Leclercia adecarboxylata strain jxja25 and application thereof

Abstract

The application discloses a non-decarboxylation klebsiella JXJA25 and application thereof, and belongs to the technical field of microbiology. The experimental verification shows that the corrected mortality of the fermentation filtrate of the non-decarboxylation klebsiella JXJA25 on second instar larvae of southern root-knot nematode is 88.37+ / -1.16%, and the corrected mortality of the fermentation filtrate of the non-decarboxylation klebsiella JXJA25 on second instar larvae of Pratylenchus penetrans is 86.09+ / -2.50%, which indicates that the non-decarboxylation klebsiella JXJA25 has good toxic killing effect on the southern root-knot nematode and Pratylenchus penetrans. In addition, the non-decarboxylation klebsiella JXJA25 can significantly inhibit the hatching rate of egg capsules of the southern root-knot nematode (after being treated by the fermentation filtrate, the hatching rate is only 14.19+ / -1.70%). The comprehensive results show that the non-decarboxylation klebsiella JXJA25 has important application value in the prevention and treatment of agricultural nematodes, and can be widely applied in the preparation of biological pesticides for preventing and treating agricultural nematodes.

Description

Technical Field

[0001] This invention relates to the field of microbiology, and in particular to a non-decarboxylated Leucobacterium strain JXJA25 and its applications. Background Technology

[0002] Plant-parasitic nematodes (PPNs) are a significant economic pest that causes plant diseases. It is estimated that they cause $157 billion in economic losses annually across all agricultural production. Because nematodes are small and difficult to see with the naked eye, and because their yellowing symptoms are similar to those caused by water and fertilizer deficiencies, they are easily overlooked, leading to missed opportunities for optimal control. For a long time, the application of chemical nematicides has been the primary method for controlling plant nematode diseases. However, the large-scale application of chemical agents not only leads to nematode resistance but also causes serious environmental pollution and harms human health, resulting in the banning or restriction of most highly toxic nematicides.

[0003] Biological control offers advantages such as strong environmental compatibility, abundant available resources, and the ability of biological nematicides to delay the development and progression of pesticide resistance in pests and diseases. Therefore, screening for biocontrol bacteria resources with nematode control functions is of great significance for developing new biological pesticide products and reducing or gradually replacing chemical pesticides for green control of crop nematode diseases. Summary of the Invention

[0004] The purpose of this invention is to provide a non-decarboxylated Leucobacterium strain JXJA25 and its application to solve the problems existing in the prior art. The non-decarboxylated Leucobacterium JXJA25 has good toxic effects on both Southern Root-knot Nematode and Two-tailed Scaly Blade Nematode, and can significantly inhibit the hatching rate of Southern Root-knot Nematode oocysts.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] This invention provides a non-decarboxylating Leckercia adecarboxylata strain JXJA25, which was deposited on August 8, 2024, at the Guangdong Provincial Center for Microbial Culture Collection (GDMCC No.: 64997), located at 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou, Guangdong Academy of Sciences Institute of Microbiology.

[0007] The present invention also provides the fermentation filtrate of the non-decarboxylated Reichelkia japonica JXJA25, which is obtained by culturing the non-decarboxylated Reichelkia japonica JXJA25 to obtain a bacterial suspension, and then centrifuging and filtering the bacterial suspension to obtain the fermentation filtrate.

[0008] The present invention also provides a microbial inoculum containing the aforementioned non-decarboxylated Leucobacter JXJA25 or the aforementioned fermentation filtrate.

[0009] The present invention also provides the application of the non-decarboxylated Leucobacterium JXJA25, the fermentation filtrate, or the microbial agent in the control of plant parasitic nematodes.

[0010] The present invention also provides the application of the aforementioned non-decarboxylated Leucobacterium JXJA25, or the aforementioned fermentation filtrate, or the aforementioned microbial agent in the preparation of formulations for controlling plant parasitic nematodes.

[0011] Optionally, the plant parasitic nematodes include Southern root-knot nematodes and Double-tailed Scaly-sharp nematodes.

