Method for preparing morchella esculenta nutrition medium from alkalization-sugaring combined modified straw and morchella esculenta nutrition medium

Abstract

The invention belongs to the technical field of morchella esculenta cultivation, and particularly relates to a method for preparing a morchella esculenta nutrition medium through alkalization-sugaring combined modification of straw and the morchella esculenta nutrition medium. The crushed straw is heated with an alkaline solution for alkalization treatment, then a sugar solution is adopted for normal-temperature dipping treatment, and main raw materials are obtained after draining; mixing the main raw materials with the pre-wetted auxiliary raw material 1 and the pre-wetted auxiliary raw material 2, bagging and sterilizing to obtain the morchella esculenta nutrition medium. Wherein the auxiliary raw material 1 has air permeability and water binding capacity, and the auxiliary raw material 2 is used for keeping the substrate within a pH range required by growth of morchella esculenta. The matrix can reduce dependence on staple food grains such as wheat, improve the straw utilization value and support normal growth of morchella hyphae, the optimization scheme effect is better than that of a conventional wheat matrix, the cultivation cost can be reduced, and economic and ecological benefits are achieved.

Description

Technical Field

[0001] This invention belongs to the field of morel cultivation technology, specifically relating to a method for preparing morel nutrient substrate from straw modified by alkalization-sugaring and the morel nutrient substrate itself. Background Technology

[0002] Morel mushrooms (Morchella spp.) belong to the genus Morchella in the order Plasmoales of the phylum Ascomycota. They are a rare fungus used for both food and medicine, and are highly prized for their rich nutrition and unique flavor, earning them the title of "Queen of Mushrooms." In the artificial cultivation of morel mushrooms, the "exogenous nutrient bag" feeding technology plays a crucial role. The exogenous nutrient bag is the main source of nutrition for the growth and development of morel mushrooms and is a key factor in achieving stable and high yields.

[0003] Currently, among the publicly available nutrient bag formulas in China, although the combinations of auxiliary materials vary, wheat grains are generally used as the main ingredient. For example, Roustamu et al. use wheat grains, rice husks, and corn cobs to formulate nutrient bags, while Meng Xianglin et al.'s nutrient bags include wheat grains, sawdust, rice husks, and humus. In 2024, the national morel mushroom cultivation area reached 27,000 hectares. 2 According to each hm 2 Based on the calculation that each nutrient bag consumes 7.3 tons of wheat, the annual wheat consumption for nutrient bag production is approximately 197,000 tons. Given the current high dependence of morel mushroom nutrient bags on the staple crop wheat, developing new main ingredients for nutrient bags to reduce reliance on staple crops is of significant practical importance.

[0004] On the other hand, as a major agricultural country, my country has abundant straw resources. However, the current comprehensive utilization of straw is mostly concentrated on direct return to the field, simple crushing for fuel, or coarse processing for feed. The utilization methods are still relatively simple, and the added value is low. Crop straw contains 35% to 40% cellulose. However, compared with starchy raw materials, morel mushrooms have a longer decomposition cycle for cellulose. Directly using straw as the main material for nutrient bags is not conducive to their healthy growth. In addition, the surface of straw is usually covered with lignin that morel mushrooms cannot decompose, and it also contains silicon components that morel mushrooms cannot effectively utilize. This further increases the difficulty of using straw as the main material for nutrient bags. Summary of the Invention

[0005] To address the aforementioned problems in existing technologies, this invention provides a morel mushroom nutrient substrate prepared by alkalization-sugaring combined modification of straw and its preparation method, offering a new path for reducing dependence on grain resources and promoting the development and application of non-grain nutrient bags.

[0006] The first aspect of this invention provides a method for preparing a morel mushroom nutrient substrate by alkalization-sugaring combined modification of straw. The method involves alkalizing crushed straw by heating it in an alkaline solution, then soaking it in a sugar solution at room temperature, and draining it to obtain the main raw material. The main raw material is then mixed with pre-wetted auxiliary raw material 1 and auxiliary raw material 2, and the mixture is bagged and sterilized to obtain the morel mushroom nutrient substrate. The auxiliary raw material 1 has aeration and water retention properties, and the auxiliary raw material 2 is used to maintain the substrate within the pH range required for morel mushroom growth.

[0007] As a further optimization of the method for preparing morel mushroom nutrient substrate, it includes the following steps:

[0008] (1) Straw pretreatment: The straw is mechanically crushed to a length not exceeding 1.0 cm, and then placed in a 0.4%-1.0% potassium hydroxide solution and heated at 80℃-100℃ for 3-5 hours; after alkalization, the straw is soaked in a sugar solution at room temperature for more than 24 hours. The sugar solution is a glucose or cassava starch solution with a concentration of 0.5%-1%; after treatment, it is drained to a moisture content of 65%-70% to obtain the main raw material;

[0009] (2) Preparation of auxiliary materials: Crush auxiliary material 1 to a particle size of 0.5-1.0cm and pre-moisten it to a moisture content of 65%-70%; auxiliary material 1 is one or more of rice husk, mushroom residue, cottonseed hull or corn cob; auxiliary material 2 is a pH adjuster used to adjust the pH value of the substrate to the range of 6.5-7.5.

