Bacterial agent of burkholderia cepacia JK-1 and application

Abstract

The invention relates to the technical field of microbial control, in particular to a Burkholderia cepacia JK-1 bacterial agent and application, the bacterial agent is prepared from fermentation liquor of Burkholderia cepacia JK-1, a carrier and an auxiliary agent; the Burkholderia cepacia JK-1 is preserved in the China General Microbiological Culture Collection Center on August 24, 2022, the preservation address is No.3, No.1 yard, Beichen West Road, Chaoyang District, Beijing, the preservation number is CGMCC No.25589, and the Burkholderia cepacia is classified and named as Burkholderia cepacia. According to the invention, the fermentation broth of Burkholderia cepacia JK-1 is used for inhibiting the growth of Colletotrichum siamensis, and the biological control effect on strawberry root rot caused by Colletotrichum siamensis is significantly improved.

Description

Technical Field

[0001] The invention relates to the technical field of microbial control, and in particular to a bacterial agent of Burkholderia cepacia JK-1 and application thereof. Background Art

[0002] As a common disease, strawberry root rot is characterized by widespread occurrence and serious damage, and is one of the important factors restricting the development of the strawberry industry. Strawberry root rot is a soil-borne fungal disease caused by a variety of pathogenic bacteria, among which the pathogens mainly include Fusarium spp. Fusarium spp.), Colletotrichum spp. Colletotrichum spp.), Pythium Pythium spp.), Anthrax spp. Colletotrichum spp.) and more than a dozen genera. Colletotrichum siamese is the dominant pathogen causing strawberry root rot in some areas. Strawberry root rot caused by Colletotrichum siamese is difficult to control. The incidence rate can reach 40%-50% in strawberry continuous cropping areas. When the incidence rate is high, it may even lead to total crop failure, causing serious economic losses to production. Chemical agents have poor control effects on strawberry root rot, and the large-scale use of chemical pesticides will lead to soil ecological imbalance, increased pathogen resistance and food safety, which seriously restricts the ecological and green development of agriculture.

[0003] The prevention and control of strawberry root rot includes agricultural prevention, chemical prevention and biological prevention. In the actual strawberry production process, chemical prevention is still the main prevention and control method for strawberry root rot. Although chemical prevention is fast-acting, drug resistance increases year by year, and the problem of drug residue cannot be avoided, posing a threat to human health. Biological control is a method of using biological means such as biological natural enemies and / or microbial preparations to prevent and control pathogens. In the early stage of the disease or the prevention stage, biological control uses beneficial microorganisms to inhibit pathogens, etc., which can effectively control the reproduction of pathogens and reduce the use of chemical agents. Biological control also has long-term benefits, can enhance the resistance of crops themselves, improve the stability of the ecosystem, and is environmentally friendly and sustainable. The existing technology mostly uses antagonistic bacteria to prevent and control strawberry diseases. The antagonistic bacteria used for strawberry root rot are mainly antagonistic to Fusarium, and the bacterial agents antagonistic to Siamese anthracnose are not ideal. Summary of the invention

[0004] Aiming at the technical problem that the antagonistic bacteria used for preventing and controlling strawberry root rot caused by Siamese anthracnose is not effective, the present invention provides a bacterial agent of Burkholderia cepacia JK-1 and its application. The fermentation liquid of Burkholderia cepacia JK-1 is used to inhibit the growth of Siamese anthracnose, thereby significantly improving the biological control effect of strawberry root rot caused by Siamese anthracnose.

[0005] In a first aspect, the present invention provides a bacterial agent of Burkholderia cepacia JK-1, the bacterial agent comprising Burkholderia cepacia ( Burkholderia cepacia ) fermentation broth of JK-1; Burkholderia cepacia JK-1 was deposited in the General Microbiology Center of the China Microbiological Culture Collection Administration on August 24, 2022. The deposit address is No. 3, Yard No. 1, Beichen West Road, Chaoyang District, Beijing. The deposit number is CGMCC No. 25589 and the classification name is Burkholderia cepacia Burkholderia cepacia .

