A strain of Kosakonia cowanii qzb219 and its applications

Abstract

The present invention provides a strain of Kosakonia cowanii qzb219 and its applications, and its taxonomic name is Kosakonia cowanii qzb219, and the preservation number is CGMCC NO. 31519. This strain of Kosakonia cowanii has good disease prevention effects on tobacco bacterial wilt and tobacco Fusarium root rot and can promote the growth of tobacco seedlings. The Kosakonia cowanii qzb219 of the present invention can efficiently inhibit the growth of tobacco bacterial wilt pathogens and tobacco Fusarium root rot pathogens, has amylase and protease activities, and has a growth-promoting effect on tobacco seedlings. This bacterium has a fast growth rate, is easy to ferment, and has good compatibility with the main fungicides for controlling tobacco bacterial wilt pathogens, namely thiodiazole copper and thiazole zinc. This bacterium can effectively prevent and control the occurrence of tobacco bacterial wilt and tobacco Fusarium root rot, and has a certain growth-promoting effect on tobacco seedlings. It is a biocontrol bacterium with great market potential.

Description

Technical Field

[0001] The present invention relates to the technical field of microbiology, and particularly relates to a Kosakonia cowanii qzb219 and its application. Background Art

[0002] Tobacco is an important cash crop, and root and stem diseases represented by tobacco bacterial wilt have caused great losses to the tobacco leaf production in these producing areas. In recent years, with the increase in temperature and rainfall in the north, the occurrence of tobacco root and stem diseases in the northern tobacco-growing areas of China has become increasingly serious. The pathogens of tobacco root and stem diseases can survive in tobacco field soil for a long time. Chemical pesticides have low control efficacy and are prone to cause an increase in pathogen drug resistance. Their large-scale application also has adverse effects on biodiversity, human and livestock health, and the safety of tobacco leaf products. Therefore, developing green, efficient, and pollution-free biological pesticides has become an important research direction for the prevention and control of tobacco root and stem diseases.

[0003] Microorganisms and their metabolites can effectively inhibit the growth of pathogens, thereby controlling the occurrence of diseases. Currently, a variety of microbial agents are used for the prevention and control of plant diseases. For root and stem diseases such as tobacco bacterial wilt and tobacco Fusarium root rot, most of the currently developed microbial agents are Bacillus.

[0004] Currently, most commercial microbial agents have problems such as a single strain source, a short effective period of the microbial agent, high fermentation cost, insufficient concentration of active bacteria, poor compatibility with chemical pesticides, and unstable control efficacy. It is urgent to deeply explore the antagonistic microbial resources in tobacco fields and develop efficient and green microbial agents on this basis, so as to effectively control the occurrence of tobacco root and stem diseases. Summary of the Invention

[0005] The object of the present invention is to provide a Kosakonia cowanii qzb219 and its application. This strain has strong antagonistic ability against Ralstonia solanacearum and Fusarium solani f. sp. nicotianae, fast growth rate, strong tolerance to fungicides, and has a certain growth-promoting effect on tobacco seedlings. The microbial agent prepared from this bacterium has a high concentration of viable bacteria, can effectively inhibit the growth of Ralstonia solanacearum and Fusarium solani f. sp. nicotianae, and promote the growth of tobacco seedlings.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] In the first aspect of the present invention, a Kosakonia cowanii ( Kosakonia cowanii ) qzb219 is provided, and the preservation number of the Kosakonia cowanii ( Kosakonia cowanii ) qzb219 is: CGMCC NO.31519.

[0008] In the second aspect of the present invention, a fermentation microbial agent is provided, and the fermentation microbial agent includes:

[0009] The fermentation broth or bacterial suspension obtained by fermenting and culturing the Kosakonia cowanii qzb219;

[0010] Or the dry powder bacterial agent obtained by spray-drying the fermentation broth.