[0010] (3) Raw material compounding: The main raw materials obtained in step (1), auxiliary raw material 1 and auxiliary raw material 2 in step (2) are compounded; the main raw materials account for 40%-80% by mass percentage, and the auxiliary raw material 1 accounts for 19%-59%;

[0011] (4) Bagging and sterilization: The compounded raw materials are filled into nutrient bags and sterilized.

[0012] As a further optimization of the method for preparing morel mushroom nutrient substrate, in step (1), the straw is one of rice, wheat or corn straw.

[0013] As a further optimization of the method for preparing the nutrient substrate for morel mushrooms, in step (1), the sugar solution is a 1% cassava starch solution or a 0.5% glucose solution.

[0014] As a further optimization of the method for preparing morel nutrient substrate, in step (1), the concentration of potassium hydroxide solution used for alkalization is 0.8%, and the treatment time is 3 hours.

[0015] As a further optimization of the method for preparing morel mushroom nutrient substrate, in step (2), auxiliary material 1 is rice husk; auxiliary material 2 is a mixture of lime and gypsum in a mass ratio of 1:1.

[0016] As a further optimization of the method for preparing morel mushroom nutrient substrate, in step (3), the formula used for raw material compounding is selected from the high-yield target formula or the stable-yield target formula; in the high-yield target formula, the main raw material accounts for 70%-80%, auxiliary raw material 1 accounts for 19%-29%, and auxiliary raw material 2 accounts for 0.8-1.2%; in the stable-yield target formula, the main raw material accounts for 40%-60%, auxiliary raw material 1 accounts for 39%-59%, and auxiliary raw material 2 accounts for 1%.

[0017] As a further optimization of the method for preparing morel mushroom nutrient substrate, in step (4), atmospheric pressure steam sterilization or high pressure steam sterilization is adopted; the atmospheric pressure steam sterilization conditions are 98℃-105℃ for 10-16 hours, and the high pressure steam sterilization conditions are 121℃-126℃ for 2-2.5 hours.

[0018] As a further optimization of the method for preparing morel mushroom nutrient substrate, in step (1), the main raw material is rice straw that has been treated with 0.8% potassium hydroxide solution at 80°C for 3 hours and then soaked in 1% cassava starch solution or 0.5% glucose solution for 48 hours.

[0019] The second aspect of the present invention is to provide a morel mushroom nutrient substrate, which is prepared according to the above method. The prepared morel mushroom nutrient substrate is composed of straw that has undergone alkalization-sugaring combined modification treatment as the main raw material, as well as auxiliary raw material 1 and auxiliary raw material 2.

[0020] Beneficial effects

[0021] Compared with existing technologies, the present invention has significant beneficial effects. On the one hand, it effectively breaks the high dependence of morel mushroom nutrient substrate on staple crops such as wheat, alleviating the pressure of grain consumption. At the same time, it transforms straw, which is traditionally used in a low-value-added manner, into a core raw material for morel mushroom cultivation through modification, greatly improving the utilization value of agricultural waste and contributing to the development of circular green agriculture. On the other hand, through the alkalization-sugaring combined modification strategy, alkalization can effectively remove lignin and silica from straw that hinder morel mushroom utilization and minimize cellulose degradation. Sugaring optimizes the carbon source supply mode to solve the deficiency that a single cellulose carbon source cannot meet the needs of robust morel mushroom growth. The two work together to overcome the technical bottleneck of straw utilization in morel mushroom cultivation. In practice, the nutrient substrate prepared by this modified straw can fully support the normal growth of morel mycelium, and its overall performance is roughly equivalent to that of conventional wheat nutrient substrate (CK). This fully verifies the feasibility of straw replacing wheat as the main material. Moreover, the optimized scheme (0.8% potassium hydroxide alkalization treatment + 1% cassava starch sugar treatment) is significantly better than conventional wheat nutrient substrate in core indicators such as morel mycelial density, colony radius expansion rate, and growth stability. At the same time, the cost of straw raw materials is lower, which can significantly reduce cultivation costs and improve economic benefits. It also alleviates the current problems of limited farmland storage capacity, difficulty in returning straw to the field in situ, high transportation costs, and difficulty in utilizing straw off-field, thus achieving good economic and ecological benefits. Attached Figure Description

[0022] Figure 1 The graphs show the comparison of hyphal length and growth rate under different treatments. (a) is a bar chart comparing the hyphal length of Morel under different treatments, and (b) is a bar chart comparing the hyphal growth rate of Morel under different treatments.

[0023] Figure 2 This image shows the mycelial growth status in culture media with different treatments.

[0024] Figure 3 The diagram shows the mycelial growth status under different treatments.

