1. An Acinetobacter oleophilic (Acinetobacter oleivorans) strain MRP20, which is characterized in that the strain is preserved in Guangdong province collection center of microorganism strains at 11/5/2021 with the preservation number being GDMCC No: 61653.

2. the 16S rDNA of Acinetobacter oleophilic strain MRP20 as claimed in claim 1, having the sequence shown in SEQ ID No. 1.

3. Use of acinetobacter oleophilus strain MRP20 according to claim 1 for breeding cadmium virus resistant plants.

4. Use of acinetobacter oleophilus strain MRP20 as defined in claim 1 for reducing cadmium inhibition of plant growth or for preparing a product capable of reducing cadmium inhibition of plant growth.

5. Use of acinetobacter oleophilus strain MRP20 according to claim 1 for promoting synthesis of chlorophyll in plant leaves, or for preparing a product capable of promoting synthesis of chlorophyll in plant leaves.

6. Use of acinetobacter oleophilus strain MRP20 as defined in claim 1 for promoting phosphorus uptake by plants or for preparing products capable of promoting phosphorus uptake by plants.

7. Use of acinetobacter oleophilus strain MRP20 according to claim 1 for preparing a growth promoter, cadmium poison-resistant microbial pesticide, chlorophyll biosynthesis promoter or phosphorus absorption promoting microbial agent suitable for plants.

8. The use of claim 7, wherein the plant is a plant of the family Sojae.

9. Use of acinetobacter oleophilus strain MRP20 as defined in claim 1 for solubilizing poorly soluble phosphorus or for preparing a product capable of solubilizing poorly soluble phosphorus.

10. A method for growing soybean characterized in that soybean seedlings are treated by using a suspension or drenching of the Acinetobacter oleophilic strain MRP20 as claimed in claim 1.

Background

Cadmium is not an essential element for plant growth and development. When the content in the plant exceeds a certain concentration, the plant is seriously damaged, such as wilting and yellowing, weak growth and the like. The plant root system can easily absorb cadmium and then transport the cadmium to the overground part, so that the plant can be poisoned, the absorption of nutrient elements is influenced, and the growth of the plant is inhibited. Cadmium also destroys root structure, thereby affecting the absorption of plant nutrients.

Phosphorus is one of the most important essential nutrient elements of plants, and is a macronutrient element essential for key metabolic processes such as plant cell division, energy generation, macromolecular biosynthesis, membrane integrity, signal transduction and photosynthesis. It also plays a role in plant respiration and nitrogen fixation in legumes. Although the soil contains a large amount of phosphorus compounds, plants can actually utilize very little soluble phosphorus. Because most of the phosphorus in the soil exists in a poorly soluble form, only the phosphorus source in the form of phosphate can be absorbed by the plants.

Microorganisms are closely related to plants, and microorganisms either positively or negatively affect the growth and development of plants. Under the influence of plant root secretion, microorganisms in soil establish stable symbiotic relationship with plant rhizosphere and root systems, and some bacteria can infect the plant root systems and colonize inside plants. The Chinese invention patent, CN104974962A, discloses an acinetobacter calcoaceticus strain which can effectively reduce the pH value of a solution and dissolve insoluble phosphorus in the solution, and promote the growth of tomato and eggplant plants. However, the strain is not cadmium-tolerant, and cannot solve the technical problem that plants are stressed by cadmium toxicity.

Disclosure of Invention

The invention aims to provide a novel Acinetobacter oleophilic (Acinetobacter oleivorans) strain MRP20, which is symbiotic with plants and can solve the technical problems of low phosphorus stress and cadmium toxicity stress of plants. The strain has the characteristics of auxin secretion, acid resistance, cadmium resistance, phosphorus dissolution and siderophore production. The soybean inoculated with the acinetobacter oleophilus can improve the biomass (dry weight) of soybean, obviously improve the chlorophyll SPAD value and phosphorus content and promote the growth of soybean roots; but also can overcome the effect of cadmium on the growth inhibition of the soybean, in particular the effect of cadmium on the growth of soybean roots.

