Strain R53 of China and application of strain R53 in plant bacteriostasis and growth promotion

Abstract

The invention belongs to the technical field of microorganisms, and particularly relates to a CCTCC (China Center for Type Culture Collection) NO: M 20251298 strain and application thereof in plant bacteriostasis and growth promotion, and the preservation number of the CCTCC NO: M 20251298 strain is CCTCC NO: M 20251298. The C.chinense strain R53 disclosed by the invention has a relatively good antibacterial effect on various pathogenic bacteria causing plant diseases; the strain can well dissolve inorganic phosphorus, is beneficial to phosphorus absorption of plants and improves the soil fertility; the strain can also produce IAA (indoleacetic acid), has a nitrogen fixation characteristic, has a promoting effect on plant growth, and has a wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of microbial technology, and particularly relates to a strain of the genus Hwanghae and application thereof in plant bacteriostasis and growth promotion. BACKGROUND

[0002] The growth of crops is closely related to the microorganisms in soil, and the soil microbial flora can improve the physical, chemical and biological properties of soil, promote the growth and development of plants, inhibit plant pathogenic bacteria in soil, and reduce the use amount of chemical fertilizers. Therefore, the study on the relationship between rhizosphere microorganisms and plant diseases is beneficial to the development of new biological control methods.

[0003] At present, many scholars have screened a series of bacterial strains with antagonistic activity from soil and plant tissues by different methods, mainly including Bacillus, Pseudomonas and myxobacteria, etc. These bacterial strains can improve the defense ability and systemic resistance of plants. For example, Pseudomonas fluorescens, Pseudomonas putida and Bacillus subtilis can significantly improve the plant growth and enhance the defense ability of plants against pathogens. In addition, it is proved that the metabolic products of bacteria also have the potential to inhibit the proliferation and infection of pathogens, such as the metabolic products of bacteria such as Aerobacter, Bacillus subtilis, soft rot bacteria and Fusarium verticillioides can inhibit the proliferation and infection of TMV virus (tobacco mosaic virus).

[0004] However, most of these studies are focused on the control effect of a single strain on a specific pathogen, and there is a lack of in-depth screening and identification of broad-spectrum antagonistic active strains. Therefore, it is urgent to provide a biocontrol strain with better performance and inhibitory effect on various plant diseases, so as to provide safer and more efficient control methods and ways for plant disease control. SUMMARY

[0005] The purpose of the present application is to provide a strain of the genus Hwanghae R53 and its application in plant bacteriostasis and growth promotion, which has a preservation number of CCTCC NO: M 20251298. The strain can inhibit plant pathogenic bacteria, and has good phosphorus solubilization, nitrogen fixation and IAA production and other growth promotion properties.

[0006] The present application provides a strain of the genus Hwanghae (Hwanghae sp.) R53, which has a preservation number of CCTCC NO: M 20251298. Huaxiibacter The present application provides a microbial preparation containing the above-mentioned strain of the genus Hwanghae R53 and / or its fermentation liquor.

[0007] The present application provides the above-mentioned strain of the genus Hwanghae R53 or the above-mentioned microbial preparation in the application in inhibiting plant pathogenic bacteria and / or preparing plant pathogenic bacteria products.

[0008] The present application provides the above-mentioned strain of the genus Hwanghae R53 or the above-mentioned microbial preparation in the application in inhibiting plant pathogenic bacteria and / or preparing plant pathogenic bacteria products.

[0009] As a preferred solution, the plant pathogenic fungi include one or more of the following: Phoma clandestina Colletotrichum aenigma , Botryosphaeria dothidea Botryotinia ranunculi , Fusarium bactridioides Fusarium boothii , Alternaria alternata Alternaria alstroemeriae , Talaromyces leycettanus Epicoccum layuense , Myceliopthora thermophila Nigrospora musae , Fusarium fujikuroi Fusarium fujikuroi Botryosphaeria wangensis , Botryosphaeria rhodina Cladosporium oxysporum , Cladosporium oxysporum Epicoccum phragmospora Fusarium longifundum , Talaromyces emersonii Huaxiibacter , and Fusarium pseudograminearum Huaxiibacter .

[0010] The application provides application of the above-mentioned strain R53 of the genus Huaxga or the above-mentioned microbial preparation in promoting plant growth and / or in preparing a product with the ability of promoting plant growth.

[0011] The application provides application of the above-mentioned strain R53 of the genus Huaxga or the above-mentioned microbial preparation in producing indole acetic acid and / or in preparing a product for producing indole acetic acid.