[0006] Furthermore, the effective viable count of the bacterial agent is 5×10 8 CFU / g.

[0007] Furthermore, the method for preparing the fermentation broth of Burkholderia cepacia JK-1 comprises the following steps: Step 1: inoculate a single colony of Burkholderia cepacia JK-1 into TY liquid culture medium and culture at 30°C for 24 hours to obtain seed solution; Step 2: inoculate the seed liquid into a 500 mL fermentation tank and culture at 30°C for 60 hours to obtain a fermentation liquid; In the TY liquid culture medium, the content of tryptone is 1wt%, the content of yeast extract is 0.1wt%, and the content of CaCl2 is 0.02wt%; the components and dosage of the culture medium in the fermenter are as follows: glucose 5g / L, corn flour 16.5g / L, soybean meal 40.0g / L, K2HPO4 2.0g / L, KH2PO4 0.56g / L, (NH4)2SO4 2.2g / L, MgSO4·7H2O 0.40g / L, FeSO4 0.01g / L.

[0008] Furthermore, the bacterial agent also includes a carrier and an auxiliary agent, and the preparation method of the bacterial agent includes the following steps: S1: using the carrier to adsorb the fermentation liquid to obtain a solid loaded carrier; S2: The carrier and the auxiliary agent are mixed evenly, and the obtained mixture is the bacterial agent.

[0009] Furthermore, the carrier is medical stone powder, and the auxiliary agents are sodium alginate, sodium carboxymethyl cellulose and calcium chloride; in the bacterial agent, the amount of sodium alginate is 1wt%, the amount of sodium carboxymethyl cellulose is 2wt%, and the amount of calcium chloride is 0.2wt%.

[0010] Further, the mass fraction of the fermentation liquid in the carrier is not higher than 30%. The amount of the fermentation liquid can be adjusted according to the production requirements of the number of viable bacteria of the microbial agent. The present invention limits the mass fraction of the fermentation liquid in the carrier to no more than 20%, which can avoid the inconvenience of storage of the microbial agent due to excessive humidity on the one hand, and on the other hand, can avoid the germination of seeds and the growth of plants being inhibited due to too high a number of viable bacteria.

[0011] In a second aspect, the present invention provides a use of the above-mentioned Burkholderia cepacia JK-1 bacterial agent in preventing and controlling strawberry root rot, wherein the pathogenic bacteria of strawberry root rot is Siamese anthracnose fungus ( Colletotrichum siamense ).

[0012] Furthermore, the method of using the microbial agent is: dilute the microbial agent with water and then dip the roots for treatment, and the dilution multiple is preferably 10 times.

[0013] In a third aspect, the present invention also provides a use of the above-mentioned Burkholderia cepacia JK-1 bacterial agent in improving the quality of strawberries, wherein the bacterial agent can increase the content of vitamin C and soluble sugar in strawberries and reduce the total acid content.

[0014] The beneficial effects of the present invention are: The bacterial agent of Burkholderia cepacia JK-1 provided by the present invention and its application use the fermentation liquid of non-pathogenic Burkholderia cepacia JK-1 to inhibit the growth of Siamese anthracnose bacteria, and at the same time significantly improve the photosynthesis of strawberries, enhance the root vitality of strawberries, improve the prevention and control effect of strawberry root rot caused by Siamese anthracnose bacteria, and at the same time improve the sweetness of strawberries and the quality of strawberries. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0016] Figure 1 This is a plate confrontation picture of Burkholderia cepacia JK-1 and Colletotrichum siamensis in Example 1.

[0017] Figure 2 It is the colony map of Siamese anthrax of the second control group and the second experimental group of Example 1 after constant temperature culture for 96 hours, wherein A is the colony map of Siamese anthrax of the second control group, B, C, and D are the colony maps of Siamese anthrax of PDA plate culture medium with fermentation filtrate content of 20%, 10%, and 5%, respectively.

