CN112080447A

CN112080447A - Bacterium ZG2 capable of repairing cadmium-nickel moderately polluted soil and application thereof

Info

Publication number: CN112080447A
Application number: CN202010931504.0A
Authority: CN
Inventors: 李明堂; 赵春莉; 程志强; 王洪阶; 刘金华; 周昕霏; 王雨琦; 张崇曦; 金香一
Original assignee: Jilin Agricultural University
Current assignee: Jilin Agricultural University
Priority date: 2020-09-07
Filing date: 2020-09-07
Publication date: 2020-12-15
Anticipated expiration: 2040-09-07
Also published as: CN112080447B

Abstract

The invention provides a bacterium ZG2 capable of repairing cadmium-nickel light and medium polluted soil and application thereof, wherein the bacterium ZG2 can fix cadmium-nickel in soil and enhance the stress resistance of plants, and is stored in the common microorganism center of China Committee for culture Collection of microorganisms in 28 months in 2020, the suggested classification is called Comamonas testosteroni, and the storage number is CGMCC NO. 20155. The bacterium is loaded on biochar and applied to soil, and then can be colonized in soil for a long time, so that the biological effectiveness of cadmium and nickel in the soil and the toxic effect of the cadmium and nickel on vegetable crops are continuously reduced, and the enrichment of edible parts of the vegetables on the cadmium and nickel is reduced, thereby achieving the effects of improving the quality of the vegetable crops and increasing the yield.

Description

Bacterium ZG2 capable of repairing cadmium-nickel moderately polluted soil and application thereof

Technical Field

The invention belongs to the technical field of resources and environment, and particularly relates to a bacterium ZG2 capable of repairing cadmium-nickel moderately polluted soil and application thereof in a vegetable planting process.

Background

2014, national survey bulletin of soil pollution states shows that: the soil pollution of cultivated land in China is mainly slight, mild and moderate pollution caused by heavy metals such as cadmium, nickel and the like, the point position standard exceeding rate of cadmium and nickel in the soil is 7.0 percent and 4.8 percent respectively, and the point position standard exceeding rate is higher than the first two. The safety utilization rate of the polluted cultivated land is regulated to 90 percent and 95 percent respectively in 2020 and 2030 in the action plan for soil pollution protection, so that the development of safe production-targeted treatment and restoration on the cadmium-nickel light and medium polluted soil is an important work for soil environment protection at present and in a period of time in the future, and the development of corresponding technologies is imperative.

The method for restoring the cadmium-nickel polluted soil mainly comprises physical, chemical, biological and combined methods. The defects of large soil disturbance, high cost, easy secondary pollution, unfavorable plant growth and the like exist when the cadmium-nickel polluted soil is repaired by a physical method and a chemical method, and the method has great limitation and inoperability in the aspect of safe production of the cadmium-nickel polluted soil. The biological law is that the life metabolic process of animals, plants and microorganisms is utilized to realize the removal or fixation of cadmium and nickel in soil. The plant method mainly plants cadmium-nickel hyperaccumulator plants to absorb cadmium and nickel in soil, on one hand, the method needs to occupy arable land resources and cannot repair and produce at the same time, and on the other hand, the method has lower repair efficiency in the north with longer low temperature period, especially in the northeast. The microorganism has strong adaptability, can participate in the micro-ecological regulation and control of soil and realize production while repairing, and is increasingly paid more attention to the repair of cadmium-nickel polluted soil by aiming at safe production.

The mechanism of microbial remediation of cadmium-nickel contaminated soil mainly comprises adsorption, precipitation, oxidation-reduction of cells to cadmium-nickel, chelation and precipitation of metabolites to cadmium-nickel, and the like, and the fixation of effective cadmium-nickel in soil is realized through the processes, so that the migration capacity and biological activity of cadmium-nickel are reduced, and the purpose of soil remediation is achieved. The method is mainly applied to the remediation of the cadmium-nickel polluted soil by utilizing the adsorption effect of microbial cells on the cadmium-nickel, and because various physical, chemical and biological processes which can influence the growth and metabolism of microorganisms exist in the soil, the cadmium-nickel adsorbed by the microorganisms is at risk of being released again.

