Bacillus cereus as well as application and method of bacillus cereus in degradation of zearalenone and aflatoxin B1 for high yield of gamma-polyglutamic acid

Abstract

The invention discloses bacillus cereus as well as application and a method of degrading zearalenone and aflatoxin B1 to produce gamma-polyglutamic acid at high yield. The preservation number of the bacillus cereus is CGMCC (China General Microbiological Culture Collection Center) No. 29968. The bacillus cereus IFST-Xd-5 disclosed by the invention has a very good application prospect in the aspect of developing a microbial preparation for degrading mycotoxin and a microbial preparation for high-yield low-molecular-weight gamma-polyglutamic acid.

Description

Technical Field

[0001] The present invention relates to the fields of microbiology and biodegradation, and more specifically, to a Bacillus cereus and its application and method for degrading zearalenone and aflatoxin B1 to produce high-yield γ-polyglutamic acid. Background Art

[0002] Mycotoxins, secondary metabolites produced by fungi, are highly carcinogenic, teratogenic, and mutagenic. Therefore, screening and developing safe, non-toxic microorganisms that can efficiently degrade mycotoxins and strengthening research on fungal control have become urgent needs to ensure my country's food security and food safety.

[0003] Zearalenone (ZEN) is an estrogenic fungal toxin produced by Fusarium during secondary metabolism. ZEN contaminates a wide range of grains, such as wheat, barley, corn, oats, sorghum, rye, millet and related products of these grains. It is one of the most widely contaminated Fusarium toxins in the world. ZEN is toxic to both animals and humans, mainly affecting the reproductive function of animals, reducing the embryo survival rate of pregnant animals and the birth weight of newborns, and causing reproductive disorders in animals. Eating food contaminated by it can cause diseases such as liver cancer, testicular cancer, esophageal cancer and precocious puberty. In addition, ZEN also has immunotoxicity, hepatotoxicity, and genotoxicity, and has a certain impact on tumor occurrence.

[0004] Aflatoxins (AFs) are compounds with similar molecular structures and physical and chemical properties. They all contain a bifuran ring and a oxazinone (also called coumarin) in their structures. They are the most stable fungal toxins in physical and chemical properties discovered so far. They are carcinogenic, teratogenic, and mutagenic. A dose of only 0.294 mg / kg can cause acute poisoning and death in sensitive animals. Its main target is the liver. According to epidemiological surveys, up to 28% of primary hepatocellular carcinomas worldwide are caused by AFs. In addition, they can also cause acute lesions in the kidneys and adrenal glands. More than 20 types of AFs have been isolated and identified. Among them, AFB1 is the most common, most toxic, and most carcinogenic. In 1993, it was listed as a Class I carcinogen by the International Agency for Research on Cancer (IARC) of the World Health Organization (WHO). Its acute toxicity is 10 times that of potassium cyanide and 68 times that of arsenic. In conventional food testing, AFB1 is also used as the primary pollution detection indicator.

[0005] Methods for detoxifying mycotoxins can be divided into three categories: physical, chemical and biological. Among them, biological methods have become a hot topic in research on mycotoxin degradation and detoxification in recent years because of their high efficiency, strong specificity and no pollution to food, feed and the environment.

[0006] Polyglutamic acid (PGA) is a water-soluble polyamino acid produced by microbial fermentation in nature. Poly-γ-glutamic acid has excellent water solubility, super strong adsorption and biodegradability. The degradation product is pollution-free glutamic acid. It is an excellent environmentally friendly polymer material that can be used as a water-retaining agent, heavy metal ion adsorbent, flocculant, sustained-release agent and drug carrier, etc. It has great commercial and social value in the cosmetics, environmental protection, food, medicine, agriculture, desert control and other industries. However, the molecular weight distribution range of polyglutamic acid is different, and its physicochemical properties vary greatly. In actual production, when low molecular weight polyglutamic acid is needed, most of the low molecular weight polyglutamic acid is obtained by chemical degradation or physical ultrafiltration interception. Therefore, it is a new challenge to explore a method for efficiently producing low molecular weight polyglutamic acid from the biological field. Summary of the invention

[0007] An object of the present invention is to solve at least the above problems and to provide at least the advantages which will be described hereinafter.