[0025] Figure 4 The figures show the comparison of mycelial length and growth rate under different treatments. (a) is a bar chart comparing the mycelial length of Morel mushrooms 24 hours after inoculation, (b) is a bar chart comparing the mycelial length of Morel mushrooms 48 hours after inoculation, (c) is a bar chart comparing the mycelial length of Morel mushrooms 72 hours after inoculation, and (d) is a curve showing the change in the mycelial growth rate of Morel mushrooms with culture time.

[0026] Figure 5 Infrared spectra of treatments with different alkalization concentrations.

[0027] Figure 6 Infrared spectra of different alkalization times.

[0028] Figure 7 The image shows the mycelial growth status in the sugar-treated culture media 70 hours after inoculation.

[0029] Figure 8 The graphs show the changes in colony radius of morel mushrooms over time in MS and Glu media. (a) shows the change in colony radius over time in the cassava starch treatment group, and (b) shows the change in colony radius over time in the glucose treatment group.

[0030] Figure 9 The figures show a comparison of the mycelial growth rate of Morel mushrooms in MS and Glu media. (a) is a curve showing the change in mycelial growth rate of the cassava starch treatment group over culture time, and (b) is a curve showing the change in mycelial growth rate of the glucose treatment group over culture time.

[0031] Figure 10 Microscopic structures of morel mycelia treated with different methods. Detailed Implementation

[0032] The nutrient substrate for morel mushrooms consists of main and auxiliary materials. The main material is straw that has undergone a combined alkalization and sugar treatment to provide a carbon source for the morel mushrooms; the auxiliary materials are used to maintain the aeration, water retention, and suitable pH value of the nutrient substrate.

[0033] The straw used should be fresh crop straw harvested in the current year, such as rice, wheat, or corn straw, with rice straw being the preferred choice. It must be ensured that there are no serious diseases, pests, mold, or rot. Straw pretreatment includes three steps: mechanical crushing, alkalization, and sugar soaking. First, the straw is mechanically chopped to a length not exceeding 1.0 cm. Then, the crushed straw is placed in a 0.4%-1.0% potassium hydroxide solution and heated at 80℃-100℃ for 3-5 hours. After alkalization, the straw is further soaked in a sugar soaking solution at room temperature for at least 24 hours. The sugar source molecules must have a particle size smaller than the pore size of the cellulose after alkalization; a 0.5%-1% glucose or cassava starch solution is preferred. Finally, the straw is drained until the moisture content is 65%-70% for later use.

[0034] The auxiliary materials include Auxiliary Material 1 and Auxiliary Material 2. Auxiliary Material 1 is selected from one or more materials with strong aeration and good water retention, such as rice husks, mushroom residue, cottonseed hulls, and corn cobs. Auxiliary Material 1 needs to be crushed to a particle size of 0.5-1.0 cm and then pre-moistened to a moisture content of 65%-70%. Auxiliary Material 2 is a pH adjuster acceptable to morel mushrooms, used to maintain the pH value of the nutrient substrate within the range of 6.5-7.5 during its use cycle. For example, a lime and gypsum composition with a mass ratio of 1:1 can be used as Auxiliary Material 2.

[0035] The preparation of the nutrient substrate includes formula design, raw material compounding, raw material bagging, and raw material sterilization. The nutrient substrate formula is designed according to production targets. For high-yield targets, the mass ratios of the main raw material, auxiliary raw material 1, and auxiliary raw material 2 are 70%–80%, 19%–29%, and 1%, respectively; for stable-yield targets, the mass ratios are 40%–60%, 39%–59%, and 1%, respectively. The main raw material, after being crushed and subjected to a combined alkalization-sugaring treatment, along with pre-wetted auxiliary raw material 1 and auxiliary raw material 2, are compounded to create a coordinated "fertilizer-water-air" environment for mycelial growth. The compounded nutrient substrate is then filled into nutrient substrate packaging bags to form nutrient bags. The size of the nutrient substrate packaging bags can be selected according to actual conditions, such as 12cm×24cm or 17cm×36cm. The nutrient bags containing the nutrient substrate are sterilized using atmospheric pressure or high-pressure steam. During normal pressure steam sterilization, the temperature should be maintained at 98℃~105℃ for 10~16 hours; during high pressure steam sterilization, the temperature should reach 121℃~126℃ and be maintained for 2~2.5 hours. After sterilization, the nutrient bags are transported to the morel mushroom production site and placed in the field for application 7~10 days after sowing.

[0036] The following specific embodiments illustrate the implementation process, optimization logic, and practical application value of this invention from the perspectives of technical principle verification, key process parameter selection, and application effect comparison.

[0037] Example 1: Feasibility Study of Cellulose Carbon Source in Morel Culture

[0038] 1. Materials and Methods

[0039] (1) Experimental Design

[0040] The experimental formulation was modified based on PDA medium, and three treatment groups were set up: cellulose carbon source group (XS), cellulose + cassava starch carbon source group (XM), and cassava starch carbon source group (MS). Each treatment group was repeated 3 times.

