Bacillus paralicheniformis CQ1 and application thereof

Abstract

The application belongs to the technical field of microorganisms, and specifically provides a Bacillus paralicheniformis CQ1, which is preserved in the China Center for Type Culture Collection, and has a preservation number of CCTCC NO:M 2023491 and a 16S rDNA sequence as shown in SEQ ID NO. 1. The strain has salt tolerance, can secrete protease, siderophore and auxin, and has a growth promoting effect on tomato seeds and tomato plants. The Bacillus paralicheniformis CQ1 and secondary metabolites thereof have a broad-spectrum antibacterial property and can inhibit the growth of pathogenic bacteria.

Description

Technical Field

[0001] This invention belongs to the field of microbial technology, specifically relating to Bacillus paralichrysogenum CQ1 and its applications. Background Technology

[0002] In agricultural production, some fungi cause diseases to crops, greatly harming agricultural production. Currently, besides selecting improved varieties and improving cultivation practices, the control of plant diseases mainly relies on spraying chemical fungicides. Most of the chemical fungicides used have varying degrees of toxicity to humans and animals, and the harmful components remaining in the edible parts of plants pose a potential threat to human health. Furthermore, some chemical pesticides are difficult to decompose and accumulate in the ecosystem over a long period, causing environmental pollution and hindering sustainable socio-economic development. Moreover, existing chemical pesticides are not entirely effective against certain plant diseases. Therefore, while striving to develop a new generation of chemical pesticides, it is also necessary to vigorously research and develop efficient, safe, economical, and environmentally compatible biopesticides.

[0003] Microorganisms and their metabolites play a vital role in the biological control of plant diseases. Therefore, how to develop and correctly use biological fungicides is the primary issue for developing organic and green agriculture. Summary of the Invention

[0004] The purpose of this invention is to provide a biocontrol strain for plant diseases.

[0005] Therefore, the present invention provides a Bacillus paralichrysogenus CQ1, which is deposited at the China Center for Type Culture Collection (CCTCC) with accession number CCTCC NO:M 2023491.

[0006] Specifically, the 16S rDNA sequence of the aforementioned Bacillus paralichrysogenus CQ1 is shown in SEQ ID NO.1.

[0007] Specifically, the aforementioned Bacillus paralichrysogenus CQ1 can secrete auxin, protease, and heptaphilin.

[0008] Specifically, the aforementioned Bacillus paralichrysogenus CQ1 can inhibit pathogens.

[0009] Specifically, the aforementioned pathogens include Alternaria solanacea, Alternaria brassicae, maize leaf spot fungus, Phytophthora cucurbita, Sclerotinia sclerotiorum var. spp., Fusarium oxysporum, Curvularia crescentis, Botrytis cinerea, dragon fruit canker fungus, and citrus anthracnose fungus.

[0010] Specifically, the aforementioned Bacillus paralichrysogenum CQ1 can promote plant growth.

[0011] Specifically, the plant mentioned above is a tomato.

[0012] The present invention also provides a metabolite of Bacillus paralichrysogenus CQ1, which is prepared by the following steps: inoculating the above-mentioned Bacillus paralichrysogenus CQ1 into LB liquid medium for culture, centrifuging the cultured bacterial solution, filtering the bacterial cells, and obtaining sterile fermentation broth, which is the metabolite.

[0013] Specifically, the aforementioned metabolites can inhibit pathogens.

[0014] Specifically, the aforementioned pathogens include Botrytis cinerea, Fusarium oxysporum, Fusarium wilt of watermelon, Alternaria alternata of tea, Alternaria alternata of solanum, Anthracnose of citrus, Pyracantha fortuneana of dragon fruit, and Anthracnose of strawberry.

[0015] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0016] The *Bacillus paralichrysogenus* CQ1 provided by this invention is tolerant to salt concentrations ≤14% and can secrete proteases, hepatophiles, and plant growth hormones (IAA), thus promoting the growth of both tomato seeds and tomato plants. *Bacillus paralichrysogenus* CQ1 and its secondary metabolites possess broad-spectrum antibacterial activity, exhibiting antibacterial effects against a variety of plant pathogens.