[0012] Optionally, the non-decarboxylated Leucobacterium JXJA25 can inhibit the hatching of Southern Root-knot Nematode eggs.

[0013] The present invention also provides a formulation for preventing and controlling plant parasitic nematode diseases, wherein the active ingredient of the formulation includes the non-decarboxylated Leucobacterium JXJA25, the fermentation filtrate, or the microbial agent.

[0014] The present invention also provides a method for controlling plant parasitic nematodes, comprising the step of treating the plant parasitic nematodes with the fermentation filtrate of the non-decarboxylated Leucobacterium JXJA25.

[0015] Optionally, the plant parasitic nematodes include Southern root-knot nematodes and Double-tailed Scaly-sharp nematodes.

[0016] The present invention discloses the following technical effects:

[0017] This invention screened and identified a non-decarboxylating Leckercia adecarboxylata strain JXJA25, with accession number GDMCC No: 64997. Tests showed that the strain JXJA25 provided by this invention possesses properties such as phosphorus solubilization, potassium solubilization, and nitrogen fixation. It can produce IAA, with the IAA content reaching 45.18 mg / L after 7 days, and can also promote plant growth. Experiments verified that the fermentation filtrate of non-decarboxylated Leucobacterium JXJA25 had a corrected mortality rate of 88.37±1.16% for second-instar larvae of *Symplocos spp.* and 86.09±2.50% for second-instar larvae of *D. spp.*, indicating that it has good toxic effects on both *Symplocos spp.* and *D. spp.*. Furthermore, non-decarboxylated Leucobacterium JXJA25 can significantly inhibit the hatching rate of *Symplocos spp.* oocysts (after treatment with fermentation filtrate, the hatching rate was only 14.19±1.70%). The comprehensive results indicate that non-decarboxylated Leucobacterium JXJA25 has important application value in the control of agricultural nematodes and can be widely used in the preparation of biological agents for the control of agricultural nematode diseases. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 Colony morphology of non-decarboxylated Leucobacterium JXJA25 on LB medium;

[0020] Figure 2 A phylogenetic tree for non-decarboxylated Leucobacter JXJA25 constructed based on the 16S rDNA sequence;

[0021] Figure 3 The results are for the phosphorus solubility assay of non-decarboxylated Leucobacterium JXJA25;

[0022] Figure 4 The results are for the determination of potassium solubilizing ability of non-decarboxylated Leucobacterium JXJA25;

[0023] Figure 5 The results are for the nitrogen fixation capacity determination of non-decarboxylating Leucobacter JXJA25;

[0024] Figure 6 The results are the determination results of the IAA production capacity of non-decarboxylated Leucobacterium JXJA25. Detailed Implementation

[0025] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0026] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0027] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0028] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0029] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0030] Example 1: Isolation, screening and identification of non-decarboxylated Lechnerella vaginalis JXJA25

[0031] 1. Separation and Screening

[0032] In November 2023, the inventor collected Chinese yam from a nematode-infected area in Yongfeng County, Ji'an City, Jiangxi Province. After labeling, the yam was placed in a resealable bag and brought back to the laboratory for storage at 4℃ for later use. Using the dilution plate method, 1 g of diseased yam was weighed, rinsed with tap water, soaked in 75% alcohol for 3-5 minutes, and then rinsed 3-5 times with sterile water; next, it was soaked in 6% sodium hypochlorite for 3-5 minutes, rinsed 3-5 times with sterile water (retaining the last rinse solution), air-dried, and then ground in a sterile mortar. After grinding, 5 mL of sterile water was added and transferred to a sterile test tube, diluted with sterile water to a concentration of 10. -3 10 -410 -5 The culture was then evenly spread onto LB agar, with the final sterile water rinse serving as a control. After incubation upside down at 30°C for 1-3 days, single colonies with different morphologies were picked and streaked onto LB agar for purification. The purified colonies were then streaked onto LB agar slants and stored at 4°C. Using this method, strain JXJA25 was obtained through screening. Figure 1 ).

