Soil heavy metal cadmium treatment method based on bacillus

Abstract

The invention discloses a bacillus-based soil heavy metal cadmium treatment method, which is characterized in that heavy metal cadmium is adsorbed to the cell surface of bacillus subtilis by using the structural characteristics and secreted chemical components of the bacillus subtilis, so that heavy metal ions are deposited and passivated, thereby reducing the transfer and transformation of heavy metal to the crop ligusticum wallichii, and improving the soil quality. And a bioremediation method is provided for safe production of ligusticum wallichii.

Description

Technical Field

[0001] The invention belongs to the field of microorganisms, and in particular relates to a method for treating heavy metal cadmium in soil based on Bacillus. Background Art

[0002] Heavy metal pollution in farmland soil is a serious environmental problem. With the development of industry, the area of ​​land in my country that is contaminated by heavy metals is increasing. Heavy metal elements such as lead, arsenic, mercury, chromium, and cadmium not only threaten human health, but are also important pollutants that threaten the growth and development of crops.

[0003] Heavy metal stress-induced excessive levels of agricultural products have created serious food and drug safety risks, endangering human health. For example, the Chinese medicinal material Chuanxiong has long been plagued by excessive levels of heavy metals, which has affected the yield and quality of the medicinal material.

[0004] Chuanxiong is an important Chinese medicinal material, widely used in traditional Chinese medicine. However, excessive heavy metal content has long been an important factor that has plagued the quality of Chuanxiong.

[0005] Among them, the effect of cadmium stress on Chuanxiong is very obvious, especially under cadmium stress, the growth and production of pharmacologically active ingredients of Chuanxiong are significantly inhibited. Studies have shown that cadmium stress inhibits the biomass accumulation and root development of Chuanxiong, and activates the antioxidant system. In addition, cadmium is mainly distributed in the root tissue of Chuanxiong, and its content is high in the soluble part and cell wall. Transcriptome analysis showed that under cadmium stress, differential genes involved in the photosynthesis pathway were downregulated, while the plant hormone signaling pathway and antioxidant system responded positively to cadmium regulation. Summary of the invention

[0006] The present invention proposes a method for using Bacillus subtilis to enhance the immune tolerance of plants to environmental stress, improve the production performance of crops, etc.

[0007] To solve the above problems, the technical solution of the present invention is:

[0008] S1. Collect soil samples from the rhizosphere area of ​​chuanxiong, wetland rice fields, etc.;

[0009] S2. Perform bacterial isolation and culture on the collected soil samples, and separate different strains of Bacillus subtilis by observing characteristics such as colony morphology;

[0010] S3, determining the maximum cadmium concentration at which the bacteria can survive; screening out Bacillus subtilis strains that can tolerate higher cadmium concentrations, wherein strains that can tolerate cadmium concentrations up to 500 ppm are preferred;

[0011] S4. Optimizing the growth conditions of Bacillus subtilis;

[0012] S5, the Bacillus subtilis is applied in the cultivation process of Chuanxiong; wherein, in the cultivation process of Chuanxiong, the selected high-efficiency cadmium-resistant Bacillus subtilis strain is applied to the soil;

[0013] S7, putting the cultured Bacillus subtilis into a solution or soil containing cadmium;

[0014] S6. Observe the biomass, rhizome length, chlorophyll content and other indicators of Chuanxiong, as well as the changes in cadmium content in soil and Chuanxiong; at the same time, monitor and evaluate the effect of Bacillus subtilis in reducing cadmium pollution in Chuanxiong in order to further optimize the method.

[0015] Furthermore, soil-applied Bacillus subtilis showed the greatest cadmium removal ability in the soil environment of pH 7 and 35°C, and stirring had little effect on its cadmium adsorption.

[0016] Furthermore, in S4, the Bacillus subtilis is cultured at a temperature of 30-37° C. for a period of time.

[0017] Furthermore, in S4, LB liquid culture medium is prepared, and the formula is generally 10 g / L tryptone, 5 g / L yeast extract, and 10 g / L sodium chloride. Each component is dissolved in distilled water, and the pH is adjusted to about 7.0, and then sterilized in an autoclave at 121° C. for 15-20 minutes, and then cooled for use.

[0018] Furthermore, the step S5 further comprises tilling the soil before adding the Bacillus subtilis to increase the air permeability of the soil and the contact area between the Bacillus subtilis and the soil.

[0019] Furthermore, after adding the Bacillus subtilis bacterial solution, the soil should be kept at an appropriate moisture and aeration level so that the Bacillus subtilis can function better.

[0020] The beneficial effect of the present invention is that Bacillus subtilis can reduce the cadmium pollution of Chuanxiong in various ways, thus providing a bioremediation method for the safe production of Chuanxiong. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the changes in cadmium content in Chuanxiong after treatment with Bacillus subtilis. DETAILED DESCRIPTION

[0022] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0023] S1. Collect soil samples from the rhizosphere area of ​​chuanxiong, wetland rice fields, etc.;

[0024] S2. Perform bacterial isolation and culture on the collected soil samples, and separate different strains of Bacillus subtilis by observing characteristics such as colony morphology;

[0025] S3. Determine the maximum cadmium concentration at which the bacteria can survive; screen out Bacillus subtilis strains that can tolerate higher cadmium concentrations, wherein strains that can tolerate cadmium concentrations up to 500 ppm are preferred;

[0026] S4. Optimizing the growth conditions of Bacillus subtilis;

[0027] S4.1. Prepare LB liquid culture medium. The formula is generally 10 g / L tryptone, 5 g / L yeast extract, and 10 g / L sodium chloride. Dissolve each component in distilled water, adjust the pH to about 7.0, and then sterilize it in an autoclave at 121°C for 15-20 minutes. Cool it and set it aside.