Microorganisms capable of inducing and forming metal carbonate mineral crystals through metabolic processes exist in the nature, and the formed carbonate mineral crystals have relatively stable structures, and the microorganisms can continuously fix effective heavy metals in soil after being planted in the soil, so that attention is paid to people in the aspect of cadmium-nickel polluted soil remediation at present. However, the strain resources are less, and the strain is only screened from the carbonate mineralization perspective, so that other functions of the strain are not concerned sufficiently. Because the cadmium-nickel polluted soil often has the problem of soil environment quality reduction at the same time, plants growing in the cadmium-nickel polluted soil are often stressed by other survival, strains which can mineralize and fix the cadmium and the nickel in the soil and enhance the stress resistance of the plants are obtained by a multiple screening technology, the strains have practical significance for the safe production of the cadmium-nickel light and medium polluted soil, but the strains are extremely deficient in resources at present. In addition, heavy metal pollution of vegetable planting soil is getting more and more serious due to the use of heavy metal-containing fertilizers, sewage irrigation and atmospheric sedimentation.

Therefore, the bacteria which can fix the heavy metals in the soil and promote the growth of plants have important significance for realizing the safe production of the heavy metal light and medium polluted soil vegetables, but the application of the bacteria in the safe production of the cadmium-nickel polluted soil vegetables is not found.

Disclosure of Invention

The invention aims to provide a strain capable of mineralizing and fixing cadmium and nickel in soil and enhancing plant stress resistance, which is obtained by separating from cadmium and nickel polluted soil, can form cadmium and nickel carbonate precipitate through urease production, iron carrier production and indoleacetic acid induction, and enhances the stress resistance of vegetable crops, thereby promoting the growth of the vegetable crops, reducing the enrichment of the cadmium and the nickel, and effectively realizing the safe production of the cadmium and nickel slightly and moderately polluted soil.

The bacteria ZG2 for repairing the cadmium-nickel light and medium polluted soil is preserved in the China general microbiological culture Collection center, the suggested classification name is Comamonas testosteroni, the preservation number is CGMCC NO.20155, and the preservation time is 28

days

6 and 6 of 2020.

The bacterium ZG2 capable of repairing the cadmium-nickel light and medium polluted soil is obtained by the following steps:

(1) screening a target strain;

collecting 10g of fresh cadmium-nickel polluted soil from the vicinity of a nickel area of Panzhiling mountain Hongqiling of Jilin province, adding the fresh cadmium-nickel polluted soil into beef extract peptone culture media with cadmium and nickel concentrations of 5mg/kg and 200mg/kg respectively, culturing for 36h at 25 ℃, respectively selecting single colonies with obviously different appearances, purifying for 3 times by using the beef extract peptone culture media, observing through gram staining microscopy, obtaining pure single strains, respectively inoculating the pure single strains into the beef extract peptone culture media with the cadmium concentration of 5-50mg/kg and the nickel concentration of 200-1000mg/kg, culturing, and taking strains capable of growing and propagating when the cadmium concentration is 20mg/kg and the nickel concentration is 600mg/kg as target strains.

(2) Screening strains producing the iron carrier and the indoleacetic acid;

and culturing the obtained target strain by using a urease-producing strain screening culture medium, reserving a bacterial colony which is changed into pink, and further screening the bacterial strain producing the siderophore and the indoleacetic acid by using a chromium azure plate covering method and a Salkowski colorimetric method.

(3) Reserving the strain which can be adsorbed by the charcoal;

adding the screened strains producing the siderophore and the indoleacetic acid and the biochar into a beef extract peptone culture medium for culturing, and further screening strains which can be adsorbed by the biochar and have the adsorption capacity of 10⁷Strains above CFU/g.

(4) Identifying and preserving the strain;

and finally, performing 16S rDNA sequence amplification and sequencing on the strain, performing molecular biological identification through Blast and construction of a phylogenetic tree, and finally obtaining a strain of indigenous beneficial bacteria possibly having other environmental functions through reference and comparative analysis of literature. The obtained strain is placed in beef extract peptone culture media containing cadmium and nickel with different concentrations, the growth condition is shown in figure 1, the strain can still normally grow in the culture media containing cadmium and nickel with high concentration, and the initial cell concentration is OD₆₀₀At 0.014, after 96h of growth in beef extract peptone medium with cadmium concentration of 30mg/kg, fermentation broth OD₆₀₀Up to 0.773, see fig. 1 a; OD after 96h of growth in beef extract peptone medium with a nickel concentration of 1000mg/kg₆₀₀Up to 0.645, see fig. 1 b. The strain produced rings of discoloration in CAS medium, see FIG. 2a, indicating its ability to produce siderophores. The fermentation broth of the strain turned red after reacting with Salkowski developing solution, indicating that it has the ability to produce indoleacetic acid, as shown in FIG. 2 b. The phylogenetic identification of the strain is shown in figure 3, the genetic relationship between the strain and the comamonas testosteroni is closest, and in addition, partial physiological and biochemical reactions, colony characteristics and gram staining results are combined, so that the strain is finally identified as the comamonas testosteroni, which is named as ZG 2. The strain is preserved in China general microbiological culture Collection center (CGMCC) for 6 months and 28 days in 2020, the address is No. 3 of West Lu No. 1 of the Kyoho area in Beijing, China academy of sciences, and the suggested classification is named as testosterone plexusThe preservation number of the pseudomonas testosteroni is CGMCC No. 20155.