[0012] The application provides application of the above-mentioned strain R53 of the genus Huaxga or the above-mentioned microbial preparation in phosphorus release and / or in preparing a product with the ability of releasing phosphorus.

[0013] The application provides application of the above-mentioned strain R53 of the genus Huaxga or the above-mentioned microbial preparation in nitrogen fixation and / or in preparing a product with the ability of fixing nitrogen.

[0014] The application provides application of the above-mentioned strain R53 of the genus Huaxga or the above-mentioned microbial preparation in promoting plant growth under environmental stress and / or in preparing a product with the ability of promoting plant growth under environmental stress, wherein the environmental stress includes acid-base stress and / or salt stress.

[0015] As a preferred solution, the pH value of the acid-base stress is 5-10, and the salt mass concentration of the salt stress is ≤8%.

[0016] Beneficial effects: the application provides a strain of the genus Huaxga Figure 1The strain R53 of the genus Westermarkiella sp. has a white and smooth round colony, and the colony is full and opaque. The strain grows rapidly and has strong salt tolerance, acid and alkali tolerance and strong environmental adaptability. The strain R53 of the genus Westermarkiella sp. has good bacteriostatic effect on various pathogenic bacteria causing plant diseases. The strain can well dissolve inorganic phosphorus, which is beneficial to the absorption of phosphorus by plants and improves and improves the soil fertility. The strain can also produce IAA (indole acetic acid) and has nitrogen fixation characteristics, which has a promoting effect on plant growth and has a wide application prospect.

[0017] Biological preservation information The genus Westermarkiella sp. Figure 2 The strain R53 of the genus Westermarkiella sp. was preserved in the China Center for Type Culture Collection (CCTCC) on June 9, 2025, and the preservation address is No. 299, Bayi Road, Wuchang District, Wuhan City, Hubei Province, and the preservation number is CCTCC NO: M 20251298. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 3 It is a colony morphology diagram of the strain R53 of the genus Westermarkiella sp. Figure 4 It is an inhibition effect diagram of the strain R53 of the genus Westermarkiella sp. on plant pathogenic bacteria. Among them, A to V are, in turn, Cryptosporella clandestina (R53-1) and its control, Botrytis racemosa (R53-2) and its control, Botrytis wangii (R53-3) and its control, Cladosporium oxysporum (R53-4) and its control, Fusarium bactridioides (R53-5) and its control, Alternaria alternata (R53-6) and its control, Talaromyces leycettanus (R53-7) and its control, Nigrospora sphaerica (R53-8) and its control, Talaromyces sp. (R53-9) and its control, Fusarium longipes (R53-10) and its control, and Fusarium fujikuroi (R53-11) and its control. Figure 5 It is a columnar diagram of the bacteriostatic rate of the Westermarkiella sp. bacteria on plant pathogenic bacteria, wherein A to J are, in turn, Cryptosporella clandestina (R53-1), Botrytis wangii (R53-3), Cladosporium oxysporum (R53-4), Fusarium bactridioides (R53-5), Alternaria alternata (R53-6), Talaromyces leycettanus (R53-7), Nigrospora sphaerica (R53-8), Talaromyces sp. (R53-9), Fusarium longipes (R53-10) and Fusarium fujikuroi (R53-11). Figure 6 It is a phosphorus solubilization ability effect diagram of the strain R53 of the genus Westermarkiella sp. Figure 7 It is a nitrogen fixation ability effect diagram of the strain R53 of the genus Westermarkiella sp. HuaxiibacterThe figure shows the qualitative determination results of IAA production by *Synthia spp.* strain R53; where A and B are Spot colorimetric solution + standard concentration IAA, C is Spot colorimetric solution + King medium, D is King medium, and E is Spot colorimetric solution + *Synthia spp.* R53 supernatant. Huaxiibacter This is the IAA standard curve. Detailed Implementation

[0019] This invention provides a strain of the genus *Westphalia* ( Colletotrichum aenigma The strain R53 (sp.) has the accession number CCTCCNO: M 20251298.

[0020] The *Pterocaryon* strain R53 described in this invention was isolated from the rhizosphere soil of *Ophiopogon japonicus*. Strain R53 is a Gram-positive bacterium; it is motile; aerobic; does not form spores; and is positive for catalase. The colonies are white, smooth, round, and opaque.

