Aspergillus niger and its application in preparing black soldier fly worm plasma protein peptide

Abstract

The present invention discloses an Aspergillus niger and its application in the preparation of black soldier fly worm pulp protein peptide, belonging to the field of microbial technology. The Aspergillus niger disclosed in the present invention has a strain number of JAAS-31, which has been deposited in the Guangdong Provincial Microbial Culture Collection Center on July 18, 2023, and the deposit number is GDMCC No: 63660. The Aspergillus niger JAAS-31 provided by the present invention is subjected to bacterial enzyme synergistic treatment of black soldier fly worm pulp for 20-40h, and the content of black soldier fly worm pulp protein peptide (molecular weight <10kDa) is increased by more than 100%, the total antioxidant activity is increased by more than 50%, and the antibacterial ability is increased by more than 30%. The strain has good adaptability and is easy to culture. Based on the strain, a simple, low-cost and efficient preparation process of black soldier fly worm pulp protein peptide can be established.

Description

Technical Field

[0001] The invention belongs to the technical field of biological preparations, and particularly relates to an Aspergillus niger and application thereof in preparing a black soldier fly parasitic protein peptide. Background Art

[0002] The black soldier fly (Hermetia illucens) is an insect of the genus Hermetia, family Schizophora, order Diptera. It can convert organic solid waste such as kitchen waste, livestock and poultry manure, and abandoned crops into larvae rich in protein and fat. The black soldier fly has the characteristics of a wide range of diets, a short reproduction cycle, and a large biomass. It is an effective way to convert organic waste into protein.

[0003] Black soldier fly larvae are rich in crude protein (40%-45%), crude fat (35%-40%), chitin and minerals, and are widely used to replace part of soybean meal or fish meal protein in animal husbandry and fishery production. Black soldier fly larvae are a high-quality protein resource, rich in amino acids required by various animals, and are also a good feed additive for various farmed animals and pets; for example, Chinese patent CN112544783A uses black soldier fly larvae powder to replace fish meal; Chinese patent CN112544813A dries, crushes and defats black soldier flies, and then mixes them with poultry feed in proportion to make poultry feeding feed.

[0004] On July 1, 2020, my country completely banned the addition of growth-promoting antibiotics to feed; therefore, the development of functional protein peptide products with antibacterial, growth-promoting, and immune-enhancing effects has become a hot topic. Black soldier flies are an excellent resource insect; they contain a wealth of natural substances with biologically active ingredients, including antimicrobial peptides, antioxidants, and immunomodulatory factors. Therefore, how to increase the content of black soldier fly insect plasma protein peptides is the key to ensuring its antibacterial and biological activity, and is also one of the key factors in its replacement of fish meal or soybean meal protein. Summary of the invention

[0005] Purpose of the invention: The technical problem to be solved by the present invention is to provide an Aspergillus niger and its application in the preparation of black soldier fly parasitic protein peptide in view of the deficiencies in the prior art.

[0006] To achieve the above object, the present invention provides an Aspergillus niger, which can increase the content of protein peptide in the black soldier fly worm pulp by treating the black soldier fly worm pulp with an Aspergillus niger fermentation sample.

[0007] A niger Aspergillus niger, whose classification name is Aspergillus niger, the strain number is JAAS-31, the preservation number is GDMCC No: 63660, the preservation date is July 18, 2023, and the preservation address is Guangdong Institute of Microbiology, 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou.

[0008] The Aspergillus niger JAAS-31 was screened in Nanjing, Jiangsu Province in January 2023. The isolation and screening method of the Aspergillus niger is: the black soldier fly slurry is gradiently diluted and coated on a PDA solid plate; then, it is separated and rescreened on a protease screening plate to obtain a pure culture strain and detect its total protease activity.

[0009] The method for identifying the Aspergillus niger species is as follows: performing ITS sequencing on the pure culture strain obtained by screening, performing homology comparison with the NCBI database, and using MGEA 11 to construct a phylogenetic tree for analysis.

[0010] The second aspect of the present invention is to provide a method for preparing black soldier fly plasma protein peptide using Aspergillus niger.

[0011] The method described is a simple, low-cost and efficient method for preparing black soldier fly plasma protein peptide.

