Streptomyces mutans and application thereof

Abstract

The invention discloses streptomyces varioti and application thereof, and belongs to the technical field of agricultural biology, the classification name of the streptomyces varioti is streptomyces varioti BZ109, the streptomyces varioti is preserved in the China Center for Type Culture Collection on August 5, 2024, the preservation number of the streptomyces varioti is CCTCC NO: M 20241749, and after the streptomyces varioti is cultured on a potato dextrose agar culture medium at 28 DEG C for 7 days, the streptomyces varioti is separated from the potato dextrose agar culture medium. Aerogenous hyphae and intramedium hyphae are generated on the culture medium, pigment is not secreted, the aerial hyphae are chalk, a circle around the hyphae is light gray, and the edges of bacterial colonies are neat. The streptomyces proteus can effectively inhibit mycelial growth of phytophthora sojae, rhizoctonia solani, fusarium oxysporum and fusarium graminearum, has a good effect in prevention and control of plant gray mold and plant bacterial wilt, can promote plant growth, and has wide application potential in the field of agricultural biology.

Description

Technical Field

[0001] The invention belongs to the field of agricultural biotechnology, and specifically relates to a strain of Streptomyces mutans and application thereof. Background Art

[0002] At present, chemical fungicides are the main method for disease control. However, the long-term improper use of chemical pesticides has led to serious ecological and environmental impacts. During their growth, plants need a healthy and stable environment to maintain their normal development and high yield. However, the abuse of chemical fungicides not only destroys this balance, but may also trigger a series of chain reactions, thereby weakening the plant's disease resistance. When pesticides are widely used in the fields, beneficial organisms such as bees, birds, and aquatic invertebrates are exposed to pesticide toxicity directly or indirectly through spray drift or leaching, which in turn affects the number and health status of these organisms. This impact not only weakens the relationship between organisms in nature, but also disrupts key ecological services such as plant pollination and natural control of pests and diseases, ultimately leading to an increased dependence on plant growth and an increasingly significant dependence on chemical fungicides.

[0003] What is more serious is that the continued presence of highly toxic and residual chemical pesticides in the ecosystem will lead to bioaccumulation. This not only forms an enrichment of harmful substances in the food chain, causing greater harm to organisms at the top of the food chain, but also causes irreversible damage to human health and the environment. Chemical pesticide residues may enter the soil and water, pollute the environment, reduce the activity of soil microorganisms, affect the normal growth of plant roots, and ultimately affect the absorption capacity and overall health of plants. In addition, the long-term irrational use of chemical pesticides has also accelerated the development of fungicide resistance in plant pathogen populations. Once the pathogens develop resistance to fungicides, traditional prevention and control measures will become ineffective, causing the disease to spread rapidly among plants and cause larger areas of crop losses. In order to curb this trend, agricultural producers often have to increase the amount or frequency of pesticide use, further exacerbating the burden on the ecological environment.

[0004] In this context, biopesticides are considered to be safer and more sustainable alternatives to chemical pesticides due to their harmlessness and environmental compatibility. Biopesticides are derived from metabolites or extracts of organisms in nature. They are not only more friendly to humans and the environment, but also can effectively prevent and control pests and diseases without destroying the ecological balance. Through the rational use of biopesticides, we can reduce our dependence on chemical pesticides, maintain the diversity and stability of the ecosystem, promote the healthy growth of plants, and ensure the sustainable development of agricultural production. In addition, the use of biopesticides can also enhance the plant's own defense mechanism. For example, certain biological agents can induce resistance responses in plants and improve their resistance to pathogens. This approach not only reduces the need for external pesticides, but also improves the yield and quality of crops by improving the health of plants. Therefore, promoting the research and application of biopesticides will become an important way to achieve sustainable agricultural development. Summary of the invention

[0005] The purpose of the present invention is to solve at least one of the above-mentioned deficiencies in the prior art. For example, one of the purposes of the present invention is to provide a strain of Streptomyces mutans to solve the shortcomings of the prior art biological pesticides, such as small action range, slow effect, and large effect of the efficacy being affected by the environment.

[0006] In order to achieve the above-mentioned object, one aspect of the present invention provides a strain of Streptomyces varsoviensis, which is classified and named as Streptomyces varsoviensis BZ109, and has been deposited in the China Center for Type Culture Collection on August 5, 2024, with a deposit number of CCTCC NO: M 20241749.