The invention aims to provide an Acinetobacter oleovorans (Acinetobacter oleivorans) strain MRP 20.

Another objective of the invention is to provide application of Acinetobacter oleovorans (Acinetobacter oleivorans) strain MRP20 in cultivating cadmium toxicity-resistant plants.

Another object of the present invention is to provide the use of Acinetobacter oleovorans (Acinetobacter oleivorans) strain MRP20 for attenuating cadmium inhibition of plant growth.

Another objective of the invention is to provide the application of Acinetobacter oleovorans (Acinetobacter oleivorans) strain MRP20 in promoting the synthesis of chlorophyll by plant leaves.

Another objective of the invention is to provide the application of Acinetobacter oleovorans (Acinetobacter oleivorans) strain MRP20 in promoting the absorption of phosphorus by plants.

Another objective of the invention is the application of Acinetobacter oleophilic (Acinetobacter oleivorans) MRP20 in the preparation of growth promoter, cadmium poison resisting microbial pesticide, chlorophyll biosynthesis promoter or phosphorus absorption promoting microbial inoculum which is applicable to plants.

Another objective of the invention is to provide the application of Acinetobacter oleovorans (Acinetobacter oleivorans) strain MRP20 in dissolving insoluble phosphorus.

Another object of the present invention is to provide a method for planting soybeans.

In order to achieve the purpose, the invention provides the following technical scheme:

an applicant team obtains a strain which has the characteristics of secreting auxin, acid resistance, cadmium resistance, phosphorus dissolution and siderophore production from the rhizosphere of corn in the northern York village of the Yangjiang region in Shaoguan city through artificial separation and purification, can obviously improve the biomass, phosphorus content and SPAD value of leaves of soybeans, and enables the soybeans to be cadmium resistant. The sequencing result of the strain is completed by Guangzhou Rui Bo biotechnology, and the sequencing result of the 16S rDNA is subjected to Blast multiple sequence comparison analysis in NCBI database, so as to determine that the separated strain is a new strain of Acinetobacter oleovorans (Acinetobacter oleovorans) and is named as MRP 20. And is preserved in Guangdong province microorganism culture collection center at 2021, 5 months and 11 days, wherein the preservation number is GDMCC No: 61653.

the strain MRP20 has the following morphological characteristics: MRP20 has an optimum growth temperature of 37 ℃, forms a round, smooth, protruding and milky colony on an LB plate culture medium, and has a rod shape under an optical microscope, and gram stain is red and gram negative bacteria.

Researches show that the acinetobacter oleophilus strain MRP20 can remarkably promote the soybeans to absorb phosphorus and improve the cadmium resistance of the soybeans. The invention therefore claims:

application of acinetobacter oleophilic strain MRP20 in cultivating cadmium toxicity-resistant plants, in particular in cultivating cadmium toxicity-resistant soybean plants, and overcoming the inhibiting effect of cadmium on the root growth of soybean plants.

The acinetobacter oleophilic strain MRP20 is applied to weakening cadmium inhibition plant growth, in particular to application to promoting biomass increase and root growth of soybean plants under cadmium toxicity stress or preparation of products capable of weakening cadmium inhibition plant growth.

Application of acinetobacter oleophilus strain MRP20 in promoting synthesis of chlorophyll of plant leaves or preparing products capable of promoting synthesis of chlorophyll of plant leaves, especially chlorophyll of leaves of plants in the family of soybean.

Use of acinetobacter oleophilus strain MRP20 for promoting phosphorus uptake by plants, in particular, in plants of the family soyaceae, or for the preparation of products capable of promoting phosphorus uptake by plants.

Use of acinetobacter oleophilic strain MRP20 for solubilizing poorly soluble phosphorus, wherein preferably the poorly soluble phosphorus is Ca₃(PO₄)₂。

Application of acinetobacter oleophilus strain MRP20 in preparation of growth promoter, cadmium toxin-resistant microbial pesticide, chlorophyll biosynthesis promoter or phosphorus absorption promoting microbial inoculum for plants.