[0012] The method comprises the following steps: (1) preparing black soldier fly slurry; (2) fermenting Aspergillus niger JAAS-31 to obtain an Aspergillus niger fermentation sample; and (3) mixing the black soldier fly slurry and the Aspergillus niger fermentation sample evenly and fermenting them to obtain a black soldier fly slurry fermentation liquid.

[0013] Wherein, in step (1), the black soldier fly slurry is obtained by mixing black soldier flies and water at a mass ratio of 5:4 to 15:4. Preferably, the black soldier fly slurry is obtained by mixing black soldier flies and water at a mass ratio of 5:2, that is, weighing 200.0 g of black soldier fly larvae, adding 80.0 mL of deionized water, and homogenizing in a homogenizer. Preferably, the black soldier fly larvae are black soldier fly larvae, more preferably five-day-old black soldier fly larvae.

[0014] Wherein, in step (2), the Aspergillus niger fermentation sample is selected, a single colony of Aspergillus niger JAAS-31 is inoculated into a PDA liquid culture medium, the culture temperature is 30-40° C., the stirring speed is 100-200 rpm, and the culture time is 48-96 h to obtain an Aspergillus niger seed liquid; the seed liquid is inoculated into a fermentation tank filled with a PDA liquid culture medium at an inoculation amount of 5% to 20% by volume, the culture temperature is 30-40° C., the stirring speed is 100-400 rpm, the air ventilation volume is 0.2-2 vvm, and the culture time is 48-96 h, that is, at this time, the concentration of Aspergillus niger in the Aspergillus niger fermentation sample is 1×10 7 ~1×10 8 CFU / mL. The Aspergillus niger JAAS-31 single colony is obtained by streaking Aspergillus niger on a PDA solid plate and culturing at 30-40°C for 24 hours.

[0015] Wherein, in step (3), 3 to 10 mL of the fermented Aspergillus niger sample is added to every 100 g of the black soldier fly slurry. Preferably, 5 mL of the fermented Aspergillus niger sample is added to every 100 g of the black soldier fly slurry.

[0016] Wherein, in step (3), the black soldier fly slurry is mixed with the Aspergillus niger fermentation sample and trypsin and fermented.

[0017] Wherein, in step (3), 2.0×10 5 ~5.0×10 5 U trypsin. Preferably, the activity of each mg of trypsin added is not less than 2500 U. More preferably, 2.5×10 5 U trypsin. The enzyme activity is defined as: 25°C, pH 7.6, reaction system 3.2ml (1cm light path), enzymatic hydrolysis of Na-benzoyl-L-arginine ethyl ester (BAEE) per minute to increase the absorbance at 253nm by 0.003 is defined as one trypsin unit, expressed as U / mg. Preferably, the trypsin is added in the form of trypsin dry powder.

[0018] Wherein, in step (3), the temperature of the enzymatic fermentation is 20 to 37° C., and the fermentation time is 20 to 40 hours.

[0019] The third aspect of the present invention is to provide a black soldier fly plasma protein peptide prepared by the above method.

[0020] Wherein, the molecular weight of the black soldier fly plasma protein peptide is less than 10 kDa, preferably in the range of 1 to 10 kDa, and more preferably in the range of 3 to 10 kDa.

[0021] The fourth aspect of the present invention is to provide a use of the Aspergillus niger in the preparation of black soldier fly parasitic protein peptides.

[0022] The fifth aspect of the present invention is to provide a use of the black soldier fly plasma protein peptide in the preparation of an antioxidant and / or antibacterial product. The antibacterial activity is the inhibition of Staphylococcus aureus. The antioxidant and / or antibacterial product includes but is not limited to a feed additive.

[0023] Beneficial effects: The present invention provides an Aspergillus niger and its application in the preparation of black soldier fly plasma protein peptides. The present invention screened out a strain of Aspergillus niger JAAS-31, with a preservation number of GDMCC No: 63660. The Aspergillus niger JAAS-31 is used in combination with trypsin to synergistically treat black soldier flies with bacterial enzymes, which can increase the content of black soldier fly plasma protein peptides (molecular weight <10kDa) by more than 100%, the total antioxidant activity by more than 50%, and the ability of antimicrobial peptides to inhibit Staphylococcus aureus by more than 30%. The Aspergillus niger JAAS-31 screened out by the present invention has good adaptability and is easy to culture. Based on this strain, a simple, low-cost and efficient preparation process of black soldier fly plasma protein peptides can be established. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become more clear.