[0033] 2. Identification

[0034] 2.1 Morphological characteristics

[0035] After streaking on LB solid medium for 12 h, strain JXJA25 appeared as a round shape with neat edges, a slightly raised center, a smooth and moist surface, a diameter of about 2-3 mm, and a pale yellow to yellow color; it was opaque. Figure 1 ).

[0036] 2.2 Physiological and Biochemical Characteristics

[0037] The physiological and biochemical results are shown in Table 1. The strain JXJA25 was Gram-positive and could utilize glucose, arabinose, sucrose, lactose and maltose, but could not utilize raffinose and sorbitol; it could reduce nitrate and hydrolyze starch; but it could not liquefy gelatin or dissolve cellulose.

[0038] Table 1. Physiological and biochemical characteristics of strain JXJA25

[0039] Physiological and biochemical tests result Physiological and biochemical tests result Gram staining + glucose + Gelatin liquefaction - Raffinose - Cellulose dissolution - Arabic sugar + Nitrate reduction + sucrose + lactose + maltose + Sorbitol - Hydrolyzed starch +

[0040] Note: "+" indicates a positive result, and "-" indicates a negative result.

[0041] 2.3 Molecular biological characteristics

[0042] After culturing strain JXJA25 on LB solid medium for 12 h, single colonies were picked and cultured in LB liquid medium, and then sent to Sangon Biotech (Shanghai) Co., Ltd. for sequencing to construct a phylogenetic tree. Figure 2 The results showed that strain CZJ3 is evolutionarily closely related to the known non-decarboxylating Leclercia adecarboxylata.

[0043] Based on the above results, strain JXJA25 was identified as a non-decarboxylating Leckercia decarboxylata and named JXJA25. This strain was deposited on August 8, 2024, at the Guangdong Provincial Microbial Culture Collection Center, with accession number GDMCC No: 64997, located at 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou, Guangdong Academy of Sciences Institute of Microbiology.

[0044] Example 2 Biological assay of non-decarboxylated Lechnerella JXJA25

[0045] 1. Analysis of phosphorus solubility characteristics

[0046] The preserved JXJA25 strain was picked and cultured in LB broth liquid medium at 30℃ and 180 rpm for 24 h to activate the strain. 2.5 μL of the activated bacterial solution was then inoculated into NBRIP solid medium for phosphate-solubilizing bacteria and cultured at 30℃ for 7 days. The presence or absence of phosphate-solubilizing zones was observed and recorded.

[0047] The result is Figure 3 It is evident that the JXJA25 colony exhibits a large clear zone around its colony in the NBRIP solid medium for phosphate-solubilizing bacteria, indicating its strong phosphate-solubilizing ability.

[0048] 2. Analysis of potassium solubilization characteristics

[0049] The preserved JXJA25 strain was picked and cultured in LB broth liquid medium at 30℃ and 180 rpm for 24 h to activate the JXJA25 strain. 2.5 μL of the activated bacterial solution was then inoculated into silicate bacteria solid medium and cultured in a 30℃ incubator for 7 days. The presence or absence of potassium solubilization by the strain was observed and recorded.

[0050] The result is Figure 4 It is evident that strain JXJA25 grows well on silicate bacteria solid culture medium, indicating that it has potassium solubilizing ability.

[0051] 3. Nitrogen fixation characteristics analysis

[0052] The preserved JXJA25 strain was picked and cultured in LB broth liquid medium at 30℃ and 180 rpm for 24 h to activate the JXJA25 strain. 2.5 μL of the activated strain was then inoculated into Assumption solid medium and cultured in a 30℃ incubator for 7 days to observe its growth.

[0053] The result is Figure 5 It is evident that JXJA25 grows well on nitrogen-fixing medium, indicating that it has nitrogen-fixing ability.