The invention also aims to provide application of the bacterium ZG2 capable of repairing cadmium-nickel light and medium polluted soil in the vegetable planting process, which comprises the following specific steps: activating and enriching the bacteria ZG2 to obtain ZG2 bacterial liquid containing active thallus cells, loading the thallus cells in the bacterial liquid to charcoal, and finally applying the charcoal loaded with the thallus cells to soil.

As a more excellent technical scheme of the invention: the number of the activated thallus cells loaded on the biochar is not less than 10⁷CFU/g。

As a more excellent technical scheme of the invention: the application amount of the biochar loaded with the bacterial cells per mu is 60-120 kg.

As a more excellent technical scheme of the invention: the biochar loaded with the bacterial cells is applied to soil, and meanwhile, an organic fertilizer, urea and a nitrification inhibitor are applied to the soil.

As a more excellent technical scheme of the invention: the usage amounts of the biochar loaded with the bacterial cells, the organic fertilizer, the urea and the nitrification inhibitor are respectively 60-120kg, 200-400kg, 10-20kg and 0.08-0.16kg per mu.

As a more excellent technical scheme of the invention: the biochar is prepared by thermally cracking straws, mushroom bran and livestock and poultry manure at the temperature of 400-.

As a more excellent technical scheme of the invention: the nitrification inhibitor is DMPP.

The beneficial effects are as follows:

the bacterium ZG2 provided by the invention has the capability of producing urease, siderophore and indoleacetic acid for inducing cadmium-nickel carbonate precipitation, and the measurement result of the fermentation liquid after entering the stabilization period is OD₆₀₀1.168, pH 9.2 and urease activity 140U/mL; the strain ZG2 has good affinity with charcoal, and the charcoal-adsorbed ZG2 strain reaches the maximum value of 2.67X 10 within 3h⁷CFU/mL; after being loaded on biochar, the ZG2 can be colonized in soil for a long time, and the bioavailability of cadmium and nickel in the soil and the vegetable crop thereof can be continuously reducedThe toxicity of the fertilizer reduces the enrichment of edible parts of vegetables on cadmium and nickel, enhances the stress resistance of vegetable crops, and promotes the growth of the vegetable crops, thereby achieving the effects of improving the quality of the vegetable crops and increasing the yield, and meeting the actual requirements of safe production of the vegetables in the cadmium-nickel slightly and moderately polluted soil.

Drawings

The accompanying drawings, which form a part of the specification, illustrate embodiments of the present invention or technical solutions in the prior art more clearly, and do not limit the present invention.

FIG. 1 is a graph showing a comparison of cell concentrations of the bacterium ZG2 of the present invention grown in a medium containing cadmium (a) and nickel (b) at different concentrations;

FIG. 2 is a photograph showing a color change circle generated in a CAS medium by the bacterium ZG2 of the present invention, and a photograph showing a reaction between a fermentation broth of the bacterium ZG2 of the present invention and a Salkowski color former;

FIG. 3 is a phylogenetic analysis diagram of bacterium ZG2 of the present invention;

FIG. 4 is a graph showing changes in cell concentration of the bacterium ZG2 of the present invention in a medium at different times, a graph showing urease-producing characteristics when the bacterium ZG2 of the present invention is grown in the medium, and a graph showing alkali-producing characteristics when the bacterium ZG2 of the present invention is grown in the medium;

FIG. 5 EDS diagram of fermentation broth induced precipitation of cadmium (a) and nickel (b) carbonates by bacterium ZG2 of the present invention;

FIG. 6 is a graph showing the change of the adsorption amount of charcoal to ZG2 of the present invention at different times.

Detailed Description

In order to make those skilled in the art better understand the technical solution of the present invention, the following examples are used to illustrate the present invention, but not to limit the scope of the present invention.