[0041] The specific preparation methods for the culture media of each treatment group are as follows:

[0042] Cellulose carbon source medium (XS): Add 60g cellulose powder, 5g peptone, 1.5g ferrous sulfate, 0.15g manganese sulfate, 1g potassium dihydrogen phosphate, and 20g agar to every 1000ml of medium.

[0043] Cellulose + cassava starch carbon source medium (XM): Add 7.5g cassava starch, 30g cellulose, 5g peptone, 1.5g ferrous sulfate, 0.15g manganese sulfate, 1g potassium dihydrogen phosphate, and 20g agar to every 1000ml of medium.

[0044] Cassava starch carbon source medium (MS): Add 15g starch, 5g peptone, 1.5g ferrous sulfate, 0.15g manganese sulfate, 1g potassium dihydrogen phosphate, and 20g agar to every 1000ml of medium.

[0045] (2) Measurement indicators

[0046] The indicators measured in the experiment included: the length of the morel hyphae, the growth rate of the hyphae, and the color and density of the hyphae.

[0047] 2. Results and Analysis

[0048] Sixty hours after morel inoculation, the length and growth rate of mycelia in the culture medium of each treatment group were measured, and the results are as follows: Figure 1 As shown in the results, the mycelial length of *Morchella esculenta* varied significantly among the treatment groups, with the MS treatment group showing the highest length, followed by the XM treatment group, and the XS treatment group showing the lowest. Specifically, the mycelial length in the XS treatment group was significantly lower than that in the MS treatment group, while the mycelial length in the XM treatment group fell between that of the XS and MS treatment groups. Furthermore, the trend of mycelial growth rate in each treatment group was consistent with the trend of mycelial length, with the MS treatment group showing the fastest growth rate, followed by the XM treatment group, and the XS treatment group showing the slowest growth rate.

[0049] Depend on Figure 2 As shown in Table 1, the morel mycelia in all three treatment groups were white, with no abnormal colors, indicating that different carbon source types did not adversely affect the mycelial color. However, in terms of mycelial density, the XM and MS treatment groups were relatively dense, while the XS treatment group had a lower mycelial density than the XM and MS treatment groups.

[0050] Table 1. Mycelial color and density under different treatments

[0051]

[0052] 3. Research Summary

[0053] Cellulose can serve as a carbon source for the growth of morel mushrooms, supporting normal mycelial growth and maintaining normal mycelial color. However, cellulose alone cannot meet the needs of robust mycelial growth, leading to slow growth and reduced density. While adding starch to cellulose media can improve mycelial growth to some extent and alleviate the deficiency of cellulose alone, the overall growth of the mycelium is still weaker than that of media containing starch.

[0054] Example 2: Effects of different pretreatment methods on the utilization of rice straw by morel mushrooms

[0055] This embodiment explores the effects of different pretreatment methods on the efficiency of morel mycelium in utilizing rice straw by setting up different rice straw pretreatment schemes and constructing corresponding culture media, in order to provide a reference for the application of rice straw in morel production.

[0056] 1. Materials and Methods

[0057] (1) Experimental Design

[0058] The experiment set up three rice straw pretreatment methods and prepared corresponding culture media, while using conventional wheat culture medium as a control (CK), forming a total of 4 treatment groups: rice straw sugar treatment group (TZ), rice straw alkalization treatment group (JH), untreated rice straw group (UN), and conventional wheat formula control group (CK).

[0059] The specific formulation of the culture medium for each treatment group is uniformly as follows:

[0060] UN formula: 50% untreated straw, 49% rice husk, 0.5% lime, and 0.5% gypsum.

[0061] JH formula: 50% straw by mass after alkalization treatment, 49% rice husk, 0.5% lime, and 0.5% gypsum.

[0062] TZ formula: 50% sugar-treated straw by weight, 49% rice husk, 0.5% lime, and 0.5% gypsum.

[0063] CK formula: 50% wheat by weight, 49% rice husk, 0.5% lime, and 0.5% gypsum.

[0064] (2) Experimental process

[0065] ① Straw pretreatment

[0066] Alkalization of straw: First, prepare a 0.1 mol / L potassium hydroxide (KOH) solution (preparation method: weigh 5.611 g KOH and dilute to 1 L with distilled water). Put the chopped rice straw into the above KOH solution and heat it to 80-100℃ using an electric furnace and keep it at a constant temperature for 3 hours. After the treatment, wash the straw in pure water and drain it for later use.

[0067] Sugar-preserved straw: Soak the washed rice straw in a 0.5% glucose solution at room temperature for 48 hours. After soaking, remove and set aside.

[0068] Untreated straw: Place the chopped straw in distilled water, heat it to 80-100℃ using an electric furnace and maintain the temperature for 3 hours, then drain the water and set aside (this only simulates heating conditions and does not involve alkalization or sugaring).