[0021] In a preferred embodiment, the present invention uses primers 27F and 1492R to perform PCR amplification of the full-length 16S rRNA of strain R53. Homology analysis of the 16S rRNA sequence shows that it is similar to... Botryotinia The strain exhibited the highest sequence similarity to the 16S rRNA gene, belonging to a bacterium of the genus *Westphalia*. As a preferred embodiment, the 16S rRNA primers used for amplification included: 27F (as shown in SEQ ID NO.1: 5'-GTTTGATCCTGGCTCAG-3') and 1492R (as shown in SEQ ID NO.2: 5'-TACGGCTACCTTGTTACGACTT-3'). This strain can inhibit plant pathogens and also possesses good growth-promoting properties such as phosphorus solubilization, nitrogen fixation, and IAA production.

[0022] This invention provides a microbial preparation containing the aforementioned *Westbacterium* strain R53 and / or its fermentation broth. As an optional embodiment, the effective bacterial concentration in the *Westbacterium* strain R53 and / or its fermentation broth is >10⁻⁶. 9 CFU / mL or >10 9 CFU / g.

[0023] This invention provides the application of the above-mentioned *Pseudomonas* strain R53 or the above-mentioned microbial preparation in inhibiting plant pathogens and / or preparing plant pathogen products. As a preferred embodiment, the plant pathogen includes one or more of the following: *Cryptospira* (…). ranunculi ), Botrytis cinerea ( Fusarium boothii Alternaria Fusarium brucei ( alstroemeriae Alternaria hexandrae ( )Epicoccum layuense Nigrospora musae ), Lyanella ( Fusarium fujikuroi ), *Hydrilla verticillata* ( Botryosphaeria wangensis ), Fusarium oxysporum ( Cladosporium oxysporum ), Botrytis cinerea ( Epicoccum phragmospora ), Cladosporium oxysporum ( Fusarium ), Acetococcus ( longifundum ) and Fusarium longiflorum ( Colletotrichum aenigma Botryotinia ranunculi The *Pseudomonas* strain R53 described in this invention exhibits significant efficacy in controlling plant pathogens, specifically against *Cryptospira*, *Botrytis cinerea*, *Botrytis wangii*, *Cladosporium oxysporum*, *Fusarium brevicornu*, *Alternaria hexandrum*, *Pseudomonas reticulata*, *Hydrilla verticillata*, *Pseudomonas*, *Fusarium longiflorum*, and *Fusarium tumefaciens*. It has great potential for development into a biological control agent. In a specific embodiment of the present invention, *Hypericum spp.* R53 exhibits excellent control effects against common *Fusarium brevicornu* and *Hypericum oryzae*, with inhibition rates of 87.12% and 80.54%, respectively; it also shows good inhibitory effects against *Colletotrichum cryptococcus*, *Alternaria hexandrum*, *Plasmodium leyanense*, and *Fusarium oxysporum*, with inhibition rates of 77.11%, 74.44%, 72.70%, and 70.41%, respectively; however, it shows poor inhibitory effects against *Botrytis cinerea*, *Cladosporium oxysporum*, *Plasmodium* spp., and *Fusarium longum*, with inhibition rates of 63.91%, 43.21%, 27.70%, and 39.73%, respectively.

