Ralstonia sp. YNK-FB0054 and application thereof

Abstract

The invention provides a strain of Ralstonia sp. YNK-FB0054 as well as a microbial agent and application thereof, and belongs to the technical field of biology, the strain is Ralstonia wenshanensis, and the preservation number of the strain is CCTCC NO: M 2025293. The strain provided by the invention has the functions of dissolving zinc, fixing nitrogen, decomposing organic phosphorus, dissolving inorganic phosphorus, producing iron carriers and producing indoleacetic acid. The strain and the fungicide taking the strain as the effective active component can promote the germination of plant seeds and the growth of plants, and have high application value.

Description

Technical Field

[0001] The invention belongs to the field of biotechnology, and specifically relates to a strain of Ralstonia YNK-FB0054 and a bacterial agent and application thereof. Background Art

[0002] In recent years, long-term monoculture and the application of chemical fertilizers and pesticides have led to increasing soil degradation and crop quality problems. Microbial fertilizers are considered to be one of the most promising green fertilizers to replace chemical fertilizers because of their high efficiency and environmental protection. The screening of excellent strains is the basis for the development of efficient microbial fertilizers. Plant growth-promoting rhizobacteria (PGPR) have become a key bacterial resource for the development of microbial fertilizers due to their significant growth-promoting ability.

[0003] Plant growth-promoting rhizobacteria (PGPR) are a type of beneficial microorganisms that can promote plant growth. They play an important role in promoting plant growth and development and maintaining the health of soil ecosystems through various mechanisms such as enhancing crop nutrient absorption, inhibiting the growth of pathogens, and secreting plant hormones. However, the current development of PGPR based on biotechnology mainly relies on artificial mutagenesis screening and genetic engineering modification. The strains obtained in this way often face problems such as insufficient colonization ability or significantly lower field effects than laboratory levels in practical applications. In order to meet the needs of modern agricultural development, the development of new beneficial microbial resources with high efficiency, stable growth-promoting properties and easy colonization has become a key issue that needs to be urgently addressed in current agricultural production. Summary of the invention

[0004] The invention discloses a strain of Ralstonia YNK-FB0054 and application thereof, so as to solve the defects of the prior art.

[0005] To achieve the above object, the technical solution adopted by the present invention is: The first aspect of the present invention provides a strain of Ralstonia ( Ralstonia wenshanensis )YNK-FB0054 was deposited in the China Center for Type Culture Collection on February 25, 2025, with the deposit number: CCTCC NO: M2025293.

[0006] The second aspect of the present invention provides the use of the above-mentioned Ralstonia YNK-FB0054 in nitrogen fixation, organic phosphorus solubilization, inorganic phosphorus solubilization, siderophore production, zinc solubilization and indoleacetic acid production.

[0007] The third aspect of the present invention provides the use of the above-mentioned Ralstonia YNK-FB0054 in promoting plant growth and plant seed germination.

[0008] Through the above technical solutions, the present invention can at least achieve the following beneficial effects: 1. The Rhodococcus sp. YNK-FB0054 provided by the present invention has good nitrogen fixation and phosphorus solubilization effects. It can not only dissolve inorganic phosphorus but also decompose organic phosphorus. In addition, this strain can also dissolve zinc, produce siderophores and indole acetic acid, thereby effectively improving soil quality, increasing the content of nutrients that can be utilized by plants in the soil, and thus having a good effect on promoting plant growth.