[0069] For conventional wheat: Place the wheat in distilled water, heat it to 80-100℃ using an electric stove and maintain the temperature for 3 hours, then drain the water and set aside.

[0070] Auxiliary raw material rice husk: The auxiliary raw material rice husk is pretreated simultaneously by soaking in clean water for 24 hours.

[0071] ② Culture medium preparation

[0072] According to the formulas of each treatment group, the corresponding materials are thoroughly mixed and then placed into petri dishes, and the weight of materials in each group of petri dishes is consistent. After wrapping the petri dishes with newspaper, they are placed in a sterilization device and sterilized at 121°C for 30 minutes. After sterilization, they are cooled to room temperature for use.

[0073] ③ Morel inoculation

[0074] In a sterile environment, the morel mother culture is inoculated into the culture medium, the petri dish is covered and sealed, and the petri dish is placed in a 25°C constant temperature incubator for cultivation.

[0075] (3) Measurement indicators

[0076] The mycelial growth status, length, and growth rate were observed at 24h, 48h, and 72h after inoculation.

[0077] 2. Results and Analysis

[0078] (1) Effects of different treatments on the color and growth of morel mycelium

[0079] Figure 3 Table 2 shows the color and growth of morel mycelia in different treatment groups. All morel mycelia in each treatment group were white, with no abnormal discoloration. However, there were differences in mycelial density and uniformity among the different treatment groups. Specifically, the morel mycelia in the sugar-treated group (TZ) and the conventional wheat control group (CK) were dense and evenly distributed; while the morel mycelia in the alkalized group (JH) and the untreated rice straw group (UN) had lower density and less uniformity than those in the TZ and CK groups.

[0080] Table 2. Mycelial color and growth under different treatments

[0081]

[0082] (2) Effects of different treatments on the mycelial growth rate of morel mushrooms

[0083] At 24h, 48h, and 72h after inoculation of morel mushrooms, the mycelial length and mycelial growth rate of each treatment group were measured and calculated. The results are as follows: Figure 4As shown in the figure. 24 hours after inoculation, the mycelial length of each treatment group was as follows: conventional formula treatment (CK) > sugar-treated treatment (TZ) > alkalized treatment (JH) > untreated rice straw (UN). The difference in mycelial length between the UN and CK treatments was statistically significant. 48 hours after inoculation, the mycelial length of each treatment group maintained the order CK > TZ > JH > UN. The mycelial length of the TZ and CK treatments was significantly higher than that of the JH and UN treatments, while there was no significant difference between the TZ and CK treatments, and no significant difference between the JH and UN treatments. 72 hours after morel inoculation, there was no significant difference in mycelial length among the treatment groups.

[0084] From the perspective of mycelial growth rate, the morel mycelial growth in the CK treatment showed a trend of rapid growth followed by gradual stabilization, indicating that the CK treatment could stably supply nutrients for morel growth. The morel mycelial growth in the TZ treatment showed a trend of rapid growth followed by gradual decline, indicating that although glucose as a carbon source can provide carbon for morel growth, it is difficult to continuously supply carbon source for morel over a long period of time due to its rapid nutrient release rate. The morel mycelial growth rate in the JH and UN treatments both showed a stable upward trend, but the growth rate was relatively slow in the early stage. By 72 hours after inoculation, the difference between the mycelial growth rate of the JH and UN treatments and the CK and TZ treatments had narrowed.

[0085] 3. Research Summary

[0086] Pretreatment of straw raw materials has a significant impact on the growth rate and stability of morel mycelia. Among them, alkalization and sugar treatment can promote morel mycelial growth to a certain extent, but regardless of the treatment method, the mycelial growth of the treated group is still weaker than that of the untreated control group (CK).

[0087] Example 3: Effects of different alkalization treatments on lignin removal from rice straw

[0088] This embodiment explores the effects of different alkali treatment conditions on rice straw.

[0089] 1. Materials and Methods

[0090] (1) Experimental Design

[0091] The experiment used potassium hydroxide (KOH) solution as an alkaline treatment agent to pretreat rice straw. A total of 7 potassium hydroxide concentrations were set, namely 0%, 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, and 3%, and a total of 4 treatment times were set, namely 1h, 3h, 5h, and 7h.

[0092] (2) Experimental process

[0093] Weigh 5g of rice straw and add it to a potassium hydroxide solution of the corresponding concentration for pretreatment for the specified time. The experiment was conducted in an 80℃ water bath. After pretreatment, the rice straw was washed with distilled water, dried, and then pulverized using a ball mill. Fourier transform infrared spectroscopy was used to scan and detect the powder sample, obtaining infrared spectra. The functional groups corresponding to each characteristic peak in the spectra were labeled, including characteristic functional groups of lignin, cellulose, and silicates.

[0094] (3) Measurement indicators

[0095] Fourier transform infrared absorbance of rice straw samples under different concentration-time combinations was measured.

