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 drops to 25°C.

[0042] In this case, the indoor illuminance is preferably set to 100 to 1000 Lx. The humidity in the growth chamber may be adjusted appropriately within the bounds of common technical knowledge, and as a general guideline, it is preferably set 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 also be adjusted appropriately within the bounds of common technical knowledge, and as a general guideline, it is preferably set 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 as appropriate based on common technical knowledge. For example, it is preferable to continuously water the plant 2 to 4 times a day.

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

[0044] (First harvest) 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 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 produce fruiting bodies and the second fruiting bodies can be harvested, or the fungal bed can be left in the same growth room for 1 to 10 days in an indoor environment maintained at a predetermined temperature within the temperature range of 26 to 31°C, and then the fungal bed can be stimulated to produce fruiting bodies and the second fruiting bodies can be harvested.

[0046] It is possible to stimulate the fungal bed immediately after harvesting the first fruiting bodies to produce fruiting bodies, but from the perspective of increasing the yield of the second fruiting bodies and harvesting better quality fruiting bodies, it is preferable to leave the fungal bed in the same growth room for 1 to 10 days in an indoor environment maintained at a specified temperature within the temperature range of 26 to 31°C before stimulating the fungal 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 of stimulating the mushroom bed include physical stimuli such as temperature, vibration, cutting of the mycelium, and even oxygen deprivation, but submersion in water is the most effective method because it can apply these physical stimuli in combination. The soaking is a process of soaking the fungal bed in water, for example, in water at a temperature of 14 to 18°C ​​for about 6 to 18 hours.

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

[0049] (Harvesting of the second batch) The second fruiting body (mushroom) 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, Shiitake mushroom cultivation can be terminated as is, or, if necessary, the fungal bed can be immediately stimulated to produce fruiting bodies and the second fruiting bodies can be harvested, similar to the management after harvesting the first fruiting bodies, or the fungal bed can be left in the same growth room for 1 to 10 days in an indoor environment maintained at a predetermined temperature within the temperature range of 26 to 31°C, after which the fungal bed can be stimulated to produce fruiting bodies and the third fruiting bodies can 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 for harvesting from the third occurrence onwards, stopping at the second occurrence and increasing the facility turnover rate 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 "α to β" (α and β are arbitrary numbers) is written, unless otherwise specified, it means "not less than α and not more than β", as well as "preferably greater than α" or "preferably smaller than β". Furthermore, 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. [Example]

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

[0053] Example 1 Fresh bran (National Feed Wholesalers Cooperative), rice bran, and Neovitas HM (Kinox Co., Ltd.) were added to hardwood sawdust as nutrient sources at a mass ratio of 5:3:2, with 10% added by mass per total mass (1.2 kg) of the culture medium (60 g of fresh bran, 36 g of rice bran, and 24 g of Neovitas HM, for a total of 120 g added per bag), 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 approximately 20 mm reaching the bottom was made in the center of the culture medium, and the bag opening was temporarily sealed.The bag was then sterilized in a high-pressure sterilizer according to standard methods and cooled.Cooling was carried out in a clean room to prevent recontamination by returning air during cooling.

[0054] Thereafter, in the same clean room, shiitake seed culture (KX-S056) was aseptically inoculated onto the front surface of the culture medium, including the inoculation hole, to initiate cultivation. The cultivation was carried out in darkness 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 800-2500ppm. After the spread was complete, the cultivation room temperature was maintained at 23°C, humidity at 65-75%, and carbon dioxide concentration at 800-2500ppm, and the light intensity was changed to 300Lx during the daytime only, and the cultivation (aging) was carried out for an additional 61 days. After a total of 86 days of cultivation, the bags were removed and the cultivation procedure was carried out.

[0055] After removing the bags, the growth was controlled by watering the mushroom bed twice a day, and in order to confirm growth in high temperature ranges, 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 kept at 800-2,000 PPm, and light of approximately 500 lux was irradiated only during the daytime. Growth was controlled within an environmental humidity range of 70-95%, and the first growth was harvested.

[0056] After the first harvest, the mushroom bed was left in the growth chamber for 7 days, watered twice a day, at a temperature range of 26 to 32°C, with humidity of 80 to 95% and a carbon dioxide concentration of 800 to 2000 ppm. After that, the mushroom bed was submerged in water (water temperature 16°C) for 16 hours, and the second growth was carried out. The second growth was then harvested.

[0057] As shown in Table 4, the results for the 26°C group were that the yield per mushroom bed was 291.9 g in total up to the second fruiting stage, the total number of fruiting 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 fruiting stage, the total number of fruiting bodies produced was 22.5, and the rate of abnormal fruiting 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 area where the temperature was kept constant at 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 culture used for inoculation was changed to a commercially available variety capable of developing at 30°C shown in Table 5, the cultivation period was limited to 86 days, and the same development procedure was carried out. Growth management after the bag breaking treatment was the same as in Example 1, and after the harvest of the first development, it was left to stand for 7 days in the same way, and then development management of the second development was carried out by the same submersion treatment.