[0018] Figure 3 It is a bar chart showing the calculated results of the inhibition rate of the mycelial growth of Siamese anthrax bacteria by the PDA plate culture medium with the fermentation filtrate content of 20%, 10%, and 5% in the second experimental group of Example 1 after constant temperature culture for 48h, 72h, and 96h, respectively. The numbers above the bar chart represent the inhibition rate of the fermentation filtrate with different contents on Siamese anthrax bacteria at different culture times (%), and different lowercase letters indicate significant differences between the data in the same group ( P <0.05). DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0020] The Burkholderia cepacia JK-1 used in the specific embodiment of the present invention has been deposited in the General Microbiological Center of the China Microbiological Culture Collection Administration on August 24, 2022, with the deposit address being No. 3, Yard No. 1, Beichen West Road, Chaoyang District, Beijing, with the deposit number being CGMCC No. 25589, and the classification name being Burkholderia cepacia Burkholderia cepacia , the strain has been published in the paper "Identification of antagonistic bacteria in the rhizosphere of two American ginseng strains and their antibacterial and growth-promoting effects", Shandong Agricultural Science 2022, 54 (7): 143-148.

[0021] The PDA plate culture medium, LB culture medium, LB plate culture medium, Columbia blood plate culture medium, and TY liquid culture medium used in the specific embodiments of the present invention can all be commercially available products, or can be prepared by themselves according to conventional methods.

[0022] In the TY liquid culture medium, the content of trypsin is 10 g / L, the content of yeast extract is 1 g / L, and the content of CaCl2 is 0.2 g / L.

[0023] The components and dosages of the culture medium in the fermentation tank used in the specific embodiment of the present invention are as follows: glucose 5 g / L, corn flour 16.5 g / L, soybean meal 40.0 g / L, K2HPO4 2.0 g / L, KH2PO4 0.56 g / L, (NH4)2SO4 2.2 g / L, MgSO4·7H2O 0.40 g / L, FeSO4 0.01 g / L.

[0024] Example 1 Determination of the Antagonism of Burkholderia cepacia JK-1 by Confrontation Cultivation Method 1-1 The plate confrontation method was used to determine the inhibitory effect of Burkholderia cepacia JK-1 on the mycelial growth of Siamese anthrax. The determination method is as follows: The first experimental group: a Siamese anthrax cake with a diameter of 5 mm was inoculated in the center of the PDA plate culture medium, and a single colony of cepacia JK-1 was inoculated around the Siamese anthrax cake and 2 cm away from the Siamese anthrax cake. The culture was placed at a constant temperature of 28°C for five days. The first experimental group was set up with three replicates.

[0025] First control group: The first control group differed from the first experimental group only in that a single colony of Burkholderia cepacia JK-1 was not inoculated.

[0026] After the constant temperature culture, the colony radius of the Siamese anthrax in the first experimental group and the first control group was measured by the cross method. The plate confrontation diagram of the onion Burkholderia JK-1 and Siamese anthrax in the first experimental group and the first control group is shown in the figure below. Figure 1 As shown, the inhibition rate of cepacia JK-1 on the mycelial growth of Siamese anthracnose fungi was then calculated. The calculation formula of the inhibition rate of cepacia JK-1 on the mycelial growth of Siamese anthracnose fungi is as follows: Inhibition rate (%) = ×100.

[0027] It was calculated that the inhibition rate of cepacia JK-1 on the hyphae growth of Siamese anthrax was 72.2%, indicating that cepacia JK-1 can inhibit the hyphae growth of Siamese anthrax.

[0028] 1-2 Determination of the inhibitory effect of the fermentation filtrate of Burkholderia cepacia JK-1 on the mycelial growth of Siamese anthracnose fungi Preparation of fermentation filtrate of Burkholderia cepacia JK-1: A single colony of Burkholderia cepacia JK-1 was inoculated into LB medium, and cultured at 30°C and 180 rpm for three days to obtain a fermentation broth, and the fermentation broth was centrifuged at 5000 r / min for 5 min, and the supernatant was filtered through a 0.22 μm microporous filter membrane to obtain a fermentation filtrate of Burkholderia cepacia JK-1.