[0011] Furthermore, the preparation method of the fermentation broth includes:

[0012] Inoculating the Kosakonia cowanii qzb219 into a liquid medium for fermentation and culturing to obtain a fermentation broth.

[0013] Furthermore, the conditions for the fermentation and culturing include: the temperature is 26 - 30 °C, and the pH is 5 - 9.

[0014] Furthermore, the concentration of Kosakonia cowanii qzb219 in the bacterial agent is 1 - 10×10 9 CFU / mL.

[0015] In the third aspect of the present invention, there is provided the application of the Kosakonia cowanii qzb219 in inhibiting Ralstonia solanacearum and Fusarium solani f. sp. nicotianae.

[0016] In the said application, the concentration of Kosakonia cowanii qzb219 is 1 - 10×10 6 CFU / mL.

[0017] In the fourth aspect of the present invention, there is provided the application of the fermentation bacterial agent in inhibiting Ralstonia solanacearum and Fusarium solani f. sp. nicotianae.

[0018] In the fifth aspect of the present invention, there is provided the application of the Kosakonia cowanii qzb219 in promoting the growth of tobacco seedlings.

[0019] In the sixth aspect of the present invention, there is provided the application of the fermentation bacterial agent in promoting the growth of tobacco seedlings.

[0020] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0021] Compared with the prior art, the Kosakonia cowanii qzb219 provided by the present invention is a biocontrol bacterium different from conventional Bacillus. This bacterium has good antagonistic effects against Ralstonia solanacearum and Fusarium solani f. sp. nicotianae, which are seriously harmful in current production, and can effectively control tobacco bacterial wilt and tobacco Fusarium root rot. In addition, this bacterium has a fast growth rate and is easy to ferment. It has good compatibility with the main fungicides for controlling tobacco bacterial wilt currently, and can also significantly promote the growth of tobacco seedlings, showing great potential for developing into an efficient biocontrol agent. In addition, when Kosakonia cowanii qzb219 is used in combination with pesticides, the application amounts of the pesticides thiodiazole copper and thiazole zinc can be reduced (by 15%-20%), and the control effect of tobacco bacterial wilt is increased by 30%, showing a synergistic effect when used in combination with pesticides.

[0022] The preservation date of the Kosakonia cowanii qzb219 of the present invention is August 1, 2024, and the preservation number is CGMCC NO. 31519. Its taxonomic name is Kosakonia cowanii Kosakonia cowanii , and the preservation unit is the China General Microbiological Culture Collection Center, located at No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, with a postal code of 100101. Description of the Drawings

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0024] Figure 1 It is the colony morphology of Kosakonia cowanii qzb219;

[0025] Figure 2 It is the phylogenetic tree of Kosakonia cowanii qzb219 based on the 16S rDNA sequence;

[0026] Figure 3 It is the inhibitory effect of Kosakonia cowanii qzb219 on Ralstonia solanacearum;

[0027] Figure 4 It is the inhibitory effect of Kosakonia cowanii qzb219 on tobacco Fusarium root rot;

[0028] Figure 5 It is the starch degradation effect of Kosakonia cowanii qzb219;

[0029] Figure 6 It is the protein degradation effect of Kosakonia cowanii qzb219;

[0030] Figure 7Growth curve of Kosakonia cowanii qzb219

[0031] Figure 8 Control effect of Kosakonia cowanii qzb219 against tobacco bacterial wilt. A: Diseased control plants; B: Plants treated with qzb219

[0032] Figure 9 Growth promotion effect of Kosakonia cowanii qzb219 on tobacco seedlings. A: Plants treated with qzb219; B: Control plants Detailed implementation manners

[0033] The present invention will be specifically described below in combination with the detailed implementation manners and examples, and the advantages and various effects of the present invention will be presented more clearly therefrom. Those skilled in the art should understand that these detailed implementation manners and examples are used to illustrate the present invention rather than limit the present invention