[0008] In order to achieve these purposes and other advantages according to the present invention, a Bacillus cereus is provided, including: its deposit number is CGMCC No.29968.

[0009] The invention also provides a bacterial agent containing the Bacillus cereus.

[0010] The present invention also provides the use of the Bacillus cereus or the bacterial agent in degrading zearalenone and aflatoxin B1 and high-yielding gamma-polyglutamic acid.

[0011] The present invention also provides a method for degrading zearalenone, which uses the Bacillus cereus or the bacterial agent to degrade zearalenone.

[0012] The present invention also provides a method for degrading aflatoxin B1, using the Bacillus cereus or the bacterial agent to degrade aflatoxin B1.

[0013] The present invention also provides a method for simultaneously degrading zearalenone and aflatoxin B1, using the Bacillus cereus or the bacterial agent to degrade zearalenone and aflatoxin B1 together.

[0014] The present invention also provides a method for high-yield gamma-polyglutamic acid, which uses the Bacillus cereus or the bacterial agent to carry out fermentation treatment under the condition of introducing oxygen.

[0015] Preferably, the fermentation medium in the fermentation treatment comprises: sodium glutamate, citric acid, soybean cake powder, potassium dihydrogen phosphate, manganese sulfate and magnesium sulfate, and is prepared with distilled water.

[0016] The present invention has at least the following beneficial effects:

[0017] First, the Bacillus cereus IFST-Xd-5 of the present invention can efficiently degrade fungal toxins (zearalenone and aflatoxin B1) and can also produce a high yield of low molecular weight γ-polyglutamic acid. It has good application prospects in the development of microbial preparations for degrading fungal toxins and microbial preparations for producing a high yield of low molecular weight γ-polyglutamic acid.

[0018] Second, the Bacillus cereus IFST-Xd-5 of the present invention simultaneously degrades 98.31% and 98.97% of zearalenone and aflatoxin B1.

[0019] Third, the Bacillus cereus IFST-Xd-5 of the present invention has heat resistance and alkali resistance. In the range of 37°C to 60°C, the degradation rate of ZEN is higher than 80%, and in the range of pH 6 to 9, the degradation rate of ZEN is higher than 70%.

[0020] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The phylogenetic tree of the strain IFST-Xd-5 of the present invention based on the 16S rDNA sequence;

[0022] Figure 2 It is a liquid phase chromatogram of the degradation effect of zearalenone of the present invention;

[0023] Figure 3 The effect of the culture temperature and the culture pH on the degradation of zearalenone by the strain IFST-Xd-5 of the present invention;

[0024] Figure 4 This is a liquid chromatogram showing the degradation effect of aflatoxin B1 of the present invention;

[0025] Figure 5 The liquid chromatogram is the degradation effect of ZEN when exposed to ZEN and AFB1 simultaneously;

[0026] Figure 6 The liquid chromatogram is the degradation effect of AFB1 when exposed to ZEN and AFB1 at the same time;

[0027] Figure 7 This is a colony photo of the strain IFST-Xd-5 of the present invention.

[0028] Bacillus cereus, with a deposit number of CGMCC No.29968, was deposited in the General Microbiology Center of China National Microbiological Culture Collection Administration on March 8, 2024. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments so that those skilled in the art can implement the invention with reference to the description.

[0030] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials can be obtained from commercial channels unless otherwise specified.

[0031] Aflatoxin B1 standard: China MZ standard, product number AF031.

[0032] Zearalenone (ZEN) standard: China MZ standard, product number M51001.

[0033] Aflatoxin B1 immunoaffinity column: China MZ standard, product number HCM0350A.

[0034] Zearalenone immunoaffinity column: China MZ standard, product number HCM0525B.