[0054] 4. IAA production capacity determination

[0055] Weigh 0.0100 g of IAA standard using a 0.01% balance and place it in a 100 mL volumetric flask. Add methanol to bring the volume to 100 mL to prepare a 100 mg / L IAA standard solution. Dilute the solution with methanol to concentrations of 0, 0.5, 1, 5, 10, 20, and 50 mg / L IAA standard solutions. Take 200 μL of the standard solution and use a microplate reader to detect its concentration at OD600. 530nm Absorbance. Plotting IAA concentration on the x-axis, OD... 530nm Plot the IAA standard curve with absorbance as the ordinate. Salkowski colorimetric reagent: Add 35% perchloric acid and 0.5 mol / L FeCl3 solution to a brown bottle at a volume ratio of 50:1, and store at room temperature away from light.

[0056] The preserved JXJA25 strain was picked and cultured in LB broth for 12 h at 30℃ with shaking at 180 rpm to activate the strain. The activated bacterial culture was then inoculated at a 2% inoculation rate into King B medium containing tryptophan. Uninoculated King B medium served as a blank control (CK). The cultures were incubated at 30℃ with shaking for 7 days. After centrifugation at 8000 rpm for 5 min, 2 mL of the supernatant was transferred to a 10 mL centrifuge tube. 2 mL of Salkowski chromogenic reagent was added at a 1:1 volume ratio and mixed thoroughly. The mixture was allowed to react in the dark for 30 min, and the color change was observed. The reaction solution was then measured using a microplate reader at OD500. 530nm The absorbance value was used to calculate the IAA yield of the strain within 7 days by substituting it into the IAA standard curve.

[0057] The ability of strain JXJA25 to produce IAA is as follows: Figure 6 As shown, compared with the control group, JXJA25 produced a red substance, indicating its ability to produce IAA. The IAA content secreted by strain JXJA25 after 7 days reached 45.18 mg / L (Table 2).

[0058] Table 2. IAA content of non-decarboxylating Leucella JXJA25 (7 days)

[0059] deal with IAA content (mg / L) CK - JXJA25 45.18±2.78

[0060] Example 3: Bioactivity assay of non-decarboxylated Lechner's JXJA25 against Southern Root-knot Nematode and Two-tailed Smooth Edge Nematode

[0061] 1. Preparation of fermentation filtrate of non-decarboxylating Leucobacter JXJA25

[0062] (1) Modified LB liquid medium: Weigh 5.0 g of beef extract, 10.0 g of peptone and 5.0 g of sodium chloride into a volumetric flask, bring the volume to 1 L with deionized water, adjust the pH to 7.0 ± 0.2, and autoclave at 121℃ for 20 min before use. LB solid medium is prepared by adding 15 g / L of agar to the above liquid medium and sterilizing before use.

[0063] (2) Under aseptic conditions, strain JXJA25 was inoculated into LB solid medium and cultured in the dark at 30°C for about 12 h until it was ready for use. A single colony growing well on the plate was picked and inoculated into an Erlenmeyer flask containing 100 mL of modified LB liquid medium. After culturing at 180 rpm for 12 h on a shaker, a suspension of strain JXJA25 was prepared. The suspension was centrifuged at 10,000 rpm for 10 min at 4°C. The supernatant was then filtered through a 0.22 μm bacterial filter membrane to obtain the fermentation filtrate of strain JXJA25. Simultaneously, a blank LB liquid medium (without strain) was prepared in a shaker flask, centrifuged, and filtered through a 0.22 μm membrane as a control, and stored at 4°C for later use.

[0064] 2. Nematode rearing and nematode suspension treatment

[0065] (1) Culture and treatment of Southern root-knot nematodes

[0066] Collect cucumber roots infected with southern root-knot nematodes, gently rinse with water, and carefully remove the egg sacs. Disinfect in 1% sodium hypochlorite solution for 3 min, then rinse 3 times with sterile water. Place in a petri dish containing a small amount of sterile water and incubate at 25℃. Collect a suspension of newly hatched second-instar larvae of southern root-knot nematodes every 24 h, surface disinfect with 1% streptomycin sulfate for 15 min, then wash 3 times with sterile water. Finally, prepare a nematode suspension with a concentration of 200 nematodes / mL using sterile water.

