CN106244501B - One plant of anti-antimony bacterium NXH1 and its application - Google Patents

Abstract

The invention discloses an antimony-resistant bacterium Acinetobacter sp, and the preservation number is CGMCC No.12895. The bacteria of the present invention are highly resistant to antimony, have resistance to various heavy metals such as As ³⁺ , Cd ²⁺ , Cr ⁶⁺ , and Hg ² , and have the characteristics of promoting plant growth. It is of great significance and has broad application potential in the bioremediation of heavy metal-contaminated mining soil.

Description

An Antimony-resistant Bacteria NXH1 and Its Application

technical field

The invention belongs to the technical field of environmental biology, and in particular relates to an antimony-resistant bacterium NXH1 and its application.

Background technique

In recent years, with the continuous expansion of the scale of antimony ore mining and the discharge of waste in the antimony industry, the soil around the mining area has been seriously polluted. As environmental pollutants, antimony and antimonides have been proven to be a class of genotoxic substances and carcinogenic to humans (Huang et al., 1998; Takahashi et al., 2002; Beyersmann et al., 2008). In addition, antimony can also cause lung injury, hematuria, fibroblast death, sister chromatid exchange, circulatory system diseases, etc. (Huang et al., 1998). Antimony has been listed as a priority pollutant by the US Environmental Protection Agency and the Council of the European Community, and it is also a pollutant closely monitored by the Japanese Environmental Agency. In recent years, the pollution of antimony in my country has become more and more serious, and has gradually attracted widespread attention from all walks of life. At the same time, the mining and smelting activities of antimony mines will also cause heavy metal elements associated with antimony, such as arsenic and mercury, to enter the supergene environment of the mining area, pollute the farmland in the mining area, not only affect the growth of crops, but also reduce the quality of crops. It also caused great damage to the soil in the mining area. Research on how to repair the soil in mining areas has become a difficult problem to be solved urgently.

Although antimony is highly toxic to humans, some microorganisms can grow in extremely high concentrations, and even use this element as an energy source, or oxidize highly toxic Sb(III) into toxic Weaker Sb(Ⅴ), therefore, the theory and technology of microbial remediation of contaminated soil came into being (Teng Ying et al., 2007). Microorganisms can reduce the antimony effect on bacteria and the environment through the efflux of antimony by bacteria, the oxidation of highly toxic Sb (Ⅲ) to Sb (Ⅴ) with low toxicity, the methylation of antimony by microorganisms, and the adsorption of bacteria. toxicity. Antimony Antimony In 1971, Lyalthova first reported a strain of antimony-oxidizing bacteria, which could oxidize trivalent antimony to pentavalent antimony to provide energy for itself (Lyalthova, 1971). Since then, there have been a small number of reports on antimony-resistant microorganisms. In short, the types of antimony-resistant microorganisms that have been reported so far are relatively small. Therefore, screening antimony-resistant microorganisms is an important part of realizing antimony pollution remediation.

At present, there are not many relevant research reports on the screening and application of antimony-resistant microorganisms. Liu Chengzuo (2012) screened an antimony-resistant microorganism, which was identified as Penicillium, and its antimony concentration was 600mg/L. The bacteria in the patent of the present invention is a strain of Acinetobacter sp., and its antimony effect is obviously higher than that of Penicillium that has been reported. Moreover, the Acinetobacter has a plant growth-promoting function, can produce IAA, siderophore and ACC deaminase, and has a certain growth-promoting effect on plants; at the same time, it has a certain growth-promoting effect on As ³⁺ , Cd ²⁺ , Cr ⁶⁺ , Hg ²⁺ , etc. A variety of heavy metals have strong resistance and have potential application value.

Contents of the invention

The purpose of the present invention is to provide a highly antimony-resistant bacterium, which was initially identified as Acinetobacter sp. through 16S rDNA sequencing analysis and morphological observation, and the strain number is ^{NXH1 .} , Cd ²⁺ , Cr ⁶⁺ , Hg ² and other heavy metals, as well as the characteristics of promoting plant growth.