[0029] The inhibitory effect of the fermentation filtrate of Burkholderia cepacia JK-1 on the mycelial growth of Siamese anthracnose bacteria was determined as follows: The second experimental group: Preparation of PDA plate with fermentation filtrate: PDA purchased from Qingdao Haibo Biotechnology was weighed in three equal portions according to the instructions, each portion was 4.6g, and deionized water 80mL, 90mL, and 95mL were added to the three portions of PDA, respectively, and sterilized at 115℃ for 20 minutes to obtain 1# medium, 2# medium, and 3# medium. When 1# medium, 2# medium, and 3# medium were cooled to about 55℃, 20mL, 10mL, and 5mL of fermentation filtrate were added respectively, and after being fully mixed, they were poured into the culture dish to prepare PDA plate medium with fermentation filtrate content (volume fraction) of 20%, 10%, and 5%, respectively. Siamese anthrax cakes with a diameter of 5mm were inoculated into PDA plate medium with fermentation filtrate content of 20%, 10%, and 5%, respectively. PDA plate medium with fermentation filtrate content of 20%, 10%, and 5% was set up with three replicates, and each PDA plate medium containing fermentation filtrate was placed at 28℃ for constant temperature culture.

[0030] Second control group: The second control group differed from the second experimental group only in that the fermentation filtrate content of the PDA plate medium was 0%.

[0031] The cross method was used to measure the colony radius of Siamese anthrax in each PDA plate medium in the second experimental group and the second control group at constant temperature for 48h, 72h, and 96h, and then the inhibition rate of the fermentation filtrate of Burkholderia cepacia JK-1 on the mycelial growth of Siamese anthrax was calculated. The calculation formula of the inhibition rate of the fermentation filtrate of Burkholderia cepacia JK-1 on the mycelial growth of Siamese anthrax is as follows: Inhibition rate (%) = ×100.

[0032] In the second experimental group, the colony patterns of Siamese anthrax bacteria in PDA plate medium with fermentation filtrate content of 20%, 10%, and 5% after constant temperature culture for 96 hours were as follows: Figure 2 As shown in B, C, and D in the figure; the colony of Siamese anthrax in the PDA plate culture medium of the second control group after constant temperature culture for 96 hours is shown in Figure 2 As shown in A. Figure 2 It can be seen that the fermentation filtrate of Burkholderia cepacia JK-1 has a significant inhibitory effect on the mycelial growth of Siamese anthrax, and the higher the content of the fermentation filtrate, the stronger the inhibitory effect.

[0033] In the second experimental group, the statistical results of the calculation of the inhibition rate of the mycelial growth of Siamese anthrax bacteria on the PDA plate culture medium with a fermentation filtrate content of 20%, 10%, and 5% after constant temperature culture for 48h, 72h, and 96h, respectively, are shown in the figure below: Figure 3 As shown. Figure 3 It can be seen that the PDA plate culture medium with a fermentation filtrate content of 20% has the highest inhibition rate of 100% against Siamese anthrax when cultured at a constant temperature for 48 hours.

[0034] Example 2 Safety Test of Burkholderia cepacia JK-1 2-1 Testing the safety of Burkholderia cepacia JK-1 by hemolysis test A single colony of Burkholderia cepacia JK-1 prepared in Example 1 was streaked onto a Columbia blood plate and cultured at 30°C for 24 h. After observation, no hemolysis was found around the colony of Burkholderia cepacia JK-1, indicating that the Burkholderia cepacia JK-1 did not produce hemolysin.

[0035] 2-2 Testing the safety of Burkholderia cepacia JK-1 by virulence gene detection The genome of Burkholderia cepacia JK-1 was used as a template to amplify the specific sequence of the BCESM virulence gene, the pathogenic factor of Burkholderia cepacia JK-1, by PCR to detect whether Burkholderia cepacia JK-1 contains virulence genes. The primers used were BCESM1 and BCESM2. The PCR amplification reaction conditions were: 94℃ pre-denaturation for 5min; 94℃ denaturation for 1min, 63℃ annealing for 1min, 72℃ extension for 90s, 30 cycles; 72℃ post-extension for 10min. The amplified products were detected by 1% agarose gel electrophoresis.

