Fusion enzyme for degrading aflatoxin B1 and / or zearalenone and application thereof

Abstract

The invention belongs to the technical field of bioengineering and food safety, and particularly relates to a fusion enzyme for degrading aflatoxin B1 (AFB1) and / or zearalenone (ZEN) and application of the fusion enzyme. The fusion enzyme S1-AsDPP III disclosed by the invention can effectively degrade AFB1 and ZEN, the fusion enzyme is obtained by fusing a section of self-assembled amphiphilic oligopeptide S1 sequence at the N end of wild type AsDPP III, and the thermal stability of the fusion enzyme and the amphipathy of the fusion enzyme in an oil-water coexistence system can be remarkably improved. Under mild reaction conditions, the fusion enzyme can efficiently degrade AFB1 and ZEN in vegetable oil, and is especially suitable for detoxification treatment of common edible oil such as peanut oil and corn oil. The invention provides a green, safe and efficient scheme for removing fungaltoxin from grease food, and the method has a good industrial application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of bioengineering and food safety, and particularly relates to a fusion enzyme for degrading aflatoxin B1 and / or zearalenone. BACKGROUND

[0002] Plant oils, as an indispensable part of daily diet, not only provide the necessary heat for the human body, but also are rich in various fat-soluble vitamins and unsaturated fatty acids, and have good nutritional and health value. Plant oils are mainly extracted from oilseeds such as peanuts, corn, rapeseed and soybeans. Since oilseeds are easily contaminated by mycotoxins, the contamination of mycotoxins in plant oils has become a key food safety problem. Common mycotoxins in plant oils include aflatoxins (AFTs), zearalenone (ZEN), vomitoxin and fumonisin. It is worth noting that aflatoxin B1 (AFB1) and ZEN are the two representative toxins with the highest detection frequency and the strongest toxicity in plant oils. Among them, AFB1 is a secondary metabolite produced by fungi such as Aspergillus flavus ( Aspergillus flavus ) and Aspergillus parasiticus ( A. parasiticus ), and is the most toxic aflatoxin found so far, with extremely high hepatotoxicity and carcinogenic risk. It has been listed as a class I carcinogen by the International Agency for Research on Cancer (IARC), and a large number of studies have confirmed its close relationship with the occurrence of liver cancer. In addition, AFB1 also has significant mutagenicity, teratogenicity and immunosuppressive effect, and widely exists in plant oil products such as peanut oil and corn oil. ZEN is a secondary metabolite produced by various Fusarium fungi ( Fusarium spp.) during the contamination process of oil crops such as corn and wheat, and mainly affects the endocrine system of mammals through its estrogen-like activity. ZEN can interfere with the endocrine homeostasis of the body, causing disorders of the animal reproductive system, and even leading to decreased reproductive capacity and embryonic malformation. Studies have shown that ZEN also has certain hepatotoxicity, nephrotoxicity and neurotoxicity, and can accumulate in the human and animal body. More seriously, AFB1 and ZEN often coexist in plant oils, producing additive toxicity and posing a combined risk to human health. In order to effectively control the residue of mycotoxins in food, the international community has developed a number of strict safety standards. The European Union issued the Commission Regulation on Mycotoxins in Human Food (EC 401 / 2006) as early as 2006, which clearly stipulates the maximum residue limits of AFB1 and ZEN in plant oils and related products. However, mycotoxins have stable chemical structures and strong heat resistance, and it is difficult to be completely removed even in the conventional heating or refining process, so the removal of mycotoxins in plant oils is still a technical problem.

[0003] Currently, the plant oil detoxification technology mainly includes physical, chemical and biological methods. Although physical methods such as refining, activated carbon adsorption and ozone oxidation can reduce toxin residues to a certain extent, they have problems such as low selectivity, large nutrient loss, high equipment cost and potential secondary pollution; the chemical method (such as acid-base treatment and chemical oxidation-reduction) has a high degradation efficiency, but it is easy to cause food safety hazards and has been gradually restricted. Compared with this, the biological detoxification technology has been widely concerned due to its high degradation efficiency, strong specificity, little influence on food sensory characteristics and environmental friendliness, among which enzyme degradation is particularly prominent. Enzyme degradation, as one of the most potential directions in biological detoxification, mainly relies on detoxification enzymes with specific catalytic ability to degrade or detoxify the structure of mycotoxin molecules, so as to achieve toxicity reduction or removal. Previous studies have reported that many enzymes derived from microorganisms have the ability to degrade AFB1 and ZEN, such as laccase, peroxidase, oxidoreductase and lactonase. These enzymes show good catalytic activity in aqueous systems, but in actual plant oil systems, due to their weak hydrophobicity, they are difficult to play a stable catalytic role at the oil-water interface. In addition, the high-fat environment of plant oil challenges the stability of protein conformation, and many natural detoxification enzymes are prone to conformational changes or aggregation and precipitation in this environment, resulting in a decrease or complete loss of enzyme activity. Especially under high temperature or industrial continuous processing conditions, the thermal stability of traditional enzymes is often insufficient, and it is difficult to maintain catalytic function for a long time, which seriously limits its application effect and sustainability in plant oil detoxification.

