Synthetic bacterial consortium for preventing and treating bacterial wilt and application thereof

Abstract

The present application relates to a synthetic bacterial population for preventing and treating bacterial wilt and application thereof, and belongs to the technical field of microorganisms.The present application relates to a synthetic bacterial population for preventing and treating bacterial wilt, wherein the synthetic bacterial population comprises Streptomyces spp., Sphingomonas spp., and Nocardioides spp.Based on field investigation and bioinformatics big data, it is found that Sphingomonas spp. and Nocardioides spp. are positively correlated with Streptomyces spp., so Streptomyces spp., Sphingomonas spp., and Nocardioides spp. are combined as a synthetic bacterial population, and through pot experiment, it is verified that the synthetic bacterial population can enable plants to resist the invasion of bacterial wilt, reduce the colonization number of bacterial wilt, and play a role in preventing and treating bacterial wilt, and can also relieve the growth obstacles of crops caused by bacterial wilt.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of microbial technology, and particularly relates to a synthetic bacterial population for preventing and treating bacterial wilt and application thereof. BACKGROUND

[0002] Bacterial wilt is a kind of bacterial wilt caused by Ralstonia solanacearum, also known as Ralstonia pesudosolanacearum, which can be transmitted through soil and water. After the pathogenic bacteria invade, they multiply in the vascular bundle of the plant and secrete extracellular products, causing the plant to wilt and eventually die. There are many methods to prevent and control bacterial wilt, including chemical control, agricultural control and biological control. Agricultural control is time-consuming, costly and inefficient; chemical control has a large environmental burden and is prone to cause bacterial wilt resistance; biological control is environmentally friendly, non-polluting, pathogenic bacteria are not prone to resistance, and it is safe for humans and animals. In practical application, the biggest problem of biological control is that the complex and variable field environment leads to unstable control effect. Single biocontrol bacteria are prone to have poor stability, weak colonization ability and non-persistent biocontrol effect in complex field environment. SUMMARY

[0003] The present application aims to overcome the shortcomings of the prior art and provide a synthetic bacterial population for reducing the colonization amount of bacterial wilt and realizing the effect of preventing and treating bacterial wilt and application thereof.

[0004] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows:

[0005] In a first aspect, the present application provides a synthetic bacterial population for preventing and treating bacterial wilt, which comprises Streptomyces spp., Sphingomonas spp. and Nocardioides spp.

[0006] The present application is based on field investigation and bioinformatics big data to find that Sphingomonas spp. and Nocardioides spp. are positively correlated with Streptomyces spp., so Streptomyces spp., Sphingomonas spp. and Nocardioides spp. are combined as a synthetic bacterial population. The pot experiment proves that the synthetic bacterial population can make the plant resist the invasion of bacterial wilt, reduce the colonization amount of bacterial wilt and play a role in preventing and treating bacterial wilt, and can also alleviate the growth obstacles of crops caused by bacterial wilt.

[0007] As a preferred embodiment of the synthetic flora according to the present application, the synthetic flora comprises Streptomyces rameus, Streptomyces fodineus, Sphingomonas hengshuiensis, Sphingomonas azotifigens, Nocardioides aromaticivorans and Nocardioides luteus. The present application proves by experiments that Streptomyces rameus and Streptomyces fodineus of the genus Streptomyces can antagonize Ralstonia solanacearum, Sphingomonas hengshuiensis and Nocardioides aromaticivorans have the ability to produce IAA, and Sphingomonas azotifigens and Nocardioides luteus have the potential nitrogen fixation function, so that the obtained synthetic flora has the ability to antagonize Ralstonia solanacearum and promote plant growth, and can prevent and control Ralstonia solanacearum while also relieving the growth obstacles of crops caused by Ralstonia solanacearum.