[0007] Furthermore, the 16S rRNA sequence of Streptomyces mutans is shown as SEQ ID NO.1.

[0008] Furthermore, after being cultured on potato dextrose agar medium at 28° C. for 7 days, Streptomyces mutans produced aerial hyphae and basal hyphae on the medium without secreting pigments. The aerial hyphae were chalky white, and a circle around the hyphae was light gray, and the edges of the colonies were relatively neat.

[0009] Another aspect of the present invention provides a method for screening Streptomyces mutans, wherein the Streptomyces in a soil sample is separated by a gradient dilution method.

[0010] Furthermore, the gradient dilution method comprises the following steps: weighing 10 grams of soil, pouring it into a conical flask filled with 90 ml of sterile water, and placing it in a shaker at 28°C and 200 rpm for 30 minutes; aspirating 1 ml of the soil suspension into a centrifuge tube filled with 9 ml of sterile water and mixing it thoroughly; diluting the soil suspension to 10-3, 10-4, and 10-5 in sequence; aspirating 100 μl of the soil suspension diluted to 10-3, 10-4, and 10-5 and applying it on a starch casein solid culture medium containing nalidixic acid (25 μg / ml), cycloheximide (25 μg / ml) and nystatin (25 μg / ml), and culturing at 28°C for 5-7 days. Pick up single colonies with chalky color, rough and dry surface, and difficult-to-pick-up texture. In the late stage of culture, produce hyphae in the substrate and other characteristics that meet the culture characteristics of Streptomyces. Put them into starch casein liquid culture medium containing nalidixic acid (25μg / ml), cycloheximide (25μg / ml) and nystatin (25μg / ml), and culture them at 28℃ and 200rpm for 5-7 days. Then use a 10μl inoculation loop to inoculate into starch casein solid culture medium containing nalidixic acid (25μg / ml), cycloheximide (25μg / ml) and nystatin (25μg / ml) for streak purification culture. Pick up single colonies of purified isolates for propagation. Use glycerol to preserve the isolate suspension. The preservation operation is to mix the Streptomyces suspension with 50% glycerol in a 1:1 ratio and store it in a -80℃ ultra-low temperature refrigerator.

[0011] Another aspect of the present invention provides a biological preparation, which includes the Streptomyces mutans as described above, or its bacterial suspension, or its culture solution, or its fermentation product, or its dry powder bacterial agent.

[0012] Furthermore, the dry powder bacterial agent is obtained by fermenting Streptomyces mutans to obtain a fermentation liquid, and freeze-drying the fermentation liquid to obtain the dry powder bacterial agent; or the fermentation liquid is spray-dried to obtain the dry powder bacterial agent.

[0013] Another aspect of the present invention provides a strain of Streptomyces mutans and the use of a biological preparation thereof.

[0014] Furthermore, it includes application in inhibiting soybean phytophthora pathogen.

[0015] Furthermore, the invention also includes application in inhibiting Rhizoctonia solani.

[0016] Furthermore, the invention also includes application in inhibiting Fusarium oxysporum.

[0017] Furthermore, the invention includes application in inhibiting Fusarium graminearum and Fusarium oxysporum.

[0018] Furthermore, it includes the role in preventing and controlling plant diseases, including plant gray mold and plant bacterial wilt.

[0019] Furthermore, the invention also includes application in promoting plant growth.

[0020] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0021] 1. The Streptomyces varsoviensis BZ109 of the present invention can effectively inhibit the mycelial growth of Phytophthora sojae, Rhizoctonia solani, Fusarium oxysporum and Fusarium graminearum; under the condition of plate confrontation culture, the inhibition rate of Phytophthora sojae reaches nearly 100% after 3 to 7 days of inoculation culture, and the treatment effect is remarkable.

[0022] 2. The Streptomyces varsoviensis BZ109 of the present invention can also be well applied in the prevention and control of plant diseases, and can achieve effective prevention and control of gray mold, while also having a good prevention and control effect on typical plant bacterial wilt pathogens.