[0036] PCR amplification detection showed that cepacia JK-1 did not contain the BCESM virulence gene, indicating that cepacia JK-1 had no potential pathogenic risk.

[0037] Example 3 Potted experiment on the control of strawberry root rot by Burkholderia cepacia JK-1 Pick a single colony of Burkholderia cepacia JK-1 activated on the plate and inoculate it into LB liquid medium, shake and culture it at 30°C overnight to obtain seed solution No. 1. Inoculate the seed solution No. 1 into a shake flask containing 100mL LB liquid medium at a 1% inoculation rate, culture it at 30°C for 72h, and obtain potted fermentation liquid. Count the potted fermentation liquid with a hemocytometer, and then adjust the bacterial concentration in the potted fermentation liquid to 5.0×10 8 CFU / mL.

[0038] Three 5 mm diameter Siamese anthrax cakes were inoculated into the pathogenic bacteria liquid culture medium and cultured at 28°C for two weeks to obtain the pathogenic bacteria fermentation liquid. The pathogenic bacteria fermentation liquid was filtered with sterile lens paper to obtain a spore suspension, which was counted with a hemocytometer, and then the spore concentration of the spore suspension was adjusted to 5.0×10 6CFU / mL. The pathogenic bacteria liquid culture medium contained glucose 2 g / L, corn flour 10.0 g / L, soybean meal 5.0 g / L, K2HPO4 2.0 g / L, KH2PO4 0.56 g / L, and CaCl2 10.0 g / L.

[0039] The indoor control effect of Burkholderia cepacia JK-1 on strawberry root rot caused by Colletotrichum siamese at the seedling stage was determined by pot experiments. The test method is as follows: The soil was divided into four treatment groups and marked as blank control group, pathogen control group, pathogen + fungicide group, and pathogen + JK-1 group. Each treatment group was treated as follows: the soil of the blank control group was not added with Siamese anthracnose and Burkholderia cepacia JK-1; the soil of the pathogen control group was only inoculated with the conidia of Siamese anthracnose, and the final conidia concentration of Siamese anthracnose per gram of soil was 1.0×10 5 The soil in the pathogen + fungicide group was inoculated with the conidia of Siamese anthrax and treated with tebuconazole. The final conidia concentration of Siamese anthrax per gram of soil was 1.0×10 5 Tebuconazole was a 43% tebuconazole suspension produced by Zhongnong United Biotechnology Co., Ltd. Tebuconazole was used according to the instructions for use; the soil of the pathogen + JK-1 group was inoculated with the conidia of Siamese anthracnose and the potted fermentation liquid of Burkholderia cepacia JK-1 at the same time, so that the final conidia concentration of Siamese anthracnose in each gram of soil was 1.0×10 5 The number of Burkholderia cepacia JK-1 cells per gram of soil was 1.0×10 6 indivual.

[0040] After the treatment, the soil of each treatment group was potted, and each treatment group was potted with 15 pots, with three replicates. Sterile strawberry seedlings of the "Tianbao" variety in the three-leaf and one-heart stage were purchased. After one week of seedling acclimatization, they were planted in pots of each treatment group, with one plant planted in each pot, arranged in random blocks, and managed routinely for 30 days.

[0041] The chlorophyll content of the leaves of the strawberry seedlings in each treatment group was determined by the acetone method, and the root activity of the strawberry seedlings in each treatment group was determined by the TCC method. The incidence of strawberry root rot in the strawberry seedlings in each treatment group was investigated, the disease index was counted, and the control effect was calculated. The chlorophyll content, root activity, disease index and control effect of each treatment group are shown in Table 1. The calculation formula of the disease index is as follows: Disease index = Σ (number of diseased plants at each disease level × value of each disease level) / (total number of plants surveyed × value of the highest disease level) × 100; The disease classification standard is: Level 0, no lesions; Level 1, 0 < lesion area accounts for ≤5% of the total area, the growth of the plant is damaged; Level 2, 5% < lesion area accounts for ≤15% of the total area, lesions appear on the rhizomes of the plant; Level 3, 15% < lesion area accounts for ≤25% of the total area, the diseased part of the rhizomes of the plant expands and appears brick-red and rotten; Level 4, 25% < lesion area accounts for ≤50% of the total area, the leaves wilt and fall over; Level 5, lesion area accounts for >50% of the total area, and the plant dies.