[0009] 2. The Rhodococcus sp. YNK-FB0054 provided by the present invention is a strain isolated from the soil of a tobacco-wheat rotation farmland. Compared with the strains screened by laboratory mutagenesis, it has better adaptability to the planting environment, can colonize in the soil better, and thus can play a growth-promoting effect more stably. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a colony morphology diagram of the strain YNK-FB0054 on NA medium in Example 1; Figure 2 It is a phylogenetic tree of the strain YNK-FB0054 drawn by the Neighbor-Joining method in Example 1; Figure 3 It is for the strain YNK-FB0054 in Example 2: (A) nitrogen fixation effect diagram; (B) organic phosphorus decomposition effect diagram; (C) inorganic phosphorus dissolution effect diagram; (D) siderophore production effect diagram; (E) zinc dissolution effect diagram; Figure 4 It is a qualitative (A) and quantitative result (B) diagram of the IAA production ability of the strain YNK-FB0054 in Example 2; Figure 5 It is an experimental result diagram of the germination promotion of the strain YNK-FB0054 in Example 3; Figure 6 It is an experimental result diagram of the growth promotion of the strain YNK-FB0054 in Example 4; Figure 7 It is an analysis diagram of agronomic trait indicators in the tomato seedling pot experiment in Example 4; BIOLOGICAL DEPOSIT The Rhodococcus sp. ([[]] Ralstonia wenshanensis ) YNK-FB0054 provided by the present invention, classified and named as Ralstonia wenshanensis YNK-FB0054, was deposited at the China Center for Type Culture Collection (CCTCC) on February 25, 2025. The deposit address is Wuhan University, Wuhan, China, and its deposit number is CCTCC NO: M 2025293. DETAILED DESCRIPTION OF THE INVENTION

[0011] The endpoints and any values disclosed in this text for a range are not limited to the exact range or value. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this text.

[0012] During the research process, the inventors of the present invention isolated a strain of Rhodococcus YNK-FB0054 from the long-term flue-cured tobacco-barley rotation field soil. After testing, it was found that this strain has good nitrogen fixation, organic phosphorus decomposition, inorganic phosphorus solubilization, siderophore production, zinc solubilization, and indole acetic acid production properties. Through further research, the inventors also found that this strain can effectively promote seed germination, and when the fermentation broth of this strain is applied to the rhizosphere soil of plants, it can effectively promote plant growth, improve agricultural productivity, and promote the green and sustainable development of ecological agriculture.

[0013] Based on the above findings, on the one hand, the present invention provides a strain of Rhodococcus Ralstonia wenshanensis ) YNK-FB0054, and the preservation number of this strain is CCTCC NO: M 2025293.

[0014] On the second aspect of the present invention, it provides the application of the Rhodococcus YNK-FB0054 described in the first aspect in nitrogen fixation, organic phosphorus decomposition, inorganic phosphorus solubilization, siderophore production, zinc solubilization, and indole acetic acid production.

[0015] On the third aspect of the present invention, it provides a bacterial agent with the function of promoting plant growth, and the active ingredient in the bacterial agent includes the Rhodococcus YNK-FB0054 described in the first aspect.

[0016] According to the preferred embodiment of the present invention, wherein the bacterial agent is a liquid bacterial agent.

[0017] Preferably, the effective viable count of Rhodococcus YNK-FB0054 in the liquid bacterial agent is 1×10 6 ~1×10 11 CFU / mL. Preferably it is 1×10 7 -1×10 10 CFU / mL.

[0018] On the fourth aspect of the present invention, it provides the application of the Rhodococcus YNK-FB0054 described in the first aspect, or the biological agent described in the third aspect, in promoting plant seed germination and plant growth.

[0019] In the present invention, the method for promoting the germination of plant seeds is as follows: soaking the plant seeds in the bacterial solution of Rhodococcus sp. YNK-FB0054 described in the first aspect and / or the biological agent described in the third aspect, wherein the effective viable count of Rhodococcus sp. YNK-FB0054 in the bacterial solution is 1×10 6 -1×10 7 CFU / mL.

[0020] In the present invention, the method for promoting plant growth is as follows: applying the bacterial solution of Rhodococcus sp. YNK-FB0054 described in the first aspect or the biological agent described in the third aspect to the rhizosphere soil of plants.

[0021] According to a preferred embodiment of the present invention, the effective viable count of the bacterial solution and the biological agent is not less than 1×10 7 CFU / mL, preferably 1×10 8 -1×10 10 CFU / mL.

