Fungus imitation leather material and preparation method thereof

Abstract

The invention belongs to the technical field of biological material engineering, and particularly relates to a fungal imitation leather material and a preparation method thereof. The method comprises the following steps: firstly, adopting wild fomes fomentarius subjected to 60Co irradiation mutagenesis as a production strain of a mycelium pad, and screening and optimizing components and content of a liquid culture medium to obtain a surface culture liquid culture medium suitable for the wild fomes fomentarius; secondly, by utilizing the strain and an optimized culture medium, the low-cost and large-scale production of the mycelium pad can be realized under the optimal culture condition; and the mycelium pad is subjected to various physical and chemical treatments such as plasticizing, cross-linking, hot-pressing compaction and the like, so that the mechanical strength of the mycelium pad is further improved, and the mechanical property requirements of leather products are met.

Description

Technical Field

[0001] The invention belongs to the technical field of biomaterial engineering, and in particular relates to a fungus imitation leather material and a preparation method thereof. Background Art

[0002] Mycelium is the nutritional organ of mushrooms that absorbs nutrients for growth. Its cell wall has a structure connected by chitin, β-1,3 glucan, and glycoprotein. Mushroom mycelium grows radially on the surface of the culture medium, and the hyphae interweave to form a mesh-like mycelium film or aerial mycelium. When the mycelium film and aerial mycelium grow to a certain thickness and density, a mycelium layer mat is formed.

[0003] Liquid surface fermentation refers to a culture mode in which the inoculum forms mycelium at the interface of liquid and air under static conditions. It is an effective method for producing mycelium mats. It has more advantages than solid culture and liquid deep fermentation modes, such as lower input cost, fewer operating procedures, less energy consumption, high production efficiency, easy scalability, and adjustable thickness of mycelium mats. The product mycelium mat can be used to manufacture high-end products such as MBL and mycelial film, and the performance of the mycelium mat can be adjusted to adapt to various functions. However, fungal species, inoculum size, culture medium composition, growth conditions and post-treatment can affect the formation and mechanical properties of mycelium mats. In terms of fungal species, polyporous fungi with fast growth and large biomass production should be selected. Since mycelium mats are prone to contamination by foreign bacteria during liquid surface culture, especially for slow-growing strains, contamination will spread immediately through liquid culture. In addition, this culture method is highly dependent on environmental conditions and needs to be optimized to achieve high yield and low variability.

[0004] Therefore, in order to produce these mushroom mycelium mats with high quality, it is necessary to optimize the composition of the culture medium and the culture environment according to the fungal species used. 60 Wild phyllopora occidentalis induced by Co irradiation was used as the production strain of mycelium mat, and the components and content of the liquid culture medium were screened and optimized to obtain a surface liquid culture medium suitable for wild phyllopora occidentalis. Using this strain and the optimized culture medium, low-cost and large-scale production of mycelium mats can be achieved under optimal culture conditions, and the mycelium mats were subjected to a variety of physical and chemical treatments such as plasticization, cross-linking, and high-temperature compaction to further improve the mechanical strength of the mycelium mats and meet the mechanical property requirements of leather products. Summary of the invention

[0005] In view of the above problems, the present invention provides a fungus imitation leather material and a preparation method thereof. 60The wild phyllopora occidentalis induced by Co irradiation was used as the production strain of mycelium mats, and the components and content of the liquid culture medium were screened and optimized to obtain a liquid culture medium suitable for the surface culture of wild phyllopora occidentalis; secondly, the low-cost and large-scale production of mycelium mats can be achieved under the optimal culture conditions by using the strain and the optimized culture medium; and the mycelium mats were subjected to a variety of physical and chemical treatments such as plasticization, cross-linking, and high-temperature compaction to further improve the mechanical strength of the mycelium mats and meet the mechanical performance requirements of leather products. Specifically, it includes the following contents:

[0006] In a first aspect, the present invention provides a surface culture liquid culture medium suitable for wild Polyporaceae fungi, wherein the surface liquid culture medium is composed of: 0.18% CaCO3, 7% brown sugar, 5% cane molasses, 0.48% yeast extract, 1.04% corn steep liquor, 0.38% safflower seed oil, and an initial pH of 6.5.

[0007] Preferably, the Polyporaceae fungus is Fatty Porites occidentalis.

[0008] In a second aspect, the present invention provides the use of the surface liquid culture medium described in the first aspect in the cultivation of Polyporaceae fungi.