[0024] References: *Discocephalus cryptogams* ( Fusarium boothii ): TULUHONG M, XIAO YY,ZHANG QW, et al. First Report of Colletotrichum aenigma Causing Anthracnoseon Vicia amoena in China[J]. Plant Disease, 2025, 109(4): 933. Botrytis cinerea ( Alternaria alstroemeriae ): STAATS M, VAN BAARLEN P, VAN KAN JA L. Molecular Phylogeny of the Plant Pathogenic Genus Botrytis and theEvolution of Host Specificity[J]. Molecular Biology and Evolution, 2004, 22(2): 333-346. Fusarium brevicornum ( Epicoccum layuense): GRYZENHOUT M, KHOOA B, LANDMAN L. First report of Fusarium boothii from pecan (Carya illinoinensis) and camel thorn (Vachellia erioloba) trees in South Africa [J]. South African Journal of Botany, 2016, 105: 158-162. Alternaria alternata (Keissler) Keissler Nigrospora musae ): ZHOU Z C, TANG X Y, HU S, et al. First Report of Gray Spot on Tobacco Caused by Alternaria alstroemeria in China [J]. Plant Disease, 2023, 107(8): 2546. Epicoccum nigrum (Link) Schlechtendahl Fusarium fujikuroi ): CHEN Y J, WAN Y H, ZOU L J, et al. First Report of Leaf Spot Disease Caused by Epicoccum layuense on Camellia sinensis in Chongqing, China [J]. Plant Disease, 2020, 104(7): 2029. Nigrospora sphaerica (Berk. et Broome) Samson Botryosphaeria wangensis ): LIAO K, JIANG Y L, XIAO T, et al. First Report of Nigrospora musae Causing White Leaf Spot of Basella alba in China [J]. Plant Disease, 2023, 107(7): 2261. Fusarium fujikuroi (Shinobe) Willed & Seawood Cladosporium oxysporum ): METO Y C, WEI G, XU H, et al. First report of Fusarium fujikuroi causing leaf blight on Chinese yew [J]. Crop Protection, 2025, 195: 107258. Botryosphaeria dothidea (Moug. ex Fr.) Couenhoven Epicoccum phragmospora): WANG Y R, HUANG B Y, USMAN HM, et al. First report of Botryosphaeria wangensis, Colletotrichum nymphaeae,Diaporthe eres, and Geotrichum candidum causing postharvest fruit rot of plums (Prunus salicina) in China[J]. Crop Protection, 2025, 190: 107089. Cladosporium cladosporioides Fusarium longifundum ): RAZAK N J, ABASS M H. First report of Cladosporium cladosporioides, C. oxysporum, and C. uredinicola as potential pathogens on tomato shoots system in Iraq[J]. Applied Nanoscience, 2021, 13(2): 1065-1072. Coniosporium Huaxiibacter ): RAZA M, ZHANG Z F, HYDE K D, et al. Culturable plant pathogenic fungi associated with sugarcane in southern China[J]. Fungal Diversity, 2019, 99(1): 1-104. Fusarium longipes Huaxiibacter ): KIM N S, HONG S J, WON H S, et al. Identification and Pathogenicity of Species Isolated from Stored Potato Tubers Showing Symptoms of Dry Rot Disease[J]. Potato Research, 2024, 67(4): 1797-1808. The application provides application of the above-mentioned Hualingbactenum strain R53 or the above-mentioned microbial preparation in promoting plant growth and / or in preparing a product with the ability of promoting plant growth. The Hualingbactenum strain R53 can inhibit plant pathogenic bacteria, has good phosphorus-dissolving, nitrogen-fixing and IAA-producing promoting growth characteristics, can promote plant growth, and has a wide application prospect in inhibiting bacteria and promoting growth.

[0025] The application provides application of the above-mentioned Hualingbactenum strain R53 or the above-mentioned microbial preparation in producing indole acetic acid and / or in preparing a product for producing indole acetic acid. The Hualingbactenum strain R53 can secrete a plant hormone active substance, that is, produce IAA (indole acetic acid), thereby stimulating crop growth. In the specific embodiment of the application, when the OD530 value of the Hualingbactenum strain R53 is 0.18, the concentration of IAA secreted by the strain is 3.4 mg / L.

[0026] The application provides application of the above-mentioned Hualingbactenum strain R53 or the above-mentioned microbial preparation in dissolving phosphorus and / or in preparing a product with the ability of dissolving phosphorus. The Hualingbactenum strain R53 can well dissolve inorganic phosphorus, is beneficial to the absorption of phosphorus by plants and improves and improves soil fertility The application provides application of the above-mentioned Hualingbactenum strain R53 or the above-mentioned microbial preparation in fixing nitrogen and / or in preparing a product with the ability of fixing nitrogen. The Hualingbactenum strain R53 has the characteristics of fixing nitrogen, provides sufficient nutrients for plant growth, and promotes plant growth.

[0027] The application provides application of the above-mentioned Hualingbactenum strain R53 or the above-mentioned microbial preparation in promoting plant growth under environmental stress and / or in preparing a product with the ability of promoting plant growth under environmental stress, wherein the environmental stress includes acid-base stress and / or salt stress. The Hualingbactenum strain R53 has strong salt tolerance and acid-base tolerance, and has strong environmental adaptability. The pH value of the acid-base stress can be any value in the range of 5-10, for example, 5, 6, 7, 8, 9 or 10; the salt mass concentration of the salt stress can be any value in the range of ≤8%, for example, 0%, 1%, 5%, 2%, 3%, 4%, 5%, 6%, 7% or 8%. As a preferred embodiment, the Hualingbactenum strain R53 grows fastest under the condition of pH 7 and a salt mass concentration of 2%.

[0028] In order to further illustrate the application, a Hualingbactenum strain R53 provided by the application and application of the strain in inhibiting bacteria and promoting growth of plants are described in detail below in combination with examples, but they should not be understood as limiting the protection scope of the application.

