Method for preventing and controlling transmission of antibiotics and drug-resistant genes in soil vegetable system based on biochar-based composite material

Abstract

The invention relates to a method for preventing and controlling antibiotic and drug-resistant gene transmission in a soil vegetable system based on a charcoal-based composite material. According to the invention, agricultural waste corn straw is used as a precursor, magnetic iron and graphite phase carbon nitride are loaded through a hydrothermal reaction, and then high-temperature calcination is carried out to prepare a FeBC / g-C3N4 (short for FeBC / g-CN) biochar composite material which is used as a soil conditioner. The prepared biochar modifier is applied to polluted farmland soil to be treated, sufficient and uniform mixing is conducted, vegetable seeds are sown, illumination is provided, and a certain water content of the soil is kept, the prepared biochar modifier is simple in preparation method and application method and remarkable in effect, the reduction rate of tetracycline in soil vegetables is increased through use of the biochar modifier, and the soil quality is improved. Meanwhile, transmission of antibiotics and drug-resistant genes in a soil vegetable system is blocked and controlled.

Description

Technical Field

[0001] The present invention relates to the technical field of farmland soil remediation, and in particular to a preparation method and application of a biochar-controlled material for transmitting antibiotics and drug-resistant genes in soil and vegetables. Background Art

[0002] The development of agriculture and animal husbandry has accelerated the contamination of farmland soil with antibiotics, while leading to the enrichment of antibiotic resistance genes in the soil, posing a major threat to global ecosystems and human health. Various chemical and physical techniques have been used to remediate antibiotic-contaminated soils, but challenges related to cost, complex preparation methods, and efficacy often limit their sustainability. Soil adsorbent application is a major method to reduce the effectiveness of soil antibiotics, but traditional adsorbents have obvious performance differences and are weak in adsorbing pollutants. Therefore, how to select a low-cost soil conditioner that can effectively remove antibiotics from soil and vegetables is an important research topic to ensure food safety and human health in the future. Summary of the invention

[0003] The technical problem to be solved by the present invention is to address the above shortcomings and provide a method for preparing a biochar material that blocks the transmission of antibiotics and drug-resistant genes in soil and vegetables. Corn straw is used as a precursor, and a biochar material with strong adsorption capacity is prepared after magnetic modification and graphite carbon nitride loading, hydrothermal reaction and high-temperature calcination. The biochar material is then applied to soil contaminated by antibiotics and drug-resistant genes to achieve soil remediation, thereby protecting food safety and human health.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] The method for preventing and controlling the transmission of antibiotics and drug-resistant genes in a soil vegetable system based on a biochar-based composite material comprises the following steps:

[0006] Step 1, washing corn stalks with deionized water, drying, crushing and sieving to obtain stalk powder;

[0007] Step 2, preparing graphite carbon nitride g-C3N4;

[0008] Step 3, adding corn stalk powder and FeSO4·7H2O to deionized water, mixing and stirring evenly, magnetically stirring at room temperature for 12 hours, adding the prepared g-C3N4 and stirring evenly, continuing magnetic stirring at room temperature for 12 hours, drying in a forced air drying oven, and sieving to obtain a solid powder, wherein the mass ratio of FeSO4·7H2O, g-C3N4 and corn stalk is 1:1:1.5;

[0009] Step 4, calcining the solid powder obtained in the previous step at 650-750° C. in a muffle furnace for more than 4 hours, cooling to room temperature after the reaction is completed, washing the obtained product by centrifugation with deionized water and ethanol three times, and obtaining a FeBC / g-CN composite material after drying;

[0010] Step 5: Apply the FeBC / g-CN composite material obtained in the previous step to the soil at a rate of 0.4-0.8% of the soil mass and mix thoroughly.

[0011] Furthermore, the specific steps of step 2 are: placing urea in a quartz crucible with a lid and heating it to 550° C., maintaining the constant temperature for 2 hours, cooling and collecting to obtain g-C3N4.

[0012] Furthermore, in step 5, the application ratio of the FeBC / g-CN composite material is 0.5% of the soil mass.

[0013] The beneficial effects of the present invention are:

[0014] The composite material used in the present invention has a simple preparation method, rich precursor raw materials, and a large pore volume, and is an ideal soil improvement material; the fertilization method of the present invention is simple to operate and is suitable for small potted planting; the improvement of the prepared FeBC / g-CN biochar material can increase the decomposition of antibiotics in the soil, reduce the selective pressure of antibiotics, and block the transmission of antibiotics and drug-resistant genes in the soil vegetable system. The test results show that after the application of biochar material, the tetracycline content in the root, stem, leaf tissue and soil of lettuce decreased by 58%, 79%, 74% and 30% respectively, and the relative abundance of total drug-resistant genes decreased by 64%, 54%, 43% and 63% respectively, which has a good blocking effect on the transmission of antibiotics and drug-resistant genes in soil and vegetable tissues.

[0015] The present invention is described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The tetracycline content in the roots, stems, leaves and soil of lettuce after the lettuce is harvested;

[0017] Figure 2 The abundance of drug-resistant genes in the roots, stems, leaves and soil of lettuce tissues after the lettuce is harvested;

[0018] Figure 3 The scanning electron microscope images of the soil biochar improved material prepared by the present invention; wherein A, B and C, D are SEM scanning electron microscope images of the original corn stover (BC) and the biochar soil improved material (FeBC / g-CN) prepared by the present invention at 1300 times and 4500 times, respectively. DETAILED DESCRIPTION

[0019] The following examples are provided for a 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.