Example 1 investigation of the potential of inducing the formation of cadmium nickel carbonate precipitates using the bacterium ZG2 of the present invention.

Selecting single colony, inoculating into beef extract peptone culture medium, shake culturing at 25 deg.C and 160r/min for 24 hr, centrifuging at 4 deg.C and 8000r/min for 5min, repeatedly cleaning thallus cells with sterile water for 2 times, and repeating the stepsSuspending in sterile water to make into a suspension containing about 1 × 10/ml⁸Bacterial suspension of individual cells. Inoculating the bacterial suspension into a beef extract peptone culture medium with the urea content of 15g/L according to the inoculation proportion of 2%, culturing at 25 ℃ and 160r/min to obtain a fermentation liquid of the bacteria ZG2, and sampling every 3 h.

By measuring the OD of the fermentation broth₆₀₀pH and urease activity, and the results are shown in FIG. 4, the strain ZG2 grows well in the urea-containing culture medium, gradually enters the logarithmic growth phase after 3h, and enters the stationary phase OD after 15-18h₆₀₀pH and urease activity were 1.168, 9.2 and 140U/mL respectively.

Example 2 the precipitation of cadmium and nickel was investigated using the bacterium ZG2 of the present invention.

Inoculating the bacterial suspension of the strain ZG2 into a beef extract peptone culture medium with 15g/L urea content according to the proportion of 2%, and taking the beef extract peptone culture medium without added urea as a control, and culturing for 48h at the temperature of 25 ℃ and at the speed of 160r/min to obtain the fermentation liquor of the strain ZG 2. Adding 20mL of Cd2+ solution with the concentration of 20mg/L or 100mg/L of Ni into 50mL of fermentation liquor²⁺The solution and the control treatment without adding urea have no obvious precipitation, while the treatment with adding urea rapidly generates precipitation, the two treatments are stood for 24 hours, shaken up and then centrifuged for 10 minutes at 5000r/min, and the supernatant is filtered by a 0.45 mu m filter membrane and used for measuring Cd²⁺And Ni²⁺And (4) concentration. ZG2 fermentation broth pair Cd containing urea²⁺And Ni²⁺Removal rates of 92% and 86%, respectively, were achieved without urea control for Cd²⁺And Ni²⁺The removal rates of (a) and (b) were only 64% and 51%. The removal rate (%) is (initial concentration of heavy metal-concentration after removal)/initial concentration × 100.

Taking 200mL of the fermentation liquid, and adding 10mL of CdCl with the concentration of 0.25mol/L₂Solution and 10mL of NiCl with a concentration of 0.5mol/L₂And (3) standing the solution for 24h, filtering, and drying the obtained precipitate in a drying oven at 50 ℃. The dried precipitate was collected and stored in a sealed manner, and the result of the energy spectrum analysis is shown in FIG. 5, which indicates that the precipitate contains C, O, Cd or Ni element, i.e., of ZG2The fermentation broth can be freed of cadmium and nickel by inducing carbonate precipitation.

Example 3, study of the affinity of the bacterium ZG2 of the present invention for biochar.

Adding 2g of biochar prepared by thermally cracking chicken manure at 400 ℃ into 50mL of beef extract peptone culture medium, performing control treatment without adding the biochar, inoculating 1mL of bacterial suspension after high-pressure steam sterilization, culturing at 25 ℃ and 160r/min, respectively taking upper suspension at 0h, 1h, 2h, 3h, 4h and 5h after culture, determining the cell density (CFU/mL) of ZG2 strain by using a gradient dilution plating method, and subtracting the cell density value after adding the biochar from the cell density of the control treatment to obtain the number of ZG2 bacteria adsorbed by the biochar.

The results are shown in FIG. 6, which shows that the adsorption amount of the strain ZG2 by the charcoal increases with time, and the adsorption amount of ZG2 bacteria by the charcoal reaches the maximum value of 2.67X 10 at 3h⁷CFU/mL, the strain ZG2 is proved to have good affinity with the biochar.