Wherein, preferably, the plant is a plant of the family glycines.

A method for planting soybeans by irrigating soybean seedlings with the bacterial suspension of the acinetobacter oleophilic strain MRP20 of claim 1;

particularly preferably, the mode of treatment is irrigation;

more preferably, the method specifically comprises the following steps: after soybean seed seedling raising, irrigating a bacterial suspension of acinetobacter oleophilic strain MRP20 of claim 1 in a culture medium, and then irrigating once each 1, 3, 5 days after seedling transplanting; wherein the amount of each irrigation is preferably 80-120 mL/seedling; preferably, the bacterial suspension OD₆₀₀0.6 to 1.0.

As an alternative embodiment, the dispersion medium of the bacterial suspension is soybean nutrient solution, and the formula of the soybean nutrient solution is as follows: 2.5mM KNO₃，2.5mM Ca(NO₃)₂·4H₂O，0.08mM Fe-Na-EDTA，0.25mM K₂SO4，1mM MgSO₄·7H₂O，4.5×10^-3mM MnCl₂·4H₂O，0.3×10^-3mM ZnSO₄·7H₂O，0.16×10^-3mM CuSO₄·5H₂O，0.16×10^-3mM(NH4)₆Mo₇O₂₄·4H₂O，20×10^-3mM H₃BO₃，50×10^-3mM KH₂PO₄。

The invention has the following beneficial effects:

the invention provides a cadmium-resistant growth-promoting acinetobacter oleophilus strain MRP20, which is symbiotic with plants and can:

(1) promoting plant growth, promoting phosphorus absorption of plant, increasing biomass and chlorophyll SPAD, and is especially suitable for soybean plant.

(2) Improving the cadmium toxicity resistance of plants, overcoming the growth inhibition of cadmium on plants, in particular the growth inhibition of cadmium on soybeans.

(3) The strain has the characteristics of auxin secretion, acid resistance, phosphorus dissolution and siderophore production.

Drawings

FIG. 1 shows the phosphate solubilizing circle of Acinetobacter oleophilic strain MRP 20.

FIG. 2 shows that A.oleophilus strain MRP20 produces IAA at different tryptophan concentrations.

FIG. 3 shows a quantitative graph of IAA production by Acinetobacter oleophilus strain MRP20, where the letters a, b represent whether there was a significant difference between the mean values of the samples after analysis of variance, the letters being the same between groups represent insignificant difference between groups (P >0.05), and the letters being different represent significant difference between groups (P < 0.05).

FIG. 4 shows the cadmium tolerance curve (OD) of A.oleophilic strain MRP20₆₀₀Cadmium concentration), where the letter combinations a, ab represent whether there is a significant difference between the mean values of the samples after analysis of variance, and the same letter between groups represents an insignificant difference between groups (P)>0.05), the letters are not the same among groups, representing significant difference among groups (P)<0.05)。

FIG. 5 shows the acid resistance curve (OD) of A.oleophilic strain MRP20₆₀₀-pH), where the letter combinations a, ab and b represent whether there is a significant difference between the mean of the samples after analysis of variance, and the same letters between groups represent no significant difference between groups (P)>0.05), the letters are not the same among groups, representing significant difference among groups (P)<0.05)。

FIG. 6 shows a developmental tree of Acinetobacter oleophilic strain MRP 20.

FIG. 7 shows the variation of plant dry weight (A) and SPAD value (B) of soybeans inoculated with Acinetobacter oleophilic strain MRP20 under cadmium toxicity stress.

FIG. 8 shows the change in root length (A), root surface area (B), root diameter (C) and root volume (D) of soybeans inoculated with Acinetobacter oleophilic strain MRP20 under cadmium toxicity stress.

FIG. 9 shows the overground part cadmium concentration (A) and the root cadmium concentration (B) of soybeans inoculated with Acinetobacter oleophilic strain MRP20 under cadmium toxicity stress.