[0035] <Example 1>

[0036] Screening and identification of Bacillus cereus:

[0037] Taking natural soil as the source of bacteria, 5g of soil sample was added to 100mL of sterile saline, oscillated on a vortex oscillator for 10min and then allowed to stand for 20min, 1mL of the upper suspension was added to the primary screening liquid culture medium containing coumarin, and cultured in a shaking incubator at 37℃ and 180r / min. After 24h, 100μL of the bacterial liquid was spread on the coumarin primary screening solid culture medium, and after culturing at 37℃ for 24h, a single strain with good growth was selected and streaked three times on the coumarin primary screening solid culture medium. After a single colony was grown, the strain was purified and preserved for later use. Figure 7 This is a colony photo of strain IFST-Xd-5.

[0038] The purified strains were inoculated into LB liquid culture medium, and cultured at 37°C and 180r / min for 24h. Then, 200μL of fermentation broth was inoculated into LB liquid culture medium containing 0.5μg / mL ZEN (zearalenone) as the experimental group, and the LB liquid culture medium containing 0.5μg / mL ZEN without inoculation was used as the control group. Each group was treated with 3 parallels and cultured at 37°C and 180r / min shaking for 24h. The ZEN content in the culture medium was detected according to the ELISA kit, and the degradation rate of ZEN was calculated according to the following formula. The strain with the highest degradation rate was screened out and named IFST-Xd-5. The strain IFST-Xd-5 was stored in glycerol at -80°C for standby use.

[0039] ZEN degradation rate (%) = (residual ZEN content in the control group - residual ZEN content in the experimental group) / residual ZEN content in the control group × 100.

[0040] Identified ( Figure 1 ), the strain IFST-Xd-5 is Bacillus velezensis, Bacillus cereus IFST-Xd-5 is deposited in the General Microbiology Center of China Microorganism Culture Collection Administration, the deposit date is March 8, 2024, the deposit number is CGMCC No.29968, and the deposit address is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing.

[0041] in,

[0042] Coumarin liquid culture medium: composed of solvent and solute; coumarin 1.0g, KH2PO4 0.25g, MgSO4·7H2O0.25g, KNO3 0.5g, (NH4)2SO4 0.5g, CaCl2 0.005g, FeCl3·6H2O 0.003g, distilled water to 1L, pH 7.0, high pressure sterilization at 121℃ for 15min.

[0043] Coumarin solid medium: Add 1.5% agar to coumarin liquid medium and sterilize by high pressure at 121℃ for 15min.

[0044] LB liquid culture medium: composed of a solvent and a solute; the solutes are peptone, beef extract and NaCl, and the solvent is water; the concentration of peptone in the LB liquid culture medium is 1 g / 100 mL, the concentration of beef extract in the LB liquid culture medium is 0.3 g / 100 mL, the concentration of NaCl in the LB liquid culture medium is 0.5 g / 100 mL, and the pH of the culture medium is adjusted to 7.4 with NaOH.

[0045] <Example 2>

[0046] Degradation of Zearalenone (ZEN) by Bacillus cereus IFST-Xd-5:

[0047] 1. Inoculate Bacillus cereus IFST-Xd-5 into LB liquid medium until the initial OD 600 =0.05, 37°C, 200 rpm (rotation radius 20 mm) shaking culture for 24 h, 10000 r / min centrifugation for 10 min to collect the supernatant.

[0048] 2. Dissolve 1 mg of zearalenone (ZEN) standard (MZ standard, catalog number M51001) in 10 mL of chromatographic grade methanol to obtain a ZEN standard solution with a concentration of 100 ppm.

[0049] 3. Prepare experimental group solution:

[0050] Take 2970 μL of the bacterial solution (supernatant) collected in step 1 and place it in a 10 mL centrifuge tube. Add 30 μL of the ZEN standard solution obtained in step 2 to the centrifuge tube. Mix thoroughly and let stand at 37°C for 24 h. Then centrifuge at 10000 g for 10 min and collect the supernatant to obtain the experimental group solution.

[0051] 4. Prepare the control group solution:

[0052] According to the method of step 3, 2970 μL LB liquid culture medium was taken to replace the bacterial solution (supernatant) collected in step 1, and the other operations remained unchanged to obtain a control group solution.