[0023] 3. The Streptomyces varsoviensis BZ109 of the present invention also has good application in promoting plant growth and flowering. It can significantly promote the growth and development of plants after foliar spraying and root irrigation treatment on plants. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The Streptomyces varsoviensis BZ109 of the present invention has been deposited in China Center for Type Culture Collection (CCTCC), with a deposit address at Wuhan University, No. 299, Bayi Road, Wuchang District, Wuhan City, Hubei Province, on August 5, 2024, and a deposit number of CCTCC NO: M 20241749.

[0025] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0026] Figure 1 The morphology of Streptomyces mutans cultured on PDA medium in Example 2 of the present invention;

[0027] Figure 2 This is the morphology of the Streptomyces mutans cultured on ISP1 medium in Example 2 of the present invention.

[0028] Figure 3 This is the morphology of the Streptomyces mutans cultured on ISP2 medium in Example 2 of the present invention.

[0029] Figure 4This is the morphology of the Streptomyces mutans cultured on ISP3 medium in Example 2 of the present invention.

[0030] Figure 5 This is the morphology of the Streptomyces mutans cultured on ISP4 medium in Example 2 of the present invention.

[0031] Figure 6 This is the morphology of the Streptomyces mutans cultured on ISP5 medium in Example 2 of the present invention.

[0032] Figure 7 This is the morphology of the Streptomyces mutans cultured on ISP6 medium in Example 2 of the present invention.

[0033] Figure 8 This is the morphology of the Streptomyces mutans cultured on ISP7 medium in Example 2 of the present invention.

[0034] Fig. 9 This is a phylogenetic tree of BZ109 and other Streptomyces species generated by neighbor-joining analysis based on the 16S ribosomal RNA gene in Example 2 of the present invention.

[0035] Fig.10 This is a graph showing the inhibitory effect of strain BZ109 in Example 3 of the present invention on the mycelial growth of Phytophthora sojae, Rhizoctonia solani, Fusarium oxysporum, and Fusarium graminearum.

[0036] Fig.11 This is a graph showing the inhibitory effect of different concentrations of BZ109 culture filtrate in Example 4 of the present invention on the growth of soybean Phytophthora mycelium.

[0037] Fig.12 This is a picture of 4 pepper plants selected in Example 5 of the present invention.

[0038] Fig.13 This is a comparison chart of the inhibitory effect of BZ109 in Example 5 of the present invention on the infection of host pepper by Phytophthora sojae.

[0039] Fig.14 This is a comparison chart of the inhibitory effect of BZ109 in Example 6 of the present invention on gray mold infection of host peppers.

[0040] Fig.15 This is a graph showing the antibacterial activity of BZ109 in Example 7 of the present invention against Ralstonia persica.

[0041] Fig.16 This is a comparison chart of the growth of cucumber plants treated with the BZ109 fermentation liquid in Example 8 of the present invention and control plants on the 14th day after treatment.

[0042] Fig.17This is a comparison chart of the growth of cucumber plants treated with the BZ109 fermentation liquid in Example 8 of the present invention and control plants on the 21st day after treatment. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, 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.

[0044] Unless otherwise specified, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art in the art to which the present invention relates. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe methods and / or materials related to the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail. Regarding the "comprising", "including", "having", "containing", etc. used herein, they are all open-ended terms, that is, they mean including but not limited to. Unless the context clearly indicates otherwise, the expressions "a" and "one" used herein include plural references. For example, referring to "a cell" includes a plurality of such cells and equivalents known to those skilled in the art, etc. The term "about" used herein means a range of ±20% of the value thereafter. In some embodiments, the term "about" means a range of ±10% of the value thereafter. In some embodiments, the term "about" means a range of ±5% of the value thereafter.

[0045] Example embodiment 1.

[0046] In this exemplary embodiment, a strain of Streptomyces mutans is provided,

[0047] The classification name of this Streptomyces varsoviensis BZ109 is Streptomyces varsoviensis BZ109, which was deposited in the China Center for Type Culture Collection on August 5, 2024. The depository unit is China Center for Type Culture Collection (CCTCC), and the deposit address is Wuhan University, No. 299, Bayi Road, Wuchang District, Wuhan City, Hubei Province. The deposit date is August 5, 2024, and its deposit number is CCTCC NO: M 20241749.

[0048] In this exemplary embodiment, the 16S rRNA sequence of Streptomyces mutans is shown as SEQ ID NO.1.