[0096] 2. Results and Analysis

[0097] (1) Effect of different alkalization concentrations on the infrared spectra of each treatment

[0098] Figure 5 shows the Fourier transform infrared spectra of rice straw treated with different concentrations of KOH solution for a treatment time of 3 hours. The 460 cm⁻¹... -1 The peak at 1159 cm⁻¹ is a characteristic peak of silicides, corresponding to the Si-O bond. The peak intensity decreases significantly with increasing KOH concentration. At 0.4% concentration, the peak intensity begins to weaken noticeably; at 0.6% concentration, the peak intensity decreases further; and at 0.8% concentration, the peak essentially disappears. -1 The peak at 1515 cm⁻¹ is characteristic of cellulose, corresponding to the antisymmetric stretching vibration of the β-(1→4)-glycosidic bond COC. The absorbance of this peak is positively correlated with the degree of cellulose decomposition. When the KOH concentration does not exceed 0.8%, the peak intensity is weak, indicating a low degree of cellulose decomposition; when the concentration exceeds 1.0%, the peak intensity significantly increases, indicating that high-concentration alkali treatment leads to significant cellulose degradation, which is detrimental to cellulose retention. -1 The peak intensity gradually weakens with increasing KOH concentration (corresponding to the CH bond in the aromatic benzene ring skeleton of lignin), essentially disappearing at a concentration of 0.6% and completely disappearing at a concentration of 0.8%; 1720cm -1 The corresponding lignin carbonyl C=O bond at the location is basically eliminated when the alkali concentration is 0.4%, and completely eliminated when the concentration is increased to 0.6%.

[0099] (2) Effect of different pretreatment times on the infrared spectra of each treatment

[0100] Figure 6Fourier transform infrared (FTIR) spectra of rice straw under different pretreatment times with a fixed KOH concentration of 0.8%. With increasing treatment time, the characteristic peak of cellulose initially increased and then decreased. In the initial stage of pretreatment, the increased exposure of cellulose within the rice straw led to a stronger characteristic peak; as time progressed, some cellulose was degraded by the KOH reaction, resulting in a decrease in peak intensity. (1425 cm⁻¹) -1 The characteristic peaks at the point correspond to cellulose oxidation products, and the peak intensity gradually increases with the extension of treatment time, indicating an intensified degree of cellulose oxidation. The highest intensity of the cellulose characteristic peaks and the best cellulose retention are observed when the treatment time is 3-5 hours.

[0101] 3. Research Summary

[0102] Pretreatment of rice straw with a 0.4%-1.0% KOH alkaline solution for 3-5 hours can efficiently remove silicates and lignin from rice straw while minimizing cellulose degradation.

[0103] Example 4: Effect of alkalization-sugaring combination on morel mushroom utilization of rice straw

[0104] This embodiment uses glucose (Glu) and cassava starch (MS) as glycogen sources to treat rice straw with sugar and combine it with pre-alkalization treatment to explore and develop a cellulose source nutrient bag based on rice straw.

[0105] 1. Materials and Methods

[0106] (1) Experimental Design

[0107] The experiment used conventional wheat culture medium as a control (CK) and employed a two-factor design. Based on pre-alkalization treatment of rice straw, different types of sugar solutions were combined for impregnation treatment to prepare the main cellulose source for morel mushroom nutrient bags. The two-factor experiment used sugar solution type as the primary factor, with two treatment groups: glucose solution (Glu) and cassava starch solution (MS). Solution concentration was a secondary factor, with five concentration gradients for each sugar solution type: 0.5%, 1.0%, 1.5%, 2.0%, and 3.0%. A total of 11 treatment groups were formed (2 sugar solutions × 5 concentrations + 1 control), with each treatment group replicated three times.

[0108] (2) Experimental process

[0109] First, mechanically chop the rice straw, controlling the length of the chopped pieces to be less than 0.5 cm. Then, alkalize the rice straw using a 0.8% KOH solution. Place the chopped rice straw in the alkaline solution and heat at 80°C for 3 hours. Remove the rice straw, wash it in distilled water, and drain it. Next, soak the alkalized, washed, and drained rice straw in either a glucose solution or a cassava starch solution of the corresponding concentration at room temperature for 48 hours. After soaking, remove the straw and set it aside.

[0110] Referring to the standard formula for morel mushroom nutrient bags, the experimental group's culture medium contained pretreated rice straw as the main raw material (50%), pre-moistened rice husks as the auxiliary raw material (49%), and 0.5% lime and 0.5% gypsum. The control group (CK) culture medium contained wheat as the main raw material (50%), with the remaining auxiliary materials (49% rice husks, 0.5% lime, and 0.5% gypsum) and their proportions identical to the experimental group. The moisture content of the rice straw and rice husks in the experimental group was controlled within the range of 70%–80%.

[0111] Mix the raw materials of each treatment group according to the above formula, and put them into petri dishes in equal amounts. Sterilize at 121℃ for 30 minutes. After sterilization, allow the culture medium to cool to room temperature. In an aseptic environment, inoculate the morel mother culture into the culture medium of each treatment group. Place the inoculated petri dishes in a constant temperature and dark incubator at 20℃ for morel mycelial culture, and observe the mycelial growth status during the process.