Example 4A cabbage potting test for repairing cadmium-Nickel contaminated soil Using the bacterium ZG2 of the present invention

Collecting cadmium-nickel polluted soil from the vicinity of a Hongqiling nickel ore area in Jilin province, wherein the cadmium content and the nickel content are respectively 2.65mg/kg and 275.6mg/kg, the pH value is 5.24, the organic matter content is 3.2%, removing large stones, plant residues and other impurities, naturally air-drying, and carrying out a potting test after sieving by a 2mm sieve. The height of the pot for potting is 18cm, the diameter of the upper opening is 23cm, the soil loading is 1.5kg, and 0.2% urea is uniformly added. Preparation of bacterial cell number of 10¹⁰CFU/mL bacterial suspension and chicken manure are thermally cracked at 400 ℃ to prepare biochar, and the biochar is sieved by a 2mm sieve. Treatments were performed with the addition of only bacterial suspension (100 mL of bacterial suspension), 2% charcoal loaded with the same bacterial load and 2% charcoal only, each treatment being repeated 3 times. And performing pot culture tests in a plastic greenhouse from 4 months to 5 months in 2019, spreading 10 pakchoi seeds in each pot, covering soil, uniformly spraying water by using a spraying pot, and watering regularly during the growth process to keep the humidity. Thinning the pakchoi when the pakchoi grows to 3 leaves, keeping 3 strong seedlings with consistent growth vigor, continuously culturing, periodically spraying water, and waiting for the pakchoi to growAnd culturing for 45 days and harvesting after maturation. The content of cadmium and nickel in the edible part of the pakchoi and the effective state content of the cadmium and nickel in the soil are respectively measured.

Compared with the control, after being treated by the somatic cells, the biochar and the somatic cell-loaded biochar, the content of Cd and Ni in the edible part of the pakchoi, the content of Cd and Ni in the effective state of soil and the dry weight change of the edible part of the pakchoi are shown in the following table 1.

TABLE 1

The result shows that the bacterium ZG2 provided by the invention can reduce the enrichment of cadmium and nickel in the edible parts of the pakchoi, enhance the stress resistance of the pakchoi and increase the biomass of the edible parts of the pakchoi.

Example 6 field test of Chinese cabbage cultivation for repairing cadmium-nickel contaminated soil using the bacterium ZG2 of the present invention.

Selecting a plastic greenhouse with the greenhouse age of 3 years near a rock red flag ridge nickel ore smelting plant in Jilin province for field test, wherein the basic physical and chemical properties of soil are as follows: the pH value is 5.82, the organic matter content is 3.3%, the cadmium and nickel content is 1.54mg/kg and 216.8mg/kg respectively, and the test time is 5 months to 6 months in 2019.

Firstly, organic fertilizer, urea and soil nitrification inhibitor DMPP which are prepared by fermenting livestock and poultry manure are purchased, then the chicken manure is thermally cracked at 400 ℃ to obtain biochar, and a strain ZG2 is cultured by utilizing a beef extract peptone medium to obtain fermentation liquor. The strain ZG2 is loaded on the charcoal, so that the number of thallus cells loaded by the charcoal reaches 10⁸And about CFU/g, uniformly mixing the biochar loaded with the thallus cells and the biochar without the thallus cells, the organic fertilizer, the urea and the DMPP according to the proportion that the biochar application amount is 60 kg/mu, and the biochar, the organic fertilizer, the urea and the DMPP are 60: 200: 10: 0.08, then applying the mixture into surface soil with the thickness of 20cm, uniformly raking the mixture, keeping the water capacity of the field to be about 50% for 10 days, and simultaneously performing a control test without any addition. The cell area was 1m × 5m, and each treatment was repeated 3 times. The method is carried out according to a local Chinese cabbage planting management mode. Selecting the growth potential in each cell by using a diagonal method during harvestingAnd (3) measuring the biomass of the overground part and the cadmium-nickel content of the pakchoi of 20 pakchoi which are basically consistent, and simultaneously collecting and measuring the effective state content of the cadmium-nickel in the rhizosphere soil of the pakchoi and the fresh weight of the root system of the pakchoi.

Compared with the treatment without any addition and loading of the strain ZG2, the treatment with the strain ZG2 increases the fresh weight of the root system of the pakchoi by 10.3 percent and 8.2 percent respectively, increases the biomass of the edible part by 18.5 percent and 10.5 percent respectively, reduces the cadmium content in the edible part of the pakchoi by 44.8 percent and 18.1 percent respectively, reduces the nickel content by 42.2 percent and 16.2 percent respectively, and ensures that the nickel content in the cadmium part of the edible part of the pakchoi can meet the quality requirement of food pollutant limit standard (GB 2762 + 2017); the effective state content of cadmium in the cabbage rhizosphere soil is reduced by 48.3 percent and 29.8 percent, and the effective state content of nickel is reduced by 55.8 percent and 21.6 percent respectively.

Example 7 eggplant planting field trial for repairing cadmium-nickel contaminated soil using the bacterium ZG2 of the present invention.