[0008] As a preferred embodiment of the synthetic flora according to the present application, the Streptomyces rameus is preserved in the Guangdong Microbial Culture Collection Center, and the preservation number is GDMCC No: 64749, and the preservation date is June 13, 2024;

[0009] The Streptomyces fodineus is preserved in the Guangdong Microbial Culture Collection Center, and the preservation number is GDMCC No: 64748, and the preservation date is June 13, 2024;

[0010] The Sphingomonas hengshuiensis is preserved in the Guangdong Microbial Culture Collection Center, and the preservation number is GDMCC No: 64714, and the preservation date is June 6, 2024;

[0011] The Sphingomonas azotifigens is preserved in the Guangdong Microbial Culture Collection Center, and the preservation number is GDMCC No: 64719, and the preservation date is June 6, 2024;

[0012] The Nocardioides aromaticivorans is preserved in the Guangdong Microbial Culture Collection Center, and the preservation number is GDMCC No: 64720, and the preservation date is June 6, 2024;

[0013] The Nocardioides luteus strain described is deposited at the Guangdong Provincial Center for Microbial Culture Collection, with accession number GDMCC No: 64721 and deposit date of June 6, 2024.

[0014] In a preferred embodiment of the synthetic microbial community described in this invention, the concentration ratio of Streptomyces rameus, Streptomyces fodineus, Sphingomonas hengshuiensis, Sphingomonas azotifigens, Nocardioides aromaticivorans, and Nocardioides luteus is Streptomyces rameus : Streptomyces fodineus : Sphingomonas hengshuiensis : Sphingomonas azotifigens : Nocardioides aromaticivorans : Nocardioides luteus = 1:1:1:1:1:1:1.

[0015] Secondly, the present invention provides a compound microbial agent, wherein the compound microbial agent comprises the above-mentioned synthetic microbial community.

[0016] Thirdly, the present invention provides the application of the above-mentioned synthetic microbial groups or compound microbial agents in the prevention and control of bacterial wilt.

[0017] Fourthly, the present invention provides the application of the above-mentioned synthetic microbial groups or compound microbial agents in promoting crop growth.

[0018] Fifthly, the present invention provides the application of the above-mentioned synthetic microbial groups or compound microbial agents in the prevention and control of bacterial wilt caused by continuous cropping.

[0019] As a preferred embodiment of the application described in this invention, the synthetic microbial community or compound microbial agent can reduce the colonization of Ralstonia solanacearum in the rhizosphere of crops.

[0020] As a preferred embodiment of the application described in this invention, the synthetic microbial community or compound microbial agent can regulate the rhizosphere microecology of crops.

[0021] As a preferred embodiment of the application described in this invention, the crop includes at least one of the Solanaceae, Lamiaceae, Fabaceae, and Sesamum family.

[0022] Sixthly, the present invention provides a method for preventing and controlling bacterial wilt, comprising the following steps: applying the above-mentioned synthetic microbial flora or compound microbial agent to the roots of crops, wherein the concentration of the synthetic microbial flora or compound microbial agent is 10. 8 ~10 9 CFU / mL.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. Based on field surveys and bioinformatics big data, this invention combines Streptomyces, Sphingomonas, and Nocardia into a synthetic microbial community. Pot experiments have confirmed that this synthetic microbial community can help plants resist the invasion of Ralstonia solanacearum, reduce the colonization of Ralstonia solanacearum and thus play a role in the prevention and control of Ralstonia solanacearum, and at the same time alleviate crop growth obstacles caused by Ralstonia solanacearum.

[0025] 2. The *Streptomyces rameus* and *Streptomyces fodineus* species in the synthetic microbial community of this invention can antagonize *Ralstonia solanacearum*, *Sphingomonas hengshuiensis* and *Nocardioides aromaticivorans* have the ability to produce IAA, and *Sphingomonas azotifigens* and *Nocardioides luteus* have potential nitrogen-fixing functions. Therefore, the obtained synthetic microbial community has the ability to antagonize *Ralstonia solanacearum* and promote plant growth, and can prevent and control bacterial wilt while alleviating the crop growth obstacles caused by bacterial wilt. Attached Figure Description

[0026] Figure 1 This is a diagram showing the interaction relationships between Streptomyces and other bacterial genera in Example 1 of the present invention.