[0020] The preparation of magnetic biochar-loaded graphite phase carbon nitride (FeBC / g-CN) adsorption material and the method for reducing antibiotics and drug resistance genes in soil and vegetables include the following steps:

[0021] Step 1, washing the corn stalks with deionized water, drying, crushing and sieving to obtain corn stalk powder;

[0022] Step 2, preparation of graphite carbon nitride: place urea in a quartz crucible with a lid and heat to 550°C, keep the constant temperature for 2 hours, cool and collect to obtain g-C3N4;

[0023] Step 3: 0.76 g FeSO4·7H2O and 10 g corn straw powder were added to 50 mL deionized water and dissolved uniformly, and then magnetically stirred at constant temperature for 12 h. Then, g-C3N4 solution (0.76 g g-C3N4 was added to 20 ml deionized water, and ultrasonic dispersion and stirring were performed for 5 min) was added and magnetically stirred at constant temperature for 12 h, and then placed in a vacuum dryer at 80 ° C for 12 h to collect the light brown biomass powder.

[0024] Step 4: The collected light brown biomass powder is placed in a covered quartz crucible and calcined at 700°C in a muffle furnace for 4 hours. After the reaction is completed, it is cooled to room temperature. The obtained product is washed three times by centrifugation with deionized water and ethanol, and finally vacuum dried at 60°C overnight to obtain the final product FeBC / g-CN. The mass ratio of FeBC / g-CN, FeSO4 and g-C3N4 is 1:1.

[0025] Step 5, laboratory soil preparation: The soil was taken from the surface soil within the range of 0-20 cm in the farmland, sieved to remove the weed rhizomes, and 10 mg / kg tetracycline hydrochloride was added as an antibiotic pollutant and applied to the soil for 1 week of dark balance. After 1 week, the prepared FeBC / g-CN material was applied to the soil as an additive at 0.5% of the soil mass and mixed thoroughly;

[0026] Step 6, vegetable pot planting: The experiment was divided into two groups, control group CK: 2kg soil + 10mg / kg tetracycline; experimental group BC: 2kg soil + 10mg / kg tetracycline + 0.5% biochar material. Pot planting was carried out in a plastic pot with an inner diameter of 18 cm and a depth of 15 cm. 2kg of the mixed soil was used to plant lettuce. After the seeds germinated, the seedlings were thinned out. During the cultivation period, a certain amount of light and soil moisture were maintained. After 60 days, when the vegetables were mature, soil and vegetable tissue samples were collected to detect the abundance of antibiotics and drug-resistant genes.

[0027] Figure 1 It showed that applying 0.5% biochar-amended material to the soil reduced tetracycline in lettuce root, stem and leaf tissues and soil by 58%, 79%, 74% and 30% compared with the control treatment. Figure 2 The relative abundance of total resistance genes in lettuce root, stem and leaf tissues and soil decreased by 64%, 54%, 43% and 63% respectively. This method can reduce the accumulation and transfer of antibiotics and resistance genes in soil and plants, and effectively reduce the transmission of antibiotics and resistance genes. It provides a simple, convenient and low-cost technical guidance for food safety and the harm caused to human health. Figure 3 Figures A and C show that the surface of the original corn straw biochar (BC) is relatively smooth. Figure 3 In Figures B and D, after the introduction of magnetic iron and graphite phase carbon nitride into the soil biochar improvement material prepared by the present invention, the magnetic iron agglomerated spherical protrusions are destroyed, presenting a lamellar floc structure, which increases more adsorption sites and thus improves the adsorption performance.

[0028] The above is an example of the best implementation of the present invention, and the parts not described in detail are common knowledge of ordinary technicians in the field. The protection scope of the present invention shall be based on the content of the claims, and any equivalent transformation based on the technical enlightenment of the present invention is within the protection scope of the present invention.

Claims

1. A method for preventing and controlling the transmission of antibiotics and drug-resistant genes in soil and vegetable systems based on biochar-based composite materials, characterized in that: The following steps are involved: Step 1, washing corn stalks with deionized water, drying, crushing and sieving to obtain stalk powder; Step 2, preparing graphite carbon nitride g-C3N4; Step 3, adding corn stalk powder and FeSO4·7H2O to deionized water, mixing and stirring evenly, magnetically stirring at room temperature for 12 hours, adding the prepared g-C3N4 and stirring evenly, continuing magnetic stirring at room temperature for 12 hours, drying in a forced air drying oven, and sieving to obtain a solid powder, wherein the mass ratio of FeSO4·7H2O, g-C3N4 and corn stalk is 1:1:1.5; Step 4, calcining the solid powder obtained in the previous step at 650-750° C. in a muffle furnace for more than 4 hours, cooling to room temperature after the reaction is completed, washing the obtained product by centrifugation with deionized water and ethanol three times, and obtaining a FeBC / g-CN composite material after drying; Step 5: Apply the FeBC / g-CN composite material obtained in the previous step to the soil at a rate of 0.4-0.8% of the soil mass and mix thoroughly.

2. The method for preventing the transmission of antibiotics and drug-resistant genes in soil and vegetable systems based on biochar-based composite materials according to claim 1 is characterized in that: The specific steps of step 2 are: place urea in a quartz crucible with a lid and heat it to 550°C, maintain the constant temperature for 2 hours, cool and collect to obtain g-C3N4.

3. The method for preventing and controlling the transmission of antibiotics and drug-resistant genes in soil and vegetable systems based on biochar-based composite materials according to claim 1, characterized in that: In step 5, the application ratio of the FeBC / g-CN composite material is 0.5% of the soil mass.

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