[0009] Preferably, the polyporaceae fungus is phytomycetes. In a third aspect, the present invention provides a method for preparing a fungal imitation leather material, the method comprising the following steps:

[0010] (1) Preparation of fungus: Wild Polyporaceae fungi were 60 Co irradiation mutagenesis to obtain a mutagenized strain; activating the mutagenized strain to obtain a homogenized liquid strain;

[0011] (2) Preparation of mycelial slurry: inoculate the homogenized liquid bacteria into MEB medium for cultivation, and homogenize to obtain mycelial slurry;

[0012] (3) Preparation of mycelium mat: mixing mycelium slurry with the surface liquid culture medium described in the first aspect, and culturing to prepare mycelium mat;

[0013] (4) Post-treatment of the mycelium mat: placing the dried mycelium mat in a glycerol solution and soaking it at room temperature to form a mycelium mat; then soaking it in a crosslinking agent solution for crosslinking; then soaking it in a glycerol solution and drying it naturally to obtain a crosslinked modified mycelium mat; the crosslinking agent is selected from tannin, genipin or citric acid;

[0014] (5) Bonding and pressing of mycelium mat: using latex added with modified chitosan gel as adhesive, the cross-linked modified mycelium mat is pressed into a mycelium imitation leather material of desired thickness by hot pressing or cold pressing.

[0015] Preferably, the Polyporaceae fungus is Fatty Porites occidentalis.

[0016] Preferably, in step (3), the volume ratio of mycelium slurry to surface liquid culture medium is greater than 1:1, the liquid layer thickness is 1.2-1.6 cm, the culture time is 15-25 days, and the culture temperature is 20-32°C.

[0017] Preferably, in step (3), the mass ratio of mycelium slurry to surface liquid culture medium is 1:1, the liquid layer thickness is 1.2 cm, the culture time is 15 days, and the culture temperature is 28°C.

[0018] Preferably, during the preparation of the mycelium mat in step (3), the mycelium culture layer is turned upside down during the culture period to increase the growth thickness of the mycelium mat.

[0019] Preferably, the chitosan gel is obtained by cross-linking and modifying chitosan solution with genipin or glutaraldehyde.

[0020] Preferably, in step (4), the concentration of the glycerol solution is 10-15%, and the soaking time is 12-24 hours.

[0021] Preferably, in step (4), the concentration of the glycerol solution is 10-12.5%, and the soaking time is 24 hours.

[0022] Preferably, the concentration of the glycerol solution is 12.5%.

[0023] Preferably, the cross-linking agent in step (4) is a genipin solution.

[0024] Preferably, the concentration of the genipin solution is 1-1.5%, the pH is 4.5-5, the cross-linking temperature is 37° C., and the cross-linking time is 72 h.

[0025] Preferably, the preparation method of the mycelium slurry is: the homogenized liquid strain is inoculated into 200 mL of MEB culture medium at an inoculation rate of 5%, and shake-cultured at 130 rpm and 25°C for 3 days, and then taken out and inoculated into 1000 ml of MEB culture medium under sterile conditions, and the shake flask culture is continued for 3-5 days, and then homogenized for 20 s (10000 rpm) under sterile conditions for preparing a mycelium mat.

[0026] Preferably, the preparation method of the mycelium mat is as follows: under sterile conditions, the obtained mycelium slurry is mixed with the surface liquid culture medium in a volume ratio of 1:1, shaken evenly, poured into a stainless steel dish with an inner diameter of 12 cm×12 cm, the liquid layer height is 1.2 cm, covered with a stainless steel lid with a breathable membrane, and the edge of the lid is sealed with a plastic wrap, and cultured at 28°C for 15 days. The mycelium mat is taken out and washed 3 times, dried at 70°C for 2 hours, and then naturally air-dried. Preferably, after step (5), the following is further included:

[0027] Step (6): Repeated trampling and superposition suppression;

[0028] Step (7): dyeing and coating of mycelium mat.

[0029] Preferably, the coating is: using zein at a concentration of 15%-20% to coat the mycelium mat, and curing it with a cross-linking agent.

[0030] Preferably, the zein is dissolved in 80% ethanol solution.

[0031] In a fourth aspect, the present invention provides a fungus imitation leather material prepared according to the method described in the third aspect.

[0032] In a fifth aspect, the present invention provides the use of the fungus imitation leather material described in the fourth aspect in the preparation of materials such as packaging, interior decoration, clothing, bags, shoes, sports equipment, etc.