The Acinetobacter sp. NXH1 of the present invention is a bacterial strain isolated and screened from plant rhizosphere soil near the smelter in Xikuangshan Antimony Mining Area, Lengshuijiang City, Hunan Province, and can tolerate the highest antimony concentration of 2900mg/L Heavy metal stress. The strain was preserved on August 23, 2016 in the General Microbiology Center of the China Committee for the Collection of Microbial Cultures, which is referred to as CGMCC (unit address: No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences, zip code : 100101), the deposit number is CGMCC No.12895, and it survived after testing.

After culturing on LB solid medium for 18 hours, the characteristics of the colonies are: small colonies, light yellow, neat edges, round convex, smooth surface, moist, no wrinkle, opaque. The characteristics of its somatic cells are: bacillus, Gram staining is negative, no spores, and grows rapidly.

The 16S rDNA sequence of the strain was amplified by PCR to obtain an amplified product with a length of about 1400bp. The amplified product was sequenced by a sequencing company, and the measured sequence was compared with the sequence in the GenBank database by BLAST. The results showed that the The strain has the highest homology with Acinetobacter calcoacetate and Acinetobacter oilophilus in the genus Acinetobacter ( Acinetobacter ), with a similarity of more than 98%. Combined with morphological characteristics, cultural characteristics and 16S rDNA sequence analysis, the strain was identified as Acinetobacter sp.

The strain was cultured in CDM solid medium containing different concentrations of Sb (antimony potassium tartrate) for a certain period of time, and its growth was observed. The results showed that the strain had a strong anti-Sb ability, and its tolerance to trivalent antimony reached 2900 mg/L.

The present invention has the following beneficial effects:

The bacterial strain of the present invention is a highly antimony (Sb) bacterium isolated and screened from the plant rhizosphere soil near the smelter in Xikuangshan Antimony Mining Area, Lengshuijiang, Hunan Province. It is identified as Acinetobacter sp. . In addition to the strong antimony property of the heavy metal antimony, the bacterial strain of the invention has strong resistance to As ³⁺ , Cd ²⁺ , Cr ⁶⁺ , Hg ²⁺ and other heavy metals. At the same time, the fungus also has the function of promoting plant growth, can produce two kinds of plant growth promoting factors, IAA and siderophore, and can promote the growth of plants in Sb-contaminated soil, for example, it has a certain promoting effect on the growth of rapeseed. At present, there are no relevant reports at home and abroad on the research on various heavy metal resistance and growth-promoting effects of antimony-resistant bacteria. Therefore, it is of great significance to screen heavy metal-tolerant and high-resistance growth-promoting microorganisms from mining polluted areas to promote the growth of local vegetation and alleviate the toxicity of plants to heavy metals. The bacterium has broad application potential in the bioremediation of heavy metal-contaminated mining soil.

Description of drawings

Fig. 1 The culture of Acinetobacter sp. of the present invention.

Fig. 2 The 16S rDNA gene sequence of Acinetobacter sp. of the present invention.

Detailed ways

The present invention will be further clarified through the detailed description of specific embodiments below, but it is not intended to limit the present invention, but only for illustration.

Example 1 Isolation and screening of antimony-resistant bacteria and anti-Sb ability

Collect plant rhizosphere soil samples near the smelter in Xikuangshan Antimony Mining Area, Lengshuijiang City, Hunan Province, weigh 100g of the above fresh soil samples, add an appropriate amount of antimony potassium tartrate ([C ₈ H ₄ K ₂ O ₁₂ Sb ₂ 3(H ₂ O)]), so that the final concentration of antimony in the soil sample was 1000mg/kg, and placed in a constant temperature incubator at 28°C for enrichment and cultivation for one week. Take 10g of the above soil sample and place it in 90mL 0.85% NaCl sterile solution containing 10 glass beads, and shake it in a shaker at 30°C and 180 rpm for 30 minutes to fully disperse the sample. Take 0.1 mL and spread it on the CDM medium (CDM medium formula: MgSO ₄ 7H ₂ O 2.0 g, NH ₄ Cl 1.0 g, Na ₂ SO ₄ 1.0 g, K ₂ HPO ₄ 0.013 g, CaCl ₂ 2H ₂ O 0.067 g, Na-lactate 5.0 g, agar 15.0 g, add distilled water to 1000 mL, pH 7.2), in which antimony potassium tartrate was used as the stress factor in the CDM medium, so that the concentration of antimony in the final medium was 50 mM, at 30 °C Cultivate in a constant temperature incubator for one week, and observe its growth every day. The above preliminarily isolated strains were further isolated and purified to obtain pure strains, and the isolated strains were placed on slopes and stored at 4°C for subsequent experiments.