[0053] 5. Effect detection:

[0054] The experimental group solution and the control group solution were used as test solutions, and the following steps were performed:

[0055] 1. Add 6 volumes of anhydrous methanol to 4 volumes of the test solution, shake and extract at room temperature for 5 minutes, centrifuge at 12000r / min for 5 minutes, and take the supernatant for the next purification operation.

[0056] 2. Take the supernatant obtained in step 1 and use a zearalenone immunoaffinity column to remove impurities. The specific operation is as follows:

[0057] Take the supernatant obtained in step 1 and pass it through the ZEN immunoaffinity column, adjusting the flow rate to 1-2 drops / s until the air completely passes through the immunoaffinity column. Use 10mL of pure water to pass through the affinity column at a flow rate of 1-2 drops / s to clean the affinity column. Finally, use 1mL of anhydrous methanol to elute the affinity column at a flow rate of 1-2 drops / s, collect the eluate in a 1.5mL centrifuge tube, filter it with a 0.22μm organic phase nylon membrane, and then put it into a 2mL chromatographic injection vial to obtain a sample solution.

[0058] 3. Take the sample solution obtained in step 2 and use HPLC (post-column photochemical derivatization) to detect the sample obtained by purification and extraction.

[0059] HPLC detection conditions were as follows: mobile phase acetonitrile: water = 7:3; flow rate 1 mL / min; chromatographic column C18 150 mm × 4.6 mm, 5 μm; excitation wavelength 274 nm, detection wavelength 440 nm; column temperature 30°C; injection volume 20 μL.

[0060] The degradation rate of zearalenone (ZEN) was calculated as follows:

[0061] ZEN degradation rate (%) = (residual ZEN content in the control group - residual ZEN content in the experimental group) / residual ZEN content in the control group × 100.

[0062] The experiment was repeated five times and the results were averaged.

[0063] Test results such as Figure 2 As shown, a is the zearalenone standard (the retention time of ZEN is 6.691min); b is the control group (the retention time of ZEN is 6.605min); and c is the experimental group (the retention time of ZEN is 6.586min).

[0064] The residual ZEN content in the control group was 997.28 ± 15.33 μg / L;

[0065] The residual ZEN content in the experimental group was 12.67 ± 0.39 μg / L;

[0066] The results showed that Bacillus cereus IFST-Xd-5 had a degradation effect on ZEN, with a degradation rate of 98.73%.

[0067] <Example 3>

[0068] Optimization of conditions for degradation of zearalenone by Bacillus cereus IFST-Xd-5:

[0069] The seed liquid of Bacillus cereus IFST-Xd-5 was inoculated at a 1% inoculum size into LB liquid culture medium with a ZEN concentration of 1 mg / L, and cultured at 37°C with shaking at 200 rpm (rotation radius 20 mm) for 24 h. The effects of culture temperature (28°C, 32°C, 37°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C) and pH value (4, 5, 6, 7, 8, 9, 10, 11) on the degradation of ZEN by Bacillus cereus IFST-Xd-5 were investigated.

[0070] like Figure 3As shown in A, the culture temperature significantly affected the ability of Bacillus cereus IFST-Xd-5 to degrade ZEN (P<0.05), and the degradation rate first increased and then decreased with the increase of culture temperature. The strain IFST-Xd-5 has the characteristics of heat resistance, the optimal degradation temperature is 55℃, and the degradation rate reaches 89.11%; in the range of 37℃~60℃, the degradation rate is higher than 80%.

[0071] like Figure 3 As shown in B, the effects of different pH values ​​on the degradation of ZEN by Bacillus cereus IFST-Xd-5 were significantly different (P<0.05). With the increase of pH, the degradation rate of ZEN showed a trend of first increasing and then decreasing. The strain IFST-Xd-5 has the characteristics of alkali resistance, the optimal degradation pH is 7, and the degradation rate is 88.77%; in the pH range of 6 to 9, the degradation rate is higher than 70%.