[0017] The present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0018] Figure 1 This describes the antibacterial effect of Bacillus paralichrysogenum CQ1 against Fusarium oxysporum in Example 1 of this invention.

[0019] Figure 2 This is a schematic diagram of the morphological characteristics of Bacillus paralichrysogenum CQ1 in Embodiment 2 of the present invention.

[0020] Figure 3 This is a schematic diagram of the Gram staining results of Bacillus paralichrysogenum CQ1 in Example 2 of the present invention.

[0021] Figure 4 This is a graph showing the salt tolerance concentration test results of Bacillus paralichrysogenus CQ1 in Example 3 of the present invention.

[0022] Figure 5 This is a graph showing the detection results of IAA (A), protease (B), and ferrophile (C) secreted by Bacillus paralichrysogenus CQ1 in Example 3 of the present invention.

[0023] Figure 6 The diagram shows the results of the broad-spectrum antibacterial experiment of Bacillus paralichrysogenus CQ1 in Example 4 of this invention; A, Alternaria alternata; B, Alternaria brassicae; C, Corn leaf spot pathogen; D, Phytophthora cucurbita; E, Sclerotinia sclerotiorum; F, Fusarium oxysporum; G, Curvularia crescentis; H, Botrytis cinerea; I, Dragon fruit canker pathogen; J, Citrus anthracnose pathogen.

[0024] Figure 7 The diagram shows the antibacterial results of the metabolite of Bacillus paralichrysogenum CQ1 in Example 5 of this invention; A, Strawberry gray mold; B, Tomato Fusarium wilt; C, Watermelon wilt; D, Tea leaf spot; E, Alternaria alternata; F, Citrus anthracnose; G, Dragon fruit canker; H, Strawberry anthracnose; I, Pepper white mold.

[0025] Figure 8 This is a schematic diagram of the length of the radicle of a tomato seed in Embodiment 6 of the present invention.

[0026] Figure 9 This is a schematic diagram of the tomato plant growth in Embodiment 7 of the present invention.

[0027] Figure 10 This is a schematic diagram of the root system of each tomato plant in Embodiment 7 of the present invention. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Although representative embodiments of the present invention have been described in detail, those skilled in the art will understand that various modifications and changes can be made to the present invention without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the embodiments, but should be defined by the appended claims and their equivalents.

[0029] The following specific embodiments illustrate the study of the *Bacillus paralichrysogenus* CQ1 of the present invention and its effects.

[0030] Example 1:

[0031] This embodiment provides a method for isolating and screening Bacillus paralichrysogenus CQ1, as follows:

[0032] In October 2022, soil samples were collected from the root zone of crops such as tomatoes, peppers, rice, soybeans, pears, citrus, strawberries, corn, and rapeseed in the Green Prevention and Control Town of Caidian District, Wuhan City. The soil was collected using a 3-point sampling method, and then dried, ground, and sieved.

[0033] Weigh 5g of pre-crushed soil and pour it into a sterile Erlenmeyer flask. Add 45mL of sterile water and shake on a shaker for 30 minutes. Let it stand until it separates into layers. Take 1mL of the supernatant and add 9mL of sterile water. The concentration at this point is 10. -1 Serially diluted to 10 -3 10 -4 10 -5 Take a concentration of 10. -3 10-4 10 -5 Spread 0.1 mL of the solution evenly on a plate, repeating 3 times.

[0034] The prepared plates were inverted and incubated at 28°C for 48 hours. Colonies grew on the plates, and colonies of different morphologies were randomly selected for purification and culture. Subsequent plate confrontation tests were conducted with the pathogen. The culture medium used was LB solid medium (10 g / L peptone, 5 g / L yeast extract, 10 g / L sodium chloride, 15-20 g / L agar powder, autoclaved at 121°C for 30 min).