[0067] (2) Culture and treatment of *Nematodea scabra*

[0068] Culture of Botrytis cinerea: PDA medium was autoclaved at 121°C for 20 min and then dispensed into sterile petri dishes with a diameter of 90 mm. After the medium cooled, it was inoculated with Botrytis cinerea and cultured at 25°C for 7 days. The resulting culture was then used to feed *Botrytis cinerea*.

[0069] Surface-sterilized *Dysplice* nematodes were inoculated onto a culture medium covered with *Botrytis cinerea* and incubated at 25°C for 5 days. Before inoculation, the nematodes were isolated using the Bellman funnel method, surface-sterilized with 1% streptomycin sulfate for 15 min, washed three times with sterile water, and finally a nematode suspension with a concentration of 200 nematodes / mL was prepared with sterile water.

[0070] 3. Determination of the biological activity of plant parasitic nematodes

[0071] Fermentation filtrate (stock solution) of strain JXJA25 was taken and diluted 5 times and 10 times with sterile water to obtain 5-fold and 10-fold dilutions. The corrected mortality rates of the fermentation filtrate at different dilution ratios for the second instar larvae of Southern Root-knot Nematode and the second instar larvae of Two-tailed Scaly Blade Nematode were determined.

[0072] In a clean bench, fermentation filtrate diluted at different ratios and nematodes were added to sterile 2 mL centrifuge tubes at a 1:1 volume ratio using a pipette (100-120 second-instar larvae per tube). Sterile H2O and LB medium were used as blank controls (H2O and LB-CK), and avermectin (50 μg / mL) was used as a positive control (G-CK). Each treatment was repeated three times. The 2 mL centrifuge tubes were sealed with sealing film and placed in an incubator at 25°C. After 24 h, the total number of nematodes and the number of deaths in each well were counted.

[0073] The results showed that the original fermentation filtrate of non-decarboxylating Leucobacter JXJA25 had a corrected mortality rate of 88.37±1.16% against second-instar larvae of *Symplocos septemlobus*, and the mortality rate remained at 82.38±2.20% after a 10-fold dilution (Table 3). The original fermentation filtrate had a corrected mortality rate of 86.09±2.50% against second-instar larvae of *Diplostomum chinense*, and the mortality rate remained at 76.05±1.43% after a 10-fold dilution (Table 4). These results indicate that non-decarboxylating Leucobacter JXJA25 has good toxic effects against both second-instar larvae of *Symplocos septemlobus* and *Diplostomum chinense*.

[0074] Table 3 Corrected mortality rate of southern root-knot nematodes from fermentation filtrate of non-decarboxylated Leucobacter JXJA25

[0075] deal with Corrected mortality rate / % <![CDATA[H2O]]> - LB-CK 14.32±1.09d G-CK 89.95±1.10a Fermentation filtrate stock solution 88.37±1.16a 5x dilution 86.09±1.72b 10x dilution 82.38±2.20c

[0076] Note: Corrected mortality rates are expressed as mean ± standard error. Different letters in the same column indicate significant differences between treatments (p<0.05). The same applies below.

[0077] Table 4 Corrected mortality rate of *Nematodea scabra* from fermentation filtrate of non-decarboxylated *L. clarkii* JXJA25

[0078] deal with Corrected mortality rate / % <![CDATA[H2O]]> - LB-CK 13.09±1.26e G-CK 89.57±1.06a Fermentation filtrate stock solution 86.09±2.50b 5x dilution 81.86±2.84c 10x dilution 76.05±1.43d

[0079] Example 4: Effect of non-decarboxylated Lechner bacteria JXJA25 on hatching of southern root-knot nematode eggs

[0080] 1. Preparation of Southern Root-knot Nematode Egg Suspension

[0081] Cucumber roots inoculated with Southern Root-Knot Nematodes for 45 days were thoroughly cleaned with tap water. Plump, mature egg sacs were removed with tweezers and placed in a 2 mL centrifuge tube containing sterile water. The tube was washed three times with 1 mL of sterile water, followed by the addition of 1% sodium hypochlorite solution. The tube was vortexed for 3 minutes to release the eggs. The tube was then centrifuged at 8000 rpm for 1 minute with sterile water, the supernatant was discarded, and the tube was washed again with sterile water. The supernatant was discarded again, resulting in an egg suspension of approximately 100 eggs per 100 μL for later use.