[0042] The calculation formula of the control effect is as follows: Prevention effect (%) = (disease index of blank control group − disease index of test treatment group) / disease index of blank control group × 100.

[0043] Table 1 The control effect of potted fermentation liquid of Burkholderia cepacia JK-1 on strawberry root rot

[0044] As can be seen from Table 1, compared with the pathogen control group, the chlorophyll content and root activity of the strawberry plants increased significantly after the addition of Burkholderia cepacia JK-1, reaching the level of the blank control group, indicating that the potted fermentation liquid of Burkholderia cepacia JK-1 has a significant preventive and therapeutic effect on strawberry root rot caused by Siamese anthracnose, with a prevention efficiency of 85.18%, which is equivalent to the prevention effect of using the fungicide tebuconazole.

[0045] Example 4 Field plot test Pick a single colony of Burkholderia JK-1 grown on the LB plate medium and inoculate it into the TY liquid medium. Cultivate it at 30°C for 24 hours at a shaking speed of 180rpm to obtain the No. 2 seed liquid. Inoculate the No. 2 seed liquid into a 500L fermentation tank and culture it at 30°C for 60 hours to obtain the No. 2 fermentation liquid. Add the No. 2 fermentation liquid to the medical stone powder at a ratio of 1L of No. 2 fermentation liquid to 100 kg of medical stone for adsorption. Then add sodium alginate, sodium carboxymethyl cellulose and calcium chloride to the medical stone powder adsorbed with the No. 2 fermentation liquid, and mix them with a mixer to obtain a solid bacterial agent. In the solid bacterial agent, the mass fraction of sodium alginate is 1%, the mass fraction of sodium carboxymethyl cellulose is 2%, and the mass fraction of calcium chloride is 0.2%. The effective viable bacteria count of the solid bacterial agent is 5×10 8 CFU / g.

[0046] The field plot experiment was carried out in the strawberry greenhouse in Chengjiaoxiang Village, Dongjia Sub-district Office, Licheng District, Jinan City, Shandong Province. The strawberry variety planted was "Tianbao".

[0047] The Siamese anthrax cake activated on the PDA plate medium for 5 days was inoculated on the sterilized millet, and the number of Siamese anthrax conidia obtained after culturing in a constant temperature incubator at 28°C for 20 days was not less than 106 CFU / grain of pathogenic bacteria.

[0048] Each plot in the field plot experiment is 6m 2 (4m×1.5m), 100 strawberries were planted in each plot. Three treatment groups were set up in the field plot experiment, marked as the second blank control group, the second pathogen control group and the onion Burkholderia JK-1 group. Before planting, 20 pathogen grains were added to the planting holes of the second pathogen control group and the onion Burkholderia JK-1 group, respectively, and no pathogen grains were added to the planting holes of the second blank control group. After the strawberry seedlings were taken out of the plug tray, the substrate was shaken off, the roots were soaked in sterilized water for 15 minutes, and then they were planted in the planting holes of the second blank control group and the second pathogen control group. The solid bacterial agent of onion Burkholderia JK-1 was diluted 10 times with sterile water to obtain a suspension, and the strawberry roots were soaked in the suspension, taken out after 15 minutes, and planted in the planting holes of the onion Burkholderia JK-1 group. Each treatment group was set up with four replicates, randomly arranged, and the management and operation of each plot was consistent. The solid bacterial agent was drip-irrigated once every fifteen days during the growth period, and the drip irrigation dosage was 1 kg / mu. After thirty days, 20 plants were randomly selected from each plot to investigate the occurrence of root rot. The disease index and the calculation formula for prevention effect were the same as in Example 3. Strawberry fruits of each treatment group were randomly picked at the peak fruiting period to detect the content of vitamin C, soluble sugar, total acid, and soluble solids. The final test results are shown in Table 2.