[0022] According to a preferred embodiment of the present invention, the dosage of the bacterial solution and the biological agent is such that the effective viable count of Rhodococcus sp. YNK-FB0054 therein is 2×10 9 -2×10 13 CFU / strain / time, preferably 2×10 10 -2×10 12 CFU / strain / time. Preferably, the application frequency of Rhodococcus sp. YNK-FB0054 or the bacterial agent is 1-3 times per crop.

[0023] Preferably, the plant is selected from Solanaceae plants and Solanum plants, and most preferably tomato.

[0024] The present invention will be described in detail below through examples. It should be understood that the following examples are only used to further explain and illustrate the content of the present invention by way of example, and are not used to limit the present invention.

[0025] In the following examples, unless otherwise specified, the reagents and materials used are commercially available products purchased from regular chemical / biological reagent or material suppliers, and the reagents are all of analytical grade.

[0026] In the following examples, unless otherwise specified, the operating temperature is room temperature (25±5°C).

[0027] Example 1 This example is used to illustrate the acquisition, identification and preservation of Rhodococcus sp. YNK-FB0054.

[0028] (I) Isolation and purification of strains During the process of strain isolation and purification, nutrient agar medium (NA medium) was used, and the preparation method was as follows: Weigh 10 g of peptone, 3 g of beef powder, and 5 g of sodium chloride, add them to 1000 mL of water, adjust the pH to 7.3 ± 0.1, then add 15 g of agar, and sterilize at 121 °C under high pressure for 15 min.

[0029] A strain of bacteria was isolated and purified from the soil sample collected from the long-term flue-cured tobacco-barley rotation field by the dilution plating method and the streak plate method, and named YNK-FB0054.

[0030] (II) Strain identification 1. Identification of bacterial morphological characteristics and physiological and biochemical characteristics Refer to "Bergey's Manual of Determinative Bacteriology" and "Manual of Systematic Identification of Common Bacteria" to conduct physiological and biochemical assays on strain YNK-FB0054 and describe the colony morphological characteristics.

[0031] Colony & cell morphology: Figure 1 The colony morphology of strain YNK-FB0054 on NA medium is shown. It can be seen from the figure that the colonies of this strain are nearly circular, with a smooth surface and regular edges, light yellow, moist and shiny. Observed under an optical microscope, this strain is a rod-shaped bacterium with flagella.

[0032] Physiological and biochemical characteristics: Strain YNK-FB0054 is Gram-negative, and the pH tolerance range is 6 - 10. The activities of indole production, urease, β-glucosidase, β-galactosidase, and cytochrome oxidase are all positive; the assimilation reactions of nitrate reduction to nitrite, gelatin hydrolysis, l-arabinose, malic acid, and phenylacetic acid substrates are positive. The strain can utilize substances such as trehalose, α-d-glucose, d-fructose, d-galactose, d-fucose, l-fucose, l-aspartic acid, l-glutamic acid, Tween 40, rifamycin SV, vancomycin, tetrazolium violet, and tetrazolium blue, as well as azithromycin, etc.

[0033] 2. Molecular identification The total DNA of strain YNK-FB0054 was extracted by the Chelex extraction method as a template. 27F (5’-AGAGTTTGATCCTGGCTCAG-3’) was used as the upstream primer, and 1492R (5’-TACGGCTACCTTGTTACGACTT-3’) was used as the downstream primer. 16S rRNA amplification was carried out using the reaction system and conditions in Table 1.

[0034] Table 1 PCR system and conditions The amplified product was electrophoresed on a 1% agarose gel and purified and recovered (using a gel extraction and purification kit produced by Guangzhou Meiji Biotechnology Co., Ltd.), and then sent to Beijing Qingke Biotechnology Co., Ltd. for sequencing. The sequencing results are shown in SEQ ID NO.1. The sequencing results were analyzed by comparison in the EZBiocloud database (https: / / www.ezbiocloud.net / ). Using the phylogenetic analysis method, the 16S rRNA sequences of the model strains with higher homology were selected as the reference objects, and multiple sequence alignments were performed using Clustal X 1.8 software to calculate the similarity between the sequences of the test strains and the reference strains. Base deletion sites were excluded during phylogenetic analysis, and the neighbor-joining method was used to construct a phylogenetic tree between the test strains and the reference strains using MEGA 7.0. Among them, the Bootstrap value was set to 1000, and the rest were default values.