[0027] Figure 2 The above are the statistical results of bacterial wilt disease index in different treatment groups in Example 1 of the present invention;

[0028] Figure 3 The above are the statistical results of the bacterial wilt control effects of different treatment groups in Example 1 of the present invention;

[0029] Figure 4 The statistical results of tomato plant height and fresh weight in different treatment groups in Example 1 of the present invention;

[0030] Figure 5 The statistical results of tomato root weight and chlorophyll content in different treatment groups in Example 1 of the present invention are shown.

[0031] Figure 6 The above are the statistical results of the colonization of Ralstonia solanacearum in different treatment groups in Example 1 of the present invention;

[0032] Figure 7 The above are the statistical results of bacterial wilt disease index in different treatment groups in Example 2 of the present invention;

[0033] Figure 8 The above are the statistical results of the bacterial wilt control effects of different treatment groups in Example 2 of the present invention;

[0034] Figure 9 The statistical results of tomato plant height and fresh weight in different treatment groups in Example 2 of the present invention;

[0035] Figure 10 The statistical results of tomato stem diameter and chlorophyll content in different treatment groups in Example 2 of the present invention;

[0036] Figure 11 The relative abundance of Streptomyces in the rhizosphere soil of tomatoes in different treatment groups in Example 3 of the present invention;

[0037] In the above figure, different lowercase letters represent significant differences between the two, P < 0.05. Detailed Implementation

[0038] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0039] In this invention, the bacterial wilt pathogen can be any bacterial wilt pathogen already disclosed in the prior art or commercially available (such as Ralstonia solanacearum GMI1000, R. solanacearum UW551, etc.). The bacterial wilt pathogen used in the embodiments and effect examples of this invention is R. pesudosolanacearum FQ1, a pseudosolanaceae bacterium collected by the inventors themselves. The specific source and identification are as follows:

[0040] Ralstonia solanacearum FQ1 was isolated from the stem base of tomato plants infected with bacterial wilt in Guangzhou. After confirming FQ1 as the causative agent of tomato bacterial wilt using Koch's postulates, 16S rRNA gene amplification and sequencing of FQ1 were performed. Homology analysis of the obtained gene sequence was conducted on EzBioCloud. The results showed that strain FQ1 belongs to the genus *Ralstonia* and is related to *R. pesudosolanacearum* UQ RS 461. T R. solanacearum LMG 2299 T , R.syzygii subsp.Indonesiensis UQR S464 TThe similarities were 99.64%, 99.47%, and 99.47%, respectively. A phylogenetic tree was constructed using MEGA 11.0 software and the Neighbour Joining method, and the FQ1 strain was identified as R. pesudo solanacearum.

[0041] Unless otherwise specified, “Ralstonia solanacearum”, “R. pesudosolanacearum”, “Ralstonia solanacearum”, and “FQ1” mentioned in the following examples and effect examples are all Ralstonia pesudosolanacearum FQ1.

[0042] Unless otherwise specified, all materials and reagents used in the following examples and effect examples are commercially available.

[0043] NA solid medium: Add 3g beef extract, 10g bacteriological peptone, 5g sodium chloride, and 18g agar powder to 1000mL distilled water. After complete dissolution, autoclave at 121℃ for 15min. Cool after sterilization for later use. Remove the agar powder from the above medium to prepare NB liquid medium, and sterilize at 121℃ for 30min.

[0044] Gao's No. 1 culture medium: Take 20g soluble starch, 1g KNO3, 0.5g K2HPO4, 0.5g MgSO4·7H2O, 0.5g NaCl, 0.01g FeSO4·7H2O, and 20g agar and add them to 1000mL distilled water. Adjust the pH to 7.4-7.6, autoclave at 121℃ for 15min, and cool for later use.

[0045] PDA medium: Peel 200g of potatoes, cut them into 0.5cm cubes, add 1L of deionized water, boil for 30min, filter through 4 layers of gauze, add 20g of glucose and 20g of agar to the filtrate, bring the volume to 1L, and sterilize at 121℃ for 20min; if preparing PDB medium, do not add agar.