[0035] Fusarium oxysporum was used as an indicator bacterium. Mycelia of the pathogen were picked from test tubes and inoculated onto PDA solid medium. Other pathogens were incubated at 25°C for 7 days. The mycelia were sterilized using a 5mm diameter punch to form circular blocks (Φ5mm) and stored at 4°C for later use. The Fusarium oxysporum blocks (Φ5mm) were placed on one side of the PDA solid medium, and the other side was inoculated with screened and purified bacteria. The blocks were incubated at 25°C for 4-7 days to observe whether an inhibitory effect was observed. Each group was replicated three times.

[0036] One of the bacterial strains isolated from the soil showed good inhibitory effects against Fusarium oxysporum tomatoense and was named CQ1. The initial inhibition zone width was 3.05 mm, and the inhibitory effect was as follows: Figure 1 As shown.

[0037] Example 2:

[0038] This embodiment identifies the strains screened in Example 1.

[0039] 1. Morphological observation

[0040] Take the bacterial suspension after 48 hours of culture, spread it on LB solid medium at an appropriate concentration, and incubate it in a constant temperature incubator at 28°C for 48 hours. Observe the color and morphology according to Bergey's Manual of Bacteriology (8th Edition).

[0041] Gram staining procedure: Take an appropriate amount of bacterial suspension with a pipette, spread it evenly on one side of a glass slide, and fix it by heating with the outer flame of an alcohol lamp; allow it to cool naturally, add crystal violet staining solution to the fixed position, let it stand for 1 minute, and rinse with sterile water; counterstain by adding iodine solution, let it stand for 1 minute, and rinse with water; take 95% ethanol to decolorize, add it to the glass slide, gently shake the glass slide, repeat several times until the decolorization is complete, and rinse with water; stain with tomato O staining solution, let it stand for 1 minute, rinse with water, and blot dry with filter paper.

[0042] Place the slide under an oil immersion microscope and observe the shape and color of the bacteria. Blue-purple indicates Gram-positive bacteria, and red indicates Gram-negative bacteria.

[0043] On LB medium, strain CQ1 appears milky white, opaque, with a dry surface and irregularly serrated edges. Figure 2 As shown. Strain CQ1 stains blue-purple with Gram staining, indicating it is a Gram-positive bacterium. Figure 3 As shown.

[0044] 2. Identification of physiological and biochemical characteristics

[0045] Methyl red MR test: Inoculate one tube with bacteria and leave the other tube uninoculated as a control. Incubate at 28°C for 48 hours. Add methyl red indicator. If the culture medium turns red, the test is positive; if it turns yellow, the test is negative. Repeat the test three times.

[0046] VP test: Inoculate one test tube with bacteria and leave the other uninoculated as a control. Incubate at 28°C for 48 hours. Then add an equal volume of 40% NaOH, followed by a small amount of creatine oxidase powder. Wait 10 minutes or longer; if the color turns red, the test is positive. Repeat the test three times.

[0047] Catalase test: Pick a 48-hour cultured bacterial cell and spread it on a glass slide, then add 10% H2O2 and observe whether small bubbles are produced; the presence of bubbles indicates a positive result, while the absence of bubbles indicates a negative result. The test is repeated 3 times.

[0048] Aerobic or anaerobic test: The bacterial culture was dried under sterile air until it was semi-solid but still fluid at approximately 45°C. 0.1 mL of fresh bacterial solution was added, mixed thoroughly, air-dried, sealed, and incubated at 28°C for 3 days. Three growth patterns were observed: aerobic growth occurred only on the surface; anaerobic growth occurred only at the bottom; and facultative anaerobic growth occurred in both environments. The test was repeated three times.

[0049] Gelatin liquefaction test: Pour gelatin liquefaction medium into a test tube, tilt until solidified, inoculate one tube with the bacterial strain, and leave the other tube uninoculated as a control. Incubate at 28℃ for 3-14 days and observe the gelatin liquefaction. If the gelatin in the test tube is a flowing liquid, the result is positive; if the gelatin in the test tube remains solid, the result is negative. The test is repeated three times.

[0050] Starch hydrolysis test: Pick a strain and inoculate it into starch hydrolysis medium. Incubate at 28°C for 48 hours until colonies are visible on the medium. Add iodine solution and wait a moment. If the blue-black color around the colonies fades, the starch hydrolysis is positive. If the color remains blue-black, the starch has not been hydrolyzed, and the result is negative. Repeat the test three times.