[0004] Based on the strategies of molecular modification, structure design and function fusion, the construction of engineered detoxification enzymes with oil phase adaptability and thermal stability has become a research hotspot and development direction in the field of biological detoxification. Patent 202310385675.1 discloses a novel zearalenone degrading enzyme, a coding gene and its expression and application. The modified degrading enzyme S1-Zhd11d has stability at 40℃ and under specific pH conditions, and the degradation rate in peanut oil is 44.6%, but the modified degrading enzyme S1-Zhd11d has the problems of degrading only a single toxin and low stability. Therefore, developing enzyme preparations with high stability, good amphiphilicity and multi-toxin degradation is a key technical bottleneck for promoting the industrial application of enzyme degradation in plant oil detoxification. SUMMARY

[0005] To solve the above technical problems, the present application provides a fusion enzyme for degrading aflatoxin B1 and / or zearalenone and its application.

[0006] The technical scheme of the present application is as follows: On the one hand, the present application provides a fusion enzyme S1- DPP Ⅲ for degrading aflatoxin B1 and / or zearalenone. As DPP Ⅲ, and the fusion enzyme S1-As The amino acid sequence of DPP III is shown as SEQ ID No. 1.

[0007] Preferably, the fusion enzyme S1- As DPP III is S1-GS- As The polypeptide sequence of DPP III structure is obtained by connecting the self-assembled amphiphilic short peptide S1 and the degrading enzyme As DPP III through a connecting peptide.

[0008] Preferably, the connecting peptide is (G4S)3, and the amino acid sequence of the self-assembled amphiphilic short peptide S1 is shown as SEQ ID No. 3.

[0009] In the second aspect, the present application protects the above-mentioned fusion enzyme S1- As DPP III for degrading aflatoxin B1 and / or zearalenone.

[0010] In the third aspect, the present application protects a recombinant plasmid comprising the above-mentioned fusion enzyme S1- As DPP III for degrading aflatoxin B1 and / or zearalenone.

[0011] In the fourth aspect, the present application protects a recombinant strain comprising the above-mentioned recombinant plasmid.

[0012] In the fifth aspect, the present application protects a preparation method of the above-mentioned fusion enzyme S1- As DPP III for degrading aflatoxin B1 and / or zearalenone. (1) cloning the above-mentioned coding gene into the Sac I and Not I double enzyme cutting sites of the expression vector pET-28a (+) to obtain a recombinant plasmid pET-28a (+)-S1- As DPP III; (2) transforming the recombinant plasmid pET-28a (+)-S1- As DPP III obtained in step (1) into E. coli to obtain a recombinant strain; (3) culturing the recombinant strain obtained in step (2), adding isopropyl-β-D-thiogalactoside to induce expression, and then crushing, recovering and purifying to obtain the fusion enzyme S1- As DPP III.

[0013] The specific steps are as follows: using Sac I and Not I restriction enzyme cutting sites to clone the target fragment (SEQ ID No. 1) into the expression vector pET-28a (+) to obtain a recombinant plasmid pET-28a (+)-S1- AsDPP III.

[0014] The recombinant plasmid pET-28a (+) -S1- As DPP III was transformed into E. coli expression strain BL21 (DE3) by heat shock method. After 45 seconds of 42℃ water bath heat shock, it was immediately placed on ice for cooling for 2-3 min. 800 μL of LB medium was added. After 1 h of shaking culture at 37℃ and 200 rpm, 5000 rpm centrifugation was performed for 5 min. 700 μL of supernatant was discarded. The remaining culture medium was used to resuspend the bacterial body. A sterile swab was used to evenly spread the bacteria on a plate containing kanamycin resistance. After 12-16 h of inverted culture in a 37℃ incubator, positive clones were screened. Bacterial liquid PCR verification was performed to obtain successfully transformed recombinant E. coli.