[0034] Throughout the specification, unless otherwise specifically stated, the terms used herein should be understood as having the meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which the present invention belongs. In case of contradiction, this specification shall prevail

[0035] Unless otherwise specifically stated, various raw materials, reagents, instruments and equipment used in the present invention can be obtained through market purchase or by existing methods

[0036] The Ralstonia solanacearum of tobacco bacterial wilt in this application was provided by the Laboratory of Natural Product Pesticides, College of Plant Protection, Southwest University

[0037] The Fusarium solani of tobacco Fusarium root rot in this application was isolated from tobacco field soil

[0038] The technical solutions of the examples of this application are to solve the above technical problems, and the general idea is as follows

[0039] The inventors of this application collected rhizosphere soil of diseased tobacco plants in a tobacco field with severe tobacco bacterial wilt in Baoshan, Yunnan. Through isolation, purification and screening, a strain of bacteria was obtained. It was found that this strain had an antagonistic effect on Fusarium oxysporum f. sp. nicotianae. After colony morphology, biochemical and 16S rRNA sequencing analysis of this bacterium, the homology of this strain with multiple strains of Kosakonia cowanii Kosakonia cowanii was more than 96%. Combining physiological and biochemical characteristics, this strain was initially determined to belong to Kosakonia cowanii and was named Kosakonia cowanii Kosakonia cowanii .

[0040] Kosakonia cowanii of the present invention has a good promoting effect on the germination and growth of tobacco seeds and a good disease prevention effect on tobacco root rot, providing a theoretical basis for the subsequent development of biological bactericides.

[0041] Next, a strain of Kosakonia cowanii qzb219 and its application of the present application will be described in detail with reference to examples and experimental data.

[0042] Example 1: Isolation, purification and identification of Kosakonia cowanii qzb219

[0043] 1. Isolation and purification of tobacco field soil microorganisms

[0044] The culture media used in the following examples of the present invention are as follows:

[0045] LB medium: Dissolve 10 g of peptone, 5 g of yeast extract and 10 g of sodium chloride in 900 mL of water. For solid medium, add 10 g of agar powder, make up the volume to 1000 mL, and obtain it after autoclaving at 121 °C for 15 - 20 min.

[0046] Both PDA medium and Gao's No. 1 medium are purchased from Qingdao Haibo Biotechnology Co., Ltd.

[0047] 1.1 Isolation of antagonistic strains

[0048] The soil sample is the rhizosphere soil of diseased tobacco plants in a tobacco field with severe tobacco bacterial wilt in Baoshan, Yunnan.

[0049] Weigh 10 g of soil sample, add it to a conical flask containing 90 mL of sterile water, seal it with a sealing film, and enrich and culture it at 30 °C and 180 r / min for 1 d. Gradient dilute the mother liquor of the activated tobacco rhizosphere soil, and evenly coat 100 μL of the dilution solutions with dilution factors of 10 -3 、10 -4 、10 -5 、10 -6 and 10 -7 on the LB medium plate, PDA medium plate and Gao's No. 1 medium plate respectively. Use 3 petri dishes for each dilution factor. Place the coated petri dishes in a constant temperature incubator at 28 °C and culture for 48 h. Observe and record the growth of colonies on the culture medium at 24 h and 48 h of culture respectively. Use an inoculation needle to pick individual colonies and streak-culture and purify them on a new culture medium. A total of 387 strains are isolated.

[0050] 1.2 Screening of antagonistic bacteria

[0051] Pick a single colony of Ralstonia solanacearum and place it in 100 mL of LB liquid medium. Shake and activate it at 28 °C and 180 rpm in a floor-standing constant temperature shaker for 48 h. Take 100 μL of the activated Ralstonia solanacearum bacterial suspension and evenly spread it on the solid medium to prepare a plate containing Ralstonia solanacearum. Punch holes (hole diameter is 5 mm) at 25 mm from the center at the edge of each plate. The number of punched holes on each plate is 6. Use a pipette to separately aspirate 35 μL of the candidate strain bacterial liquid into the holes, with the blank LB liquid medium as the control. After the plate has fully absorbed the bacterial liquid, seal it and place it in an incubator at 28 °C for cultivation. Observe and record the growth of colonies and the antibacterial effect on the plate at 24 h and 48 h respectively. Use the cross method to measure the diameter of the antibacterial circle. Each treatment is repeated 3 times and the average value is taken.