[0025] Figure 1 This is a phylogenetic tree constructed based on ITS sequences.

[0026] Figure 2 It is the proteolytic circle of Aspergillus niger.

[0027] Figure 3 Determination of the diameter of the inhibition zone of black soldier fly antimicrobial peptide against pathogens: a, black soldier fly antimicrobial peptide in the untreated group; b, black soldier fly antimicrobial peptide in the bacterial enzyme synergistic group; c, negative control sterile water; d, positive control chloramphenicol aqueous solution. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below in conjunction with specific embodiments. The embodiments will help to understand the present invention, but the protection scope of the present invention is not limited to the following embodiments.

[0029] In the following examples, the PDA liquid culture medium is formulated as follows: 6.0 g / L potato extract, 20.0 g / L glucose, 0.1 g / L chloramphenicol, and a pH value of 5.4-5.8.

[0030] The PDA solid plate is prepared by adding 15 g / L agar into the PDA liquid culture medium.

[0031] In the following examples, the trypsin dry powder was purchased from Shanghai Yuanye Biotechnology Co., Ltd. The enzyme activity of each mg of trypsin dry powder is 2500U. The enzyme activity is defined as: 25°C, pH 7.6, reaction system 3.2ml (1cm light path), and the increase of 0.003 in the absorption value at 253nm per minute of enzymatic hydrolysis of Na-benzoyl-L-arginine ethyl ester (BAEE) is defined as one trypsin unit, expressed as U / mg.

[0032] Example 1 Screening, identification and enzyme activity detection of Aspergillus niger

[0033] 1. Isolation and purification of bacterial strains

[0034] (1) Weigh 200.0 g of fresh black soldier fly larvae fed with food waste and homogenize them. Weigh 20.0 g of the homogenized black soldier fly larvae, add 80.0 mL of deionized water, shake at 30.0°C and 200 rpm for 1 hour, and take out and let it stand for 30 minutes.

[0035] (2) Take the supernatant and dilute it with sterile water for 10 5 The diluted bacterial suspension was spread on a PDA solid plate. Incubated at 30°C for 24 hours, a single colony was selected from the plate and repeatedly spread on a PDA solid plate to obtain a pure culture of microbial strains.

[0036] 2. Identification of strains

[0037] ITS sequencing was performed on the selected fungi. The fungal genomic DNA was extracted using a column DNA method (column DNA extraction kit was purchased from Sangon Biotech (Shanghai) Co., Ltd.), and the extracted DNA was PCR amplified using ITS amplification primers ITS1 and ITS4. The ITS1 sequence was SEQ No: 1: 5'-TCCGTAGGTGAACCTGCGG-3', and the ITS4 sequence was SEQ No: 2: 5'-TCCTCCGCTTATTGATATGC-3'. The PCR amplification system is shown in Table 1, and the PCR amplification program is shown in Table 2.

[0038] Table 1 PCR amplification system

[0039]

[0040] Table 2 PCR amplification program

[0041]

[0042] Note: The three processes of cyclic denaturation-annealing-extension are repeated for a total of 30 cycles.

[0043] The PCR amplification product was sent to General Biotech (Anhui) Co., Ltd. for sequencing. The ITS fragment Seq1 (gene sequence shown in SEQ No: 3) obtained after sequencing was compared with the NCBI database for homology, and the phylogenetic tree was constructed using MGEA 11. For details, see Figure 1 .from Figure 1 It can be seen that the strain was identified as Aspergillus niger.

[0044] The above-mentioned isolated and purified Aspergillus niger strain is Aspergillus niger JAAS-31, and the preservation address is: Guangdong Institute of Microbiology, 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou, the preservation number is: GDMCC No. 63660, and the preservation date is: July 18, 2023.