[0072] <Example 4>

[0073] Degradation of aflatoxin B1 by Bacillus cereus IFST-Xd-5:

[0074] 1. Inoculate Bacillus cereus IFST-Xd-5 into LB liquid medium until the initial OD 600 =0.05, 37°C, 200 rpm (rotation radius 20 mm) shaking culture for 24 h, 10000 r / min centrifugation for 10 min, and the supernatant was collected.

[0075] 2. Dissolve 1 mg of aflatoxin B1 (AFB1) standard (MZ standard, catalog number AF031) in 10 mL of chromatographic grade methanol to obtain an AFB1 solution with a concentration of 100 ppm.

[0076] 3. Prepare experimental group solution:

[0077] Take 2970 μL of the supernatant collected in step 1 and place it in a 10 mL centrifuge tube. Add 30 μL of the AFB1 solution obtained in step 2 to the centrifuge tube. After fully mixing, let it stand at 37°C for 24 h. Then, centrifuge at 10000 g for 10 min and collect the supernatant to obtain the experimental group solution.

[0078] 4. Prepare the control group solution:

[0079] According to the method of step 3, 2970 μL LB liquid culture medium was taken to replace the supernatant collected in step 1, and the other operations remained unchanged to obtain a control group solution.

[0080] 5. Effect detection:

[0081] The experimental group solution and the control group solution were used as test solutions, and the following steps were performed:

[0082] 1. Add 6 volumes of anhydrous methanol to 4 volumes of the test solution, shake and extract at room temperature for 5 minutes, centrifuge at 12000r / min for 5 minutes, and take the supernatant for the next purification operation.

[0083] 2. Take the supernatant obtained in step 1 and use an aflatoxin B1 immunoaffinity column to remove impurities. The specific operation is as follows:

[0084] Take the supernatant obtained in step 1 and pass it through the aflatoxin B1 immunoaffinity column, adjust the flow rate to 1-2 drops / s, until the air completely passes through the immunoaffinity column. Use 10mL of pure water to pass through the affinity column at a flow rate of 1-2 drops / s to clean the affinity column. Finally, use 1mL of anhydrous methanol to elute the affinity column at a flow rate of 1-2 drops / s, collect the eluate in a 1.5mL centrifuge tube, filter it with a 0.22μm organic phase nylon membrane, and then load it into a 2mL chromatographic injection vial to obtain a sample solution.

[0085] 3. Take the sample solution obtained in step 2 and use HPLC (post-column photochemical derivatization) to detect the sample obtained by purification and extraction.

[0086] HPLC detection conditions were as follows: mobile phase methanol: water = 7:3; flow rate 1 mL / min; chromatographic column C18 150 mm × 4.6 mm, 5 μm; excitation wavelength 350 nm, detection wavelength 450 nm; column temperature 30°C; injection volume 20 μL.

[0087] Calculate the degradation rate of aflatoxin B1 (AFB1) by:

[0088] AFB1 degradation rate (%) = (residual AFB1 content of the control group - residual AFB1 content of the experimental group) / residual AFB1 content of the control group × 100.

[0089] The experiment was repeated five times and the results were averaged.

[0090] Test results such as Figure 4 As shown, a is the aflatoxin standard (the retention time of AFB1 is 5.505 min); b is the control group (the retention time of AFB1 is 5.576 min); c is the experimental group (the retention time of AFB1 is 5.564 min).

[0091] The residual AFB1 content in the control group was 995.57±10.96μg / L;

[0092] The residual AFB1 content in the experimental group was 6.87±1.61μg / L;

[0093] The results showed that Bacillus cereus IFST-Xd-5 had a degradation effect on AFB1, with a degradation rate of 99.31%.