[0033] The beneficial effects of the present invention are: 60 Wild phyllopora occidentalis induced by Co irradiation is used as a strain for producing mycelium mats, and the components and contents of the liquid culture medium are screened and optimized to obtain a liquid culture medium suitable for surface culture of wild phyllopora occidentalis. Using the strain and the optimized culture medium, low-cost, large-scale production of mycelium mats can be achieved under optimal culture conditions, and the mycelium mats are subjected to a variety of physical and chemical treatments such as plasticization, cross-linking, and high-temperature compaction to further improve the mechanical strength of the mycelium mats, meeting the mechanical property requirements of leather products. Although the present invention uses wild phyllopora occidentalis as an example to prepare fungal imitation leather materials, the method described in the present invention is not limited to wild phyllopora occidentalis, and is applicable to Polyporaceae fungi. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The results of the effect of liquid surface culture mycelial mat culture medium on mycelial mat formation; from left to right are optimized medium II-5, PDB enriched medium and MEB medium;

[0035] Figure 2 The results of the effect of mycelium slurry inoculation rate on mycelium mat formation are shown in the figure. The figure shows the photos of the fifth day of cultivation, where A is 25%, B is 50%, and C is 75%;

[0036] Figure 3 Results of the effect of hyphae slurry layer thickness on mycelial mat formation;

[0037] Figure 4 Results of the effect of culture time on mycelial mat formation;

[0038] Figure 5Mycelium mat cultured in a stainless steel dish, with the left picture showing before flipping and the right picture showing after flipping;

[0039] Figure 6 Mycelium imitation leather material dyeing effect diagram;

[0040] Figure 7 Flow chart of preparation of mycelium imitation leather material. DETAILED DESCRIPTION

[0041] The following examples are provided for better understanding of the present invention, but are not intended to limit the present invention. The experimental methods in the following examples are conventional methods unless otherwise specified. The experimental materials used in the following examples are purchased from conventional biochemical reagent stores unless otherwise specified.

[0042] 1. Strains:

[0043] Wild phyllopore fungus was collected from Mudanjiang City, Heilongjiang Province. The fruiting bodies with good shapes were selected, and wild strains were obtained through tissue separation, purification and culture. Protoplasts were prepared and 60 Co irradiation was used for mutagenesis, and strains with faster growth rate and larger mycelial biomass were selected and used as the strains for subsequent experiments.

[0044] 2. Reagents:

[0045] Glucose, lactose, sucrose, glycerol, soluble starch, adipic acid, glutaraldehyde, citric acid, tannin, K2HPO4, CaCl2, KH2PO4, CaCO3 and MgSO4·7H2O were all analytically pure or chemically pure; peptone, soy peptone, malt extract powder, yeast extract powder, agar and corn steep liquor were all biochemical reagents; genipin, potato, cane molasses, skim milk powder, brown sugar and safflower seed oil were all commercially available.

[0046] 3. Culture medium:

[0047] Activation medium: potato 20%, glucose 2%, KH2PO4 0.2%, MgSO4·7H2O 0.1%, agar 1.5%.

[0048] PDB medium: 20% potato, 2% glucose; adding 0.2% corn syrup will make it PDB enriched medium.

[0049] PDA medium: 20% potato, 2% glucose, 1.5% agar.

[0050] MEB culture medium: malt extract powder 4%, soy protein 0.4%.

[0051] Optimized culture medium (II-5): CaCO3 0.18%, brown sugar 7%, cane molasses 5%, yeast extract 0.48%, corn syrup 1.04%, safflower oil 0.38%, initial pH 6.5.

[0052] All the above culture media were sterilized at 121°C for 20 minutes.

[0053] 4. Analytical methods

[0054] Mycelium dry weight: The cultured mycelium was separated by filtration, the precipitate was washed three times with distilled water, dried at 80°C to constant weight, and the amount of mycelium dry basis was determined.

[0055] Thickness of mycelium mat: The thickness of mycelium mat was measured using an electronic caliper after air drying.

[0056] Mycelium mat growth density: refers to the weight of mycelium mat per unit area. After harvesting, the mycelium mat is washed with water three times, air-dried and weighed, the size of the mycelium mat is measured, the area is calculated, and then the weight of the mycelium mat is divided by the area to obtain the mycelium mat growth density.