[0028] S4.2, the Bacillus subtilis is cultured in the LB liquid medium at a temperature of 30-37° C. for a period of time;

[0029] S5, the Bacillus subtilis is used in the cultivation process of Chuanxiong; wherein, in the cultivation process of Chuanxiong, the screened high-efficiency cadmium-resistant Bacillus subtilis strain is applied to the soil;

[0030] S5.1. Before adding the Bacillus subtilis, the soil is tilled to increase the air permeability of the soil and the contact area between the Bacillus subtilis and the soil.

[0031] S6. Putting the cultured Bacillus subtilis into a cadmium-containing solution or soil; wherein, the soil application environment is preferably a soil environment with a pH of 7 and 35° C., in which the Bacillus subtilis exhibits the greatest ability to remove cadmium, and stirring has little effect on the adsorption of cadmium by Bacillus subtilis; further, after adding the Bacillus subtilis bacterial solution, maintaining appropriate humidity and aeration of the soil so that the Bacillus subtilis can play a better role.

[0032] S7. Observe the biomass, rhizome length, chlorophyll content and other indicators of Chuanxiong, as well as the changes in cadmium content in soil and Chuanxiong; at the same time, monitor and evaluate the effect of Bacillus subtilis in reducing cadmium pollution in Chuanxiong in order to further optimize the method.

[0033] Experimental Example 1

[0034] Crop: Chuanxiong

[0035] Control treatment: Bacillus subtilis diluted 100 times, water control

[0036] Usage: Spray soil application, use once every 20 days, use 4 times in a row, the soil environment pH is 7 and the temperature is 25℃

[0037] Heavy metals (mg / kg) 100 times treatment of dead grass Control treatment chromium 21.4 30.7 arsenic 0.285 0.5 cadmium 0.894 1.12 mercury Not detected Not detected lead 1.6 2.15

[0038] Experimental Example 2

[0039] Crop: Chuanxiong

[0040] Control treatment: Bacillus subtilis diluted 300 times, water control

[0041] Usage: Spray soil application, use once every 20 days, use 4 times in a row, the soil environment pH is 7 and the temperature is 30℃

[0042] Heavy metals (mg / kg) 300 times treatment of dead grass Control treatment chromium 32.6 24.3 arsenic 0.57 0.462 cadmium 1.56 1.14 mercury 0.00643 0.0115 lead 2.84 2.24

[0043] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific variations and combinations that do not deviate from the essence of the present invention based on the technical revelations disclosed by the present invention, and these variations and combinations are still within the protection scope of the present invention.

Claims

1. A method for treating heavy metal cadmium in soil based on Bacillus, characterized in that ,include, S1. Collect soil samples from the growing environment of Chuanxiong; S2. performing bacterial isolation and culture on the collected soil samples to isolate different strains of Bacillus subtilis; S3, determining the maximum cadmium concentration at which Bacillus subtilis can survive; screening out Bacillus subtilis strains that can tolerate high cadmium concentrations, wherein Bacillus subtilis strains that can tolerate cadmium concentrations up to 500 ppm are preferably selected; S4, optimizing the growth conditions of the Bacillus subtilis strain; S5, using the Bacillus subtilis bacterial solution in the process of cultivating Chuanxiong; specifically, in the process of cultivating Chuanxiong, applying the selected Bacillus subtilis strain with high cadmium resistance to the soil and / or cadmium-containing solution for cultivating Chuanxiong; S6. Observe the biomass, rhizome length, chlorophyll content and other indicators of Chuanxiong, as well as the changes in cadmium content in the soil or the solution and Chuanxiong at intervals of 2-3 days to determine the optimal method.

2. The method for treating heavy metal cadmium in soil based on Bacillus according to claim 1, characterized in that The method for applying the Bacillus subtilis strain in step S5 is to apply the Bacillus subtilis in a soil environment with a pH of 7 and a temperature of 35°C.

3. The method for treating heavy metal cadmium in soil based on Bacillus according to claim 1, characterized in that In step S4, the Bacillus subtilis is cultured at a temperature of 30-37°C.

4. The method for treating heavy metal cadmium in soil based on Bacillus according to claim 3, characterized in that , S4 also includes preparing LB liquid culture medium, the culture medium includes 10 g / L tryptone, 5 g / L yeast extract, and 10 g / L sodium chloride, dissolving the components in distilled water, and adjusting the pH to 7.0; Sterilize in an autoclave at 121°C for 15-20 minutes and set aside after cooling.

5. The method for treating heavy metal cadmium in soil based on Bacillus according to claim 1, characterized in that , The step S5 also includes the step of increasing the air permeability of the soil and the contact area between the Bacillus subtilis and the soil before adding the Bacillus subtilis.

6. The method for treating heavy metal cadmium in soil based on Bacillus according to claim 5, characterized in that , also includes steps to maintain soil moisture and aeration.

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