Pseudomonas nitroreducens GXN01 and application thereof

Abstract

The invention discloses pseudomonas nitroreducens GXN01 and application thereof, the pseudomonas nitroreducens GXN01 is preserved in Guangdong Microbial Culture Collection Center on December 20, 2024, the preservation number of the pseudomonas nitroreducens GXN01 is GDMCC NO: 65658, and the preservation address of the pseudomonas nitroreducens GXN01 is the 5th building, No. 59 building, No. 100 Courtyard, Xianlie Middle Road, Guangzhou. The pseudomonas nitroreducens provided by the invention has a remarkable and rapid degradation effect on quorum sensing signal molecules BDSF, and has huge application potential in the aspect of prevention and treatment of pathogenic bacteria caused by DSF family quorum sensing signal molecules, so that a new possibility is provided for replacing chemical prevention and treatment with biological prevention and treatment; and a new development way is provided for a prevention and control strategy taking a pathogenic bacteria quorum sensing system as a new target.

Description

Technical Field

[0001] The invention belongs to the technical field of biological control, and particularly relates to nitroreducing Pseudomonas GXN01 and applications thereof. Background Art

[0002] Citrus canker ( Xanthomonas citri pv. citri , Xcc Citrus canker, induced by citrus fruit, has become a major disease that hinders the sustainable development of citrus. The amount of pesticides used to treat citrus canker on Wogan accounts for 50% of the total pesticide cost. During the peak canker season, spraying is done once a week. Commonly used pesticides include copper-containing preparations, antibiotics, and antagonistic live bacteria. Due to the scarcity of non-copper preparations, or their poor effectiveness and high price, copper-containing preparations account for over 80% of the market share and are used more than 15 times a year. The long-term and extensive use of copper preparations and antibiotics increases risks to the ecological environment and promotes the resistance of pathogens. With the increasing use of copper preparations, the negative impacts of prevention and control (drug residues, decreased immunity of citrus trees, and pesticide damage) have attracted great attention. There is an urgent need to develop low-toxic, highly effective, low-residue, and environmentally friendly non-copper fungicides.

[0003] Quorum sensing (QS) is a cell-to-cell communication mechanism typically achieved by diffusible small molecules synthesized and secreted within bacterial cells. Through this mechanism, microorganisms can detect the concentration of self-secreted small signaling molecules, thereby understanding their population density. Based on this information, microorganisms can regulate the expression of specific genes to adapt to environmental changes and enhance survival and competitiveness. Specifically, as the number of cells in a microbial population increases, the concentration of signaling molecules released into the environment also increases. Once these signaling molecules reach a certain threshold, microorganisms sense this change and trigger a series of changes in gene expression related to growth, metabolism, virulence factor production, and biofilm formation. This mechanism enables microorganisms to coordinate their actions at high population densities, optimize resource utilization, and enhance overall adaptability and survival. Because many pathogenic bacteria use quorum sensing signals to regulate various physiological activities such as motility, biofilm formation, and exoenzyme production, they can better adapt to their surroundings and enhance their pathogenicity to their host plants. Therefore, quorum sensing systems are considered an ideal new target for controlling the occurrence and development of diseases. Previous studies have shown that Xanthomonas disease can be prevented and controlled through signal quenching (quorum quenching, QQ), simulated signal interference, biofilm disaggregation, etc. Some research has been carried out on citrus canker fungus.

[0004] Quorum quenching is a process that disrupts or disrupts the quorum sensing system. While it doesn't affect bacterial growth, it can weaken the expression of pathogenicity factors, keeping bacterial populations at a low density. Quorum quenching doesn't create natural selection pressure in bacteria, and therefore doesn't contribute to the development of drug resistance.

[0005] Quorum quenching occurs through three main pathways: inhibiting the synthesis of signal molecules by quorum sensing signal synthases, quenching and degrading the quorum sensing signal molecules themselves, and inhibiting the receptor proteins that produce quorum sensing signals. Quorum quenching primarily interferes with these three targets: the signal molecule synthase, the signal molecules themselves, and the signal receptor proteins. This weakens the expression of many virulence factors, further reducing the pathogenicity of the pathogen to its host plant.

[0006] Currently, the most widely studied and effective application of quorum quenching is quorum quenching enzymes, which have been widely tested and applied in agriculture, aquaculture, and other fields. Identifying microbial strains that can effectively degrade the DSF signaling family of molecules has far-reaching practical significance for enriching microbial resources and preventing and treating citrus canker.