[0015] The successfully transformed recombinant E. coli was inoculated into LB medium containing kanamycin for expansion culture until OD 600 0.6-0.8 was reached. Then, isopropyl-β-D-thiogalactoside (IPTG) was added to the medium at a final concentration of 0.5 mM. The culture was induced at 16℃ and 120 rpm for 24 h. After the induction was completed, the bacterial body was collected by centrifugation at 8000 x g for 10 min. The bacterial body was resuspended in PBS solution (pH 7.4). Ultrasonic wave crushing was performed under ice bath conditions for 30 min (pulse 4 s, interval 4 s). The crushed liquid was removed from the precipitate. The supernatant was obtained by passing through a 0.45 μm filter membrane. The supernatant was slowly loaded into a Ni-NTA affinity chromatography column that was previously equilibrated with a binding buffer containing 10 mM imidazole. The recombinant protein with His tag was specifically combined with Ni 2+ in the column. Subsequently, non-specifically combined impurity proteins were removed by sequentially using a low concentration imidazole washing buffer (20 mM imidazole). The target protein was gradually eluted by using a high concentration imidazole elution buffer (250 mM imidazole). The elution fraction was collected. Imidazole was removed by ultrafiltration to obtain the purified protein, In a fifth aspect, the present application protects the fusion enzyme S1- As DPP III described above or the coding gene described above or the recombinant plasmid described above or the recombinant strain described above is applied in the degradation of plant oil aflatoxin B1 and / or zearalenone.

[0016] Preferably, the plant oil described above includes but is not limited to peanut crude oil and corn crude oil; 0.02-0.1 mg of the fusion enzyme S1- As DPP III is added per gram of plant oil; the degradation temperature is 40-60℃, and the time is 24-48 h.

[0017] The specific steps are as follows: 10 g of toxin-contaminated oil sample is weighed. The fusion enzyme S1- AsDPP III (0.5 mg) was placed in a constant temperature oscillator at 50 DEG C, and the reaction time was set to 24 h and 48 h.

[0018] The present application has the following beneficial effects: The present application provides a dipeptidyl peptidase which can effectively degrade AFB1 and ZEN As The fusion enzyme S1 of DPP III As The fusion enzyme S1 of DPP III is obtained by fusing a self-assembled amphiphilic short peptide S1 sequence to the N-terminus of wild-type DPP III As The fusion enzyme S1 of DPP III is obtained by fusing a self-assembled amphiphilic short peptide S1 sequence to the N-terminus of wild-type DPP III The fusion enzyme S1 of DPP III has high thermal stability in the range of 30-60 DEG C, retains more than 75% of the enzyme activity after 12 hours of pretreatment at 70 DEG C, and retains about 60% of the enzyme activity after 12 hours of treatment at 80 DEG C. The fusion enzyme has good amphiphilicity, is suitable for oil-water coexistence system, and improves the degradation efficiency of AFB1 and ZEN. The fusion enzyme can degrade 83.4% of AFB1 in peanut oil and 70.1% of ZEN in corn oil within 48 h. The present application provides a green, safe and efficient fungal toxin removal scheme for oil and fat food, and has good industrial application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0020] Figure 1 The pET-28a (+) -S1 As The DPP III fusion enzyme recombinant plasmid.

[0021] Figure 2 The PCR electrophoresis map of the bacterial liquid.

[0022] Figure 3 The fusion enzyme S1 As The SDS-PAGE electrophoresis map of DPP III, M: protein marker; P: purified S1 As DPP III.

[0023] Figure 4 The fusion enzyme S1 As The optimal pH determination result of DPP III for degrading AFB1 and ZEN.

[0024] Figure 5 The fusion enzyme S1 As The optimal temperature determination result of DPP III for degrading AFB1 and ZEN.

[0025] Figure 6 For different metal ions to fusion enzyme S1- As The results of DPP III on the degradation of AFB1 and ZEN.

[0026] Figure 7 For fusion enzyme S1- As The degradation effect of DPP III on AFB1 and ZEN in plant oil, wherein A is the degradation effect of AFB1 in peanut oil; B is the degradation effect of ZEN in corn oil.