[0046] SMSA medium: Take 16g agar, 10g peptone, 1g acid-hydrolyzed casein, 5mL glycerol, 10mL 1% polymyxin, 0.5mL 1% crystal violet, 5mL 1% TTC, 2.5mL 1% bacitracin, 0.5mL penicillin, 10mL 1% chloramphenicol, and 10mL 1% actinomycin. Add them to 1000mL distilled water, dissolve completely, and sterilize at 121℃ for 20min.

[0047] Preparation method of general microbial fermentation broth and bacterial suspension: After activating the microorganism in NA medium or Gao's No. 1 medium, transfer it to NB medium and culture for 24 hours to obtain seed liquid. Inoculate the seed liquid into NB medium at an inoculation rate of 5% and culture at 180 rpm and 30℃ for 24 hours to obtain fermentation broth. Centrifuge the fermentation broth at 8000 rpm and 4℃ for 8-10 minutes, collect the bacterial precipitate, and resuspend it in sterile water to obtain bacterial suspension.

[0048] Method for preparing Streptomyces bacterial suspension: Activate Streptomyces on Gao's No. 1 medium, transfer to PDA medium and culture until spores are produced, add an appropriate amount of sterile water to the culture dish to scrape and wash the spores to obtain a spore suspension, which is the bacterial suspension.

[0049] The method for preparing sterile vermiculite involves mixing vermiculite with Hoagland's nutrient solution. When the vermiculite reaches a moisture level where it cannot be squeezed dry by hand, it is sterilized at 121℃ for 30 minutes. This sterilization process is repeated three times to obtain sterile vermiculite. The dosage of sterile vermiculite in seedling pots is 400g / pot. The method for measuring the colonization quantity of Ralstonia solanacearum on and within plant roots includes the following steps:

[0050] (1) Root surface counting: 0.3 g of root sample was taken from each treatment and placed in a centrifuge tube containing 15 mL PBS. The sample was sonicated once (30 s, 50-60 Hz) to remove microorganisms from the root surface. The roots were then removed, and the liquid PBS was retained. The PBS solution was diluted to 10. -4 10 -5 10 -6 Prepare SMSA medium, spread 100 μL of the diluted suspension on the medium, incubate at 30°C for 2 days, and count the colony forming units (CFU).

[0051] (2) Root counting: 0.3 g of root sample was taken from each treatment and sonicated twice with PBS solution to remove all microorganisms from the root surface; the sample was disinfected with 1% (v / v) sodium hypochlorite for 10 min and rinsed 5-6 times with sterile water; the root sample was ground into a homogenate in a sterile mortar and the suspension was diluted 10 times. -2 10 -3 10 -4 Prepare SMSA medium, spread 100 μL of the diluted suspension onto the medium, incubate at 30°C for 2 days, and count the colony forming units (CFU).

[0052] Example 1

[0053] This embodiment provides a synthetic microbial community for the prevention and control of bacterial wilt. The method for constructing the synthetic microbial community includes the following steps:

[0054] 1. Analysis of the Spearman correlation between the relative abundance of Streptomyces and other microorganisms.

[0055] Rhizosphere soil samples from healthy tomatoes were collected at a tomato base in Guangzhou. The bacterial community species abundance in these samples was detected using high-throughput sequencing with 16S rRNA amplicon sequencing. The corresponding raw data were obtained, and the Spearman correlation between the relative abundance of microorganisms and Streptomyces was calculated using the R package “ggcor” (Dixon P. VEGAN, a package of Rfunctions for community ecology[J]. J Veg Sci. 2003; 14(6):927-30.). In the healthy rhizosphere soil samples, the top 50 bacteria with the highest relative abundance and an absolute correlation coefficient greater than 0.6 with Streptomyces were used to construct a network. The interaction network analysis results were plotted on the ChiPlot website, showing the interaction network analysis results. Figure 1 .

[0056] like Figure 1 As shown, Streptomyces, Sphingomonas, Nocardioides, norank_f_JG30-KF-CM45, unclassified_f_intrasporangiaceae, and norank_f_Roseiflexaceae are positively correlated.