[0035] 16S rRNA sequence of strain YNK-FB0054 (SEQ ID NO.1): Figure 2 The phylogenetic tree of the drawn strain YNK-FB0054 is shown, from which it can be seen that YNK-FB0054 has the highest homology with Ralstonia wenshanensis 56D2, and the homology rate reaches 99.86%.

[0036] 3. Identification results Combining the molecular detection results of strain YNK-FB0054 and the detection results of bacterial morphological characteristics and physiological and biochemical characteristics, this strain was identified as Ralstonia wenshanensis .

[0037] (III) Strain preservation The obtained Ralstonia wenshanensis YNK-FB0054 was preserved in the China Center for Type Culture Collection on February 25, 2025. The address is Wuhan University, No. 299, Bayi Road, Wuchang District, Wuhan City, Hubei Province, and the preservation number is CCTCC NO: M2025293.

[0038] Example 2 This example is used to illustrate the nitrogen fixation, organic phosphorus decomposition, inorganic phosphorus solubilization, siderophore production, zinc solubilization, and indole acetic acid production effects of Ralstonia sp. ( Ralstonia wenshanensis ) YNK-FB005.

[0039] (I)Nitrogen fixation effect test Preparation method of Asbhy nitrogen-free medium: Weigh 10 g of glucose, 0.2 g of dipotassium hydrogen phosphate, 0.2 g of sodium chloride, 0.2 g of magnesium sulfate monohydrate, 0.2 g of potassium sulfate, and 5 g of calcium carbonate, add them to 1000 mL of water and dissolve, then add 18 ± 2 g of agar. Autoclave at 121 °C for 20 min.

[0040] Using the plate four-point inoculation method, the strain YNK-FB0054 obtained in Example 1 was inoculated on the Asbhy nitrogen-free culture plate, and 3 plates were inoculated repeatedly. After inoculation, the plates were placed in a constant temperature incubator at 30 °C for 7 days, and the bacterial growth status and the formation of clear zones around the colonies were observed every day during the cultivation.

[0041] Figure 3 (A) shows the nitrogen fixation effect of strain YNK-FB0054. It can be seen from the figure that strain YNK-FB0054 can produce a clear zone when cultured on the Asbhy nitrogen-free medium, indicating that this strain has nitrogen fixation ability. Using the cross method to measure the size of the clear zone, the ratio of the clear zone diameter (D) to the colony diameter (d) was calculated as D / d = 4.38 ± 0.64, indicating that strain YNK-FB0054 has strong nitrogen fixation ability.

[0042] (II)Organic phosphorus decomposition effect test Method for preparing organic phosphorus solid medium: Weigh 10 g of glucose, 0.5 g of ammonium sulfate, 0.5 g of yeast extract powder, 0.3 g of sodium chloride, 0.3 g of potassium chloride, 0.3 g of magnesium sulfate, 0.03 g of ferrous sulfate, 0.03 g of manganese sulfate, 0.2 g of lecithin, and 1 g of calcium carbonate, add them to 1000 mL of water and dissolve. Adjust the pH to 7.3 ± 0.2, and add 18 ± 2 g of agar. Sterilize at 121 °C under high pressure for 20 min.

[0043] Using the four-point inoculation method on a plate, inoculate the strain YNK-FB0054 obtained in Example 1 onto the organic phosphorus culture plate, and repeat the inoculation on 3 plates. After inoculation, place the plates in an incubator at 30 °C for 7 days, and observe the bacterial growth status and the formation of clear zones around the colonies every day during the cultivation period.