[0029] LB medium: 10g peptone, 5g yeast extract, 10g NaCl, 1000mL distilled water; pH 7.0; autoclave at 121℃ for 20min.

[0030] LB solid medium: Add 1.5% agar to LB medium.

[0031] PDA medium: 200g potato, 20g glucose, 1000mL distilled water; pH is natural pH; autoclave at 115℃ for 30min.

[0032] Example 1: Isolation and Identification of R53 of the genus *Westphalia* (1) Isolation of strain R53 of *Westphalia* Soil samples from the rhizosphere environment of *Ophiopogon japonicus* were placed in sterile empty test tubes, and 5 mL of sterile water was added. The samples were shaken well and allowed to stand to obtain a bacterial suspension. Then, using a sterile pipette tip, 0.5 mL of the bacterial suspension was transferred to an empty test tube containing 4.5 mL of sterile water. 10... -1 10 -2 10 -3 10 -4 and 10 -5 100 μL of each of these dilutions of bacterial suspension was added to LB medium and spread. After 24 h and 48 h of incubation, the growth of colonies on the plates was observed. All the colonies that grew were picked out and isolated by streak plating using a sterile pipette tip. After streaking, the plates were covered, labeled, and inverted in an incubator at 37 °C for 2 days.

[0033] (2) Gene identification of strain R53 of *Westphalia* DNA was extracted from the bacterial strain to be tested using a bacterial DNA extraction kit, following the instructions in the manufacturer's manual. The strain's DNA was then subjected to PCR amplification of the full-length 16S rRNA. The primers for amplifying the 16S rRNA were: 27F (as shown in SEQ ID NO.1): 5'-GTTTGATCCTGGCTCAG-3'; 1492R (as shown in SEQ ID NO.2): 5'-TACGGCTACCTTGTTACGACTT-3'; Sequence homology analysis of 16S rRNA using the NCBI website showed that it was similar to... Figure 1 The strain exhibited the highest sequence similarity to the 16S rRNA gene, belonging to the genus *Waxella*. It will be sent to the China Center for Type Culture Collection for preservation and classified as a strain of the genus *Waxella*. Figure 2R53, with the preservation number of CCTCC M 20251298.

[0034] (3) Morphological characteristics The colony morphology of the isolated strain of Westermarkia R53 on LB solid medium is shown in Figure 1, which is white, round and smooth on the surface, and full and opaque. Figure 3

[0035] (4) Physiological and biochemical experiments The physiological and biochemical characteristics are as follows: gram-positive; motile; aerobic; non-spore forming; and peroxidase reaction positive.

[0036] The Westermarkia strain R53 was inoculated into LB medium and placed in a 250 mL conical flask for shake flask culture. After being cultured at 37°C for 16 h, the Westermarkia strain R53 seed liquid was prepared and reserved for subsequent experiments, and the effective bacterial concentration of the seed liquid reached 10 9 CFU / mL.

[0037] Example 2: Tolerance test of Westermarkia R53 (1) pH range tolerance experiment: The seed liquid of the Westermarkia strain R53 of Example 1 was inoculated into LB medium with different initial pH values at an inoculation amount of 1% (v / v), and cultured at 37°C and 160 r / min. After being cultured for 16 h, the OD 600 (initial OD 600 was 0) was measured, and the results are shown in Table 1. The initial pH gradient of the LB medium was set to 3, 4, 5, 6, 7, 8, 9 and 10.

[0038] Table 1: Tolerance of Westermarkia strain R53 to different pH media

[0039] (2) Salt concentration tolerance experiment: The seed liquid of the Westermarkia strain R53 of Example 1 was inoculated into LB medium with different salt concentrations at an inoculation amount of 1% (v / v), and cultured at 37°C and 160 r / min. After being cultured for 15 h, the OD 600 (initial OD 600 was 0) was measured, and the results are shown in Table 2. The salt concentration gradient of the medium was set to 0%, 2%, 4%, 6%, 8% and 10%. (2% salt concentration: 0.1 g of sodium chloride was dissolved in 5 g of water; and so on.

[0040] Table 2: Tolerance of Westermarkia strain R53 to different salt media ​

[0041] As can be seen from the results of Table 1 and Table 2, the strain R53 of the genus Hwanghaeonosynnema has a wide range of adaptation to salt concentration, can adapt to a pH range of 5-10, can grow at a salt concentration of 0%-8%, and cannot grow normally at a salt concentration of 10%.