[0057] Mechanical properties of mycelium imitation leather material: At least 7 dog-bone samples were cut from each mycelium mat (or mycelium imitation leather material). The thickness of each sample was measured at 3 random positions using an electronic caliper. The mass was measured using an analytical balance. The tensile measurement was performed using a Shimadzu EZ-LX single-column electronic universal testing machine at RT with a displacement of 50 mm / min. The ultimate tensile strength (σ) was calculated by dividing the maximum force (N) of each sample by the cross-sectional area (mm 2 ). The elongation at break (ε) is calculated as a percentage of the gauge length before and after the test.

[0058] Example

[0059] 1. Preparation of strains

[0060] Wild phytomycetes 60 The strain obtained after Co irradiation mutagenesis was transferred to the newly prepared activation medium, and actively growing mycelium was obtained after culturing at 24°C for 7 days. Under sterile conditions, 5-10 mL of sterile water (or saline, liquid culture medium) was pipetted onto the activation plate with a pipette, and then the mycelium layer was smeared with a glass coating rod to wash off the spores, and then 5 mL of the eluate was pipetted into a triangular flask containing 100 mL of PDB culture medium, sealed with a sealing film, and cultured at 130 rpm and 25°C for 3-5 days, and homogenized for 30 seconds under sterile conditions as the strain for subsequent experiments.

[0061] 2. Preparation of Mycelial Slurry

[0062] The homogenized liquid strain was inoculated into 200 mL of MEB medium at an inoculation rate of 5%, and shake-cultured at 130 rpm and 25°C for 3 days. Then, it was taken out and inoculated into 1000 mL of MEB medium under sterile conditions, and the shake flask culture was continued for 3-5 days. Then, it was homogenized at 10000 rpm for 20 seconds under sterile conditions to prepare mycelium mats.

[0063] 3. Preparation of Mycelial Mats

[0064] The obtained mycelium slurry was mixed with the surface liquid culture medium (PDB enriched culture medium, MEB culture medium and optimized culture medium (II-5)) under sterile conditions, shaken evenly, poured into a stainless steel dish with an inner diameter of 12 cm × 12 cm, with a liquid layer height of 0.4 cm-1.6 cm, covered with a stainless steel lid with a breathable membrane (with a hole of 1.5 cm in diameter), and the edge of the lid was sealed with plastic wrap, and cultured at 20-32°C for 5-25 days, turning the mycelium culture layer upside down during the culture process. The mycelium pad was taken out, washed 3 times, dried at 70°C for 2 hours, and then naturally air-dried.

[0065] 3.1 Selection of liquid culture medium for surface culture

[0066] Under sterile conditions, the obtained mycelium slurry was mixed with PDB enriched medium, MEB medium and optimized medium (II-5) at a volume ratio of 1:1 to grow mycelium mats. Figure 1 As shown in Table 1: On the fifth day of culture, the mycelial slurry was completely colonized on both the PDB-enriched medium and the MEB medium, while the mycelial slurry in the optimized medium II-5 had not yet completed colonization. However, as the culture time increased, the mycelial slurry on the optimized medium II-5 also completely colonized. By measuring the thickness and growth density of the mycelial mat grown in each culture medium, it was found that the thickness and growth density of the mycelial mat grown on the optimized medium II-5 reached 0.57 mm and 15.96 mg / cm 2 , which were higher than those of PDB-enriched medium and MEB medium, indicating that the optimized medium II-5 was more suitable for the preparation of mycelial mats.

[0067] Table 1 Growth of mycelium mat under different culture media (10 days)

[0068] Culture medium Optimized Medium II-5 PDB-enriched medium MEB medium Average thickness of mycelium mat 0.57mm 0.4mm 0.37mm Average density of mycelium mat <![CDATA[15.96mg / cm 2 ]]> <![CDATA[9.75mg / cm 2 ]]> <![CDATA[7.2mg / cm 2 ]]>

[0069] 3.2 Growth performance of mycelium mats

[0070] The experiment showed that in the mycelium liquid surface culture, the liquid fungal species, the activity of the strain, the addition ratio (inoculum rate), the nutrient composition, the culture temperature, the liquid layer thickness, the culture time and the culture method have different effects on the formation of the mycelium mat and the mechanical properties of the mycelium mat. This example investigates the effects of key factors such as the inoculation rate, the liquid layer thickness, the culture time and the culture temperature on the growth performance of the Ganoderma lucidum mycelium mat. The experimental design is as follows:

[0071] The ratio of mycelium slurry to culture medium was set to 25%, 50%, and 75% by volume; the thickness of the liquid layer was set to 4 mm, 8 mm, 12 mm, and 16 mm; the culture time was set to 5 days, 10 days, 15 days, 20 days, and 25 days; the culture temperature was set to 20° C., 24° C., 28° C., and 32° C. The dry basis content of biomass in the mycelium slurry for inoculation was controlled at 1.5% (mass percentage), and three parallel experiments were performed for each experiment.