[0007] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute prior art known to ordinary technicians in the field. Summary of the Invention

[0008] The present invention aims to provide a nitroreducing Pseudomonas GXN01 and its use. The nitroreducing Pseudomonas of the present invention has a significant and rapid degradation effect on the quorum sensing signal molecule BDSF, and has great application potential in preventing and controlling the harm of BDSF-mediated pathogenic bacteria. This provides new possibilities for replacing chemical control with biological control and provides a new development path for control strategies with the pathogen quorum sensing system as a new target.

[0009] In order to achieve the above object, the present invention provides a nitroreducing Pseudomonas, wherein the nitroreducing Pseudomonas ( Pseudomonas nitroreducens ) GXN01, deposited in Guangdong Provincial Microbial Culture Collection Center, the deposit number is GDMCC NO: 65658, the deposit time is December 20, 2024, and the deposit address is: 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou.

[0010] Preferably, the 16S rDNA sequence of the nitroreducing Pseudomonas sp. GXN01 is shown in SEQ ID NO.1 in the sequence listing.

[0011] The second object of the present invention is to provide a use of the nitroreducing Pseudomonas GXN01 in degrading quorum sensing signal molecules, wherein the signal molecules belong to the DSF quorum sensing signal molecule family.

[0012] Preferably, the DSF comprises: BDSF (cis-2-dodecenoic acid).

[0013] The third object of the present invention is to provide a use of the nitroreducing Pseudomonas GXN01 in the preparation of a biocontrol agent for pathogenic bacteria that rely on the quorum sensing signal molecule DSF family to cause disease, wherein the pathogen is citrus canker ( Xanthomonascitri pv. Citri , Xcc ) or / and Angular leaf spot of mango ( Xanthomonas citri pv. mangiferaeindicae , Xcm ).

[0014] The fourth object of the present invention is to provide a biocontrol agent for pathogenic bacteria that rely on the quorum sensing signal molecule BDSF and / or the DSF family to cause disease, wherein the biocontrol agent comprises the nitroreducing Pseudomonas GXN01.

[0015] The fifth object of the present invention is to provide a method for preventing and treating citrus canker and mango bacterial angular spot, wherein the plants are treated with the bacterial suspension of the nitroreducing Pseudomonas GXN01.

[0016] Preferably, when used, the culture medium used to prepare the nitroreducing Pseudomonas GXN01 bacterial suspension is LB culture medium, whose formula is: 10.0 g / L tryptone, 5.0 g / L yeast extract and 10.0 g / L sodium chloride.

[0017] Preferably, when used, the cultured Pseudomonas nitroreducens GXN01 is resuspended in PBS buffer.

[0018] Preferably, when applied, the treatment is carried out by spraying the plants.

[0019] The nitroreducing Pseudomonas GXN01 of the present invention and its application have the following advantages: (1) The nitroreducing Pseudomonas of the present invention has a significant and rapid degradation effect on the quorum sensing signal molecule DSF (such as BDSF), can grow normally in a culture medium with a concentration of up to 5 mM BDSF as the sole carbon source, and can completely degrade the quorum sensing signal molecule BDSF with an initial concentration of 0.5 mM within 6 to 9 hours. It has great application potential in preventing and controlling the harm of pathogens that cause disease mediated by BDSF, which provides new possibilities for replacing chemical control with biological control and provides a new development path for control strategies with the quorum sensing system of pathogens as a new target; (2) The nitroreducing Pseudomonas strain GXN01 of the present invention has strong resistance to ampicillin and streptomycin, and its growth is hardly affected when the antibiotic concentration reaches 200 μg / mL. It also has strong resistance to rifampicin, carbenicillin and chloramphenicol. Although its growth is inhibited to a certain extent at 200 μg / mL, it can still maintain growth. (3) The nitroreducing Pseudomonas strain GXN01 of the present invention can significantly inhibit the growth of citrus canker pathogens in mandarin orange leaves and can be used to prevent and treat citrus canker. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a colony morphology diagram of the strain GXN01 of the present invention on LB culture medium.

[0021] Figure 2 This is a single colony morphology diagram of the strain GXN01 of the present invention on LB culture medium.

[0022] Figure 3 This is a phylogenetic tree analysis diagram of the strain GXN01 of the present invention.

[0023] Figure 4 This is a diagram showing the growth of the strain GXN01 of the present invention in different antibiotics.

[0024] Figure 5 LC-MS graph (A) of BDSF degradation by the strain GXN01 of the present invention at 9 h and a control graph (B) of BDSF content at 0 h.