FIG. 10 shows the change in the overground part phosphorus content (A) and the root phosphorus content (B) of soybeans inoculated with Acinetobacter oleophilus strain MRP20 under cadmium toxicity stress.

0.01< P <0.05, 0.001< P <0.01, P < 0.001.

Detailed Description

The invention is further described with reference to the drawings and the following detailed description, which are not intended to limit the invention in any way. Reagents, methods and apparatus used in the present invention are conventional in the art unless otherwise indicated. Unless otherwise indicated, reagents and materials used in the following examples are commercially available.

Example 1: separation and purification of bacterial strains

1. Isolation and purification of the strains

In the northern village of Yangjiang region of Shaoguan city, the strain is separated from the corn rhizosphere of corn (Zhengtian 68) planted on cadmium-polluted soil. Respectively cutting 5g of corn roots, brushing surface soil with a small brush, rinsing with sterile water for multiple times until no attached soil exists, placing in a 250mL triangular bottle with serial number containing 100mL of sterile water, shaking at 37 ℃ for 30min at 180 r/min. Adding 10-20 glass beads in the conical flask to help break soil and release bacteria from soil, standing the soil suspension for 10min after shaking to obtain soil suspension, taking supernatant, diluting with 10 times of gradient concentration, and diluting to 10 times of gradient concentration^-1、10^-2、10^-3、10^-4、10^-5、10^-6Then 0.1mL of diluent is sucked and coated on an LB plate, each concentration gradient is repeated for three times, inverted culture is carried out at 37 ℃, the growth condition of colonies is observed, monoclonals with different phenotypes are picked, each colony is numbered on the back of a culture medium, the colony morphology and the time for growing the colony are recorded, each type of monoclonals is picked into a 1.5mL centrifuge tube to be shaken, the monoclonals are cultured at 37 ℃ at 180r/min, and then streaked and purified for 3-4 times by an LB solid culture medium (until the colony morphology under a microscope is consistent, the purification is finished), and sterilized glycerol with the concentration of 25 percent is added for preservation at-80 ℃.

And separating 55 strains at the rhizosphere of the corn, wherein the strains are numbered MRP 1-55, and the strains are separated and purified to be tested.

Example 2: strain screening

2.1 preliminary screening of phosphorus-solubilizing bacteria

And (3) inoculating the screened strains on a PKO solid culture medium, inoculating each plate for three times, culturing in an incubator at 28 ℃, measuring the sizes of the outer diameter (D) and the colony diameter (D) of a phosphorus-dissolving ring of the strains at the 7 th D, and taking pictures, wherein the phosphorus-dissolving ring can dissolve phosphorus. Then comparing the ratio of (D/D) to judge the phosphorus dissolving capacity of the strain.

1mL of the bacterial solution of the strain having the phosphorus-solubilizing loop was aspirated, inoculated into 20mL of LB liquid medium (50mL centrifuge tube), cultured for 24 hours, and then OD was measured₆₀₀About 1.0, 1mL of the bacterial suspension was inoculated into 20mL of PKO liquid medium (50mL centrifuge tube), each strain was replicated three times, and the CK control group was inoculated with an equal amount of sterile water and cultured in a shaker at 28 ℃ and 180 r/min. The pH value of the PKO liquid culture medium is measured at the 7 th day, 1mL of supernatant (1200R/min, 5min of centrifugation) is sucked into a 25mL volumetric flask to be measured, 5mL of molybdenum-antimony anti-chromogenic solution is sucked, secondary water is used for constant volume to 25mL, after reaction for 30min, an absorbance value at 880nm is measured by using a microplate reader (in order to remove the influence of the color of the culture medium, 880nm measurement is applied, and a standard curve (y is 0.4833x +0.0002(R is 0.4833x + 0.0002) is obtained through a conversion formula²0.9997). Converted to obtain the corresponding phosphorus concentration (mg/L).