[0057] 2. Screening for culturable microorganisms

[0058] according to Figure 1 As a result, two Streptomyces strains, two Sphingomonas strains, and two Nocardioides strains were selected from the rhizosphere soil samples of healthy tomatoes for IAA production and nitrogen fixation function experiments. A plate antagonism experiment was also conducted with FQ1. The experimental procedures were performed according to Bergey's Manual of Bacteriology (R.E. Buchanan, N.E. Gibbons, et al.) and Methods for Plant Disease Research (Fang Zhongda). The strain information and experimental results are shown in Table 1. All strains mentioned in Table 1 are deposited at the Guangdong Provincial Microbial Culture Collection Center, located at 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou, Guangdong Province. The accession number and accession date of each strain are shown in Table 1.

[0059] Table 1 Characteristics of different strains

[0060]

[0061]

[0062] As shown in Table 1, all streptomycin species have certain antagonistic properties against FQ1, and some sphingomonas and nocardia species have IAA production and potential nitrogen-fixing functions.

[0063] 3. Compatibility experiment of synthetic microbial communities

[0064] The strains in Table 1 were subjected to a compatibility test, and the specific steps are as follows:

[0065] The cross-streaking method was used on PDA medium to detect whether the synthetic bacterial groups were antagonistic to each other. The medium after inoculation was placed in a 28°C incubator for 5 days, and the presence of inhibition zones was observed. If inhibition zones were present, the strains were antagonistic to each other; if no inhibition zones were present, the strains were compatible. In the subsequent construction of synthetic bacterial groups, compatible strains were used as candidate strains, and the results are shown in Table 2.

[0066] Table 2. Results of compatibility experiments with synthetic microbial communities

[0067]

[0068]

[0069] As shown in Table 2, there were no antagonistic effects among the strains, indicating good compatibility. Therefore, a bacterial culture of synthetic flora SyⅠ was selected, consisting of Streptomyces rameus, Streptomyces fodineus, Sphingomonas hengshuiensis, Sphingomonas azotifigens, Nocardioides aromaticivorans (a type of aromatic nocardi), and Nocardioides luteus (a type of luteolin) in a 1:1 concentration ratio. The final concentration of each strain was 10. 8 cfu / mL.

[0070] Comparative Examples 1-7

[0071] Comparative Examples 1-7 each provide a biocontrol bacterium for controlling bacterial wilt. Comparative Examples 1-6 are all single biocontrol bacteria, while Comparative Example 7 is a combination of two biocontrol bacteria. Specifically:

[0072] Comparative Example 1 was Streptomyces rameus (strain number 30240);

[0073] Comparative Example 2 was Streptomyces fodineus (strain number 30177);

[0074] Comparative Example 3 was Sphingomonas hengshuiensis (strain number 2536);

[0075] Comparative Example 4 was Sphingomonas azotifigens (strain number 06703);

[0076] Comparative Example 5 was Nocardioides aromaticivorans (strain number 06764), a species that feeds on aromatic plants.

[0077] Comparative Example 6 was Nocardioides luteus (strain number 06986);

[0078] Comparative Example 7 consisted of Streptomyces rameus (strain number 30240) and Streptomyces fodineus (strain number 30177).

[0079] Example of effect 1

[0080] To verify the efficacy of the synthetic microbial community in controlling bacterial wilt in sterile vermiculite, a pot experiment was conducted using the synthetic microbial community obtained in Example 1 and the microbial agents of Comparative Examples 1-7. The specific procedures are as follows:

[0081] 1. Preparation of microbial agents

[0082] The synthetic bacterial group from Example 1 and the bacterial agents from Comparative Examples 1-7 were prepared into fermentation broths. The fermentation broths were centrifuged at 4°C and 8000 rpm to obtain bacterial cells, which were then resuspended in sterile water for later use.

[0083] 2. Plant preparation

[0084] Tomatoes were used as the test subject. Tomato seeds were disinfected with 1% sodium hypochlorite (v / v) for 15 minutes, rinsed several times with sterile water, soaked in sterile water for 2-3 hours, and then transferred to sterile seedling trays. When the tomato seedlings had grown 3-4 true leaves, they were transplanted into pots containing sterile vermiculite and left for 3 days before use.