[0025] Figure 6 The figure shows the transparent zone produced by the strain GXN01 of the present invention when it degrades BDSF on a solid MM inorganic salt medium plate with BDSF as the sole carbon source.

[0026] Figure 7 Graphs showing the growth and degradation curves of the strain GXN01 of the present invention when BDSF is used as the sole carbon source.

[0027] Figure 8The disease condition of citrus leaves 10 days after the strain GXN01 of the present invention was inoculated alone and in combination with citrus canker pathogen; (A) Xcc 306; (B) GXN01+ Xcc 306; (C) GXN01; (D) PBS.

[0028] Figure 9 The bacterial leaf growth curves of the strain GXN01 of the present invention inoculated alone and inoculated with citrus canker bacteria on citrus leaves for 10 days; 306 in the figure is Xcc 306.

[0029] Figure 10 The disease occurrence of mango leaves 14 days after the strain GXN01 of the present invention was inoculated alone or co-inoculated with the bacterial angular leaf spot pathogen of mangoes; (A) Xcc 306; (B) Xcm ;(C)GXN01+ Xcm . DETAILED DESCRIPTION

[0030] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0031] Note: If specific conditions are not specified in the examples, the experiments were conducted under conventional conditions or those recommended by the manufacturer. Instruments used without manufacturer information are commercially available. Raw materials and reagents used without manufacturer information are commercially available or can be prepared by known methods.

[0032] Throughout this disclosure, all features, such as values, amounts, amounts, and concentrations, specified in numerical ranges or percentage ranges are provided for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to encompass and specifically disclose all possible subranges and individual values ​​within those ranges (including integers and fractions).

[0033] The features described in this disclosure may be combined in any manner, and as long as there are no conflicts between the combinations of these features, all possible combinations should be considered within the scope of this specification. Each feature disclosed in this specification may be replaced by any alternative feature that provides the same, equivalent, or similar purpose. Therefore, unless otherwise specified, the features disclosed are merely general examples of equivalent or similar features.

[0034] Example 1 Acquisition and Identification of Nitroreducing Pseudomonas GXN01 1. Isolation and screening of strain GXN01 The soil samples were collected from the soil 5 cm deep below the roots of citrus plants suffering from citrus canker in the specimen garden of Guangxi University in Nanning, Guangxi Zhuang Autonomous Region on November 23, 2022, and brought back to the laboratory as microbial resources for strain isolation.

[0035] (1) Preparation of culture medium: Prepare LB solid medium and MM* inorganic salt medium containing 0.5, 1, or 5 mM BDSF as the sole carbon source, adjust the pH to 7.0, and sterilize at 121°C for 20 min.

[0036] The inorganic components and concentrations of MM* inorganic salt medium are: 10.5 g / L K2HPO4, 4.5 g / L KH2PO4, 2.0 g / L (NH4)2SO4, 0.2 g / L MgSO4·7H2O, 0.009 g / L FeSO4·7H2O, 0.01 g / L CaCl2 and 0.003 g / L MnCl2·4H2O.

[0037] The composition and concentration of LB medium are: 10.0 g / L tryptone, 5.0 g / L yeast extract, and 10.0 g / L sodium chloride (NaCl).

[0038] Preparation of MM* inorganic salt medium with 5 mM BDSF as the sole carbon source: Use methanol as the solvent to prepare BDSF stock solution, mix the BDSF stock solution with MM inorganic salt medium that has been heated and then cooled to about 55°C, and pour the mixture into the plate to make the final BDSF concentration 5 mM.

[0039] The preparation of MM*Mineral Salts medium with 0.5 or 1 mM BDSF as the sole carbon source refers to the preparation of MM*Mineral Salts medium with 5 mM BDSF as the sole carbon source.

[0040] The above solid culture medium formulas all add 1% (w / v) agar to the liquid culture medium and sterilize it with high temperature and moist heat.

[0041] (2) Strain isolation and purification: Gradient dilution and plate spreading methods were used for isolation.

[0042] For each 1 g of soil sample, 100 mL of sterilized saline was used to soak the sample and cultured overnight in a shaker at 28°C and 200 rpm. The overnight cultured sample was allowed to stand at room temperature for 30 min, and the supernatant was diluted with sterile water to a gradient of 10 -1 ~10 -3Concentration. Take 100 μL of each dilution and evenly spread it on MM* inorganic salt solid medium plates with BDSF at a final concentration of 1 mM as the sole carbon source. Spread three plates for each concentration as replicates. Place the plates upside down in a 28°C incubator and incubate until single colonies are visible to the naked eye.