[0044] Figure 3 The effect of the strain YNK-FB0054 on degrading organic phosphorus is shown in (B). It can be seen from the figure that the strain YNK-FB0054 can produce a clear zone when cultured on the organic phosphorus culture plate. Use the cross method to measure the size of the clear zone, and calculate the ratio of the clear zone diameter (D) to the colony diameter (d) as D / d = 3.40 ± 0.35. This indicates that the strain has good ability to degrade organic phosphorus.

[0045] (III) Test for the effect of degrading inorganic phosphorus Method for preparing inorganic phosphorus solid medium: Weigh 10 g of glucose, 0.5 g of ammonium sulfate, 0.3 g of sodium chloride, 0.3 g of potassium chloride, 0.3 g of magnesium sulfate heptahydrate, 0.03 g of ferrous sulfate heptahydrate, 0.03 g of manganese sulfate tetrahydrate, and 5 g of tricalcium phosphate, add them to 1000 mL of water and dissolve. Adjust the pH to 7.3 ± 0.2, and add 18 ± 2 g of agar. Sterilize at 121 °C under high pressure for 20 min.

[0046] Using the four-point inoculation method on a plate, inoculate the strain YNK-FB0054 obtained in Example 1 onto the inorganic phosphorus culture plate, and repeat the inoculation on 3 plates. After inoculation, place the plates in an incubator at 30 °C for 7 days, and observe the bacterial growth status and the formation of clear zones around the colonies every day during the cultivation period.

[0047] Figure 3 (C) shows the effect of the strain YNK-FB0054 on degrading inorganic phosphorus. It can be seen from the figure that the strain YNK-FB0054 can produce a clear zone when cultured on the inorganic phosphorus culture plate, indicating that the strain has the ability to degrade inorganic phosphorus. Use the cross method to measure the size of the clear zone, and calculate the ratio of the clear zone diameter (D) to the colony diameter (d) as D / d = 2.26 ± 0.30.

[0048] (IV) Test for the effect of producing siderophores 1. Qualitative detection Preparation method of CAS solid detection medium: Weigh 60.5 mg of Chrome Azurol S (CAS), 72.9 mg of Hexadecyltrimethylammonium Bromide (HDTMA), 2.645 mg of Ferric Chloride Hexahydrate, 295.25 mg of Sodium Dihydrogen Phosphate Dihydrate, 1213.5 mg of Disodium Hydrogen Phosphate Dodecahydrate, 125 mg of Ammonium Chloride, 37.5 mg of Potassium Dihydrogen Phosphate, and 62.5 mg of Sodium Chloride, add them to 1000 mL of water and dissolve. Adjust the pH to 6.8 ± 0.1, and add 18 ± 2 g of agar. Autoclave at 121 °C for 20 min.

[0049] Using the plate four-point inoculation method, inoculate the strain YNK-FB0054 obtained in Example 1 on the CAS solid culture plate, and repeat inoculation on 3 plates. After inoculation, place the plates in a constant temperature incubator at 30 °C for 7 days, and observe the bacterial growth status and the formation of orange halos around the colonies every day during the cultivation.

[0050] Figure 3 The effect of the strain YNK-FB0054 in producing siderophores is shown in (D). It can be seen from the figure that when the strain YNK-FB0054 is cultured on the CAS solid culture plate, it can produce an orange halo, indicating that the strain has the ability to produce siderophores. Use the cross method to measure the size of the clear zone, and calculate the ratio of the clear zone diameter (D) to the colony diameter (d) as D / d = 4.39 ± 0.26.

[0051] 2. Quantitative detection Preparation method of CAS chromogenic reagent: Add 60.5 mg of Chrome Azurol S (CAS) to 50 mL of deionized water, and then mix it with 10 mL of Fe 3+ solution (1 mM FeCl3·6H2O, 10 mM HCl).