[0052] A total of 102 strains with antagonistic effects against Ralstonia solanacearum were screened from 387 strains, and the diameter range of their antibacterial circles was 6.17 mm - 29.5 mm.

[0053] 1.3 Re-screening of antagonistic bacteria

[0054] Perform an antagonistic test on the 102 initially screened antagonistic bacterial strains again using the antibacterial circle method to confirm their antagonistic effects. Punch holes (hole diameter is 5 mm) at 25 mm from the center at the edge of the re-screening plate. The number of punched holes on each plate is 3. The remaining operations are the same as the initial screening. 74 antagonistic bacterial strains with inhibitory effects on Ralstonia solanacearum were screened from the 102 antagonistic bacterial strains, and the diameter range of their antibacterial circles was 8.5 mm - 38.5 mm.

[0055] The antibacterial effect of strain qzb219 is stable. The diameters of the antibacterial circles in the initial screening and re-screening are 29.2 mm and 38.5 mm respectively, showing good antagonistic effects against Ralstonia solanacearum. The pure colony of strain qzb219 was obtained after multiple streak purifications.

[0056] 2. Identification of strain qzb219

[0057] The colonies of strain qzb219 on the LB medium are circular, light yellow, with no wrinkles, smooth and slightly shiny on the surface, moist, opaque, and with regular edges ( Figure 1 )

[0058] Using the DNA of strain qzb219 as a template, amplify the 16S rDNA gene fragment using the universal primers for bacterial 16S rDNA, and send the amplified product to Sangon Biotech (Shanghai) Co., Ltd. for sequencing. The amplification primers are:

[0059] 27F (SEQ ID NO.1): 5’-AGAGTTTGATCCTGGCTCAG-3’,

[0060] 1492R (SEQ ID NO.2): 5'-GGTTACCTTGTTACGACTT-3'.

[0061] The PCR amplification system (20 μL) is as follows: 2×Taq Master Mix 10 μL; 0.5 μL each of the upstream and downstream primers; 1 μL of template DNA; ddH 2 O is made up to 20 μL.

[0062] The PCR amplification conditions are: pre-denaturation at 94°C for 5 min; denaturation at 94°C for 40 s, annealing at 55°C for 50 s, extension at 72°C for 60 s, for 35 cycles; and then extension at 72°C for 10 min.

[0063] The sequencing result is shown as SEQ ID NO.3.

[0064] SEQ ID NO.3:

[0065]

[0066] The obtained 16S rDNA sequence was subjected to BLAST homology alignment in the NCBI database. The sequence similarity of this strain with Kosakonia cowanii exceeded 99%, showing a high degree of homology. It was analyzed using the software MEGA 7 to determine the taxonomic status of this strain, and a phylogenetic tree ( Figure 2 ) was constructed using the MEGA software. Strain qzb219 clustered with Kosakonia cowanii.

[0067] Combined with colony morphological characteristics and molecular biology analysis, strain qzb219 was identified as Kosakonia cowanii and named Kosakonia cowanii qzb219. This strain was deposited at the China General Microbiological Culture Collection Center on August 1, 2024, with the deposit number CGMCC No. 31519; the deposit address is No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing.