[0043] Use a sterile toothpick to pick single bacterial colonies of different morphologies and transfer them to LB liquid medium. Incubate overnight at 28°C and 200 rpm. Streak the culture onto an LA plate to purify the single colonies. Transfer the single colonies to LB liquid medium and culture overnight. Add 50% glycerol to the resulting culture at a 1:1 volume ratio, mix thoroughly, and store at -80°C until ready for screening. This will yield the strain to be screened.

[0044] (3) Strain screening: The strains isolated from the soil samples were screened again using MM* inorganic salt medium with 5 mM BDSF as the sole carbon source.

[0045] After activating the preserved strains, pick a single colony with a sterile toothpick and inoculate it onto an MM* plate containing 5 mM BDSF as the sole carbon source. Incubate in a 28°C incubator for 48 hours. Select a single colony with a larger transparent zone and transfer it to LB liquid medium. Incubate overnight at 28°C and 200 rpm. Adjust the concentration of the overnight culture to OD 600 = 1, centrifuge at 10,000 rpm for 1 minute, and resuspend in MM* inorganic salt liquid medium. Take 1 μL of the bacterial suspension and inoculate it onto a plate containing 5 mM BDSF for further screening. Place the plate in a 28°C incubator for 48 hours. After 48 hours, observe the size of the clearing zone produced by each strain on the plate. After statistical analysis, the strain with the largest clearing zone was identified and named GXN01 for further research.

[0046] 2. Identification and phylogenetic analysis of strain GXN01 (1) Colony morphology characteristics: The strain GXN01 was streaked onto LA solid medium and incubated upside down in a constant temperature incubator at 28°C for 24 h. The colonies appeared as beige circular colonies with a smooth and translucent surface, neat edges, and a slight bulge in the middle. Figure 1 When strain GXN01 is cultured at 28℃ for more than 48 hours, the colonies appear light pink, with neat edges, a smooth and translucent surface, and a slight bulge in the middle. Figure 2 shown.

[0047] (2) 16S rDNA sequence and phylogenetic analysis: By sequencing the whole genome of strain GXN01, it was found that the 16S rDNA gene sequence of strain GXN01 was 1525bp in length, and the gene sequence was shown in SEQ ID NO.1. Comparison with the NCBI database revealed that strain GXN01 had high similarity with other published genomes of nitroreducing Pseudomonas. Its phylogenetic tree is shown in Figure 3 shown.

[0048] The sequence SEQ ID NO.1 is shown below:

[0049] In summary, through the identification and analysis of the morphological characteristics and 16S rDNA gene sequence of the strain GXN01, it was identified that the strain belongs to Pseudomonas nitroreducens ( Pseudomonas nitroreducens ), the strain was named nitroreducing Pseudomonas GXN01 strain, and was deposited in Guangdong Provincial Microbiological Culture Collection Center (GDMCC) on December 20, 2024, with the deposit number GDMCC NO: 65658. The deposit address is: 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou.

[0050] Example 2 Antibiotic Sensitivity Analysis of Strain GXN01 In order to better investigate the biocontrol potential of strain GXN01 obtained in Example 1, the biological characteristics of strain GXN01 were studied in depth. The sensitivity of strain GXN01 to different antibiotics was investigated. Nine antibiotics commonly used for disease control in the laboratory and field (polymyxin Pb, rifampicin Rif, gentamicin Gen, ampicillin Amp, tetracycline Tc, kanamycin Kan, carbenicillin Card, chloramphenicol Cm, and streptomycin Str) were selected and the concentration range was set between 0 and 200 μg / mL. The overnight culture of GXN01 was adjusted to an OD of 0. 600 = 1, inoculated into LB liquid medium containing the corresponding antibiotic concentration at a volume ratio of 1:100, cultured at 28 °C and 200 rpm for 48 h, and the OD was measured. 600 Each experiment was repeated three times, and the whole experiment was repeated three times. The specific results are as follows Figure 4 shown.

[0051] Experimental results showed that the strain GXN01 was highly resistant to ampicillin (Amp) and streptomycin (Str), and its growth was hardly affected when the antibiotic concentration reached 200 μg / mL. It was also highly resistant to rifampicin (Rif), carbenicillin (Card), and chloramphenicol (Cm). Although its growth was inhibited to a certain extent at 200 μg / mL, it was still able to maintain growth. It was relatively sensitive to polymyxin (Pb), gentamicin (Gen), tetracycline (Tc), and kanamycin (Kan), with a resistance range of less than 25 μg / mL.