As a result: the phosphorus solubilizing circle ratio of strain MRP20 was found to be greater than 1.5 (figure 1 and table 1). In a phosphorus dissolving quantitative test, the strain MRP20 shows stronger phosphorus dissolving capacity, and can dissolve phosphorus to 22.61 +/-0.58.

TABLE 1

Strain numbering	D(cm)	d(cm)	D/d	Concentration of dissolved phosphorus (mg/mL)
					MRP20	1.58	0.92	1.73	22.61±0.58

2.2 screening for secreted IAA

LB liquid culture medium with L-tryptophan concentration of 0, 100, 200 and 500mg/L respectively is prepared, the screened strains are inoculated into the liquid culture medium, each strain is repeatedly cultured for three times (the same culture medium without inoculation is used as blank control) at 28 ℃ and 180r/min for 2d, 200 mu L of supernatant is taken out for each repetition, 200 mu L of Salkowski developing solution is added into a 96-hole enzyme label plate, the same liquid culture medium with the added non-inoculated strain and 200 mu L of Salkowski developing solution are used as control, the temperature is kept away from the sun for 20min at room temperature, and then the wavelength is measured at 530nm by using an enzyme label instrument. The corresponding IAA production was checked on the standard curve. IAA production is in mg/mL.

The qualitative results show (FIG. 2) that strain MRP20 has IAA-producing ability, but is weak. MRP20 showed that the releasing ability of strain IAA was increased with increasing tryptophan concentration in the tryptophan concentration range of 0-500mg/L (FIG. 3).

2.3 screening for siderophore production Capacity

1mL of bacterial suspension of the strain to be tested is sucked and inoculated into MKB liquid culture medium. Culturing at 28 deg.C and 180r/min for 48 h. The culture was centrifuged for 10min (1200r/min), 200. mu.L of the supernatant (200. mu.L of uninoculated MKB liquid medium was added for the reference value (Ar)) was taken and mixed with the CAS detection solution at a ratio of 1: 1. After reacting for 1h at normal temperature, the OD value (A) at the wavelength of 630nm is measured by an enzyme-labeling instrument. In the experiment, if no siderophore production occurred, the CAS broth appeared blue as in the control, and if the strain produced siderophore production, the CAS broth changed to orange. The relative content of the siderophore in the sample is expressed by the ratio of A/Ar, the smaller the value is, the stronger the siderophore production capacity of the strain is expressed, the higher the activity unit of the siderophore in the sample is expressed by the ratio of (Ar-A)/Ar, the stronger the siderophore production capacity is.

As a result, the MRP20 strain has the highest activity unit of producing siderophore in MRP 1-55 strains, and the activity unit reaches 58.30 +/-11.29%.

2.4 screening for cadmium tolerance

Preparing 6 LB liquid culture media with cadmium concentration of 0, 4, 8, 12, 16, 20mg/L, sterilizing at 121 deg.C for 20 min. 2 96-well sterilized cell culture plates were prepared, and 200. mu.L each of the prepared LB liquid media with different cadmium concentrations was pipetted onto the culture plates. After the strains to be detected are activated and cultured for 24h, each strain absorbs 5 mu L of the strains to culture holes with different cadmium concentration values, each strain is repeatedly cultured for 4 times at 37 ℃ for 48h at 180r/min, and the light absorption value of the bacterial liquid at 600nm is measured.

As a result: under the condition of Cd concentration of 0-20mg/L, the growth rate of MRP20 is almost unchanged, and the cadmium resistance is extremely strong (figure 4).

2.5 acid resistance screening

6 LB culture media with pH values of 4.5, 5.0, 5.5, 6.0, 6.5 and 7.0 are prepared respectively, and sterilized at 121 ℃ for 20 min. 2 96-well sterilized cell culture plates were prepared, and 200. mu.L each of prepared LB liquid media of different pH was pipetted onto the culture plates. After the strains to be detected are activated and cultured for 24h, each strain absorbs 5 mu L of the strains to culture holes with different pH values, each strain is repeatedly cultured for 4 times at 37 ℃ for 48h at 180r/min, and the light absorption value of the bacterial liquid at 600nm is measured.