[0072] The inoculation ratio of mycelium slurry affects the formation of mycelium mats cultured on the surface of liquid. Figure 2 As shown in the figure: On the fifth day of cultivation, mycelium layers were formed at inoculation rates of 50% and 75%, but a complete mycelium mat was not formed at an inoculation rate of 25%; the appearance showed that mycelium mat C was denser than B. After the cultivation, the thickness of mycelium mats B and C were 0.4 mm and 0.2 mm, respectively, and the weight per unit area was 13.96 mg / cm 2 and 8.13 mg / cm 2 The results showed that the greater the inoculation rate, the easier it was to form a mycelium mat, and the denser the mycelium mat was.

[0073] The thickness of the surface culture solution layer affects the thickness of the mycelium mat formed and the preparation cost of the mycelium mat. Figure 3 As shown in the figure, with the increase of the thickness of the mycelial slurry layer, the thickness and growth density of the mycelial mat also increase. When the thickness of the mycelial slurry layer is 1.2 cm, the thickness and growth density of the mycelial mat reach the maximum value of 0.7 mm and 13.6 mg / cm 2 , indicating that when culturing mycelium mats on the liquid surface, the optimal mycelium slurry layer thickness is 1.2-1.6 cm.

[0074] The incubation time affected the thickness of the mycelial mat growth. Figure 4 As shown in the figure, with the extension of growth time, the thickness and growth density of the mycelium mat also increased. When the culture was carried out for 20 days, the thickness and growth density of the mycelium mat reached the maximum value of 1.1 mm and 26.85 mg / cm 2 , and then the culture liquid under the mycelium mat decreased or dried up. This showed that the best culture time for culturing mycelium mat on the liquid surface was 15 days.

[0075] The culture temperature affects the growth rate of the mycelium mat. The results are shown in Table 2: As the culture temperature increases, the thickness and growth density of the formed mycelium mat increase accordingly. The results show that the higher the temperature, the faster the mycelium colonization and growth rate. Considering the production cost, the optimal culture temperature for the mycelium mat is 28°C.

[0076] Table 2 Growth of mycelium mat at different culture temperatures

[0077] Temperature ℃ 20 24 28 32 Mycelium mat thickness 0.25mm 0.38mm 0.48mm 0.60mm Mycelial mat density <![CDATA[5.73mg / cm 2 ]]> <![CDATA[6.14mg / cm 2 ]]> <![CDATA[6.14mg / cm 2 ]]> <![CDATA[8.4mg / cm 2 ]]>

[0078] In summary, the optimal conditions for culturing mycelium mats on liquid surfaces are: mycelium slurry to liquid culture medium volume ratio of 1:1, liquid layer thickness of 1.2 cm, culture time of 15 days, and culture temperature of 28°C. The growth conditions of mycelium mats under the optimal conditions are as follows: Figure 5 shown.

[0079] 4. Biotanning of mycelium mats

[0080] The mycelium mat obtained by liquid surface culture is dry and brittle after drying, and needs to be tanned to improve the flexibility and strength of the mycelium mat. This study optimizes the plasticization and bio-tanning conditions of the mycelium mat to determine the best bio-tanning process for the mycelium mat.

[0081] 4.1 Plasticization of mycelium mats

[0082] Glycerol, PEG-400, PEG-6000 and D-sorbitol were used as plasticizers to plasticize the mycelium mats, so as to select the appropriate plasticizer. In the experiment, the mycelium mat with a thickness of 0.6 mm was cut into 10 cm × 5 cm, placed in a 12.5% ​​plasticizer solution, soaked at room temperature for 24 hours, taken out and dried naturally, and sensory evaluation was performed. The results are shown in Table 3: When glycerol was used as a plasticizer, the mycelium mat had better softness, PEG-400 and D-sorbitol had similar softness, and the mycelium mat plasticized by PEG-6000 was brittle and easy to break. It shows that the most suitable plasticizer is glycerol.