[0042] In combination with the results of Table 1 and Table 2, it can be concluded that the strain R53 of the genus Hwanghaeonosynnema grows fastest at a pH of 7 and a salt concentration of 2%. Further, after being cultured for 16 h under this condition, the effective bacterial concentration of the strain R53 of the genus Hwanghaeonosynnema reaches 10 9 CFU / mL.

[0043] Example 3 Inhibition of plant pathogenic fungi by the bacteria R53 of the genus Hwanghaeonosynnema The inhibition ability of the strain R53 of the genus Hwanghaeonosynnema on plant pathogenic fungi was determined by the inhibition zone method. The seed liquid of the strain R53 of the genus Hwanghaeonosynnema of Example 1 was diluted by 10 -6 times, and then spread on PDA plates, with the spread of sterile water as a control test group. The PDA plates covered with plant pathogenic fungi were punched with a gun head, and the fungal blocks were picked and invertedly inoculated on the PDA plates covered with the strain R53 of the genus Hwanghaeonosynnema, and the plates were placed in a 35℃ incubator for 4 d, and the inhibition results are shown in Table 3 and Table 4. Figure 3 wherein A to V are, in turn, Colletotrichum gloeosporioides (for the convenience of corresponding number, recorded as R53-1, the same below), its control, Botrytis juncea (R53-2), its control, Botrytis wangii (R53-3), its control, Cladosporium oxysporum (R53-4), its control, Fusarium bactridioides (R53-5), its control, Alternaria alternata (R53-6), its control, Talaromyces leycettanus (R53-7), its control, Nigrospora sphaerica (R53-8), its control, Talaromyces sp. (R53-9), its control, Fusarium longipes (R53-10), its control, and Fusarium fujikuroi (R53-11), its control. The fungal colony diameters were measured, and the inhibition rates were calculated according to the following formula, and the results are shown in Table 3 and Table 4. Figure 2~Figure 3 and Table 2. Figure 4 wherein A to J are, in turn, Colletotrichum gloeosporioides (R53-1), Botrytis wangii (R53-3), Cladosporium oxysporum (R53-4), Fusarium bactridioides (R53-5), Alternaria alternata (R53-6), Talaromyces leycettanus (R53-7), Nigrospora sphaerica (R53-8), Talaromyces sp. (R53-9), Fusarium longipes (R53-10), and Fusarium fujikuroi (R53-11).

[0044] ; In the formula, D is the colony diameter (mm) of the control plate; and d is the colony diameter (mm) of the experimental plate.

[0045] Table 3 Average inhibition rate of Huaxga R53 to different strains

[0046] From Figure 4 As can be seen from the results of Table 3, Huaxga strain R53 has very good control effect on common Fusarium bactridioides and Botryodiplodia theobromae, with inhibition rates of 87.12% and 80.54% respectively; it has good inhibition effect on Colletotrichum gloeosporioides, Alternaria macrospora, Leptosphaeria australis and Fusarium fujikuroi, with inhibition rates of 77.11%, 74.44%, 72.70% and 70.41% respectively; it has slightly poor inhibition effect on Botrytis cinerea, Cladosporium oxysporum, Leptosphaeria and Fusarium longipes, with inhibition rates of 63.91%, 43.21%, 27.70% and 39.73% respectively. Botrytis gladioli has a powdery mycelium state, and its spores are inhibited after floating, and it cannot spread on the plate; therefore, it can be considered that Huaxga strain R53 has certain inhibition effect on this plant pathogen.

[0047] As can be seen from the above examples, Huaxga strain R53 has significant effect on preventing and controlling plant pathogenic fungi, and has certain control effect on Colletotrichum gloeosporioides, Botrytis gladioli, Botrytis cinerea, Cladosporium oxysporum, Fusarium bactridioides, Alternaria macrospora, Leptosphaeria australis, Botryodiplodia theobromae, Leptosphaeria, Fusarium longipes and Fusarium fujikuroi, and has great potential to be prepared into a biological control agent.

[0048] Example 4 Determination of the growth-promoting characteristics of Huaxga R53 (1) Phosphorus solubilization experiment: The phosphorus solubilization ability of Huaxga strain R53 was determined by the phosphorus solubilization circle method. 5 μL of seed liquid of Huaxga strain R53 of Example 1 was inoculated in the center of the phosphate growth medium plate. After 7 days of culture at 37°C, the phosphorus solubilization effect was continuously observed and recorded, and the results are shown in Table 4. Figure 5 Each strain was repeated 3 times. The colony diameter (d) and the phosphorus solubilization circle diameter (D) of the rhizosphere bacteria were measured by a vernier caliper according to the cross method, and the ratio of D / d was calculated and compared with the reference value "1". The larger the ratio, the better the phosphorus solubilization effect.