[0045] The ITS fragment gene sequence SEQ No: 3 is as follows:

[0046]

[0047] 3. Determination of Aspergillus niger protein hydrolysis circle

[0048] (1) Preparation of Aspergillus niger JAAS-31 bacterial culture

[0049] Take out the frozen Aspergillus niger JAAS-31 strain from the -80°C refrigerator. Spread it on a PDA solid plate and culture it at 30°C for 24 hours. Take out 1-2 rings of Aspergillus niger single colonies from the PDA solid plate and inoculate them into 100 mL PDA liquid culture medium. Culture them in a constant temperature incubator (30°C, 200rpm) for 24 hours to obtain Aspergillus niger JAAS-31 bacterial liquid.

[0050] (2) Aspergillus niger protein hydrolysis circle

[0051] Take an appropriate amount of Aspergillus niger JAAS-31 bacterial liquid and gently spot it on the protease screening plate (protease screening plate formula: skim milk 20g / L, agar 20g / L), invert and culture at 30℃ for 24h to observe and measure the diameter of the Aspergillus niger protein hydrolysis zone. Figure 2 As shown, the results showed that the diameter of the Aspergillus niger protein hydrolysis zone was 30.4 mm.

[0052] 4. Determination of total protease activity of Aspergillus niger

[0053] The protease activity of Aspergillus niger JAAS-31 bacterial suspension was determined using the total protease activity assay kit produced by Nanjing Jiancheng Bioengineering Institute, and the enzyme activity was 4.15 azocasein / h / mg.

[0054] Example 2 Untreated process of black soldier fly slurry

[0055] (1) Preparation of black soldier fly slurry

[0056] Weigh 200.0 g of five-day-old fresh black soldier fly larvae fed with food waste, add 80.0 mL of sterile water to a homogenizer and homogenize to obtain black soldier fly slurry.

[0057] (2) Self-fermentation of black soldier fly paste

[0058] 100.0 g of black soldier fly slurry was weighed and placed in a constant temperature incubator (30.0° C., 200 rpm) for fermentation for 24 h to obtain the fermentation liquid of the black soldier fly slurry of the untreated group.

[0059] Example 3 Process for preparing black soldier fly slurry by enzymatic hydrolysis of Aspergillus niger

[0060] 1. Preparation of Black Soldier Fly Pulp

[0061] The black soldier fly slurry was prepared according to the method of Example 2.

[0062] 2. Fermentation of Aspergillus niger JAAS-31 to obtain Aspergillus niger fermentation samples

[0063] Aspergillus niger JAAS-31 was streaked and inoculated on a PDA solid plate, and cultured at 30°C for 24 hours to obtain an activated single colony of Aspergillus niger. A single colony of Aspergillus niger was selected and inoculated into a PDA liquid culture medium, and the culture temperature was 30°C, the stirring speed was 150 rpm, and the culture time was 60 hours to obtain an Aspergillus niger seed liquid; the seed liquid was inoculated into a fermenter filled with a PDA liquid culture medium at an inoculation amount of 10% by volume, and the culture temperature was 30°C, the stirring speed was 300 rpm, the air ventilation volume was 0.4 vvm, and the culture time was 60 hours to obtain an Aspergillus niger fermentation sample.

[0064] 3. Black soldier fly paste fermented by Aspergillus niger

[0065] Weigh 100.0 g of black soldier fly slurry, add 5 mL of Aspergillus niger fermentation sample and mix well, put it into a constant temperature incubator (30.0° C., 200 rpm) and ferment it for 24 hours to obtain the black soldier fly slurry fermentation liquid of the Aspergillus niger fermentation group.

[0066] 4. Dialysis bag dialysis of black soldier fly protein peptide

[0067] (1) Dialysis bag pretreatment:

[0068] Cut the dialysis bag with a molecular weight cutoff of 10 kDa into small pieces of 11 cm in length. Before use, boil it with EDTA (pH=8.0) to remove surface impurities. After taking out the dialysis bag, wash it thoroughly with distilled water to ensure that no detergent or impurities remain on the surface of the dialysis bag.