[0068] Example 2, Inhibitory effect of Kosakonia cowanii qzb219 on Ralstonia solanacearum

[0069] Prepare a plate containing Ralstonia solanacearum according to the method described in Example 1. Punch holes (hole diameter is 5 mm) 25 mm from the center of the plate edge. The number of punched holes on each plate is 3, and each hole is used as a replicate. Inoculate the activated bacterial liquid into the holes, with the sample loading volume of 35 μL. After culturing at a constant temperature of 28 °C for 48 h, measure the diameter of the inhibition zone and calculate the inhibition rate.

[0070] Inhibition rate (%) = (diameter of inhibition zone - diameter of sample application hole) / diameter of inhibition zone × 100%.

[0071] The results of the antibacterial test are as Figure 3 shown. The diameters of the inhibition zones of the three replicates are 30.2 mm, 30.5 mm, and 30.3 mm respectively. It is calculated that the inhibition rate of Kosakonia cowanii qzb219 on Ralstonia solanacearum is 83.52%.

[0072] Example 3, Inhibitory effect of Kosakonia cowanii qzb219 on Fusarium solani

[0073] Place a 5-mm diameter cake of Fusarium solani at the center of the medium. Inoculate 8 μL of the activated bacterial liquid on one side 25 mm away from the cake, and use the non-inoculated bacterial liquid on the other side as a control. Repeat 3 times. After culturing at a constant temperature of 28 °C for 120 h, measure the radius of Fusarium solani and calculate the inhibition rate.

[0074] Inhibition rate (%) = (radius of control colony - radius of treated colony) / radius of control colony × 100%.

[0075] The results of the antibacterial test are as Figure 4 shown. It is calculated that the inhibition rate of Kosakonia cowanii qzb219 against Fusarium oxysporum f. sp. nicotianae is 65.21%.

[0076] Example 4. Hydrolytic enzyme activity of Kosakonia cowanii qzb219

[0077] The activated qzb219 bacterial solution was spotted onto the starch screening medium, and whether there was a clear zone was observed to judge whether it had starch hydrolase activity. The results are as Figure 5 shown. Kosakonia cowanii qzb219 can degrade starch.

[0078] The activated qzb219 bacterial solution was spotted onto the casein screening medium. The appearance of a clear zone on the plate indicates that the strain has the ability to degrade proteins. The results are as Figure 6 shown. Kosakonia cowanii qzb219 can degrade proteins.

[0079] In summary, Kosakonia cowanii qzb219 can secrete proteases, amylases, etc. to degrade biological macromolecules, has strong metabolic activity, is easy to be fermented and cultured in large quantities, and is also beneficial to its colonization in the soil and exerting its biocontrol effect.

[0080] Example 5. Growth curve of Kosakonia cowanii qzb219

[0081] The activated qzb219 bacterial solution was inoculated into LB medium at an inoculation amount of 0.05%, and cultured with shaking at 28 °C and 180 rpm. Samples were taken at 0, 2, 4, 6, 8, 10, 11, 12, 13, 15, 17, 19, 21, 23, 25, 36 h to measure the OD600 absorbance value, and the growth curve was plotted. As Figure 7 shown, the growth curve of the qzb219 strain is an S-shaped growth curve. The growth is slow in the first 6 h, and then it enters the exponential growth stage after 6 h. The growth trend is still shown at 13 h, but the growth rate is relatively slow. The peak value is reached at 25 h, and then it starts to decrease. Considering the production cost comprehensively, the production of the microbial agent can be completed by culturing for 18 - 20 h.

[0082] Example 6. Compatibility of fungicides with Kosakonia cowanii qzb219

[0083] Select bactericides such as thiodiazole copper and thiazole zinc, which are mainly used in production to control Ralstonia solanacearum in tobacco, as the test agents. Dilute the bactericides 300 times to prepare a high-concentration medicated LB liquid medium, and this concentration exceeds the recommended maximum application concentration of each bactericide. The control is an LB medium added with sterile water. Inoculate the activated qzb219 bacterial liquid into the LB medium at an inoculation amount of 0.1%, and culture it with shaking at 28 °C and 180 rpm for 18 h. Use the gradient dilution method to calculate the bacterial content of each treatment and the control, and determine its compatibility with the bactericide.