The strain MRP20 grew most rapidly at pH 5.5-7.0 (FIG. 5), indicating that the strain grew well under mildly acidic conditions.

Example 3 Strain identification

The screened strain MRP20 is identified through comprehensive consideration in many aspects.

3.1 morphological characterization of the strains

The strain MRP20 was inoculated on LB solid medium for culture and observed for recording. After culturing for 5-7 days under the optimal growth conditions (pH 7.0 and temperature 37 ℃), observing the state of a single colony of the separated and purified strain MRP20, wherein the state mainly comprises the size, the color, the surface state of the colony, the edge state of the colony and the like. On the other hand, the strain MRP20 in the logarithmic growth phase was stained by smear, and the morphology of the cells was observed by an optical microscope.

On LB plate culture medium, forming round, smooth, protuberant, milky colony, rod-shaped under optical microscope, and gram-negative bacteria with red gram stain.

3.2 molecular characterization

Through various screening and comprehensive consideration, the strain MRP20 is screened for identification and continued research. Inoculating the strain into LB culture medium, culturing at 37 deg.C and 180r/min for 24 hr, extracting total DNA of the strain with total DNA extraction kit, sequencing with biological company, performing Blast sequence comparison analysis on the obtained strain sequence in NCBI database, and constructing phylogenetic tree with MEGA7.0 (FIG. 6).

According to the sequencing result, MRP20 is Acinetobacter oleophilic (Acinetobacter oleivorans), and the 16S rDNA sequence of the MRP20 is shown as SEQ ID NO. 1; and the Acinetobacter oleophilic (Acinetobacter oleivorans) strain MRP20 is preserved in the Guangdong province collection center of microorganism strains at 2021, 5 and 11 days, with the preservation number being GDMCC No: 61653.

example 4 Bacto soybean test of Acinetobacter oleophilic MRP20

4.1 Tie-back test

This study used a matrix soil potting test. Three cadmium concentration groups are set in the experiment, and are respectively 0, 10 and 20mg/kg CdCl₂·5/2H₂O, Acinetobacter oleophilus MRP20 was inoculated and each pot was low phosphorous treated, 4 replicates each.

The mixed matrix treatment method of the matrix and the vermiculite comprises the following steps: weighing the fertilizer-free matrix and vermiculite according to the ratio of 3: 1 (0.5kg mixed soil is 0.125kg vermiculite +0.375kg substrate), sterilizing at 121 ℃ for 40min, repeating the sterilization once after 24h intervals, and standing for one week for later use. A flowerpot with the capacity of 2L is taken, soaked overnight in 10% sodium hypochlorite, then fully washed with clear water for a plurality of times, and air-dried for later use. Weighing quantitative cadmium chloride, dissolving in water, preparing 0, 10, 20mg/kg solution, weighing certain volume, pouring into mixed matrix, and mixing 125mg Ca per basin (0.5kg)₃(PO4)₂(equivalent to 50mg/kg of pure phosphorus), weighing and uniformly mixing each pot, and standing for one week for later use.

Seeds were sterilized with hydrochloric acid-sodium hypochlorite generating chlorine for 4h, with grit: medium sand is 1: 2, breeding the seedlings by using the mixed sand, selecting soybean plants (Brazil 10) with basically consistent growth after one week of breeding, and transplanting one soybean plant in each pot. After 1, 3 and 5 days of seedling transplantation, the bacterial suspension is irrigated for 3 times, wherein the bacterial suspension is 100mL for one time.

Preparing a bacterium suspension nutrient solution: inoculating the strain into LB culture solution containing 250mL, shaking and culturing at 37 ℃ for about 18h at 180r/min, centrifugally collecting the strain, resuspending the strain with low-phosphorus nutrient solution when the OD of the turbid strain is between 0.6 and 1.0, and poking the matrix on the root surface of the seedling with a sterilizing gun head. And pouring the bacteria heavy suspension nutrient solution into the roots, and pouring the bacteria into the matrix along with the nutrient solution.