[0052] Inoculate the strain YNK-FB0054 in NB liquid medium, culture it at 150 rpm on a constant temperature shaker at 30 °C for 48 h. After the cultivation, pipette about 2 mL of the culture solution, filter it through a 0.22-μm sterile filter membrane, add an equal volume of CAS detection solution, let it stand for 1 h, and then use a full-wavelength microplate reader to measure the OD630 of the inoculated bacterial solution (denoted as “As”), and measure the OD630 of the non-inoculated liquid medium in the same way as the reference value (denoted as “Ar”). The concentration of siderophores is expressed in siderophore unit (SU), SU = [(Ar - As) / Ar] × 100%, and the measurement is repeated 3 times, and the average value is taken for comparison.

[0053] According to the detection results, it is calculated that the concentration of siderophores produced by the strain YNK-FB0054 in NB liquid medium after culturing for 48 h is 55.51%.

[0054] (V) Zinc dissolution effect test Method for preparing zinc-dissolving solid medium: Weigh 1 g of zinc oxide, 10 g of glucose, 0.2 g of potassium chloride, 1 g of ammonium sulfate, 0.2 g of magnesium sulfate, and 0.1 g of dipotassium hydrogen phosphate, add them to 1000 mL of water and dissolve. Adjust the pH to 7.3 ± 0.1, add 20 g of agar, and sterilize at 121 °C under high pressure for 20 min.

[0055] Using the four-point inoculation method on a plate, inoculate the strain YNK-FB0054 obtained in Example 1 on the zinc-dissolving culture plate, and repeat inoculation on 3 plates. After inoculation, place the plates in an incubator at 30 °C for 5 days, and observe the bacterial growth status and the formation of clear zones around the colonies every day during the cultivation.

[0056] Figure 3 (E) shows the zinc dissolution effect of the strain YNK-FB0054. It can be seen from the figure that when the strain YNK-FB0054 is cultured on the zinc-dissolving culture plate, it can produce a clear zone, indicating that the strain has the ability to dissolve zinc. The size of the clear zone is measured by the cross-cross method, and the ratio of the clear zone diameter (D) to the colony diameter (d) is calculated as D / d = 4.52 ± 0.38.

[0057] (VI) Indole-3-acetic acid production effect test 1. Qualitative detection KB medium: 20 g of peptone, 15 ml of glycerol, 1.5 g of K2HPO4, 1.5 g of MgS04·7H2O, 0.1 g of tryptophan, add them to 1000 mL of water and dissolve. Adjust the pH to 7.2 ± 0.2. Sackowcki's color reagent: Slowly add 150 mL of concentrated sulfuric acid to 250 mL of deionized water while stirring. After the solution cools, add 7.5 mL of 0.5 mol / L FeCl3·6H2O solution.

[0058] Pick a single colony of the strain YNK-FB0054 obtained in Example 1 and inoculate it into the KB medium. Cultivate it at 30 °C and 180 rpm / min for 24 h. Under sterile conditions, pipette 1 mL of the fermentation broth into a centrifuge tube, quickly mix it with 4 mL of Sackowcki's color reagent, and let it stand for color development in the dark at room temperature for 40 min. Observe and record the color change. If it turns pink, it is positive, indicating that the strain can secrete IAA.

[0059] Figure 4 (A) shows the color development of the strain YNK-FB0054, and its pink color development indicates the production of IAA.

[0060] 2. Quantitative detection After culturing the strain in NB medium for 1 day, a seed solution was prepared and inoculated into KB liquid medium containing L-tryptophan at an inoculation amount of 1%. After shaking culture at 30 °C in a constant temperature shaker at 180 r / min, 4 ml of the supernatant was aspirated every day and mixed with 4 ml of Sackowcki's chromogenic reagent. After standing for 40 min in a dark environment, the OD value was measured at a wavelength of 535 nm. The obtained absorbance value was substituted into the standard curve for calculation to obtain the indole-3-acetic acid content produced by the strain, as Figure 4 (B) It was determined that the indole-3-acetic acid content produced by the strain YNK-FB0054 was the highest on the second day, which was 35.34 ± 0.68 μg / mL.