[0027] Figure 8 For fusion enzyme S1- As The results of the thermal stability determination of DPP III. DETAILED DESCRIPTION

[0028] The technical solutions of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0029] The test methods used in the following experimental examples are conventional methods unless otherwise specified; the materials, reagents, etc. used are reagents and materials available through commercial channels unless otherwise specified.

[0030] The present application provides a new type of fusion enzyme, which combines a hydrophobic and hydrophilic dual short peptide with a high-efficiency detoxification enzyme structural unit, has excellent two-phase interface adaptability and thermal stability, can stably catalyze the degradation of AFB1 and ZEN in complex matrices such as plant oil, and has broad application prospects and important industrialization value.

[0031] Luria-Bertani medium (LB medium): 10 g·L -1 Tryptone, 5 g·L -1 Yeast extract powder, 10 g·L -1 Sodium chloride, adjust pH to 7.0-7.2, 121℃ high-pressure sterilization for 20 min.

[0032] Example 1: Fusion enzyme S1- As Heterologous expression of DPP III 1. Construction of expression vector. The self-assembled amphiphilic short peptide (S1, AEAEAKAKAEAEAKAK (SEQ ID No. 3)) is fused to the AFB1 and ZEN degradation enzyme gene AsThe N-terminal of DPP III was cloned into the expression vector pET-28a (+) using Sac I and Not I restriction enzyme sites to obtain the recombinant plasmid pET-28a (+)-S1- As DPP III (as shown in SEQ ID No. 1) was cloned into the expression vector pET-28a (+) using Sac I and Not I restriction enzyme sites to obtain the recombinant plasmid pET-28a (+)-S1- Figure 1

[0033] 2. Transformation of the fusion enzyme. The recombinant plasmid pET-28a (+)-S1- As DPP III was transformed into the E. coli expression strain BL21 (DE3) by heat shock method. After 45 seconds of 42°C water bath heat shock, it was immediately placed on ice for 2-3 min, 800 μL of LB medium was added, and after 1 h of 37°C, 200 rpm shaking, 5000 rpm centrifugation was performed for 5 min, 700 μL of supernatant was discarded, and the remaining medium was used to resuspend the bacterial cells. A sterile spreader was used to evenly spread the bacteria on a plate containing kanamycin. After 12-16 h of inverted culture in a 37°C incubator, positive clones were selected, and bacterial liquid PCR verification was performed, as shown in SEQ ID No. 1, to obtain successfully transformed recombinant E. coli. Figure 2

[0034] 3. Expression and purification of the fusion enzyme. The successfully transformed recombinant E. coli was inoculated into LB medium containing kanamycin for large-scale culture until the OD 600 reached 0.6-0.8. Then, isopropyl-β-D-thiogalactoside (IPTG) was added to the medium at a final concentration of 0.5 mM, and the culture was induced at 16°C, 120 rpm for 24 h. After induction, the bacterial cells were collected by centrifugation at 8000 x g for 10 min, resuspended in PBS solution (pH 7.4), and broken by ultrasonic wave under ice bath conditions for 30 min (pulse 4 s, interval 4 s). The broken liquid was centrifuged at 12000 x g for 10 min to remove the broken precipitate, and the supernatant was obtained by passing through a 0.45 μm filter membrane. The supernatant was slowly loaded onto a Ni-NTA affinity chromatography column previously equilibrated with binding buffer containing 10 mM imidazole, and the recombinant protein with His tag was specifically bound to the Ni 2+ in the column. Subsequently, non-specifically bound impurity proteins were removed with low-concentration imidazole washing buffer (20 mM imidazole), and the target protein was gradually eluted with high-concentration imidazole elution buffer (250 mM imidazole). The eluted fractions were collected and further subjected to ultrafiltration to remove imidazole, obtaining the purified protein, and the purity was verified by SDS-PAGE, as shown in SEQ ID No. 1. Figure 3

[0035] Example 2: Determination of the optimal pH of AFB1 and ZEN degradation by fusion enzyme S1- As DPP III ​​​The purified protein obtained in Example 1 was used to determine the protein concentration using a Bradford protein detection kit. The degradation reaction system was 500 μL, containing 20 μg / mL S1- As DPP III protein, 5 μg / mL AFB1 or 10 μg / mL ZEN, 1 mM Cu 2+ In different pH buffer solutions (pH 5.0-6.0: phosphate buffer solution, pH 7.0-8.0: Tris-HCl buffer solution, pH 9.0-10.0: Gly-NaOH buffer solution), incubated at 40°C for 24 h. After the reaction was completed, 500 μL of methanol was added to each reaction system to terminate the reaction, and the concentration of AFB1 or ZEN was determined by high performance liquid chromatography (HPLC), and the degradation rate under each pH condition was calculated.