[0112] (3) Measurement indicators

[0113] During the experiment, the color and growth of mycelium, mycelial length and growth rate, and mycelial microstructure were observed and measured.

[0114] 1. Results and Analysis

[0115] (1) Effects of different treatments on the color and growth of morel mycelium

[0116] Figure 7Table 3 shows the color and growth status of morel mycelia in the culture medium under different sugar treatment conditions. In all groups of culture media treated with cassava starch solution and glucose solution, the morel mycelia were white. Compared with the control group (CK) on conventional wheat culture medium, when the cassava starch solution concentration was 1.0% and the glucose solution concentration was 0.5%, the mycelial density and distribution were similar in both groups, showing dense and uniform mycelia. The reasons for this phenomenon are speculated as follows: Starch is a polysaccharide carbon source that morels can utilize, but morels need to secrete amylase to further decompose starch into absorbable carbon sources. If the starch concentration is too low, the carbon source in the nutrient bag cannot fully meet the growth needs of morels; if the starch concentration is too high, morels need to preferentially generate amylase to decompose starch during growth, which affects their timely acquisition of carbon sources. Glucose is a carbon source that morel mushrooms can directly absorb and utilize. It is a readily available carbon source. If the glucose concentration is too high, it will accelerate the consumption of carbon source by morel mycelia, thereby affecting the sustainability of carbon source supply in the later stages.

[0117] Table 3. Mycelial color and growth of culture medium under different sugar treatments.

[0118]

[0119] (2) Effects of different treatments on the hyphal length and growth rate of morel mushrooms

[0120] Figure 8 The changes in the colony radius of morel mushrooms in the culture medium of each treatment group were presented. In the cassava starch (MS) treatment groups, the colony radius gradually increased at all concentrations with the extension of culture time; and with the increase of cassava starch saccharification concentration, the colony radius showed a trend of first increasing and then decreasing, with the colony radius of the 1% saccharification concentration treatment group being significantly higher than that of other treatment groups. Compared with the CK (wheat) control group, the colony radius of each MS treatment group was significantly larger.

[0121] In the glucose (Glu) treatment groups, the colony radius gradually increased with increasing culture time at all concentrations; however, the colony radius gradually decreased with increasing Glu solution concentration, with the 0.5% sugar concentration treatment group showing a significantly higher colony radius than the other treatment groups. Compared with the CK (wheat) control group, the colony radius of each Glu sugar treatment group was significantly higher than that of the CK group during the 0–51 h culture period; however, after 51 h, the colony radius of each Glu sugar treatment group was smaller than that of the CK group.

[0122] Figure 9The growth rate of Morel mycelia in the culture medium of each treatment group was presented. In the cassava starch (MS) treatment group, the mycelial growth rate at all concentrations showed a rapid growth trend from 0 to 43 h, and entered a plateau phase from 43 to 51 h. During the period from 51 to 74 h, the growth rate of different concentration treatment groups showed differences: the mycelial growth rate of the 1.0% and 1.5% concentration treatment groups continued to increase, while the mycelial growth rate of the 0.5%, 2.0%, and 2.5% concentration treatment groups gradually decreased. The mycelial growth rate of the CK control group showed the same trend as that of the 0.5%, 2.0%, and 2.5% concentration groups in the MS treatment group, but the mycelial growth rate was lower than that of these three concentration groups.

[0123] In the glucose (Glu) treatment groups, the mycelial growth rate at each concentration showed a gradual increasing trend from 0 to 51 hours, and a gradual decreasing trend from 51 to 74 hours. Furthermore, among different concentration treatment groups, the mycelial growth rate increased with increasing Glu solution concentration. Compared with the CK (wheat) control group, the mycelial growth rate of each Glu sugar-treated group was significantly higher than that of the CK group during the 0-51 hour culture period; however, after 51 hours, the mycelial growth rate of each Glu sugar-treated group was lower than that of the CK group.

[0124] (3) Microstructure of morel mycelia under different treatments

[0125] To further verify the promoting effect of alkalization treatment on the utilization of rice straw by morel mushrooms, scanning electron microscopy (SEM) was used to observe the CK treatment and MS treatment. 1％ The microstructure of morel mycelia during processing. For example... Figure 10 As shown in the figure, a, b, and c represent the microscopic morphology of Morel mycelia in CK medium at 200x, 500x, and 1000x magnification, respectively; d, e, and f represent the microscopic morphology of MS medium. 1％ Microscopic morphology of morel mycelia in culture medium at the same magnification. Observations show that MS... 1％ The treated morel mycelia all exhibited dense and uniform distribution at 200x, 500x, and 1000x magnification; compared with the control (CK) treatment, MS... 1％ The density of morel mycelium is higher during the treatment.