[0060] [Table 5]

[0061] In addition, no mushrooms grew in No. 706 when 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 fungal 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 fruiting bodies can be dispersed into two stages and the rest period after the first development can be shortened to less than half of the usual period. However, compared to the Shiitake mushroom spawn (KX-S056), commercially available varieties that can be grown at 30°C tend to be inferior in terms of yield and rate of malformation as the temperature increases, and a decrease in the amount of mushrooms grown was confirmed in the second growth.

[0063] In the above examples, the cultured fungal bed was placed in an indoor environment maintained at a predetermined temperature within the temperature range of 26 to 31°C, allowing the development of fruiting bodies and the formation of primordia to proceed simultaneously. Based on past experience and common technical knowledge, if fruiting body emergence and primordium formation proceed simultaneously when placed in an indoor environment where the temperature is maintained at a constant 31°C, then it is likely that fruiting body emergence and primordium formation 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 in post-harvest management.

[0064] <Example 2> In order to confirm the formation of primordia during high-temperature culture, 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 was carried out by watering the mushroom bed twice a day, setting the ambient temperature at a constant 20°C, maintaining a carbon dioxide concentration of 800-2,000 ppm, irradiating light of approximately 500 lux only during the daytime, and controlling growth within an ambient humidity range of 70-95%, with only the first crop harvested. As shown in Table 6, no significant difference in the development status was observed even when cultured at a constant high temperature of 29°C, and it was confirmed that the formation of primordia, which are the source of mushroom development, was occurring normally, just as in cultures at an initial culture temperature of 23°C.

[0065] [Table 6]

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

[0067] [Table 7]

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

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

[0070] <Consideration> From the above examples and the results of tests conducted by the inventors to date, it has been confirmed that by using a high-temperature-resistant Shiitake mushroom species and placing the cultured fungal bed in an indoor environment maintained at a predetermined temperature within the temperature range of 26 to 31°C, or by placing the cultured fungal bed in an indoor environment of 15 to 35°C, it is possible to prevent fruit body generation from concentrating in one event and spread it over two or more events, and also to shorten the rest period after the first event to less than half the usual period. In this way, the mushrooms do not sprout in a concentrated manner during the initial stage, but rather sprout in a dispersed manner, allowing for efficient harvesting of well-shaped shiitake mushrooms. In addition, the rest period after the first growth can be shortened to less than half of the usual period, which significantly reduces the number of days required for cultivation, allowing 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 twice and allowing the first and second generations to occur almost continuously, it is possible to avoid a decline in quality due to 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 generation can be significantly reduced to around 17 days, and it is expected that a fully air-conditioned factory-type cultivation system for shiitake mushroom growth on mushroom beds will be realized.

[0071] Furthermore, when the new strain of the present invention was used and cultivation was terminated at the second emergence, it was possible to shorten the growth period by approximately 46 days compared to the normal cultivation method in which two rest periods were followed until the third emergence. In the case of the second emergence, cultivation was possible in a total of 107 days, including the 90-day cultivation period. This is the same number of days as the total cultivation periods for mushrooms cultivated in air-conditioned facilities up to now, such as 55 days for enokitake mushrooms, 75 days for nameko mushrooms, and 110 days for bunashimeji mushrooms, so it can be said that cultivation in a full-scale air-conditioned facility is possible.

[0072] By placing the cultivated fungal bed in an indoor environment maintained at a predetermined temperature within the range of 26 to 31°C, or by placing the cultivated fungal bed in an indoor environment of 15 to 35°C, the development of fruiting bodies can be dispersed into two periods, and the rest period after the first development can be shortened to less than half of the usual period.The mechanism behind this can be thought of as follows. Specifically, by placing the cultured fungal bed in an indoor environment maintained at a predetermined temperature within the range of 26–31°C, or by placing the cultured fungal bed in an indoor environment of 15–35°C, the first fruiting body grows while buds (primordia) for the second and subsequent generations are formed. This eliminates the need for a long rest period after harvesting the first fruiting body for the formation of primordia for the second and subsequent generations. Furthermore, because the fungal bed is placed in a high-temperature environment, a certain percentage of the primordia die, suppressing the formation of the first fruiting body (high-temperature suppression) and limiting the number of new fruiting bodies. This prevents the first fruiting body from concentrating and allows the development of fruiting bodies to be dispersed over two periods. This frequent cycle of primordial life and death is presumably a characteristic of high-temperature-resistant bacteria.

Claims

1. New Lentinula edodes 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, comprising 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 fungal 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, wherein the fungal bed is placed in an indoor environment within a temperature range of 26 to 31°C and the cultivation is carried out.

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