Inoculate the screened strains into LB medium (LB medium formula: peptone 10g, yeast extract 5g, NaCl 10g, agar 15g, add distilled water to 1000 mL, pH 7.2), activate for 24 h, take 2 mL to transfer Put it into a 250 mL triangle filled with 100 mL LB liquid medium, shake at 30 °C and 150 r/min, take the uninoculated LB liquid medium as a control, select a wavelength of 600 nm, and use a microplate reader to measure the bacterial suspension at different culture times The optical density value (OD600) of the liquid. Taking the culture time as the abscissa and OD600 as the ordinate, draw the growth curve of the bacteria to understand the growth cycle of the strain, which is suitable for further research on the tolerance, resistance and growth-promoting effect of the strain to heavy metals such as Sb and As. Bacteria in the growth cycle. Add Sb stock solution to the CDM medium, so that the final concentrations of Sb in the medium are 1, 2, 4, 6, 8, and 10 mmol/L or above, and increase the concentration of heavy metals in sequence according to the experimental results, and store the slant The anti-Sb strain was activated in LB culture medium for 24 hours, isolated and purified on solid medium to obtain a single colony, and then transferred to solid medium containing corresponding concentration of Sb to observe the growth of the strain. The lowest concentration that can inhibit the growth of the strain The minimum inhibitory concentration (Minimum inhibitory concentration, MIC) of the strain.

Through the above isolation and screening, several Sb-resistant bacteria were obtained. Most of the strains entered the stable phase at 48h, and the logarithmic phase of the strains was 6h-36h. Among them, the strain of the present invention (coded as NXH1) grows faster and enters a stable phase after 24 hours, so the following experiments take the bacteria cultured for 24 hours for research. By measuring the minimum inhibitory concentration of Sb to the isolated strains, it was found that the resistance of the strain NXH1 to Sb was very high, the minimum inhibitory concentration was 24mM, and the converted mass concentration was approximately 2900mg/L.

The identification of embodiment 2 NXH1 bacterial strain

The strain was subjected to morphological, cultural characteristics and sequence analysis of 16S rDNA. The 16S rDNA molecular identification was carried out according to the following steps: pick a single colony of the screened strain and inoculate it in liquid LB medium, culture it on a shaking table at 30°C and 150r/min, take out the culture medium at 24h, and centrifuge at 5000r/min for 1min to get the supernatant According to the bacterial genomic DNA extraction kit (provided by Tiangen Biochemical Technology Co., Ltd.), the colony DNA was extracted; the general primers 27F and 1492R were used for PCR amplification of the extracted bacterial DNA; the sequence of 27F was 5′-AGA GTT TGA TCC TGG CTC AG -3'; 1492R sequence is 5'-AAG GAG GTG ATC CAG CCG CA-3' primers were synthesized by Beijing Ruibo Xingke Biotechnology Co., Ltd.; the PCR products were sequenced, and the sequencing results were analyzed by BLAST in the NCBI database , and perform homology comparisons.

The morphological characteristics of the NXH1 strain are as follows: the colony is small, light yellow, with neat edges, rounded protrusions, smooth, moist surface, no wrinkles, and opaque. The characteristics of its somatic cells are: bacilli, negative Gram staining, no spores, and rapid growth, as shown in Figure 1. The length of the 16S rDNA gene sequence of the strain was 1415 bp. The gene sequence was submitted to Genbank for homology comparison, and then the phylogenetic tree was drawn using MEGA 6.0 software to determine the species of the strain. The results showed that the sequence had the highest similarity with the 16S rDNA gene sequence of each bacteria in Acinetobacter (Acinetobacter sp . ), whose 16SrDNA gene sequence is shown in Figure 2. The bacterium was preserved on August 23, 2016 in the General Microbiology Center of the China Committee for the Collection of Microbial Cultures, which is referred to as CGMCC (unit address: No. 3, No. 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences, Post Code: 100101), the deposit number is CGMCC No. 12895.