[0083] Table 3 Selection of plasticizers

[0084] Temperature ℃ glycerin PEG-400 PEG-6000 D-Sorbitol Sensory description Softer soft crisp soft Points ++++(best) +++ +(worst) ++

[0085] In subsequent experiments, glycerol was used as a plasticizer for mycelium mats to optimize the optimal concentration of glycerol and plasticization time. In the experiment, the concentration of glycerol was set to 5%, 7.5%, 10%, 12.5%, and 15%, and plasticization was performed at room temperature for 24 hours; the plasticization time was set to 12 hours, 24 hours, 36 hours, 48 ​​hours, and 60 hours, and the plasticizer concentration was 12.5%. After the samples were dried, sensory evaluation was performed, and the results are shown in Table 4: As the concentration of glycerol solution increased, the softness of the mycelium mat increased, but when the concentration of glycerol solution exceeded 12.5%, the water content of the mycelium mat increased, causing the surface to become moist, and the weight per unit area was higher than 12.68 mg / cm 2 When the concentration of glycerol solution is constant, the weight per unit area of ​​mycelium mat increases with the extension of soaking time, and the odor of soaking liquid becomes more serious. It shows that the most suitable plasticizing conditions are: glycerol solution concentration of 10-12.5% ​​and soaking time of 24h.

[0086] Table 4 Selection of plasticizing conditions

[0087]

[0088]

[0089] (Note: All samples were dried naturally at room temperature after plasticization for 3 days.)

[0090] 4.2 Tanning of mycelial mats

[0091] Although the mycelium mat has a certain degree of softness after plasticization, its mechanical properties are poor and it needs to be cross-linked to improve its flexibility and tensile strength.

[0092] The mycelium mat was cross-linked and modified using genipin, citric acid, tannin, adipic acid and glutaraldehyde as cross-linking agents to screen the most suitable cross-linking agent. In the experiment, the mycelium mat with a thickness of 0.4-0.6mm was cut into 10cm×5cm size, placed in a conical flask filled with a cross-linking agent solution, placed in an oscillation box, and cross-linked at 37°C and 90rpm for 24h; the sample was taken out and re-tanned according to the same steps and under the same conditions, and then the sample was washed with pure water to elute the unreacted cross-linking agent. The results are shown in Table 5: The tensile elastic modulus of the mycelium mat when glutaraldehyde was used as the cross-linking agent was the largest, which was 34.49N / mm 2 , citric acid and adipic acid are equivalent, which are 17.91N / mm 2 and 18.88N / mm 2, while genipin and tannin were the lowest. This shows that the best cross-linking agent is glutaraldehyde. Considering that glutaraldehyde is toxic to the human body, easily pollutes the environment, and is irritating to the skin and mucous membranes of humans and animals, adipic acid is also a low-toxic chemical raw material that is irritating to the skin and eyes. Genipin, tannin and citric acid have no negative impact on humans and the environment. Subsequent experiments use genipin as the cross-linking agent for mycelium mats. In addition, the thickness of the mycelium mats after cross-linking with the cross-linking agent is reduced.

[0093] Table 5 Selection of cross-linking agents

[0094]

[0095]

[0096] Cross-linking conditions such as cross-linking agent concentration, cross-linking temperature, cross-linking time and cross-linking agent pH will affect the cross-linking degree of the material. In this experiment, mycelium mats were cross-linked with genipin as the cross-linking agent to select the best cross-linking conditions. In the experiment, the cutting size of the mycelium mat sample was 10cm×5cm, the total weight was 2g, and the thickness was 0.6mm (thickness after plasticization). The concentration gradient of the cross-linking agent genipin solution was set to 0.5%, 1%, 1.5% and 2%, pH5, and cross-linked at 40℃ for 24h; the pH value gradient of the cross-linking agent solution was 4, 4.5, 5, 5.5 and 6, and cross-linked at 40℃, 1% cross-linking agent solution for 24h; the cross-linking temperature gradient was 20, 30 and 40℃, pH5, and cross-linked in 1% cross-linking agent solution for 24h.

[0097] The results of cross-linking agent concentration selection are shown in Table 6: As the concentration of genipin increases, the elastic modulus of the mycelium mat increases accordingly. When the concentration is 1.5%, the elastic modulus of the mycelium mat reaches a maximum value of 18.09 N / mm 2 , indicating that the optimal cross-linking agent concentration for cross-linking mycelial mats with genipin is 1.5%.