[0036] Fusion enzyme S1- As The degradation rate of DPP III on AFB1 and ZEN can be calculated by the following formula: Degradation rate = (1-C0 / C1) x 100% Wherein, C0 and C1 represent the concentration of toxins before and after degradation.

[0037] As Figure 4 shown, the fusion enzyme S1- As The optimum pH for DPP III to degrade AFB1 and ZEN was 7.0 and 8.0, respectively, and the degradation rate was 98.4% and 88.2%, respectively.

[0038] Example 3: Determination of the optimum temperature for fusion enzyme S1- As DPP III to degrade AFB1 and ZEN Using the degradation reaction system in Example 2, the optimum temperature for fusion enzyme S1- As DPP III to degrade AFB1 was determined in 50 mM Tris-HCl buffer (pH 7.0), and the optimum temperature for ZEN degradation was determined in 50 mM Tris-HCl buffer (pH 8.0), with a temperature range of 20-80°C, and the results are shown in Figure 5 As The optimum temperature for DPP III to degrade AFB1 and ZEN was 40°C and 60°C, respectively, and the degradation rate was 98.5% and 97.6%, respectively.

[0039] Example 4: Effect of metal ions on fusion enzyme S1- As DPP III to degrade AFB1 and ZEN Using the degradation reaction system in Example 2, the effect of metal ions on fusion enzyme S1- As ​The effect of DPP III on the degradation of AFB1 was determined in 50 mM Tris-HCl buffer (pH 7.0), and different metal ions were added to the reaction system at a final concentration of 1 mM, and the temperature was controlled at 40°C.

[0040] The effect of metal ions on the degradation of AFB1 by fusion enzyme S1- As The effect of DPP III on the degradation of ZEN was determined in 50 mM Tris-HCl buffer (pH 8.0), and different metal ions were added to the reaction system at a final concentration of 1 mM, and the temperature was controlled at 60°C.

[0041] The results are shown in Figure 6 Cu 2+ significantly enhanced the degradation rate of fusion enzyme S1- As DPP III to AFB1 and ZEN, which increased to 98.5% and 97.9%, respectively.

[0042] Example 5: Fusion enzyme S1- As DPP III degradation effect on AFB1 and ZEN in vegetable oil Peanut oil and corn oil were prepared by leaching method, respectively, as the vegetable oil matrix of this example. The toxin standard was added to the peanut oil and corn oil, respectively, to simulate the contaminated sample: AFB1 standard was added to the peanut oil to make the final concentration 200 μg / kg; ZEN standard was added to the corn oil to make the final concentration 600 μg / kg, and it was fully mixed and ready for use.

[0043] 10 g of the above toxin-contaminated oil sample was weighed, and fusion enzyme S1- As DPP III (added amount was 0.5 mg) was added, and the reaction was carried out in a constant temperature oscillator at 50°C, and the reaction time was set at 24 h and 48 h. The sample without adding fusion enzyme was set as a blank control group.

[0044] After the reaction was completed, methanol-water (volume ratio 70:30) was used as the extractant to extract the reaction mixture. After extraction with chloroform, the concentration of residual AFB1 (peanut oil) and ZEN (corn oil) in the reaction system was determined by HPLC.

[0045] The results are shown in Figure 7 After 24 h of reaction, the wild-type enzyme As DPP III in peanut oil had a degradation rate of only 30.8%, while the degradation rate of fusion enzyme S1- As DPP III was 70.7%, which was 2.3 times that of the wild-type. The wild-type enzyme AsDPP III only has a degradation rate of 25.9% on ZEN in corn oil, while the fusion enzyme S1- As DPP III has a degradation rate of 52.2%, which is twice that of the wild type. After 48 h of reaction, the fusion enzyme S1- As DPP III has a degradation rate of 83.4% on AFB1 in peanut oil and a degradation rate of 70.1% on ZEN in corn oil. Under the conditions described in this embodiment, the fusion enzyme S1- As DPP III can significantly degrade AFB1 and ZEN in plant oil. Compared with the control group, a significant decrease in the content of target toxins was observed at 24 h and 48 h, indicating that the fusion enzyme still has good degradation ability and application potential in complex lipid matrices such as plant oil.