[0069] (2) Dialysis and protein peptide content determination:

[0070] Take out the black soldier fly worm slurry fermentation liquid obtained in step 3, put the fermentation liquid into a dialysis bag, and clamp both ends with a dialysis clip or a cable tie. The dialysis bag containing the worm slurry is placed in a beaker, 50mL of distilled water is added, and it is ensured that the dialysis bag is completely immersed in distilled water, dialyzed for 36 hours, and the distilled water is changed every 12 hours. After the dialysis is completed, the dialysate is mixed 3 times, and the protein peptide content is determined by the BCA method, and the free amino acid content is determined by a free amino acid content kit (purchased from Suzhou Ge Ruisi Biotechnology Co., Ltd.).

[0071] Test results:

[0072] Compared with the untreated group described in Example 2, the protein peptide content and free amino acid content of the black soldier fly worm paste in the Aspergillus niger fermentation group of this example are improved. As shown in Table 3, the protein peptide content of the Aspergillus niger fermentation group is 1.64 times that of the untreated group, and the free amino acid content is 1.32 times that of the untreated group. Aspergillus niger has a rich enzyme system, and the protease secreted during the fermentation process can hydrolyze the macromolecular protein in the black soldier fly worm paste into polypeptides and amino acids. Compared with macromolecular proteins, polypeptides and amino acids are more easily absorbed, and the nutritional value of black soldier fly worm paste is significantly improved.

[0073] Table 3 Contents of protein peptides and free amino acids in black soldier fly pulp in the untreated group and the Aspergillus niger fermentation group

[0074] name Protein peptide (<10kDa) (mg / g) Free amino acids (mg / g) Untreated group 112.124 25.013 Aspergillus niger fermentation treatment group 184.250 33.867

[0075] Example 4: Bacteria-enzyme synergistic enzymatic hydrolysis process of black soldier fly slurry

[0076] 1. Preparation of Black Soldier Fly Pulp

[0077] The black soldier fly slurry was prepared according to the method of Example 2.

[0078] 2. Obtaining Aspergillus niger fermentation samples by Aspergillus niger fermentation

[0079] Aspergillus niger JAAS-31 was streaked and inoculated on a PDA solid plate, and cultured at 30°C for 24 hours to obtain an activated single colony of Aspergillus niger. A single colony of Aspergillus niger was selected and inoculated into a PDA liquid culture medium, and the culture temperature was 30°C, the stirring speed was 150 rpm, and the culture time was 60 hours to obtain an Aspergillus niger seed liquid; the seed liquid was inoculated into a fermenter filled with a PDA liquid culture medium at an inoculation amount of 10% by volume, and the culture temperature was 30°C, the stirring speed was 300 rpm, the air ventilation volume was 0.4 vvm, and the culture time was 60 hours to obtain an Aspergillus niger fermentation sample.

[0080] 3. Fermentation of black soldier fly paste with bacterial enzymes

[0081] On the basis of Example 2, trypsin was added to the enzymatic hydrolysis system. 100.0 g of black soldier fly slurry was weighed, 5 mL of Aspergillus niger fermentation sample and 0.1 g of trypsin powder were added, mixed evenly, and fermented in a constant temperature incubator (37° C., 200 rpm) for 24 h to obtain a fermentation liquid of black soldier fly slurry in the bacterial enzyme synergistic group.

[0082] 4. Dialysis bag dialysis of black soldier fly plasma protein peptide

[0083] The black soldier fly protein peptide was dialyzed according to the method described in Example 2, the BCA method was used to determine the change in the content of the black soldier fly protein peptide before and after fermentation, and the free amino acid content was determined by a free amino acid content kit (purchased from Suzhou Grace Biotechnology Co., Ltd.). The dialysate was transferred to a freeze dryer, and the freeze-dried powder was used for biological activity determination.

[0084] Test results:

[0085] Compared with the untreated group of Example 2 and the Aspergillus niger fermentation group of Example 3, the protein peptide content and free amino acid content of the bacterial enzyme synergistic group are further improved. As shown in Table 4, the protein peptide content of the bacterial enzyme synergistic group is 2.03 times that of the untreated group and 1.23 times that of the Aspergillus niger fermentation group; the free amino acid content of the bacterial enzyme synergistic group is 1.65 times that of the untreated group and 1.22 times that of the Aspergillus niger fermentation group. This experimental result proves that Aspergillus niger and trypsin have good synergistic effects, and the combined action of the two can more efficiently hydrolyze large molecular proteins into small molecular peptides and amino acids. This process further improves the nutritional value of black soldier fly worm paste.