[0098] Table 6 Selection of crosslinker concentration

[0099]

[0100] The results of cross-linking pH value selection are shown in Table 7: As the pH value of the genipin solution increases, the elastic modulus of the mycelium mat increases accordingly. When the pH value is 5, the elastic modulus of the mycelium mat reaches a maximum value of 12.84 N / mm 2 , indicating that the optimal cross-linking agent solution pH for cross-linking mycelium mats with genipin is 5.

[0101] Table 7 Selection of crosslinking pH

[0102]

[0103]

[0104] The results of cross-linking temperature selection are shown in Table 8: As the cross-linking temperature increases, the elastic modulus of the mycelium mat increases, reaching a maximum value of 10.59 N / mm at 30 °C 2 , and then decreased. Combined with literature reports, the optimal cross-linking temperature of genipin was determined to be 37°C.

[0105] Table 8 Selection of crosslinking temperature

[0106]

[0107] The results of cross-linking time selection are shown in Table 9: As the cross-linking time increases, the elastic modulus of the mycelium mat increases. When the cross-linking time is 72 h, the elastic modulus of the mycelium mat reaches a maximum value of 17.21 N / mm 2 , and then the elastic modulus decreased, indicating that the optimal cross-linking time for cross-linking mycelium mats with genipin was 72 h.

[0108] Table 9 Selection of cross-linking time

[0109]

[0110] In summary, the optimal cross-linking conditions for genipin cross-linked mycelium mats were: cross-linking agent concentration of 1.5%, cross-linking temperature of 37°C, cross-linking time of 72 h and cross-linking agent solution pH of 5.

[0111] 5. Repeated trampling and superposition of mycelium mats

[0112] Although the mycelium mat has certain mechanical properties after the initial tanning, it still cannot reach the thickness and mechanical properties required for leather use, so the mycelium mat needs to be bonded and re-tanned. The thickness of general leather is 0.8-1.5mm, and if the thickness of the mycelium mat is less than 0.8mm after pressing, it is necessary to use an adhesive (such as latex) to stack and bond multiple layers of mycelium mats to achieve the 0.8mm thickness requirement. The operation process of re-tanning mycelium mats is the same as that of initial tanning, and different cross-linking agents can also be selected.

[0113] The results of the influence of the thickness of the mycelium mat stacking on the mechanical properties of the material are shown in Table 10. As the thickness of the mycelium mat stacking increases, the tensile strength of the sample increases and the elongation at break decreases, indicating that by stacking the mycelium mat, the mechanical properties of the mycelium imitation leather material can be effectively enhanced while increasing the thickness. In actual production, the appropriate number of stacking layers can be selected according to application requirements.

[0114] Table 10 Effect of mycelium mat stacking thickness on material mechanical properties

[0115] Mycelium mat thickness Tensile strength / MPa Elongation at break / % 0.8mm 16.68 36.88 1.2mm 21.38 31.27 1.6mm 24.66 27.64 2mm 28.88 16.94

[0116] 6. Dyeing and coating of mycelium mat

[0117] After tanning, plasticization, and superimposed hot pressing, the flexibility and strength of the mycelium mat are further enhanced, and the surface roughness is improved to a certain extent. However, to be used as a commercial imitation leather material, the surface smoothness and hydrophobicity of the material need to be further improved, so the thickened mycelium mat needs to be dyed, embossed, and coated. Zein and polyurethane are used for coating. In the experiment, 15%-20% concentration of zein (dissolved in 80% ethanol solution) was used to coat the mycelium mat, and a cross-linking agent was used for curing. The dyeing effect of the mycelium imitation leather material is shown in the figure below. Figure 6 shown.

[0118] In summary, the preparation flow chart of mycelium imitation leather material is as follows Figure 7 shown.

[0119] The best conditions for culturing mycelium mats on the surface of liquid are: the volume ratio of mycelium slurry to liquid culture medium is 1:1, the liquid layer thickness is 1.2 cm, the culture time is 15 days, and the culture temperature is 28°C. In addition, the experiment also found that the depth of the culture plate, the supply of clean air (oxygen), and the air flow above the culture plate also have a great influence on the thickness and mechanical properties of the mycelium mat formed by liquid surface culture. Therefore, by designing a special culture device, the liquid surface culture mycelium mat can achieve the best process and technical effect.

[0120] The optimal plasticizer for mycelium mat is glycerol. The best plasticization treatment is obtained when the dried mycelium mat is soaked in 10-12.5% ​​glycerol solution for 24 hours. The optimal tanning agent for mycelium mat is genipin. When the cross-linking agent concentration is 1.5%, the cross-linking temperature is 37°C and the cross-linking agent solution pH is 5, it shows high mechanical properties. In addition to genipin, tannin and glutaraldehyde are also cross-linking agents with good cross-linking modification of mycelium mat.