[0061] Example 3 This example is used to illustrate the germination-promoting effect of the bacterium Rhodococcus sp. YNK-FB0054 ( Ralstonia wenshanensis ) CCTCC NO: M2025293 on tomato seeds.

[0062] Experimental group settings: CK1: sterile water; CK2: NB blank medium; T1: 1.0×10 8 CFU / mL of the strain fermentation supernatant (obtained by inoculating the strain YNK-FB0054 obtained in Example 1 into NB medium, fermenting for 24 h, centrifuging at 12,000 rpm for 5 min, and then taking the supernatant); T2: 1.0×10 7 CFU / mL of the strain fermentation supernatant; T3: 1.0×10 6 CFU / mL of the strain fermentation supernatant.

[0063] Specific implementation method: Select tomato seeds as the experimental object. The seeds were soaked in 70% alcohol for 10 min and then washed 3 times with sterile water to complete disinfection. Take the seeds that sank to the bottom of the water, soak them in water at room temperature for 12 h, and then place the seeds of each group in a 9.00 cm transparent culture dish lined with 2-3 layers of sterilized filter paper. There were 15 seeds in each dish for each treatment, and it was repeated 3 times. Then, 2 mL of the liquid of each group was used to moisten the filter paper, and it was placed in an artificial climate chamber at 26 °C and cultured under alternating light and dark for 16 h and 8 h. Thereafter, 2.00 mL of sterile water was added regularly every day to keep the filter paper always moist. After 7 days, the germination situation was recorded, and the root length and the whole plant length were measured.

[0064] Table 2 Seed germination data results table * Different letters in the data in the table represent significant differences Germination-promoting experiment results: Figure 5 It shows the seed germination situation of each experimental group on the 7th day after treatment. Among them, after the control group 2 was treated with NB blank medium, the seeds did not germinate on the 7th day; the experimental group 1 used 1.0×108 After the filter paper wetted with the fermentation supernatant of the strain at a concentration of CFU / mL was treated for 7 days, the seeds germinated but no cotyledons were seen. In experimental group 3, after the filter paper wetted with the fermentation supernatant of the strain at a concentration of 1.0×10 6 CFU / mL was treated for 7 days, the seeds germinated significantly. In this group, the root length was 6.36±0.16 cm and the whole plant length was 9.39±0.19 cm, which were significantly higher than those of other groups. Secondly, in experimental group 2, after the filter paper wetted with the fermentation supernatant of the strain at a concentration of 1.0×10 7 CFU / mL was treated for 7 days, the root length of the seeds in this group was 4.23±0.13 cm and the whole plant length was 7.18±0.18 cm. The specific results are shown in Table 2. It can be seen that the fermentation supernatant of the strain at a concentration of 1.0×10 6 -1.0×10 7 CFU / mL had a good promoting effect on seed germination. The experiment shows that the application of Rhodococcus sp. YNK-FB0054( Ralstonia wenshanensis ) has a significant promoting effect on the germination of tomato seeds.

[0065] Example 4 This example is used to illustrate the growth-promoting effect of Rhodococcus sp. YNK-FB0054( Ralstonia wenshanensis ) CCTCC NO: M 2025293 on tomato plants.

[0066] Preparation of the bacterial agent: The strain YNK-FB0054 obtained in Example 1 was inoculated into NB liquid medium and cultured at 30°C with shaking at 180 rpm for 48 h. The obtained fermentation broth was the bacterial agent of strain YNK-FB0054 (the viable count was about 1×10 10 CFU / mL).

[0067] Planting of plants: The same weight of soil was added to each flower pot, and the plants were randomly grouped into 6 pots for each treatment. One tomato seedling with similar growth vigor was planted in each pot.

[0068] Setting of experimental groups: CK1: Sterilized water; CK2: Sterilized NB liquid medium; T1: Bacterial liquid of strain YNK-FB0054 at a concentration of about 1×10 10 CFU / mL; T2: Bacterial liquid of strain YNK-FB0054 at a concentration of about 1×10 9 CFU / mL; T3: Bacterial liquid of strain YNK-FB0054 at a concentration of about 1×10 8 CFU / mL.