[0086] Table 4 Contents of black soldier fly plasma peptides and free amino acids in the untreated group and the bacterial enzyme synergistic group

[0087] name Protein peptide (<10kDa) (mg / g) Free amino acids (mg / g) Untreated group 112.124 25.013 Bacterial enzyme synergistic fermentation group 227.115 41.239

[0088] Example 5 Detection of the total antioxidant activity of black soldier fly plasma protein peptide

[0089] The black soldier fly worm plasma protein peptide freeze-dried powder prepared by the bacterial enzyme synergistic group was taken out and prepared into a series of solutions with a concentration of 10 mg / mL with ultrapure water. The total antioxidant capacity determination test was carried out according to the instruction manual of the total antioxidant capacity determination kit (purchased from Nanjing Jiancheng Bioengineering Institute).

[0090] Test results: The black soldier fly protein peptides prepared by the untreated group described in Example 2 and the bacterial enzyme synergistic group described in Example 4 both showed antioxidant activity. When the concentration of black soldier fly protein peptide was 10 mg / g, as shown in Table 5, the total antioxidant capacity of the untreated group was 33.25 U / mg, and the total antioxidant capacity of the bacterial enzyme synergistic group was 50.00 U / mg, which was 1.504 times that of the untreated group.

[0091] Table 5 Total antioxidant activity of black soldier fly protein peptides

[0092] Processing conditions Total antioxidant activity U / mg Untreated group 33.25 Bacterial enzyme synergistic group 50.00

[0093] Example 6 Detection of antibacterial activity of black soldier fly plasma protein peptide

[0094] 1. Extraction of black soldier fly antimicrobial peptides

[0095] (1) Prepare antimicrobial peptide extract (10% acetic acid, 0.01 mol / L Na2EDTA).

[0096] (2) The black soldier fly slurry fermentation liquid described in Example 2-4 was mixed evenly with the antimicrobial peptide extract (v:v=1:10), extracted at 200 rpm and 37°C for half an hour, transferred to a centrifuge (3500 rpm, 25 min) to collect the supernatant as the crude antimicrobial peptide extract, which was further freeze-dried to obtain the black soldier fly antimicrobial peptide.

[0097] 2. Determination of antibacterial activity of black soldier fly antimicrobial peptides

[0098] The negative control was sterile water; the antibiotic chloramphenicol was used as the positive control, and the concentration was prepared as 0.5 mg / mL chloramphenicol aqueous solution. Staphylococcus aureus was inoculated into LB liquid medium and cultured at 37°C for 36 hours to obtain Staphylococcus aureus liquid, which was diluted to a concentration of 1.0×10 8 CFU / mL, take an appropriate amount of bacterial solution and evenly spread it on the LB solid medium. Gently place an Oxford cup with a diameter of 7.5mm on the LB solid plate, add an equal amount of black soldier fly antimicrobial peptide to the Oxford cup, culture it in a constant temperature incubator at 37℃ for 12h, and observe and measure the diameter of the inhibition zone.

[0099] Test results: The black soldier fly antimicrobial peptide was tested for antibacterial activity in vitro. The antibacterial effects are as follows: As can be seen from Table 6, both the untreated group and the bacterial enzyme synergistic group had antibacterial circles, and the diameters of the antibacterial circles of the untreated group and the bacterial enzyme synergistic group were 22±0.2mm and 29±0.1mm, respectively. Figure 3 a, b), the diameter of the inhibition zone of the chloramphenicol positive control group was 24±0.2 mm ( Figure 3 d), the diameter of the inhibition zone of the sterile water negative control group was 0 mm ( Figure 3 c) The test results show that the antibacterial performance of the black soldier fly in the bacterial enzyme synergistic group is significantly improved.