Selecting a plastic greenhouse with the greenhouse age of 3 years near a rock red flag ridge nickel ore smelting plant in Jilin province for field test, wherein the basic physical and chemical properties of soil are as follows: the pH value is 5.82, the organic matter content is 3.3%, the cadmium and nickel content is 1.54mg/kg and 216.8mg/kg respectively, and the test time is 4 months and 15 days to 9 months and 2 days in 2019.

Firstly, organic fertilizer, urea and soil nitrification inhibitor DMPP which are prepared by fermenting livestock and poultry manure are purchased, then the chicken manure is thermally cracked at 400 ℃ to obtain biochar, and a strain ZG2 is cultured by utilizing a beef extract peptone medium to obtain fermentation liquor. The strain ZG2 is loaded on the charcoal, so that the number of thallus cells loaded by the charcoal reaches 10⁸And about CFU/g, uniformly mixing the biochar loaded with the bacterial cells, the organic fertilizer, the urea and the DMPP according to the proportion that the application amount of the biochar is 120 kg/mu, and the biochar, the organic fertilizer, the urea and the DMPP are 120: 400: 20: 0.16, then applying the mixture into surface soil with the thickness of 25cm, uniformly raking, keeping the water capacity of the field about 50% for 15 days, and simultaneously performing a control test without any additive. The plot area was 3m x 6m, the planting density was 9 plants per square meter, and each treatment was repeated 3 times. Managing according to a local greenhouse eggplant planting management mode. Selection during growth by diagonal methodAnd (3) performing fixed-point measurement on 5 plants with basically consistent growth vigor in each cell, sampling successively according to the maturing time of the eggplants, calculating the total yield according to the average number of the single-plant results of the fixed-point plants, the average single fruit weight and the number of plants per hectare, and simultaneously measuring the content of cadmium and nickel in the eggplants and the content of effective cadmium and nickel in soil.

Compared with the control without any addition, the treatment loaded with the strain ZG2 respectively reduces the cadmium and nickel contents in the eggplants by 18.6 percent and 30.7 percent, the cadmium and nickel contents in the eggplants can meet the quality requirement of food pollutant limit standard (GB 2762-2017), the yield of the eggplants is increased by 16.5 percent, and the effective cadmium and nickel contents in the soil are respectively reduced by 32.7 percent and 47.8 percent.

The bacteria ZG2 have obvious repairing effect on the cadmium-nickel polluted soil, and after being loaded on the surface of the charcoal, the bacteria ZG2 are used together with an organic fertilizer, urea and a nitrification inhibitor, so that the effective cadmium-nickel in the soil can be effectively fixed, the influence of the cadmium-nickel on the growth of vegetable crops and the content of the cadmium-nickel in edible parts of the vegetables can be obviously reduced, the yield of the vegetable crops can be increased, and the aim of safely producing the vegetables in the cadmium-nickel slightly and moderately polluted soil can be fulfilled.

Claims

1. A bacterium ZG2 for repairing cadmium-nickel light and medium polluted soil is characterized in that:

the ZG2 is preserved in China general microbiological culture Collection center with the preservation number of CGMCC NO.20155, and the proposed classification is called Comamonas testosteroni, and the preservation time is 28 days 6 months 2020.

2. The use of the bacteria ZG2 for repairing cadmium-nickel soil with light and medium pollution in the process of planting vegetables as claimed in claim 1.

3. The application of claim 2, comprising the following steps: activating and enriching the bacteria ZG2 to obtain bacteria liquid, loading the bacteria cells in the bacteria liquid on charcoal, and applying the charcoal loaded with the bacteria cells into soil.

4. Use according to claim 3, characterized in that: the number of the activated thallus cells loaded on the biochar is not less than 10⁷CFU/g。

5. The use of claim 3, wherein the biochar loaded with the somatic cells is applied to the soil simultaneously with the application of the organic fertilizer, urea and nitrification inhibitor to the soil.

6. Use according to claim 3, characterized in that: the usage amounts of the biochar loaded with the bacterial cells, the organic fertilizer, the urea and the nitrification inhibitor are respectively 60-120kg, 200-400kg, 10-20kg and 0.08-0.16kg per mu.

7. Use according to claim 3, characterized in that: the biochar is prepared by thermally cracking straws, mushroom bran and livestock and poultry manure at the temperature of 400-.

8. Use according to claim 3, characterized in that: the nitrification inhibitor is DMPP.