[0052] Example 3 Determination of BDSF-degrading ability of strain GXN01 Pick a single GXN01 colony that grows well on the LA plate, transfer it to LB liquid medium, and culture it overnight at 28°C and 200 rpm. Adjust the bacterial concentration to OD 600= 0.5, centrifuge the bacterial solution at 10,000 rpm for 1 min, discard the supernatant, resuspend in 1 mL of MM* inorganic salt liquid medium, and then inoculate the bacterial solution into MM* inorganic salt liquid medium with a final concentration of 0.5 mM BDSF as the sole carbon source at a volume ratio of 1:100. Culture the cells in a shaking incubator at 28°C and 200 rpm, and measure the OD at 3 h, 6 h, 9 h, 12 h, and 24 h, respectively. 600 The growth curve of GXN01 in MM* inorganic salt liquid medium was drawn, and 3 mL of bacterial liquid was extracted three times with equal volumes of ethyl acetate. The organic layer was concentrated, dissolved with 400 μL of chromatography-grade methanol, and directly sent for LC-MS detection and analysis of BDSF concentration.

[0053] LC-MS test results are as follows Figure 5 As shown in the figure (B is the BDSF content detected at 0 h), the LC-MS detection results showed that strain GXN01 could completely degrade BDSF with an initial concentration of 0.5 mM within 9 h.

[0054] In addition, strain GXN01 degraded BDSF on MM inorganic salt solid medium with BDSF as the only carbon source, and produced transparent hydrolysis circles as shown in the following figure. Figure 6 The growth and degradation curves of strain GXN01 with BDSF as the sole carbon source are shown in Figure 7 As shown, it was also shown that strain GXN01 had a significant degradation effect on BDSF.

[0055] Example 4 Study on the biocontrol effect of strain GXN01 on citrus canker This example studies the effect of strain GXN01 on citrus canker ( Xanthomonascitri pv. citri , that is, the following Xcc 306) are as follows: The cultured GXN01 and Xcc 306 bacterial suspensions were adjusted to OD 600 = 1, washed twice with PBS and resuspended for use. Xcc 306 were mixed in a volume ratio of 1:1 as the experimental group. Xcc A 1:1 volume ratio of 306 mixed with PBS served as a positive control, a 1:1 volume ratio of GXN01 mixed with PBS served as a negative control, and an equal volume of PBS served as a blank control. Fresh, young, and age-matched mandarin orange leaves were sterilized with 0.8% NaClO for 15 minutes, then rinsed at least three times with sterile water until no NaClO remained. The leaves were then air-dried and placed on a glass plate lined with moistened sterile filter paper. The petioles were then wrapped with sterile cotton.

[0056] Use a sterile needle to poke holes on both sides of the veins on the back of the leaves, poke 4 holes on each leaf, and poke 3 holes in each part. Use a hole puncher to punch the filter paper into small discs and sterilize them in advance. Cover the small holes with the sterilized small discs and add 10 μL of the above-mentioned bacterial solution and PBS for each treatment group. Wrap the plate with a fresh-keeping bag and place it in a constant temperature incubator at 28℃. Remove the small discs after 24 hours. Take out at least 3 leaves every other day and use a hole puncher to take the mixed inoculation of GXN01 and Xcc 306. Single vaccination Xcc For lesions of 306, add 1 mL of sterile water and grind the lesions together in a sterile mortar. After gradient dilution, select the gradient as needed. Pipette 10 μL of the grinding solution and spot it on a NA solid medium plate containing rifampicin. After 3 days, observe and count the single colonies that grow. Plot the number of days as the horizontal axis and the number of colonies as the vertical axis. Xcc The leaf growth curve of 306 was analyzed.

[0057] like Figure 8 As shown, 10 days after inoculation, both the blank control PBS and the negative control GXN01 could not produce lesions on the leaves of Wogan ( Figure 8 A, B); while the positive control 306 strain (i.e. Xcc 306) can produce obvious ulcer spots on the leaves of Wogan. The surface of the lesions is raised, yellow-brown, and spreads around the inoculation needle hole ( Figure 8 C); Compared with the positive control, the lesion surface of the mandarin orange leaves inoculated with a 1:1 mixture of GXN01 and 306 strains had almost no ridges and was relatively flat, with a lighter yellow color, and the area of ​​the lesions spreading around the pinholes became smaller ( Figure 8 D).