[0049] Table 2 Control effects of each treatment group in the field trial and test results of strawberry fruit

[0050] As shown in Table 2, the Burkholderia JK-1 group had a control effect of 80.18% on root rot. The contents of vitamin C and soluble sugar in the strawberry fruit of this group were significantly higher than those of the second blank control and the second pathogen control group, and the total acid content was significantly lower than that of the second blank control and the second pathogen control group. The above results show that the solid bacterial agent of Burkholderia JK-1 can not only effectively prevent and control strawberry root rot caused by Siamese anthracnose, but also improve the quality of strawberry fruit, and has great application potential.

[0051] Although the present invention has been described in detail with reference to the accompanying drawings and in combination with the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions shall be within the scope of the present invention. Any person of ordinary skill in the art may easily think of changes or substitutions within the technical scope disclosed by the present invention, and these shall be within the scope of protection of the present invention.

Claims

1. A bacterial agent of Burkholderia cepacia JK-1, characterized in that: Bacterial agents include Burkholderia cepacia ( Burkholderia cepacia ) fermentation broth of JK-1; Burkholderia cepacia JK-1 was deposited in the General Microbiology Center of the China Microbiological Culture Collection Administration on August 24, 2022. The deposit address is No. 3, Yard No. 1, Beichen West Road, Chaoyang District, Beijing. The deposit number is CGMCC No. 25589 and the classification name is Burkholderia cepacia Burkholderia cepacia .

2. The bacterial agent of Burkholderia cepacia JK-1 according to claim 1, characterized in that: The effective viable count of the bacterial agent is 5×10 8 CFU / g.

3. The bacterial agent of Burkholderia cepacia JK-1 according to claim 1, characterized in that: The method for preparing the fermentation liquid of Burkholderia cepacia JK-1 comprises the following steps: Step 1: inoculate a single colony of Burkholderia cepacia JK-1 into TY liquid culture medium and culture at 30°C for 24 hours to obtain seed solution; Step 2: inoculate the seed liquid into a 500 mL fermentation tank and culture at 30°C for 60 hours to obtain a fermentation liquid; In the TY liquid culture medium, the content of tryptone was 1wt%, the content of yeast extract was 0.1wt%, and the content of CaCl2 was 0.02wt%; the composition and dosage of the culture medium in the fermenter were as follows: glucose 5g / L, corn flour 16.5g / L, soybean meal 40.0g / L, K2HPO4 2.0g / L, KH2PO4 0.56g / L, (NH4)2SO4 2.2g / L, MgSO4·7H2O 0.40g / L, and FeSO4 0.01g / L.

4. The bacterial agent of Burkholderia cepacia JK-1 according to claim 1, characterized in that: The microbial agent also includes a carrier and an auxiliary agent. The preparation method of the microbial agent includes the following steps: S1: using the carrier to adsorb the fermentation liquid to obtain a solid loaded carrier; S2: The carrier and the auxiliary agent are mixed evenly, and the obtained mixture is the bacterial agent.

5. The bacterial agent of Burkholderia cepacia JK-1 according to claim 4, characterized in that: The carrier is medical stone powder, and the auxiliary agents are sodium alginate, sodium carboxymethyl cellulose and calcium chloride; in the bacterial agent, the amount of sodium alginate is 1wt%, the amount of sodium carboxymethyl cellulose is 2wt%, and the amount of calcium chloride is 0.2wt%.

6. The bacterial agent of Burkholderia cepacia JK-1 according to claim 4, characterized in that: The mass fraction of the fermentation liquid in the loading carrier is not higher than 20%.

7. Use of the bacterial agent of Burkholderia cepacia JK-1 according to any one of claims 1 to 6 in preventing and treating strawberry root rot, characterized in that: The causative agent of strawberry root rot is Colletotrichum siamese ( Colletotrichum siamense ).

8. The use according to claim 7, characterized in that The method of using the fungal agent is: dilute the agent with water and then dip it in the roots.

9. Use of the Burkholderia cepacia JK-1 inoculum according to any one of claims 1 to 6 in improving strawberry quality, characterized in that: The inoculant can increase the content of vitamin C and soluble sugar in strawberries and reduce the total acid content.

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