[0085] 3. Test Content

[0086] Before inoculation, the tomato seedlings were treated to prevent root damage. The tomato seedlings were treated according to Table 3, with 6 replicates for each treatment. The potted plants were cultivated in an environment with a temperature of 28-30℃, humidity of 65-80%, and a photoperiod of 12h. They were watered evenly and appropriately every day.

[0087] After the tomatoes showed signs of wilting, the disease incidence was recorded daily for 35 days. Physiological indicators such as plant height, fresh weight, root weight, and chlorophyll content were measured. On day 35 after inoculation with FQ1, the number of Ralstonia solanacearum colonizing the tomato plants on the root surface and in the roots was counted. According to the grading standards in *Plant Disease Research Methods* (Fang Zhongda, 1998): Grade 0: Healthy plants; Grade 1: Less than 25% of leaves wilted; Grade 2: 25%-50% of leaves wilted; Grade 3: 50%-75% of leaves wilted; Grade 4: More than 75% of leaves wilted.

[0088] Incidence rate % (DI) = Number of infected plants / Total number of plants × 100%;

[0089] Disease index = [Σ(disease level × number of plants with that disease level) / (highest disease level × total number of plants)] × 100%;

[0090] The efficacy (BE) percentage is calculated as follows: [(Disease index of control group - Disease index of treatment group) / Disease index of control group] × 100%.

[0091] Incidence rate, disease index, and prevention and control efficacy are shown in Table 4 and Figures 2-3 Plant height, fresh weight, root weight, and chlorophyll content are shown in Table 4 and 5. Figures 4-5 The colonization quantity of Ralstonia solanacearum is shown in Table 4 and Figure 6 .

[0092] Table 3. Tomato seedling treatments in pot experiments

[0093]

[0094]

[0095] Table 4. Statistical results of morbidity and other indicators on day 35 after FQ1 vaccination in different treatment groups.

[0096]

[0097] As shown in Table 4 and Figure 2As shown, the disease incidence of tomatoes in different treatment groups began to differ from day 7 after inoculation with Ralstonia solanacearum. On day 7, the disease indices of the four treatment groups RS, T1, T2, and T3 were 20.14%, 11.25%, 4.09%, and 2.86%, respectively, while no symptoms of bacterial wilt were observed in the T4, T5, T6, and T7 treatment groups. From day 14 onwards, bacterial wilt symptoms began to appear in the T4, T5, T6, and T7 treatment groups, with disease indices of 20.83%, 4.5%, 10.42%, and 16.67%, respectively, while no disease had yet appeared in the SyⅠ treatment group. From day 14 to day 28, except for the SyⅠ treatment group, the disease incidence index of the other seven treatment groups showed an upward trend. On day 28, the disease incidence indices of the T1, T2, T3, T4, T5, T6, and T7 treatment groups were 97.5%, 84%, 98%, 47.92%, 47.5%, 47.5%, and 41.5%, respectively. From day 28 to day 35, the SyⅠ treatment group began to develop the disease, with a disease incidence index of 8.34%.

[0098] As shown in Table 4 and Figure 3 As shown, the control effects of treatment groups T4, T5, T6 and T7 were significantly higher than those of treatment groups T1, T2 and T3 (P<0.05), while the control effect of treatment group SyⅠ was significantly higher than that of the other 7 treatment groups (P<0.05).

[0099] As shown in Table 4 and Figures 4-5 As shown, the plant height of the CK, T6, T7, and SyⅠ treatment groups was significantly higher than that of the T1, T2, T3, T4, T5, and RS treatment groups, with no significant difference in plant height among the CK, T6, T7, and SyⅠ treatment groups. The fresh weight of the CK, T4, T5, T6, T7, and SyⅠ treatment groups was significantly higher than that of the T1, T2, T3, and RS treatment groups, with no significant difference in fresh weight among the CK, T4, T5, T6, T7, and SyⅠ treatment groups. There were significant differences in root weight among the different treatment groups, with the CK group having the highest root weight at 3.54 g, but no significant difference compared to the root weight of the T4, T6, T7, and SyⅠ treatment groups. The chlorophyll content of the CK treatment group was significantly higher than that of the other nine treatment groups.