Example 3: Tolerance of Acinetobacter NXH1 to various heavy metals

CDM solid medium containing different concentrations of As ³⁺ , Cd ²⁺ , Cr ⁶⁺ , and Hg ² heavy metals ^{were prepared respectively} . 200mg/L, 400mg/L, 800mg/L, 1200mg/L, 1600mg/L, with no heavy metal treatment as the control. Inoculate the NXH1 strain of Acinetobacter sp. into heavy metal-free CDM medium for activation and culture for 24 hours, take 0.1 mL and inoculate them in medium containing different types and concentrations of heavy metals, and culture them at 30°C for 24 hours , observe the growth of the bacteria in the medium containing various types and different concentrations of heavy metals, the results are shown in Table 1. It can be seen from the table that the NXH1 strain has strong tolerance to the above heavy metals, and the tolerance concentrations to As ³⁺ , Cd ²⁺ , Cr ⁶⁺ , and Hg ² are 1600 mg/L and 1200 mg/L respectively. L, 1200ml/L and 800mg/L.

Table 1 Growth of Acinetobacter NXH1 under different heavy metal concentrations

Note: "+" indicates good growth; "-" indicates no growth; "+/-" indicates growth but poor growth

Example 4 Plant growth-promoting properties of Acinetobacter NXH1

Microorganisms with plant growth-promoting effects often promote plant growth by secreting indole-3-acetic acid (IAA) into the environment, producing siderophore and ACC deaminase. Through the following experimental operations, it can be verified that Acinetobacter NXH1 has plant growth-promoting properties. The functional identification method for producing IAA is as follows: Add 0.5 g/L L-tryptophan (about 2.5 mmol/L) to the specific liquid medium for cultivating microorganisms and then sterilize at high temperature, pick the strains into the liquid with a toothpick The culture medium was cultured in a constant temperature culture shaker at 30°C for 24 hours, 2 mL of bacterial liquid was drawn, and 2 mL of Salkowski reagent (12 g FeCl ₃ , 430 mL 98% H ₂ SO ₄ , 570 mL H ₂ O) was added to the 2 mL bacterial liquid for color development. The pink bacterial solution is positive, indicating that the strain produces IAA. The functional identification method for siderophore production is as follows: prepare CAS detection medium, spot the isolated and purified strains on the CAS detection medium in an ultra-clean bench, and cultivate them in an incubator at 30 °C; observe the orange color formed by the secretion of siderophore by bacteria The size of the halo is used for qualitative screening. The larger the orange halo, the stronger the siderophore production ability of the strain. The identification method of ACC deaminase is as follows: Prepare DF medium (DF medium formula: KH ₂ PO ₄ 4 g, Na ₂ HPO ₄ 6 g, MgSO ₄ 7H ₂ O 0.2 g, FeSO ₄ 7H ₂ O 0.2 g, Glucose 2g, gluconic acid 2 mL, citric acid 2 g, (NH ₄ ) ₂ SO ₄ 2 g, distilled water to 1 L, pH 7.2), use a clean toothpick to pick the strain to be tested into the solid medium for streak culture , placed in a constant temperature incubator, cultured for 24 hours, and then the strains were picked with a clean toothpick into the ADF medium containing nitrogen and ACC (3mmol/LACC instead of (NH ₄ ) in the DF medium ₂ SO ₄ as the only nitrogen source), cultured in a constant temperature incubator at 30°C for 24 hours to observe the results, the strains that can grow colonies on the ADF medium can be preliminarily determined to have ACC deaminase activity.

The preparation method of CAS detection medium is as follows:

Solution a: Dissolve 0.012g CAS (chrome azure S) in 10ml distilled water, then add 1mmol/L FeCl ₃ solution containing 10mmol/L HCl 2ml;

Solution b: Dissolve 0.015g HDTMA (hexadecyltrimethylammonium bromide) in 8mL distilled water;

Dye solution c: slowly add solution a to solution b, shake gently, so that the two solutions are evenly mixed with each other, and obtain dye solution c;

Add 10×MM9 salt solution: (Na ₂ HPO ₄ 30g, KH ₂ HPO ₄ 1.5g, NaCl 2.5 g, NH ₄ Cl 5g, double distilled water 500ml) 20mL and piperazine diethanolsulfonic acid 6.04g into 150ml of bis In a clean Erlenmeyer flask with distilled water, adjust the pH to 6.8 with 50% NaOH after mixing, and add 3.2 g of agar powder to obtain medium d.