[0051] Lipase: Add 1% Tween 80% to LB medium, then streak the strain onto the medium and incubate at 28°C. Observe daily for the formation of halos; the presence of halos indicates a positive result, while the absence of halos indicates a negative result. The experiment was repeated three times.

[0052] Citrate utilization: The strain was streaked on citrate medium and incubated at 28°C for 48 hours. The medium was then observed for color change. No color change indicated a negative result, while color change indicated a positive result. The experiment was repeated three times.

[0053] The physiological and biochemical characteristics of CQ1 were analyzed, and the results are shown in Table 1.

[0054] Table 1. Physiological and Biochemical Identification of CQ1

[0055]

[0056]

[0057] Note: "-" indicates negative, "+" indicates positive.

[0058] 3. 16S rDNA sequence analysis

[0059] DNA extraction was performed using the TSINGKE Plant DNA Extraction Kit (General Type) (Catalog No.: TSP101).

[0060] PCR amplification was performed using universal primers for bacterial identification listed in Table 2. The amplification products were analyzed by agarose gel electrophoresis to determine whether the PCR product bands matched the target size, whether they were single, and whether there were any trailing bands.

[0061] Table 2 Primers for bacterial species identification

[0062]

[0063] After the PCR product passes the test, the target band is cut and purified and recovered. The recovered product is then used for Sanger sequencing.

[0064] The sequencing results were compared and analyzed using the following methods:

[0065] (1) The Sanger sequencing results were spliced ​​using the software ContigExpress, and inaccurate parts at both ends were removed.

[0066] (2) Batch alignment of the assembled sequences with a nucleic acid database using BLASTN (latest version v2.13). The latest version of the NT library was selected as the nucleic acid database, and alignment was performed with the NT library using BLASTN.

[0067] By comparison, the Accession Number of the homologous sequence, as well as species identification and annotation, can be obtained.

[0068] The 16S rDNA sequence detection results of strain CQ1 are shown in SEQ ID NO.1.

[0069] SEQ ID NO.1:

[0070] GTCTTACGCTGTGGCGCGAAGCGTGGGGAGCGAACAGGATTAGATACCCTGGTAGTCCACGCCGTAAACGATGAGTGCTAAGTGTTAGAGGGTTTCCGCCCTTTAGTGCTGCAGCAAACGCATTAAGCACTCCGCCTGGGGAGTACGGTCGCAAGACTGAAACTCAAAGGAATTGACGGGGGCCCG CACAAGCGGTGGAGCATGTGGTTTAATTCGAAGCAACGCGAAGAACCTTACCAGGTCTTGACATCCTCTGACAACCCTAGAGATAGGGCTTCCCCTTCGGGGGCAGAGTGACAGGTGGTGCATGGTTGTCGTCAGCTCGTGTCGTGAGATGTTGGGTTAAGTCCCGCAACGAGCGCAACCCTTGATCTTAGTTGCCAGCATTCAGTTGGGCACTCTAAGGTGACTGCCGGTGACAAACCGGAGGAAGGTGGGGATGACGTCAAATCATCATGCCCCTTATGACCTGGGCTACACACGTGCTACAATGGACAGAACAAAGGGCAGCGAAGCCGCGAGGCTAAGCCAATCCCACAAATCTGTTCTCAGTTCGGATCGCAGTCTGCAACTCGACTGCGTGAAGCTGGAATCGCTAGTAATCGCGGATCAGCATGCCGCGGTGAATACGTTCCCGGGCCTTGTACACACCGCCCGTCACACCACGAGAGTTTGTAACACCCGAAGTCGGTGAGGTAACCTTTTGGAGCCAGCCGCCGAAGGTGGGACAGATGATTGGGGTGAAGTCGTAACAGGGTAAGCCGTAAAATTAAGATGTTTATT

[0071] Table 3 Identification Results

[0072]

[0073] Based on morphological observation, physiological and biochemical identification, and 16S rDNA sequence analysis, strain CQ1 was identified as Bacillus paralicheniformis. It was deposited at the China Center for Type Culture Collection (CCTCC) on April 9, 2023, and named Bacillus paralicheniformis CQ1; accession number: CCTCC NO: M 2023491; location: Wuhan University, Wuhan, China.