[0094] <Example 5>

[0095] Simultaneous degradation of zearalenone and aflatoxin B1 by Bacillus cereus IFST-Xd-5:

[0096] 1. Prepare the experimental group solution: take 2970 μL of the treated supernatant (Bacillus cereus IFST-Xd-5 bacterial solution cultured in LB liquid medium in step 1 of Example 4) and place it in a 10 mL centrifuge tube, adjust the pH to 9.0, add 30 μL of the above-mentioned ZEN solution and AFB1 solution to the centrifuge tube respectively, so that the final concentration is 1 mg / L, vortex thoroughly, and culture at 60°C, 180 r / min shaking table for 24 h to obtain the experimental group solution.

[0097] 2. Prepare the control solution: replace the supernatant with 2970 μL LB liquid culture medium and keep other operations unchanged to obtain the control solution.

[0098] 3. Effect detection:

[0099] The experimental group solution and the control group solution were used as test solutions, and the following steps were performed:

[0100] 1. Add an equal volume of chromatographic grade methanol to the solution to be tested, shake and extract at room temperature for 5 minutes, centrifuge at 12000r / min for 10 minutes, and take the supernatant for the next purification operation.

[0101] 2. Take the supernatant obtained in step 1 and use the zearalenone immunoaffinity column and the aflatoxin B1 immunoaffinity column to remove impurities, respectively. The specific operation is the same as above. The obtained eluate is filtered through a 0.22 μm organic phase nylon membrane and then placed in a 2 mL chromatographic injection vial to obtain a sample solution.

[0102] 3. Take the sample solution obtained in step 2 and use HPLC (post-column photochemical derivatization) to detect the sample obtained by purification and extraction. The HPLC and degradation rate calculation methods are the same as above.

[0103] The experiment was repeated three times and the results were averaged.

[0104] Test results such as Figure 5 and 6 As shown, a is the CK control group (LB+ZEN+AFB1); b is the experimental group (supernatant+ZEN+AFB1).

[0105] The results showed that when ZEN and AFB1 existed simultaneously, Bacillus cereus IFST-Xd-5 had no significant effect on the degradation of the two.

[0106] The ZEN content in the control group was 1002.89±25.09μg / L, and the residual ZEN content in the experimental group was 16.95±4.21μg / L. The degradation rate was 98.31%, which only decreased by 0.38%.

[0107] The AFB1 content in the control group was 998.56±15.88μg / L, and the residual AFB1 content in the experimental group was 10.29±0.53μg / L. The degradation rate was 98.97%, which only decreased by 0.34%.

[0108] <Example 6>

[0109] Application test of producing γ-polyglutamic acid by Bacillus cereus IFST-Xd-5:

[0110] 1) Preparation of seed solution: Bacillus cereus IFST-Xd-5 (inoculation concentration OD 600 =0.8, inoculation size 1%) was inoculated into the seed culture medium, shaken at 180 rpm, and cultured at 37°C for 24 h until OD 600 The value is greater than 3.0, and a seed solution is obtained, wherein the formula of the seed culture medium is: 10 g / L tryptone, 5 g / L yeast extract, 10 g / L sodium chloride, and distilled water;

[0111] 2) Fermentation culture: The seed liquid in step 1) is inoculated into a fermentation medium at an inoculum amount of 3%, the fermentation medium liquid volume of a 7.5L fermenter is 4L, the ventilation ratio is controlled at 1.0vvm (the ratio of the ventilation volume per minute to the actual liquid volume of the tank), the initial pH value is 6.5, and the culture is carried out at 28°C for 48h to obtain a fermentation liquid, wherein the formula of the fermentation medium is: 45g / L sodium glutamate, 50g / L citric acid, 40g / L soybean cake powder, 1g / L potassium dihydrogen phosphate, 0.05g / L manganese sulfate, 1.2g / L magnesium sulfate, and distilled water;

[0112] 3) Detection: The fermentation broth obtained in step 2) is diluted (the concentration is controlled to be below 1 g / L), and then the molecular weight and yield of γ-polyglutamic acid in the dilution are detected by high performance liquid chromatography.

[0113] The results showed that the molecular weight of γ-polyglutamic acid in the fermentation broth was about 95 kDa, and the yield of γ-polyglutamic acid in the fermentation broth was 61.5 g / L.