Wherein the formula of the low-phosphorus nutrient solution is 2.5mM KNO₃，2.5mM Ca(NO₃)₂·4H₂O，0.08mM Fe-Na-EDTA，0.25mM K₂SO4，1mM MgSO₄·7H₂O，4.5×10^-3mM MnCl₂·4H₂O，0.3×10^-3mM ZnSO₄·7H₂O，0.16×10^-3mM CuSO₄·5H₂O，0.16×10^-3mM(NH4)₆Mo₇O₂₄·4H₂O，20×10^-3mM H₃BO₃，50×10^-3mM KH₂PO₄。

4.2 index detection

The soybeans were cultured for 30 days and then harvested. Measuring SPAD values of different parts of the inverted three leaves of the plant by using a SPAD instrument under the condition of sufficient illumination, and then averaging. The tap water is flushed and then is put into a refrigeration house, and scanning is carried out in time within one week. Scanning the root system by a desk type scanner (Epson1460XL), spreading the root system as flat as possible to prevent the root system from overlapping, cutting and scanning the overlarge root system without influencing the scanning result, covering a blue light shielding plate, after the scanning is finished, analyzing the root system characters of each sample root by root system analysis software WinRHIO (Regent Instruments Inc., Canada),

separating the overground part and the root of the crop, weighing the fresh weight of the overground part and the root, putting the overground part into a 105 ℃ oven for deactivation of enzymes for 30min, drying in the oven, taking out, standing at room temperature for 10min, cooling, and weighing the dry weight. The roots are scanned by a root scanner and weighed, and the rest parts are dried after being de-enzymed and weighed as dry weights.

Soaking the soybean root in 10mmol/L Na₂-EDTA solution for 5min to remove surface adsorbed Cd²⁺Then, washing the root system and the stem leaf part by secondary water, drying the root system and the stem leaf part at 75 ℃, weighing dry weight, and then measuring the phosphorus content and cadmium concentration of the overground part; and the root is put in a cold storage for root sweeping, dried and weighed after the root sweeping is finished, and the phosphorus content and the cadmium concentration of the root are measured. The phosphorus is measured by ultraviolet spectrophotometry, and the cadmium is measured by flame absorption of atomic absorption spectrophotometer.

The results are as follows:

(1) with the increase of cadmium concentration, the dry weight of the plants is obviously reduced, and compared with 0Cd, the biomass of the plants without inoculation treatment (CK group) is 10mg/kg Cd²⁺And 20mg/kg Cd²⁺Under the condition (10Cd and 20Cd groups), the reduction rate is 31 percent and 55 percent respectively, and the dry weight of soybean plants treated by inoculated strain MRP20 is 10mg/kg Cd²⁺And 20mg/kg Cd²⁺The reduction under the condition is 31 percent and 41 percent respectively. At 20mg/kg Cd²⁺Under the conditions, the dry weight of the soybean plants inoculated with the strain MRP20 was significantly higher than that of the soybeans without inoculation treatment by 34%. It was shown that vaccination with MRP20 alleviated cadmium poisoning (FIG. 7A).

(2) At 20mg/kg Cd²⁺Under the condition, the SPAD value of the soybean leaves inoculated with MRP20 is obviously higher than that of the soybean leaves not inoculated with CK by 20%, which shows that the soybean nitrogen absorption can be promoted by inoculating MRP20 (figure 7B).

(3) At 0mg/kg Cd²⁺Under the conditions, the total root length of the soybean inoculation treatment is obviously higher than that of the non-inoculation treatment (CK group), and the root surface area is obviously higher than that of the non-inoculation treatment (CK group), so that the inoculation of MRP20 can obviously promote the growth of the soybean root system (figure 8).