[0126] 3. Research Summary

[0127] A combined alkalization-sugaring treatment of rice straw significantly promoted the absorption and utilization of rice straw material by morel mushrooms. Specifically, cassava starch (MS) was more effective than glucose (Glu) in the sugaring stage. Overall, this combined treatment scheme was roughly equivalent to conventional wheat culture medium (CK), demonstrating the feasibility of using rice straw as a substitute for wheat in morel mushroom cultivation. Crucially, the optimal combined treatment scheme (0.8% KOH alkalization + 1% cassava starch sugaring) determined through screening significantly outperformed the conventional wheat culture medium (CK) scheme in three core indicators: morel mycelial density, colony radius expansion, and growth stability.

[0128] The above embodiments are exemplary and are intended to illustrate the technical concept and features of the present invention, so that those skilled in the art can understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing morel mushroom nutrient substrate from straw modified by alkalization-sugaring, characterized in that, After the crushed straw is alkalized by heating with an alkaline solution, it is then soaked in a sugar solution at room temperature and drained to obtain the main raw material. The main raw material is mixed with auxiliary raw material 1 and auxiliary raw material 2 that have been pre-wetted, and then bagged and sterilized to obtain the morel mushroom nutrient substrate. The auxiliary raw material 1 has aeration and water retention properties, and the auxiliary raw material 2 is used to keep the substrate within the pH range required for morel mushroom growth.

2. The method for preparing morel mushroom nutrient substrate according to claim 1, characterized in that, Includes the following steps: (1) Straw pretreatment: The straw is mechanically crushed to a length not exceeding 1.0 cm, and then placed in a potassium hydroxide solution with a concentration of 0.4%-1.0% and heated at 80℃-100℃ for 3-5 hours; after alkalization treatment, the straw is soaked in a sugar solution at room temperature for more than 24 hours, wherein the sugar solution is glucose or cassava starch solution with a concentration of 0.5%-1%; after treatment, it is drained to a moisture content of 65%-70% to obtain the main raw material; (2) Preparation of auxiliary raw materials: crush auxiliary raw material 1 to a particle size of 0.5-1.0 cm and pre-moisten it to a moisture content of 65%-70%; the auxiliary raw material 1 is one or more of rice husk, mushroom residue, cottonseed hull or corn cob; the auxiliary raw material 2 is a pH adjuster used to adjust the pH value of the substrate to the range of 6.5-7.

5. (3) Raw material compounding: The main raw materials obtained in step (1), auxiliary raw material 1 and auxiliary raw material 2 in step (2) are compounded; by mass percentage, the main raw materials account for 40%-80% and the auxiliary raw material 1 accounts for 19%-59%; (4) Bagging and sterilization: The compounded raw materials are packed into nutrient bags and sterilized.

3. The method for preparing morel mushroom nutrient substrate according to claim 2, characterized in that, In step (1), the straw is one of rice, wheat or corn straw.

4. The method for preparing morel mushroom nutrient substrate according to claim 2, characterized in that, In step (1), the sugar solution is a 1% cassava starch solution or a 0.5% glucose solution.

5. The method for preparing morel mushroom nutrient substrate according to claim 2, characterized in that, In step (1), the concentration of potassium hydroxide solution used for alkalization is 0.8%, and the treatment time is 3 hours.

6. The method for preparing morel mushroom nutrient substrate according to claim 2, characterized in that, In step (2), the auxiliary raw material 1 is rice husk; the auxiliary raw material 2 is a mixture of lime and gypsum in a mass ratio of 1:

1.

7. The method for preparing morel mushroom nutrient substrate according to claim 2, characterized in that, In step (3), the formula used for raw material compounding is selected from the high-yield target formula or the stable-yield target formula; in the high-yield target formula, the main raw material accounts for 70%-80%, auxiliary raw material 1 accounts for 19%-29%, and auxiliary raw material 2 accounts for 0.8-1.2%; in the stable-yield target formula, the main raw material accounts for 40%-60%, auxiliary raw material 1 accounts for 39%-59%, and auxiliary raw material 2 accounts for 1%.

8. The method for preparing morel mushroom nutrient substrate according to claim 2, characterized in that, In step (4), sterilization is performed using atmospheric pressure steam or high pressure steam. The atmospheric pressure steam sterilization conditions are 98℃-105℃ for 10-16 hours, and the high pressure steam sterilization conditions are 121℃-126℃ for 2-2.5 hours.

9. The method for preparing morel mushroom nutrient substrate according to claim 2, characterized in that, In step (1), the main raw material is rice straw that has been treated with 0.8% potassium hydroxide solution at 80°C for 3 hours and then soaked in 1% cassava starch solution or 0.5% glucose solution for 48 hours.

10. A morel nutrient substrate, characterized in that, The preparation method according to any one of claims 1-9 comprises straw that has undergone alkalization-sugaring combined modification treatment as the main raw material, and auxiliary raw material 1 and auxiliary raw material 2.

Images