[0114] <Example 7>

[0115] Application test of Bacillus cereus IFST-Xd-5 on degradation of fungal toxins in toxin-producing corn:

[0116] Adjust the moisture of corn to 28%, sterilize with 1% sodium hypochlorite solution for 2 min, then rinse with sterile water 3 times, and put into tissue culture bottles, 100 g corn per bottle. Add 1 mL of Aspergillus flavus spore suspension (10 6 CFU / mL), 1mL spore suspension of Fusarium graminearum (10 6 CFU / mL) and 1mL Bacillus cereus IFST-Xd-5 (10 8 CFU / mL) as the experimental group, and the control group was added with 1 mL of sterile water instead of Bacillus cereus IFST-Xd-5 (10 8 CFU / mL), shake well, set up 3 parallels in each experimental group and control group, and culture the two groups at 28℃ for 16 days.

[0117] in,

[0118] Aspergillus flavus, numbered NRRL3357, was obtained from Professor Xing Fuguo of the Institute of Agro-product Processing, Chinese Academy of Agricultural Sciences.

[0119] Fusarium graminearum, numbered PH-1, was obtained from Professor Guo Wei, Institute of Agro-product Processing, Chinese Academy of Agricultural Sciences.

[0120] After the cultivation, the content of mycotoxins (zearalenone and aflatoxin B1) in corn was detected. The determination method was as follows:

[0121] The experimental group solution and the control group solution were used as test solutions, and the following steps were performed:

[0122] 1. Add an equal volume of chromatographic grade methanol to the solution to be tested, shake and extract at room temperature for 5 minutes, centrifuge at 12000r / min for 10 minutes, and take the supernatant for the next purification operation.

[0123] 2. Take the supernatant obtained in step 1 and use the zearalenone immunoaffinity column and the aflatoxin B1 immunoaffinity column to remove impurities, respectively. The specific operation is the same as above. The obtained eluate is filtered through a 0.22 μm organic phase nylon membrane and then placed in a 2 mL chromatographic injection vial to obtain a sample solution.

[0124] 3. Take the sample solution obtained in step 2 and use HPLC (post-column photochemical derivatization) to detect the sample obtained by purification and extraction. The HPLC and degradation rate calculation methods are the same as above.

[0125] The experiment was repeated three times and the results were averaged.

[0126] The results showed that the zearalenone content of corn in the control group was 121.56±1.83μg / L, and the aflatoxin B1 content was 312.27±2.60μg / L. The zearalenone content of corn in the experimental group was 16.95±4.21μg / L, and the degradation rate was 86.06%; the aflatoxin B1 content was 19.29±0.53μg / L, and the degradation rate was 93.82%.

[0127] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A Bacillus cereus, characterized in that include: Its deposit number is CGMCC No.29968.

2. A bacterial agent containing the Bacillus cereus according to claim 1.

3. Use of the Bacillus cereus according to claim 1 or the bacterial agent according to claim 2 in degrading zearalenone and aflatoxin B1 and in high-yield γ-polyglutamic acid.

4. A method for degrading zearalenone, characterized in that: The zearalenone is degraded by using the Bacillus cereus described in claim 1 or the bacterial agent described in claim 2.

5. A method for degrading aflatoxin B1, characterized in that: Aflatoxin B1 is degraded using the Bacillus cereus described in claim 1 or the bacterial agent described in claim 2.

6. A method for simultaneously degrading zearalenone and aflatoxin B1, characterized in that: The Bacillus cereus described in claim 1 or the bacterial agent described in claim 2 is used to degrade zearalenone and aflatoxin B1 together.

7. A method for high-yield γ-polyglutamic acid, characterized in that: The Bacillus cereus according to claim 1 or the bacterial agent according to claim 2 is used for fermentation treatment under the condition of introducing oxygen.

8. The method for high-yield γ-polyglutamic acid according to claim 7, characterized in that: The fermentation medium in the fermentation process includes sodium glutamate, citric acid, soybean cake powder, potassium dihydrogen phosphate, manganese sulfate and magnesium sulfate, and is prepared with distilled water.

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