[0074] Example 3:

[0075] This embodiment investigated the salt tolerance of Bacillus paralichrysogenum CQ1 and measured its secretion of plant growth hormone IAA, protease, and hepatophilia.

[0076] 1. Salt tolerance: Prepare LB medium, inoculate the above strains, and incubate at 200 r / min and 30℃ for 24 h as seed culture; add 2%, 4%, 6%, 8%, 10%, 12%, and 14% sodium chloride to LB medium respectively, using LB medium as a control, and inoculate 1 mL of seed culture for each; incubate at 200 r / min and 30℃ for 48 h, and observe the turbidity of the medium to confirm whether the strain has grown.

[0077] like Figure 4 As shown, strain CQ1 has a salt tolerance of ≤14%.

[0078] 2. IAA Secretion Detection: Prepare 50 mL LB liquid medium, add 1% L-tryptophan, and then inoculate with biocontrol bacteria Bs wy-1 and Bs-9. Incubate at 28℃ for 48 h at 200 rpm. Transfer the bacterial culture to centrifuge tubes and centrifuge at 10000 rpm for 20 min. Take 1 mL of the supernatant, add 2 mL of Salkowaski reagent, followed by two drops of orthophosphate. Incubate the mixture at 28℃ for 2 h and observe whether the solution turns red. If it turns red, it indicates that the biocontrol bacteria can secrete IAA. The experiment was repeated three times.

[0079] like Figure 5 As shown in Figure A, the culture medium turns red after a water bath, indicating that CQ1 can produce IAA.

[0080] 3. Protease detection: 0.1% peptone; 0.5% beef extract; 0.5% sodium chloride; 2% agar; 1L distilled water; pH 7.00-7.2; 0.3% skim milk powder (sterilized separately at 112℃). The strain was then inoculated in the middle of the culture medium. If a clear zone was formed, it indicates that the strain can secrete protease.

[0081] Ferrophilin detection: CAS medium; sterilized at 116℃ for 20 min. The strain was then inoculated in the middle of the medium. If a clear zone was formed, it indicates that the strain can secrete ferrophile.

[0082] like Figure 5 As shown in B-5C, both the protease medium and the heptaphilic medium produced clear zones, indicating that CQ1 can produce both protease and heptaphilic substances.

[0083] Example 4:

[0084] This embodiment investigated the broad-spectrum antibacterial activity of Bacillus paralichrysogenus CQ1.

[0085] like Figure 6 As shown in Table 4, CQ1 exhibits antibacterial effects against the following pathogens. The best antibacterial effect was observed against Sclerotinia sclerotinia in lettuce, followed by Botrytis cinerea and dragon fruit canker. The differences among the three were not significant, and the antibacterial effects of all three were ≥40%. This indicates that CQ1 possesses biocontrol potential, exhibiting different inhibitory effects against different pathogens and demonstrating broad-spectrum antibacterial efficacy.

[0086] Table 4. Broad-spectrum antibacterial activity of CQ1

[0087]

[0088]

[0089] Note: "±" indicates mean ± standard deviation; different lowercase letters after the numbers indicate significant differences at the 0.05 level using Duncan's new multiple range method; CK is the blank control.

[0090] Example 5:

[0091] This embodiment investigated the antibacterial effect of Bacillus paralichrysogenus CQ1 metabolites.

[0092] Preparation of sterile fermentation broth: A small amount of CQ1 strain that had been streaked on a plate for 48 hours was inoculated into LB liquid medium using an inoculation loop. The medium was then incubated at 30°C for 48 hours on a shaker at 180 rpm. The cultured broth was centrifuged at 9000 rpm for 10 minutes and filtered through a 0.22 μm sterile filter membrane. The sterile fermentation broth was then stored at 4°C for later use.

[0093] Punch holes at equal intervals with a sterile pipette tip on PDA solid medium, then add 100 μL of sterile fermentation filtrate, inoculate the pathogenic bacterial cake in the middle of the plate, incubate for 4-7 days, and measure the width of the inhibition zone with vernier calipers.