(4) The data show that as the cadmium concentration increases, the cadmium concentration in the upper and root parts of the soybean increases significantly. 0mg/kg Cd²⁺、10mg/kg Cd²⁺And 20mg/kg Cd²⁺Under the conditions, the cadmium concentration of the upper part of the soybean inoculated with Acinetobacter oleivorus MRP20 has no significant change compared with that of the CK inoculated with no bacteria (FIG. 9A), but the cadmium concentration of the upper part of the soybean is 20mg/kg Cd²⁺Under the condition, CK is compared with that after being inoculated without being inoculatedThe root cadmium concentration was reduced by 60% (fig. 9B).

(5) At 0mg/kg Cd²⁺Under the condition, compared with the soybeans which are not inoculated with CK bacteria and are inoculated with acinetobacter oleophilus MRP20, the phosphorus content of the overground part of the soybeans is improved by 145 percent. It was shown that MRP20 has significant phosphate-solubilizing and growth-promoting effects (FIG. 10).

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

SEQUENCE LISTING

<110> southern China university of agriculture

<120> cadmium-resistant growth-promoting acinetobacter oleophilus strain and application thereof

<130> YGZS214949

<160> 1

<170> PatentIn version 3.5

<210> 1

<211> 1406

<212> DNA

<213> 16S rDNA of Acinetobacter oleivorans MRP20

<400> 1

tgcagtcgag cggagagagg tagcttgcta ctgatcttag cggcggacgg gtgagtaatg 60

cttaggaatc tgcctattag tgggggacaa catttcgaaa ggaatgctaa taccgcatac 120

gtcctacggg agaaagcagg ggatcttcgg accttgcgct aatagatgag cctaagtcgg 180

attagctagt tggtggggta aaggcctacc aaggcgacga tctgtagcgg gtctgagagg 240

atgatccgcc acactgggac tgagacacgg cccagactcc tacgggaggc agcagtgggg 300

aatattggac aatgggcgga agcctgatcc agccatgccg cgtgtgtgaa gaaggcctta 360

tggttgtaaa gcactttaag cgaggaggag gctactttag ttaataccta gagatagtgg 420

acgttactcg cagaataagc accggctaac tctgtgccag cagccgcggt aatacagagg 480

gtgcaagcgt taatcggatt tactgggcgt aaagcgcgcg taggcggcta attaagtcaa 540

atgtgaaatc cccgagctta acttgggaat tgcattcgat actggttagc tagagtgtgg 600

gagaggatgg tagaattcca ggtgtagcgg tgaaatgcgt agagatctgg aggaataccg 660

atggcgaagg cagccatctg gcctaacact gacgctgagg tgcgaaagca tggggagcaa 720

acaggattag ataccctggt agtccatgcc gtaaacgatg tctactagcc gttggggcct 780

ttgaggcttt agtggcgcag ctaacgcgat aagtagaccg cctggggagt acggtcgcaa 840

gactaaaact caaatgaatt gacgggggcc cgcacaagcg gtggagcatg tggtttaatt 900

cgatgcaacg cgaagaacct tacctggcct tgacatagta agaactttcc agagatggat 960

tggtgccttc gggaacttac atacaggtgc tgcatggctg tcgtcagctc gtgtcgtgag 1020

atgttgggtt aagtcccgca acgagcgcaa cccttttcct tatttgccag cgagtaatgt 1080

cgggaacttt aaggatactg ccagtgacaa actggaggaa ggcggggacg acgtcaagtc 1140

atcatggccc ttacggccag ggctacacac gtgctacaat ggtcggtaca aagggttgct 1200

acctagcgat aggatgctaa tctcaaaaag ccgatcgtag tccggattgg agtctgcaac 1260

tcgactccat gaagtcggaa tcgctagtaa tcgcggatca gaatgccgcg gtgaatacgt 1320

tcccgggcct tgtacacacc gcccgtcaca ccatgggagt ttgttgcacc agaagtagct 1380

agcctaactg caaagagggc ggtacc 1406