[0046] Example 6: Fusion enzyme S1- As Thermal stability determination of DPP III Fusion enzyme S1- As Determination method of enzyme activity of DPP III: The total reaction system is 500 μL, and the reaction system contains: 5 μg / mL of AFB1, 20 μg / mL of enzyme solution, 1 mM Cu 2+ The reaction buffer solution is 50 mM Tris-HCl buffer (pH 7.0).

[0047] The above reaction system is reacted at 40℃ for 12 h, and after the reaction is completed, 500 μL of methanol is added to terminate the reaction. The enzyme activity is defined as the amount of enzyme required to catalyze the degradation of 1 nmol of AFB1 per hour under the above reaction conditions.

[0048] The fusion enzyme S1- As DPP III was pretreated at 30, 40, 50, 60, 70 and 80℃ for 12 h, and after the treatment was completed, an equal amount of enzyme solution was taken for the above enzyme activity determination. The enzyme activity of the fusion enzyme without heating treatment was taken as the control group (relative activity defined as 100%), and the residual activity of the fusion enzyme after different temperature pretreatment was calculated to determine its thermal stability.

[0049] The results are shown in Figure 8 The fusion enzyme S1- As DPP III has high thermal stability in the range of 30-60℃, and the residual enzyme activity remains above 90% after treatment; after pretreatment at 70℃ for 12 h, the enzyme activity remains above 75%; after treatment at 80℃, about 60% of the activity is retained, indicating that the fusion enzyme S1- As DPP III has good thermal stability.

[0050] The above merely provides the preferred embodiment of the present application, and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A fusion enzyme S1- degrading aflatoxin B1 and / or zearalenone As DPP III, characterized in that The fusion enzyme S1- As The amino acid sequence of DPP III is shown in SEQ ID No.

1.

2. The fusion enzyme S1 degrading aflatoxin B1 and / or zearalenone according to claim 1 As DPP III characterized in that The fusion enzyme S1- As DPP III is obtained by fusing the self-assembling amphiphilic short peptide S1 with the degrading enzyme As DPP III at the N-terminal.

3. The fusion enzyme S1 degrading aflatoxin B1 and / or zearalenone according to claim 2 As DPP III characterized in that The connecting peptide is (G4S)3, and the amino acid sequence of the self-assembled amphiphilic short peptide S1 is shown as SEQ ID No.

3.

4. The fusion enzyme S1 degrading aflatoxin B1 and / or zearalenone according to any one of claims 1 to 3. As The coding gene of DPP III is characterized in that: The nucleotide sequence of the coding gene is shown as SEQ ID No.

2.

5. A recombinant plasmid, characterized by: The fusion enzyme S1 degrading aflatoxin B1 and / or zearalenone according to claim 4 As The coding gene of DPP III.

6. A recombinant bacterial strain, characterized in that: The plant oil is peanut crude oil or corn crude oil; the degradation temperature is 40-60℃, and the time is 24-48 h.

7. The fusion enzyme S1 degrading aflatoxin B1 and / or zearalenone according to any one of claims 1 to 3. ​ Process for the preparation of DPP III, characterized in that ​ (1) The coding gene of claim 4 was cloned into the double enzyme cleavage site between Sac I and Not I of expression vector pET-28a (+) to obtain recombinant plasmid pET-28a (+)-S1- ​ DPP III; (2) The recombinant plasmid pET-28a (+) -S1 obtained in step (1) is transformed into E. coli to obtain a recombinant strain; ​ DPP III is transformed into E. coli to obtain a recombinant strain; (3) The recombinant strain obtained in step (2) is cultured, and isopropyl-β-D-thiogalactoside is added to induce expression. After crushing, recovery and purification, the fusion enzyme S1 is obtained. ​ DPP III.

8. The fusion enzyme S1 of claim 3 ​ The use of DPP III or the encoding gene of claim 4 or the recombinant plasmid of claim 5 or the recombinant strain of claim 6 in degrading aflatoxin B1 and / or zearalenone in vegetable oil.

9. Use according to claim 8, characterized in that: ​ 10. Use according to claim 9, characterized in that: 0.02-0.1 mg fusion enzyme S1 per gram of plant oil A sDPP III.

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