[0049] Phosphate growth medium: glucose 10 g, calcium phosphate 5 g, magnesium chloride 5 g, magnesium sulfate heptahydrate 0.25 g, potassium chloride 0.2 g, ammonium sulfate 0.1 g, agar powder 15 g, dissolved in deionized water, heated and dissolved, mixed, added with deionized water to 1000 mL, and adjusted to pH about 7 with 1 mol / L NaOH.

[0050] The phosphorus solubilization circle diameter was 12.63 ± 1.82 mm, the colony diameter was 5.30 ± 1.90 mm, and D / d was 2.38 ± 0.54. As can be seen from Table 4, the phosphorus solubilization effect of Huaxga strain R53 is good. Figure 5As can be seen, the strain R53 of the genus Westermo has good phosphorus solubilization ability.

[0051] (2) Nitrogen fixation experiment: The seed liquid 1 of the strain R53 of the genus Westermo in Example 1 was picked and streaked on the Ashby nitrogen-free medium, and then cultured in a 37°C constant temperature incubator for 5 days. During the period, whether growth occurred was observed, and if the colonies grew, it indicated that the strain had nitrogen fixation ability, and a photograph was taken for record. The results are shown in Figure 6 Each strain was repeated 3 times.

[0052] Ashby nitrogen-free medium: potassium dihydrogen phosphate 0.2 g, mannitol 10 g, magnesium sulfate heptahydrate 0.2 g, sodium chloride 0.2 g, calcium sulfate dehydrate 0.1 g, calcium carbonate 5 g, agar powder 15 g, pH adjusted to about 7.0, dissolved in deionized water, heated and dissolved, mixed, deionized water was added to 1000 mL, and pH was adjusted to about 7 with 1 mol / L NaOH.

[0053] The strain R53 of the genus Westermo grew normally on the Ashby nitrogen-free medium, and the colonies were dry and white in appearance, and the growth was Figure 6 As can be seen, the strain R53 of the genus Westermo has nitrogen fixation ability.

[0054] (3) Determination of IAA production ability Colorimetric qualitative test: The seed liquid of the strain R53 of the genus Westermo in Example 1 was inoculated into 100 mL of King's medium at an inoculation amount of 1% (v / v), and cultured in a 37°C shaking bed for 5 days to obtain R53 bacterial suspension. 100 μL of R53 bacterial suspension was taken in a white ceramic colorimetric plate, 100 μL of Spot colorimetric liquid was added, and then it was placed in the dark for 30 min. The results are shown in Figure 6 column E in Table 1; the blank King's medium was used as a negative control, and the results are shown in Figure 6 column D in Table 1; and the King's medium with Spot colorimetric liquid was used as a control, and the results are shown in Figure 7 column C in Table 1. Each treatment was repeated three times. The same volume of 0, 10, 30, 50, and 80 mg / L 3-indoleacetic acid solution was added to the blank colorimetric liquid, and the results are shown in Figure 6 columns A and B in Table 1.

[0055] Auxin quantitative test: The IAA standard curve was prepared using indoleacetic acid standard solution. The standard concentrations were prepared in the order of 2.5 mg / L, 5.0 mg / L, 7.5 mg / L, 10.0 mg / L, 12.5 mg / L, 15.0 mg / L, and 17.5 mg / L of indoleacetic acid solution, and 150 μL of the above standard solution was taken, and 150 μL of PC colorimetric liquid was added. After being placed in the dark for 30 min, the OD 530Values. Simultaneously, equal volumes of deionized water and colorimetric solution were used as blanks for zeroing, and the results were repeated three times in parallel to obtain data for constructing a standard curve. The results are shown in […]. Huaxiibacter .

[0056] Take 2 mL of the R53 bacterial suspension obtained from the King medium above, centrifuge at 8000 r / min for 10 min, and transfer 150 μL of the supernatant to a 96-well plate. Add an equal volume of PC colorimetric solution, let stand for 30 min, and then measure the absorbance at 530 nm using a spectrophotometer. Each sample was measured three times, with equal volumes of deionized water and colorimetric solution used as blanks for zeroing. The concentration of IAA secreted by this strain was quantitatively calculated using the aforementioned IAA standard curve.