[0069] Verification of growth promotion effect: On the 7th day after transplanting tomato seedlings into flower pots, the above-mentioned bacterial agent was used to irrigate the roots of tomato seedlings at a rate of 200 mL / plant. At the same time, sterile water and NB medium shaken for 48 h under the same culture conditions in equal amounts were used to treat tomato seedlings in the same way as the control groups (CK1 and CK2). The tomato seedlings after root irrigation were placed in the greenhouse to grow naturally, and sufficient soil moisture was maintained during this period. 21 days after root irrigation, the above-ground fresh weight, underground (root) fresh weight, stem diameter, root length, and plant height of the tomato plants were measured.

[0070] The specific measurement methods are as follows: Above / below-ground fresh weight: Cut off the part above the base of the tomato plant and weigh the above / below-ground fresh weight on an analytical balance, retaining two decimal places.

[0071] Stem diameter: Use a vernier caliper to measure the diameter of the thickest part of the plant stem.

[0072] Root length: After straightening the root, use a ruler to measure the root length.

[0073] Plant height: After straightening the plant, use a ruler to measure the above-ground length from the highest point of the leaves.

[0074] It can be seen that Figure 7 21 days after root irrigation with the bacterial solution of strain YNK-FB0054, the plant height, stem diameter, above-ground fresh weight, root length, and underground fresh weight of the tomato plants were significantly increased compared with the control group (CK1) treated with clear water and the control group (CK2) treated with NB medium. Among them, the plant height of the T1 treatment group was 15.79% and 22.89% higher than that of the control groups CK1 and CK2 respectively, the root length of the T1 treatment group was 39.68% and 50.78% higher than that of the control groups CK1 and CK2 respectively, the stem diameter of the T1 treatment group was 18.76% and 45.05% higher than that of the control groups CK1 and CK2 respectively, the above-ground fresh weight of the T1 treatment group was 42.87% and 56.99% higher than that of the control groups CK1 and CK2 respectively, and the underground fresh weight of the T1 treatment group was 61.03% and 87.95% higher than that of the control groups CK1 and CK2 respectively. It can be seen that whether to apply the bacterial solution for treatment has a significant effect on the growth of plants, proving that the application of strain YNK-FB0054 has a significant promoting effect on the growth of tomatoes.

[0075] Figure 6 The comparison diagrams of tomato plants in the experimental group and the control group 21 days after root irrigation are shown. It can be seen from the figure that after root irrigation with the bacterial solution of strain YNK-FB0054, the overall growth rate of tomato plants is faster than that of tomato plants irrigated only with clear water and NB liquid medium, the sizes of roots, stems, and leaves are larger, and the growth of tomato roots is also more developed.

[0076] The above results indicate that strain YNK-FB0054 can effectively promote the growth of tomato seedlings.

[0077] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in terms of form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A strain of Rhodococcus sp. Ralstonia wenshanensis ) YNK-FB0054, characterized in that The preservation number of the strain is: CCTCC NO: M 2025293.

2. Use of the Ralstonia sp. YNK-FB0054 according to claim 1 in dissolving zinc, nitrogen fixation, decomposing organic phosphorus, dissolving inorganic phosphorus, producing siderophores and producing indole acetic acid.

3. A microbial preparation with the function of promoting plant growth, characterized in that, The active ingredient in the microbial preparation includes a bacterial agent containing the Ralstonia sp. according to claim 1.

4. The microbial preparation according to claim 3, wherein, The microbial agent is a liquid microbial agent; in the liquid microbial agent, the content of the genus Rhodococcus is not less than 1×10 6 CFU / mL.

5. Use of the microbial preparation according to any one of claims 3-4 or the Ralstonia sp. according to claim 1 in promoting plant growth and plant seed germination.

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