Sterilize dye solution c, medium d, 1mmol·L ^-1 CaCl ₂ , 1mmol·L ^-1 MgSO ₄ 7H ₂ O, 20% glucose respectively (115°C, 20min), 10% acid hydrolyzed casein After filtration and sterilization, all were placed in a 50°C water bath to keep warm for later use.

Take the above 0.2ml 1mmol/L CaCl ₂ 4ml, 1mmol/L MgSO ₄ 7H ₂ O 6ml, 10% casamino acids and 2ml 20% glucose respectively, add them to the medium d and then add the dye solution c along the bottle wall , and mix well to obtain the blue qualitative detection medium, then pour 30ml per dish into a petri dish, and place it on a sterile operating table for use.

Through the above experiments, the results show that Acinetobacter NXH1 can produce IAA and siderophores, and has potential plant growth-promoting functions.

Example 5 Effect of Acinetobacter NXH1 on Rapeseed Growth

Farmland soil in a certain area of Beijing was used as the potting substrate. After the soil is air-dried, pass through a 20-mesh sieve to measure the water content. Weigh the corresponding air-dried soil weight with the weight of the dried soil at 20Kg. The amount of antimony that should be added is configured into a 250mL solution, and it is fully mixed with the above soil to make the concentration of antimony in the soil 20 mg/Kg, 50 mg/Kg, 100 mg/Kg, 250 mg/Kg, 500 mg/Kg, add corresponding deionized water at 70% of the field water holding capacity, and place it in the dark for 2 months. The antimony concentration of 0 mg/kg was used as the control without adding antimony, and the balanced soil was filled into pots and set aside. Before the experiment, a certain number of rapeseed seeds with full grains and uniform size were selected and soaked in 10% hydrogen peroxide solution for 15 minutes, then rinsed with ddH ₂ O, and the sterilized seeds were evenly sprinkled on a petri dish covered with three layers of gauze. Cultivate in the incubator for 2 days. When the seeds are white, select seeds with similar germination potential to sow in the above-mentioned different antimony-contaminated soils. Sow 30 seeds per pot. After sowing, add about 10 ⁸ CFU/g cultured bacterial solution to each pot with 10mL , with no inoculation treatment as the control, each treatment set up 3 replicates. Regular watering and 8 h of light per day were maintained, and the plant height and root length were measured after the plants were grown in the greenhouse for 14 days. It can be seen from Table 2 that in the soil with different antimony concentrations, the plant height and root length of the rapeseed treated with Acinetobacter NXH1 were higher than those without the addition of bacteria, indicating that Acinetobacter NXH1 can reduce the toxicity of antimony to plants, It has potential application value in promoting plant growth.

Table 2 Effects of Acinetobacter NXH1 on plant height and root length of rapeseed

Sb (mg/kg) No strain height Plus strain height no mycorrhizal length Mycorrhizal length 0 12.43 13.34 3.43 6.45 20 13.23 14.96 4.38 7.56 50 13.77 15.42 4.15 7.22 100 13.17 14.05 3.68 6.10 250 12.76 13.42 3.77 5.27 500 11.68 12.39 3.38 6.16

Claims (4)

1. one plant of anti-antimony bacterium acinetobacter calcoaceticus (AcinetobacterSp.), deposit number is CGMCC No.12895.

2. acinetobacter calcoaceticus as described in claim 1 (AcinetobacterSp.) in the mining soil biology of heavy metal pollution Application in reparation.

3. application as claimed in claim 2, it is characterised in that: the heavy metal is Sb³⁺、As³⁺、Cd²⁺、Cr⁶⁺、Hg²⁺。

4. acinetobacter calcoaceticus as described in claim 1 (AcinetobacterSp.) the application in plant growth-promoting.