[0121] Although the mycelium mat has certain mechanical properties after the initial tanning, it still cannot reach the thickness and mechanical properties required for leather use. It is necessary to use an adhesive (such as latex) to stack and bond multiple layers of mycelium mats to achieve a thickness requirement of ≥0.8mm. The flexibility and strength of the mycelium mat after tanning, plasticization, and stacking hot pressing are further enhanced, and the surface roughness is improved to a certain extent. However, to be used as a commercial imitation leather material, the surface smoothness and hydrophobicity of the material need to be further improved, so the thickened mycelium mat needs to be dyed, embossed, and coated.

[0122] The above-described embodiments only describe the basic principles, main features and preferred embodiments of the present invention. Without departing from the scope of the present invention, various improvements to the technical solutions of the present invention should fall within the scope of protection of the claims of the present invention.

Claims

1. A liquid culture medium suitable for the surface culture of wild Polyporaceae fungi, characterized in that: The surface culture liquid culture medium comprises: 0.18% CaCO3, 7% brown sugar, 5% sugarcane molasses, 0.48% yeast extract powder, 1.04% corn steep liquor, 0.38% safflower seed oil, and an initial pH of 6.

5.

2. Application of the surface culture liquid culture medium as claimed in claim 1 in the cultivation of wild phytomycetes.

3. A method for preparing a fungus imitation leather material, characterized in that: The method comprises the following steps: Step (1) strain preparation: wild Polyporaceae fungi are 60 Co irradiation mutagenesis to obtain a mutagenized strain; activating the mutagenized strain to obtain a homogenized liquid strain; Step (2) Preparation of mycelium slurry: inoculating the homogenized liquid bacteria into MEB medium for cultivation, and homogenizing to obtain mycelium slurry; Step (3) Preparation of mycelium mat: mixing mycelium slurry with the surface culture liquid culture medium according to claim 1, and culturing to prepare mycelium mat; Step (4) post-treatment of the mycelium mat: the mycelium mat is dried and then immersed in a glycerol solution to form a soft mycelium mat; then immersed in a cross-linking agent solution for cross-linking; then immersed in a glycerol solution and naturally dried to obtain a cross-linked modified mycelium mat; the cross-linking agent is selected from tannin, genipin or citric acid; Step (5) bonding and pressing of mycelium mat: using latex added with modified chitosan gel as adhesive, pressing the cross-linked modified mycelium mat into a mycelium imitation leather material of desired thickness by hot pressing or cold pressing; the chitosan gel is obtained by cross-linking modified chitosan solution with genipin or glutaraldehyde.

4. The preparation method according to claim 3, characterized in that: The Polyporaceae fungus is Polyporaceae.

5. The preparation method according to claim 4, characterized in that: In the step (3), the volume ratio of mycelium slurry to surface culture liquid culture medium is greater than 1:1, the liquid layer thickness is 1.2-1.6 cm, the culture time is 15-25 days, the culture temperature is 20-32° C., and the mycelium culture layer is turned upside down during the culture process; in the step (4), the concentration of the glycerol solution is 10-15%, and the soaking time is 12-24 hours.

6. The preparation method according to claim 5, characterized in that: In the step (3), the mass ratio of mycelium slurry to surface culture liquid culture medium is 1:1, the liquid layer thickness is 1.2 cm, the culture time is 15 days, and the culture temperature is 28° C.; in the step (4), the concentration of the glycerol solution is 10-12.5%, and the soaking time is 24 hours.

7. The preparation method according to claim 4, characterized in that: In the step (4), the cross-linking agent is 1-1.5% genipin, the pH of the cross-linking agent solution is 4.5-5, the cross-linking temperature is 37° C., and the cross-linking time is 72 hours.

8. The preparation method according to claim 4, characterized in that: After step (5), the method further comprises: Step (6) re-trampling and stacking the mycelium mat; Step (7) dyeing and coating of mycelium mat; The coating is: using 15%-20% concentration of zein to coat the mycelium mat, and curing it with a cross-linking agent.

9. The fungus imitation leather material prepared according to any one of claims 3 to 8.

10. Use of the fungus imitation leather material as claimed in claim 9 in the preparation of materials such as packaging, interior decoration, clothing, bags, shoes, sports equipment, etc.

Images