[0094] As shown in Table 5 and Figure 7As shown, the aseptic fermentation filtrate of CQ1 exhibited varying degrees of antibacterial effects against strawberry gray mold, tomato sickle, watermelon wilt, tea leaf spot, Alternaria alternata, citrus anthracnose, dragon fruit canker, and strawberry anthracnose. The best antibacterial effect was observed against Alternaria alternata, with an inhibition band width of 10.19 mm, showing a significant difference compared to the others. The second best results were against strawberry gray mold (6.51 mm) and tomato sickle (5.57 mm), with no significant difference between the two. The antibacterial effect against pepper white mold was not ideal.

[0095] Table 5. Antibacterial effect of CQ1 metabolites

[0096]

[0097]

[0098] Note: "±" indicates mean ± standard deviation. Different lowercase letters after the numbers indicate differences at the 0.05 level in Duncan's new multiple range method.

[0099] Example 6:

[0100] This embodiment studies the effect of Bacillus paralichrysogenum CQ1 on promoting the growth of tomato seeds.

[0101] Preparation of CQ1 fermentation broth: Prepare LB liquid medium, and use an inoculation loop to pick up a small amount of CQ1 single bacteria and drop it into the LB liquid medium. Incubate at 30℃ for 48 hours with a shaker at 180 rpm. The bacterial count of the fermentation broth (≥1 billion CFU / mL) is determined by the plate dilution method.

[0102] The fermentation broth was diluted serially at 0, 10, 100, 200, 300, 400, 500, 600, 700, 800, 900, and 1000 times, and set aside. Tomato seeds were treated at 55℃ for 20 min, disinfected with 75% ethanol for 1 min, rinsed three times with sterile water, disinfected with sodium hypochlorite for 30 s, and rinsed three times with sterile water. The disinfected tomato seeds were then soaked in the fermentation broth at different dilutions, with seeds soaked in water as a control, for 3 h. The seeds were then neatly arranged in petri dishes lined with a layer of moist sterile filter paper. 1 mL of the fermentation broth at different dilutions was added to each petri dish, and 1 mL of water was added to the control. The dishes were sealed with sealing film and incubated at 30℃ for 48 h. The germination rate was recorded at 24 h and 48 h. After recording the germination rate, the seeds were continued to be cultured, with 1 mL of the fermentation broth at different dilutions and water added as needed. After 7 days of culture, the length of the seed radicle was measured with a ruler. The CK group was the control group that was not treated with fermentation broth, with 30 seeds per treatment.

[0103] As shown in Table 6, the highest seed germination rates at 24 hours were achieved with CQ1 800x and 1000x dilutions, both reaching 83.33%, significantly higher than the control (73.33%). At 48 hours, the highest germination rate was achieved with the 800x dilution (100%), followed by the 700x and 1000x dilutions (90.00%), compared to the control's 76.67%. CQ1 fermentation broth showed a trend of high concentration inhibiting germination and low concentration promoting it. The 800x dilution exhibited the best germination-promoting effect.

[0104] Table 6 Seed germination rates at 24h and 48h

[0105]

[0106] As shown in Table 7 and Figure 8 As shown, when the dilution ratio is greater than or equal to 600 times, the length of the seed radicle is greater than that of the control (2.38 cm). The best radicle length is achieved with the 800-fold dilution (3.62 cm), followed by the 900-fold dilution (3.33 cm), 1000-fold dilution (2.82 cm), 600-fold dilution (2.80 cm), and 700-fold dilution (2.46 cm).

[0107] Table 7 Seed radicle length

[0108]

[0109]

[0110] In summary, taking tomato seeds as an example, the best effect on promoting seed germination rate and seed radicle length is achieved with a CQ1 solution diluted 800 times. When using CQ1 to promote seed germination, the recommended dilution ratio of CQ1 fermentation broth (bacterial content ≥1 billion CFU / mL) is 600-1000 times.

[0111] Example 7:

[0112] This embodiment studies the growth-promoting effect of Bacillus paralichrysogenum CQ1 on tomato plants.