[0100] As shown in Table 4 and Figure 6 As shown, except for the CK group, all treatment groups had Ralstonia solanacearum colonizing on the root surface and inside the roots. Among them, the number of Ralstonia solanacearum colonizing on the root surface of the T5 and SyⅠ treatment groups was significantly lower than that of the other 8 treatment groups. This indicates that applying the synthetic microbial group SyⅠ before inoculating with Ralstonia solanacearum can effectively enable tomatoes to resist Ralstonia solanacearum infection and reduce the number of Ralstonia solanacearum colonizing in the tomato roots and on the root surface.

[0101] In summary, in sterile vermiculite potted plants, the synthetic microbial community SyⅠ of this invention can effectively control the occurrence of bacterial wilt of tomatoes by resisting the infection of Ralstonia solanacearum, thereby reducing the colonization of Ralstonia solanacearum in the plant roots and on the root surface. At the same time, the synthetic microbial community SyⅠ can improve the slow plant growth caused by RS and promote plant growth.

[0102] Example 2

[0103] To verify the efficacy of the synthetic microbial community in controlling bacterial wilt in continuously cropped soil, pot experiments were conducted on the synthetic microbial community obtained in Example 1 and the microbial agents of Comparative Examples 1-7. The specific scheme was similar to that of Example 1, except that the sterile vermiculite used was replaced with continuously cropped soil, while the other steps and parameters remained unchanged. The indicators tested were disease incidence, disease index, control effect, plant height, fresh weight, stem diameter, and chlorophyll content. The test indicators are shown in Table 5 and [Table data missing]. Figures 7-10 .

[0104] Table 5. Statistical results of morbidity and other indicators on day 35 after FQ1 vaccination in different treatment groups.

[0105]

[0106] As shown in Table 5 and Figure 7 As shown, 7 days after inoculation with the pathogen, the T1, T2, and T3 treatment groups began to show symptoms of bacterial wilt, while the other seven treatment groups did not develop the disease. From day 14 onwards, the T1, T2, T3, T4, T5, T6, and T7 treatment groups all showed symptoms of bacterial wilt, while the SyⅠ treatment group had not yet developed the disease. The disease indices for the T1, T2, T3, T4, T5, T6, and T7 treatment groups were 68.34%, 12.5%, 12.5%, 12.5%, 4.13%, 10.42%, and 14.59%, respectively. From day 21 to day 28, the disease indices for the T1, T2, T3, T4, T5, T6, and T7 treatment groups all showed an upward trend, and the SyⅠ treatment group also began to show symptoms, with a disease index of 16.67%.

[0107] As shown in Table 6 and Figure 8 As shown, the control effects of treatment groups T5 and T6 were significantly higher than those of treatment groups T1, T2, T3, T4, and T7 (P<0.05), while the control effect of treatment group SyⅠ was significantly higher than that of treatment groups T1, T2, T3, T4, T5, T6, and T7 (P<0.05).

[0108] As shown in Table 6 and Figures 9-10As shown, compared with the CK group, the plant height of the T3, T6, and SyⅠ treatment groups was significantly higher by 33.21%, 50.02%, and 41.10%, respectively (P<0.05). The fresh weight and chlorophyll content of the SyⅠ treatment group were not significantly different from the CK group, but the chlorophyll content of the SyⅠ treatment group was significantly higher than that of the RS, T1, T2, T3, T4, T5, T6, and T7 treatment groups. There were differences in stem diameter among the different treatment groups; the CK group was significantly lower than the T3 treatment group, and the stem diameter of the T3 treatment group was 29.31% higher than that of the CK group (P<0.05). The stem diameter of the T2, T5, T6, T7, and SyⅠ treatment groups was not significantly different from that of the CK group.

[0109] In summary, the synthetic microbial community SyⅠ of this invention also exhibits superior efficacy in controlling bacterial wilt in plants grown in continuously cropped soil. Continuously cropped soil often contains various pathogens, including Ralstonia solanacearum. Continuous cropping of Solanaceae plants easily leads to susceptibility to bacterial wilt. Experiments have demonstrated that the synthetic microbial community SyⅠ can alleviate plant susceptibility caused by continuous cropping, thus mitigating the obstacles posed by continuous cropping.