[0084] Table 1 Compatibility of Kosakonia cowanii qzb219 with different agents

[0085] Name of fungicide Manufacturer Concentration of agent in the medium (mg / ) Number of viable bacteria (CFU / mL) Sterile water control - - <![CDATA[3.07×10 9 > 20% Copper thiazole suspension Zhejiang Longwan Chemical Industry Co., Ltd. 666.6 <![CDATA[50.2×10 9 > 20% Zinc thiazole suspension Zhejiang Xinnong Chemical Co., Ltd. 666.6 <![CDATA[4.12×10 8 > 5% Allitridi microemulsion Chengdu New Sun Crop Science Co., Ltd. 166.7 <![CDATA[2.75×10 5 > 10% Kasugamycin soluble granule Shaanxi Meibang Pharmaceutical Group Co., Ltd. 333.3 0

[0086] As shown in Table 1, Kosakonia cowanii qzb219 has good compatibility with the main bactericides thiodiazole copper and thiazole zinc for controlling tobacco bacterial wilt in the Yunnan tobacco-growing area. High-concentration thiazole zinc slightly inhibits the growth of Kosakonia cowanii qzb219; high-concentration thiodiazole copper not only does not inhibit the growth of the qzb219 strain, but its viable bacteria concentration is even higher than that of the control, and instead promotes the growth of the qzb219 strain. The test agents allicin and kasugamycin inhibit the growth of qzb219. Therefore, Kosakonia cowanii qzb219 has good compatibility with the main bactericides thiodiazole copper and thiazole zinc for tobacco bacterial wilt, and the application of bactericides does not affect the use of qzb219, and it can be applied in combination with bactericides to increase the control effect.

[0087] Example 7 Control effects of Kosakonia cowanii qzb219 on tobacco bacterial wilt and tobacco Fusarium root rot

[0088] When the tobacco seedlings have 4-5 true leaves, transplant them from the seedling tray to a plastic flower pot with a diameter of 15 cm, and the flower pot is filled with soil collected from a tobacco field in the tobacco-growing area of Baoshan, Yunnan, where tobacco bacterial wilt occurs severely. Two days after transplantation, inoculate 5 mL of Kosakonia cowanii qzb219 bacterial liquid (1×10 6 CFU / mL) to each tobacco seedling, and apply 5 mL of sterile water to the control tobacco seedlings. Two days after inoculating the qzb219 bacterial liquid, cut the lateral roots at a distance of 1-2 cm from the tobacco plants with scissors, and then inoculate 5 mL of Ralstonia solanacearum bacterial liquid (1×10 7 CFU / mL) or Fusarium solani spore suspension (1×10 7 spores / mL). Place the treated and control tobacco seedlings in an artificial climate chamber at 30 °C, relative humidity 85%, and light for 12 h, and observe and record the disease status of the plants every day.

[0089] Five days after inoculating Ralstonia solanacearum, the control plants began to show stem necrosis and leaf wilting, and no disease was observed in the tobacco plants treated with qzb219 ( Figure 8After inoculating with Ralstonia solanacearum for 10 days, the incidence rate of the control plants was counted as 65% and the disease index was 43.3 at this time; the incidence rate of the tobacco plants treated with qzb219 was 10% and the disease index was 7.8, and the control effect on Ralstonia solanacearum was 82%.

[0090] After inoculating with Fusarium solani f. sp. nicotianae for 7 days, the control plants began to wilt, and no disease was found in the tobacco plants treated with qzb219. After inoculating with Fusarium solani f. sp. nicotianae for 14 days, the incidence rate of the control plants was counted as 45% and the disease index was 35.3 at this time; the incidence rate of the tobacco plants treated with qzb219 was 15% and the disease index was 12.2, and the control effect on Fusarium solani f. sp. nicotianae was 65.4%. The application rates of pesticides thiodiazole copper and thiazole zinc can be reduced (reduced by 15%-20%), and the control effect on tobacco bacterial wilt is increased by 30%.