[0058] like Figure 9 As shown in the figure, the results of leaf growth showed that when GXN01 and 306 strains were mixed and inoculated into Wogan leaves in a ratio of 1:1, the number of pathogens in the leaves was significantly lower than that when 306 was inoculated alone, indicating that GXN01 had a significant inhibitory effect on the growth of 306 in Wogan leaves.

[0059] In summary, strain GXN01 Xcc It has a significant biocontrol effect on citrus canker caused by 306.

[0060] Example 5 Study on the biocontrol effect of strain GXN01 on bacterial angular leaf spot of mango This example studies the effect of strain GXN01 on bacterial angular leaf spot of mango ( Xanthomonascitri pv. mangife raeindicae , that is, the following Xcm The biocontrol effects of The cultured GXN01 and Xcm The bacterial suspension was adjusted to OD 600 =1, washed twice with PBS and resuspended for use. Xcm The experimental group was mixed in a volume ratio of 1:1. Xcm A 1:1 volume ratio of GXN01 mixed with PBS served as a positive control, while a 1:1 volume ratio of GXN01 mixed with PBS served as a negative control. Fresh mango leaves of the same growth and age were sterilized with 0.8% NaClO for 15 minutes. The leaves were then rinsed at least three times with sterile water until no NaClO remained and air-dried. Three small holes were pierced in each location from the dorsal aspect of the leaf toward the veins. The leaves were placed on a glass plate lined with moistened sterile filter paper, and the petioles were wrapped with sterile cotton.

[0061] Place the treated bacterial solution in a pre-sterilized spray bottle and evenly spray the front and back of the mango leaves. Cover the plate with a glass plate and place it in a 28°C incubator. Observe the plate every other day to ensure the filter paper remains moist. After 14 days, observe the mango leaves for signs of disease and take photos.

[0062] like Figure 10 As shown, 14 days after inoculation, strain GXN01 and mango bacterial leaf spot Xcm Co-vaccination vs single vaccination Xcm The results showed that the strain GXN01 was effective against bacterial angular leaf spot of mango. Xcm It has a significant biocontrol effect on the angular leaf spot disease caused by it.

[0063] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description is not intended to limit the present invention. After reading the above description, various modifications and substitutions of the present invention will become apparent to those skilled in the art. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A nitroreducing Pseudomonas sp. GXN01, characterized by: The nitroreducing Pseudomonas Pseudomonas nitroreducens ) GXN01, deposited in Guangdong Provincial Microbial Culture Collection Center, the deposit number is GDMCC NO: 65658, the deposit time is December 20, 2024, and the deposit address is: 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou.

2. The nitroreducing Pseudomonas GXN01 according to claim 1, characterized in that: The 16S rDNA sequence of the nitroreducing Pseudomonas sp. GXN01 is shown in the sequence table as SEQ ID NO.

1.

3. A use of the nitroreducing Pseudomonas GXN01 according to claim 1 in degrading quorum sensing signal molecules, characterized in that: The signal molecule is a DSF quorum sensing signal molecule family.

4. The use according to claim 3, characterized in that: The DSF comprises: BDSF.

5. Use of the nitroreducing Pseudomonas GXN01 according to claim 1 in the preparation of a biocontrol agent for pathogenic bacteria that rely on the quorum sensing signal molecule DSF family for pathogenicity, characterized in that: The pathogenic bacteria is Xanthomonas citri ulcerans ( Xanthomonascitri pv. citri ) or / and Angular leaf spot of mango ( Xanthomonas citri pv. mangiferaeindicae ).

6. A biocontrol agent for pathogenic bacteria that rely on the DSF family of quorum sensing signal molecules for pathogenicity, characterized by: The biocontrol agent comprises the nitroreducing Pseudomonas GXN01 according to claim 1.

7. A method for preventing and treating citrus canker and mango bacterial angular spot, characterized in that: The plants are treated with the bacterial suspension of the nitroreducing Pseudomonas GXN01 according to claim 1.

8. The method according to claim 6, characterized in that During application, the culture medium used for preparing the nitroreducing Pseudomonas GXN01 bacterial suspension is LB culture medium, and its formula is: 10.0 g / L tryptone, 5.0 g / L yeast extract and 10.0 g / L sodium chloride.

9. The method according to claim 6, characterized in that When used, the cultured nitroreduced Pseudomonas GXN01 was resuspended in PBS buffer.

10. The method according to claim 6, characterized in that When applied, the treatment method is to spray the plants.

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