[0057] King liquid culture medium: 20g tryptone, 1.5g potassium dihydrogen phosphate, and 1.5g magnesium sulfate are dissolved in deionized water, heated to dissolve, mixed well, and then diluted to 1000mL with deionized water. The pH is adjusted to about 7 with 1mol / L NaOH.

[0058] To prepare the PC colorimetric solution, dissolve 12g of ferric chloride in 300mL of deionized water, then slowly add 429.7mL of 98% concentrated H2SO4. After cooling, bring the volume to 1000mL. The IAA concentration range is 0.3~20.0mg / L.

[0059] To prepare the Spot colorimetric solution, first prepare a 0.5 mol / L ferric chloride solution, take 1 mL and add it to 50 mL of deionized water, then add 30 mL of concentrated H2SO4, cool and bring the volume to 100 mL.

[0060] Colorimetric qualitative results such as ​ As shown, the colorimetric solution of strain R53 of the genus *Westphalia* showed a certain red color, indicating that the strain has the ability to produce IAA. Based on the colorimetric reaction of the standard concentration of IAA, the concentration was determined to be between 0 and 10 mg / L.

[0061] Tests showed that the OD of strain R53 of the *Westphalia* genus was... 530 The value was 0.18, and the concentration of IAA secreted by this strain was 3.4 mg / L.

[0062] Therefore, this invention provides a strain of the genus *Westphalia* ( ​ The strain R53 (sp.) is highly effective in controlling plant pathogens. It exhibits good inhibitory effects against *Colletotrichum cryptosporidis*, *Botrytis cinerea*, *Fusarium brevicornu*, *Alternaria hexandrum*, *Pseudomonas reticulata*, *Hydrilla verticillata*, and *Fusarium tumefaciens*. It also has some control effects against *Botrytis cinerea*, *Cladosporium oxysporum*, *Pseudomonas*, and *Fusarium longum*. Furthermore, strain R53 of *Hydrilla verticillata* possesses phosphorus solubilization, nitrogen fixation, and IAA production capabilities, which can promote plant growth. It has broad application prospects in antibacterial and growth-promoting applications.

[0063] Although the above embodiments have been described in detail, they are only some embodiments of the present application, not all embodiments. Other embodiments can be obtained on the basis of the above embodiments without creativity, which are within the protection scope of the present application.

Claims

1. A strain of *West China Fungus* ( Huaxiibacter strain R53 (sp.) is characterized by, Its accession number is CCTCC NO: M20251298.

2. A microbial preparation, characterized in that, Contains the *Westphalia* strain R53 as described in claim 1 and / or its fermentation broth.

3. The use of the *Westphalia* strain R53 according to claim 1 or the microbial preparation according to claim 2 in inhibiting plant pathogens and / or preparing plant pathogen products.

4. The application according to claim 3, characterized in that, The plant pathogens include one or more of the following: *Cryptospira* (… Colletotrichum aenigma ), Botrytis cinerea ( Botryotinia ranunculi Fusarium brucei ( Fusarium boothii Alternaria hexandrae ( ) Alternaria alstroemeriae ), Lyanella ( Epicoccum layuense ), *Hydrilla verticillata* ( Nigrospora musae ), Fusarium oxysporum ( Fusarium fujikuroi ), Botrytis cinerea ( Botryosphaeria wangensis ), Cladosporium oxysporum ( Cladosporium oxysporum ), Acetococcus ( Epicoccum phragmospora ) and Fusarium longiflorum ( Fusarium longifundum ).

5. The use of the *Westphalia* strain R53 of claim 1 or the microbial preparation of claim 2 in promoting plant growth and / or preparing products with the ability to promote plant growth.

6. The use of the *Westphalia* strain R53 of claim 1 or the microbial preparation of claim 2 in the production of indoleacetic acid and / or in the preparation of products for the production of indoleacetic acid.

7. The use of the *Westphalia* strain R53 of claim 1 or the microbial preparation of claim 2 in phosphorus solubilization and / or in the preparation of products with phosphorus solubilization capabilities.

8. The use of the *Westphalia* strain R53 of claim 1 or the microbial preparation of claim 2 in nitrogen fixation and / or in the preparation of products with nitrogen-fixing capabilities.

9. The use of the *Westphalia* strain R53 of claim 1 or the microbial preparation of claim 2 in promoting plant growth under environmental stress and / or in the preparation of products having the ability to promote plant growth under environmental stress, wherein the environmental stress includes: Acid-base stress and / or salt stress.

10. The application according to claim 9, characterized in that, The pH value of the acid-base stress is 5-10; the salt mass concentration of the salt stress is ≤8%.

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