[0100] Table 6 Antibacterial activity of black soldier fly antimicrobial peptides

[0101] Processing conditions Diameter of inhibition zone (mm) Untreated group (Black Soldier Fly Antimicrobial Peptide Concentration 5 mg / g) 22.00 Bacteria enzyme synergistic group (black soldier fly antimicrobial peptide concentration 5mg / g) 29.00 Positive control group (chloramphenicol concentration 0.5 mg / mL) 24.00 Negative control group (sterile water) 0

[0102] The present invention provides an idea and method for using Aspergillus niger and its application in the preparation of black soldier fly worm plasma protein peptide. There are many methods and ways to implement the technical solution. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention. All components not specified in this embodiment can be implemented by existing technologies.

Claims

1. A strain of Aspergillus niger, which is classified and named Aspergillus niger ( Aspergillus niger ), strain number JAAS-31, preservation number is GDMCC No: 63660, and preservation time is July 18, 2023.

2. A method for preparing black soldier fly plasma protein peptide using the Aspergillus niger strain according to claim 1, characterized in that: The method comprises the following steps: (1) Preparing black soldier fly slurry; (2) Fermentation of Aspergillus niger JAAS-31 to obtain Aspergillus niger fermentation samples; (3) The black soldier fly slurry is mixed with the Aspergillus niger fermentation sample and subjected to enzymatic fermentation to obtain a black soldier fly slurry fermentation liquid.

3. The method according to claim 2, characterized in that In step (1), the black soldier fly worms and water are mixed and homogenized in a mass ratio of 5:4 to 15:4 to obtain the black soldier fly worm slurry.

4. The method according to claim 2, characterized in that: In step (2), a single colony of Aspergillus niger JAAS-31 is picked and placed in a PDA liquid culture medium, the culture temperature is 30-40° C., and the culture time is 48-96 h to obtain an Aspergillus niger seed liquid; the seed liquid is inoculated into a fermentation tank filled with a PDA liquid culture medium at an inoculation amount of 5% to 20% by volume, the culture temperature is 30-40° C., and the culture time is 48-96 h to obtain the Aspergillus niger fermentation sample.

5. The method according to claim 2, characterized in that: In step (3), 3-10 mL of Aspergillus niger fermentation sample is added to every 100 g of black soldier fly slurry.

6. The method according to claim 2, characterized in that In step (3), the black soldier fly slurry is mixed with the Aspergillus niger fermentation sample and trypsin and fermented.

7. The method according to claim 6, characterized in that In step (3), 2.0×10 5 ~5.0×10 5 UTriespase.

8. The method according to claim 2, characterized in that: In step (3), the enzymatic fermentation is carried out at a temperature of 20-37°C and a fermentation time of 20-40 hours.

9. A black soldier fly plasma protein peptide, which is prepared according to the following steps: (1) Preparing a black soldier fly slurry; mixing the black soldier fly slurry with water in a mass ratio of 5:4 to 15:4 to obtain the black soldier fly slurry; (2) fermenting the Aspergillus niger JAAS-31 described in claim 1 to obtain an Aspergillus niger fermentation sample; picking a single colony of the Aspergillus niger JAAS-31 described in claim 1 to a PDA liquid culture medium, culturing at a temperature of 30 to 40° C. for 48 to 96 hours, to obtain an Aspergillus niger seed liquid; inoculating the seed liquid in a fermentation tank filled with a PDA liquid culture medium at an inoculation rate of 5% to 20% by volume, culturing at a temperature of 30 to 40° C. for 48 to 96 hours, to obtain the Aspergillus niger fermentation sample; (3) The black soldier fly slurry is mixed with the Aspergillus niger fermentation sample and subjected to enzymatic fermentation to obtain a black soldier fly slurry fermentation liquid; 3 to 10 mL of the Aspergillus niger fermentation sample is added to every 100 g of the black soldier fly slurry; the black soldier fly slurry is mixed with the Aspergillus niger fermentation sample and trypsin and fermented; 2.0×10 5 ~5.0×10 5 U trypsin; the enzymatic fermentation temperature is 20-37°C and the fermentation time is 20-40h.

10. The black soldier fly plasma protein peptide according to claim 9, characterized in that The molecular weight of the black soldier fly plasma protein peptide is less than 10 kDa.

11. Use of the black soldier fly plasma protein peptide according to claim 9 in the preparation of antioxidant and / or antibacterial products, wherein: The antibacterial effect is the inhibition of Staphylococcus aureus.

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