[0113] Prepare CQ1 (1×10) 9 Based on the results of its seed-promoting effect, fermentation broth diluted 800 times and 1000 times was used for root irrigation of plants. Simultaneously, Bacillus belye CY30 fermentation broth diluted 800 times (1×10⁻⁶ CFU / mL) was used. 10CFU / mL and root irrigation with plain water (CK) served as controls. For the first four weeks after transplanting, 20 mL of water was applied weekly, with other treatments maintained at the same level. Irrigation was then discontinued. Data on plant growth were collected over a period of two months, from seed germination to plant measurements. Plant height and root length were measured using a ruler, stem diameter using calipers, and the fresh and dry weight of the above-ground parts of the plants were measured using an electronic balance.

[0114] As shown in Tables 8 and 9 below, Figure 9 and Figure 10 As shown, CQ1-800× exhibited the best overall plant height, root length, stem diameter, and fresh and dry weight of the upper root, showing a significant difference compared to the control. CQ1-1000× and CY30-800× followed, with no significant difference between them. Considering all aspects of the plant data, CQ1-800× demonstrated the best growth-promoting effect.

[0115] Table 8. Plant height, root length, and stem diameter for each treatment

[0116]

[0117]

[0118] Note: "±" indicates mean ± standard deviation. Different lowercase letters after the numbers indicate significance. Duncan's new multiple range method shows that differences are significant at the 0.05 level. The same applies below.

[0119] Table 9 Fresh and dry weights of aboveground parts for each treatment

[0120]

[0121] In summary, Bacillus paralichrysogenum CQ1 exhibits broad-spectrum antibacterial activity, showing inhibitory effects against a variety of plant pathogens, and its secondary metabolites can also inhibit pathogen growth. CQ1 is tolerant to salt concentrations ≤14% and can produce proteases, hepatophiles, and plant growth regulators (IAA). It also promotes the growth of tomato plants after seed production.

[0122] The above examples are merely illustrative of the present invention and do not constitute a limitation on the scope of protection of the present invention. All designs that are the same as or similar to the present invention are within the scope of protection of the present invention.

Claims

1. A strain of Bacillus paralichrysogenum CQ1, characterized in that: The Bacillus paralicheniformis CQ1 strain is deposited at the China Center for Type Culture Collection (CCTCC) with accession number CCTCC NO: M2023491.

2. The *Bacillus paralichrysogenum* CQ1 as described in claim 1, characterized in that: The 16S rDNA sequence of *Bacillus paralichrysogenum* CQ1 is shown in SEQ ID NO.

1.

3. The use of Bacillus paralichrysogenum CQ1 as described in any one of claims 1-2 in the secretion of auxin, protease and hepatophilia.

4. The application of *Bacillus paralichrysogenus* CQ1 as described in any one of claims 1-2 in inhibiting pathogens; wherein the pathogens are *Alternaria alternata*, *Alternaria brassicae*, *Maize leaf spot fungus*, *Phytophthora cucurbita*, *Sclerotinia sclerotiorum*, *Fusarium oxysporum*, *Curvaria crescentis*, *Botrytis cinerea*, *Dragon fruit canker fungus*, and *Anthracnose fungus*.

5. The application of Bacillus paralichrysiformis CQ1 as described in any one of claims 1-2 in promoting plant growth.

6. The application as described in claim 5, characterized in that: The plant in question is a tomato.

7. A metabolite of Bacillus paralichrysogenum CQ1, characterized in that, The metabolite is prepared by the following steps: inoculating the Bacillus paralichrysogenum CQ1 of any one of claims 1-2 into LB liquid medium for culture, centrifuging the cultured bacterial solution, filtering the bacterial cells, and obtaining sterile fermentation broth, which is the metabolite.

8. The application of the metabolite as described in claim 7 in inhibiting pathogens; wherein the pathogens are Botrytis cinerea, Fusarium oxysporum, Fusarium wilt of watermelon, Alternaria leaf spot of tea, Alternaria alternata, Anthracnose of citrus, Pyracantha fortuneana, and Anthracnose of strawberry.

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