[0110] Example 3

[0111] To verify the impact of synthetic microbial communities on the plant rhizosphere microecology, tomato rhizosphere soils from the CK, RS, T5, T6, T7, and SyⅠ treatment groups in Example 2 were collected. High-throughput sequencing of 16S rRNA amplicon was performed by Meiji Biotechnology Co., Ltd., and the relative abundance of *Streptomyces* in different treatment groups was calculated. The results are shown in […]. Figure 11 .

[0112] like Figure 11 As shown, the relative abundance of Streptomyces in the SyⅠ treatment group was the highest among the six treatments, and significantly higher than that in the CK and T6 treatment groups; the relative abundance of Streptomyces in the T7 treatment group was significantly higher than that in the T6 treatment group, indicating that the synthetic microbial community of the present invention can significantly increase the relative abundance of Streptomyces in the plant rhizosphere soil.

[0113] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A synthetic bacterial consortium for controlling bacterial wilt, characterized in that, The components of the synthetic flora are Streptomyces rameus 30240, Streptomyces fodineus 30177, Sphingomonas hengshuiensis 02536, Sphingomonas azotifigens 06703, Nocardioides aromaticivorans 06764 and Nocardioides luteus 06986 preserved in the Guangdong Microbial Digital Culture Collection Center, and the address is No. 59, 5th Floor, Institute of Guangzhou, Guangzhou, Guangdong Province, China; The preservation number of the Streptomyces rameus 30240 is GDMCC No: 64749, and the preservation date is June 13, 2024; The preservation number of the Streptomyces fodineus 30177 is GDMCC No: 64748, and the preservation date is June 13, 2024; The preservation number of the Sphingomonas hengshuiensis 02536 is GDMCC No: 64714, and the preservation date is June 6, 2024; The preservation number of the Sphingomonas azotifigens 06703 is GDMCC No: 64719, and the preservation date is June 6, 2024; The preservation number of the Nocardioides aromaticivorans 06764 is GDMCC No: 64720, and the preservation date is June 6, 2024; The preservation number of the Nocardioides luteus 06986 is GDMCC No: 64721, and the preservation date is June 6, 2024; The concentration ratio of the Streptomyces rameus 30240, Streptomyces fodineus 30177, Sphingomonas hengshuiensis 02536, Sphingomonas azotifigens 06703, Nocardioides aromaticivorans 06764 and Nocardioides luteus 06986 is Streptomyces rameus 30240:Streptomyces fodineus 30177:Sphingomonas hengshuiensis 02536:Sphingomonas azotifigens 06703:Nocardioides aromaticivorans 06764:Nocardioides luteus 06986 = 1:1:1:1:1:

1.

2. A complex microbial agent, characterized in that, The complex microbial agent comprises the synthetic microbial flora of claim 1.

3. The synthetic microbial flora of claim 1 or the complex microbial agent of claim 2 is used for preventing and treating tomato bacterial wilt.

4. The use according to claim 3, wherein the compound is ###0002### The synthetic microbial flora or the complex microbial agent can reduce the colonization amount of tomato bacterial wilt in the rhizosphere of crops.

5. Use according to any one of claims 3 to 4, characterized in that, The synthetic microbial flora or the complex microbial agent can regulate the microecology in the rhizosphere of crops. The synthetic microbial flora or the complex microbial agent can reduce the colonization amount of tomato bacterial wilt in the rhizosphere of crops. The synthetic microbial flora or the complex microbial agent can regulate the microecology in the rhizosphere of crops.

6. A method for controlling bacterial wilt of tomato, characterized by, The method comprises the following steps: applying the synthetic bacterial flora in claim 1 or the composite microbial agent in claim 2 to the roots of crops, wherein the concentration of the bacterial bodies of the synthetic bacterial flora or the composite microbial agent is 10 8 ~10 9 cfu / mL.

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