[0091] Example 8, Kosakonia cowanii qzb219 promotes the growth of tobacco seedlings

[0092] Tobacco seeds were sown in a seedling tray and transplanted to a flower pot with a diameter of 14 cm when they grew to 3-4 true leaves. Two days after transplantation, 5 mL of qzb219 bacterial liquid (1×10 6 CFU / mL) was inoculated by irrigation. The blank medium was diluted according to the inoculation ratio as a control. Each plant was used as a replicate, and there were 30 plants in each of the treatment and the control. After inoculation, the tobacco seedlings were cultured in an artificial climate chamber at 30 °C, relative humidity of 85%, and light for 12 h.

[0093] Table 2 Effects of Kosakonia cowanii qzb219 on the growth of tobacco seedlings

[0094] Test treatment Number of leaves Plant height (cm) Fresh weight of leaves (g) Fresh weight of stems (g) Fresh weight of roots (g) Fresh weight of plants (g) Control 4.6±0.24 10.15±0.41 3.58±0.38 0.88±0.15 0.37±0.03 4.99±0.63 qzb219 5.8±0.20 11.13±0.63 6.01±0.40 1.24±0.83 0.58±0.05 7.83±0.38

[0095] After 25 days of inoculation, the treated plants grew vigorously and the growth of plants was consistent among plants, while the control plants were relatively weak and the growth of plants was uneven ( Figure 9 ). After measurement, the average plant height, number of leaves, fresh weight of leaves, roots and plants of the tobacco seedlings treated with qzb219 were significantly higher than those of the control (p < 0.05), and the average fresh weight of stems was also higher than that of the control (p = 0.19), indicating that irrigation treatment with Kosakonia cowanii qzb219 can significantly promote the growth of tobacco seedlings.

[0096] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and shall be included in the protection scope of the present invention.

[0097] Finally, it should also be noted that the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article or apparatus comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or elements inherent to such process, method, article or apparatus.

[0098] Although embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications once they learn the basic creative concept. Therefore, the appended claims are intended to be construed to include the embodiments as well as all changes and modifications falling within the scope of the present invention.

[0099] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A strain of Cossackia coli qzb219, characterized in that The taxonomic name of the cossackia is Cossackia cossackia ( Kosakonia cowanii ), its deposit number is: CGMCC NO.31519.

2. Use of the Cossackia cohnii qzb219 according to claim 1 in inhibiting tobacco bacterial wilt pathogen or tobacco Fusarium solani root rot pathogen, wherein the tobacco Fusarium solani root rot pathogen is Fusarium solani.

3. Use of the Cossackia cohnii qzb219 according to claim 1 in promoting the growth of tobacco seedlings.

4. A fermentation agent, characterized in that: The fermentation agent comprises: A fermentation broth or bacterial suspension obtained by fermenting the Cossackia cohnii qzb219 according to claim 1; Or the fermentation liquid is spray-dried to obtain a dry powder bacterial agent.

5. The fermentation agent according to claim 4, characterized in that: The method for preparing the fermentation broth comprises: The Cossackia cohnii qzb219 is inoculated into a liquid culture medium for fermentation to obtain a fermentation liquid.

6. The fermentation agent according to claim 5, characterized in that: The fermentation culture conditions include: temperature of 26-30° C. and pH of 5-9.

7. Use of the fermentation agent according to any one of claims 4 to 6 in inhibiting tobacco bacterial wilt pathogen or tobacco Fusarium root rot pathogen, wherein the tobacco Fusarium root rot pathogen is Fusarium solani.

8. Use of the fermentation agent according to any one of claims 4 to 6 in promoting the growth of tobacco seedlings.

Images