[0082] The fermentation filtrate (stock solution) of strain JXJA25 from Example 3 was diluted 5-fold and 10-fold with sterile water to obtain 5-fold and 10-fold dilutions. Bioactivity assays were performed using 24-well plates. Approximately 120 eggs and 960 μL of each dilution were added to each well. Blank controls (H2O and LB-CK) were used, along with sterile H2O and culture medium filtrate without strain JXJA25. Avermectin solution was used as a positive control (G-CK). Each concentration was repeated four times. The 24-well plates were incubated at 25°C in a constant temperature incubator. After 7 days, the hatching rate and hatching inhibition rate of *Strombus heterophylla* eggs were observed under a microscope. Relative inhibition rate (%) = (Number of nematodes hatched from control eggs - Number of nematodes hatched from treated eggs) / Number of nematodes hatched from control eggs × 100.

[0083] Table 5. Inhibitory effect of non-decarboxylated Lechner bacteria JXJA25 on hatching of southern root-knot nematode eggs.

[0084] deal with Hatching rate / % Relative hatching inhibition rate / % <![CDATA[H2O]]> 51.57±2.49a - LB-CK 43.00±2.46b 16.61±4.77c G-CK 12.65±1.11d 75.46±2.16a Fermentation filtrate stock solution 14.19±1.70d 72.49±3.30a 5x dilution 15.29±1.69d 70.36±3.28a 10x dilution 20.47±2.79c 60.31±5.41b

[0085] As shown in Table 5, after treatment with the original fermentation filtrate of non-decarboxylated Leucobacter JXJA25, the hatching rate of Southern Root-knot Nematode eggs was only 14.19±1.70%, and the relative hatching inhibition rate reached 72.49±3.30%. After dilution by 10 times, the hatching rate increased to 20.47±2.79%, and the relative hatching inhibition rate was 60.31±5.41%.

[0086] In summary, the fermentation filtrate of non-decarboxylated Leucobacterium JXJA25 not only has a strong toxic effect on the second instar larvae of Southern Root-knot Nematode and Two-tailed Scaly Blade Nematode, but also can greatly inhibit the hatching rate of Southern Root-knot Nematode egg sacs, thus having important application value for the prevention and control of crop root-knot nematode disease.

[0087] Example 5: Non-decarboxylating Lekker bacteria JXJA25 promote cucumber growth

[0088] 1. Pretreatment of cucumber seeds with strain JXJA25

[0089] Pretreatment of cucumber seeds: Disinfect cucumber seeds with 70% alcohol for 30 seconds, then rinse with sterile water 3-5 times; then disinfect with 4% sodium hypochlorite solution for 10 minutes, then rinse with sterile water 3-5 times. Place the disinfected cucumber seeds in a 90 mm petri dish and incubate in the dark at 28℃ for 5-7 days.

[0090] Pretreatment of JXJA25 strain: The preserved JXJA25 strain was picked and cultured in LB broth at 30℃ with shaking at 180 rpm for 12 h to activate the strain. 1 mL of the bacterial suspension was transferred to a 2 mL centrifuge tube and centrifuged at 8000 rpm for 5 min. The supernatant was discarded, and the precipitate was thoroughly mixed with 1 mL of ddH2O until the OD of the bacterial suspension was adjusted. 600 Approximately 1.0. The JXJA25 bacterial suspension was serially diluted to obtain JXJA25 bacterial suspensions diluted 5 times and 10 times, respectively.

[0091] 2. The promoting effect of exogenous addition of JXJA25 on cucumber seedlings

[0092] Germinated cucumber seeds were inoculated into seedling trays and cultured for 10 days. After that, cucumber seedlings with similar growth were transplanted into new planting pots. Five days after transplanting, the seedlings were treated as follows:

[0093] A: Apply 50 mL of sterile water;

[0094] B: Add 50 mL of LB broth culture medium;

[0095] C: Apply 50 mL of JXJA25 bacterial suspension stock solution;

[0096] D: Apply 50 mL of a 5-fold diluted JXJA25 bacterial suspension;

[0097] E: Apply 50 mL of a 10-fold dilution of JXJA25 bacterial suspension;

[0098] Each treatment was set up with 3 replicates, and 45 cucumber seedlings were planted in each replicate. The biomass of the plants was measured after 30 days of co-cultivation, and the growth-promoting effect is shown in Table 6.

[0099] Table 6. Biomass of cucumber plants after root irrigation with different solutions

[0100] Group Plant height / cm Fresh weight / g A 40.09±3.88b 4.69±1.28b B 41.46±5.20b 5.36±1.28b C 48.52±5.91a 6.99±1.50a D 47.31±5.79a 7.35±1.35a E 46.98±6.17a 7.07±1.36a

[0101] As shown in Table 6, 30 days after planting, compared with the blank control (A), the JXJA25 bacterial suspension treatment group (C) showed an increase of 21% in cucumber plant height and 49% in fresh weight. Furthermore, there were no significant differences between the undiluted treatment group (C) and the 5-fold (D) and 10-fold (E) dilutions of the JXJA25 bacterial suspension, indicating that the JXJA25 bacterial suspension has a significant promoting effect on cucumber seedling growth.

[0102] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A non-decarboxylated Lechner bacterium ( Leckercia adecarboxylata JXJA25, characterized in that, The non-decarboxylated Leucella JXJA25 was deposited on August 8, 2024, at the Guangdong Provincial Center for Microbial Culture Collection, with accession number GDMCCNo: 64997, located at 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou, Guangdong Academy of Sciences Institute of Microbiology.

2. The fermentation filtrate of non-decarboxylating Leucobacterium JXJA25 as described in claim 1, characterized in that, A bacterial suspension was obtained by culturing non-decarboxylated Leucobacter JXJA25, and the bacterial suspension was centrifuged and filtered to obtain the fermentation filtrate.

3. A microbial inoculant, characterized in that, Contains the non-decarboxylated Leucobacterium JXJA25 as described in claim 1 or the fermentation filtrate as described in claim 2.

4. The application of the non-decarboxylating Cladosporium JXJA25 as described in claim 1, or the fermentation filtrate as described in claim 2, or the microbial agent as described in claim 3, in the control of plant parasitic nematodes, characterized in that, The plant parasitic nematodes mentioned are Southern Root-knot Nematode and Double-tailed Smooth-striped Nematode.

5. The application of the non-decarboxylating Cladosporium JXJA25 as described in claim 1, or the fermentation filtrate as described in claim 2, or the microbial agent as described in claim 3, in the preparation of formulations for controlling plant parasitic nematodes, characterized in that, The plant parasitic nematodes mentioned are Southern Root-knot Nematode and Double-tailed Smooth-striped Nematode.

6. The application as described in claim 4 or 5, characterized in that, The non-decarboxylated Lekker bacteria JXJA25 can inhibit the hatching of Southern root-knot nematode eggs.

7. A preparation for controlling plant parasitic nematode diseases, characterized in that, The active ingredient of the preparation includes the non-decarboxylated Lechnerella JXJA25 of claim 1, or the fermentation filtrate of claim 2, or the microbial agent of claim 3; The plant parasitic nematodes mentioned are Southern Root-knot Nematode and Double-tailed Smooth-striped Nematode.

8. A method for controlling plant parasitic nematodes, characterized in that, The method includes the step of treating the plant parasitic nematode with the fermentation filtrate of the non-decarboxylated Leucobacterium JXJA25 as described in claim 1. The plant parasitic nematodes mentioned are Southern Root-knot Nematode and Double-tailed Smooth-striped Nematode.

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