[0049] In this exemplary embodiment, after being cultured on potato dextrose agar medium at 28° C. for 7 days, Streptomyces varsoviensis BZ109 produced aerial hyphae and basal hyphae on the medium without secreting pigments. The aerial hyphae were chalky white, with a circle around the hyphae being light gray, and the edges of the colonies were relatively neat.

[0050] Example 2:

[0051] In this exemplary embodiment, a method for screening a strain of Streptomyces mutans is provided. The strain of Streptomyces mutans in exemplary embodiment 1 can be obtained by the gradient dilution screening method in this exemplary embodiment.

[0052] The specific steps include:

[0053] Weigh 10 g of soil, pour it into a conical flask filled with 90 ml of sterile water, and place it in a shaker at 28°C and 200 rpm for 30 minutes.

[0054] Pipette 1 ml of soil suspension into a centrifuge tube containing 9 ml of sterile water, mix thoroughly, dilute the soil suspension to 10-3, 10-4, and 10-5 in sequence, and apply 100 μl of the soil suspension diluted to 10-3, 10-4, and 10-5 on a starch casein solid culture medium containing nalidixic acid (25 μg / ml), cycloheximide (25 μg / ml) and nystatin (25 μg / ml), and culture at 28°C for 5-7 days.

[0055] Pick colonies with chalky color, rough and dry surface, and difficult-to-pick-up texture. In the later stage of culture, produce hyphae in the substrate and other single colonies that meet the culture characteristics of Streptomyces. Put them into starch casein liquid culture medium containing nalidixic acid (25μg / ml), cycloheximide (25μg / ml) and nystatin (25μg / ml), and culture them at 28℃, 200rpm for 5-7 days.

[0056] Then, a 10 μl inoculation loop was used to inoculate the solid starch casein medium containing nalidixic acid (25 μg / ml), cycloheximide (25 μg / ml) and nystatin (25 μg / ml) for streak purification culture.

[0057] The purified single colony of the isolate was picked for propagation, and the propagated isolate suspension was subjected to a bacteria preservation operation with glycerol. The bacteria preservation operation was to mix the Streptomyces suspension with 50% glycerol in a 1:1 ratio and store it in a -80°C ultra-low temperature refrigerator.

[0058] Example 3:

[0059] In this exemplary embodiment, a biological agent produced based on the Streptomyces varsoviensis BZ109 described in exemplary embodiment 1 is provided.

[0060] The biological agent in this exemplary embodiment includes Streptomyces varsoviensis BZ109 obtained in the above exemplary embodiments.

[0061] Or the bacterial suspension prepared according to the Streptomyces mutans in the above exemplary embodiment.

[0062] Or the culture solution of Streptomyces mutans according to the above exemplary embodiment.

[0063] Or the fermentation product obtained by fermenting it with Streptomyces mutans in the above exemplary embodiment.

[0064] Alternatively, according to the Streptomyces mutans in the above exemplary embodiment, the Streptomyces mutans is fermented to obtain a fermentation broth, and the fermentation broth is freeze-dried to obtain a dry powder bacterial agent, or the dry powder bacterial agent is obtained by spray drying.

[0065] Example 4:

[0066] In this exemplary embodiment, an application of a strain of Streptomyces mutans as in exemplary embodiment 1 or a biological agent obtained as in exemplary embodiment 3 is provided, specifically comprising:

[0067] Application of strain BZ109 and its biological preparations in inhibiting soybean Phytophthora pathogen.

[0068] Application of strain BZ109 and its biological preparations in inhibiting Fusarium oxysporum.

[0069] Application of strain BZ109 and its biological preparations in inhibiting Fusarium oxysporum.

[0070] Application of strain BZ109 and its biological agents in inhibiting Fusarium graminearum.

[0071] The role of strain BZ109 and its biological agents in preventing and controlling plant diseases, including plant gray mold and plant bacterial wilt.

[0072] Application of strain BZ109 and its biological preparations in promoting plant growth.

[0073] In order to better understand the strain of Streptomyces mutans and its application provided in this example, the content of the present invention is further explained below in conjunction with the accompanying drawings and examples.

[0074] Embodiment 1,

[0075] Isolation, purification and preservation of Streptomyces varsoviensis BZ109 (hereinafter referred to as "strain BZ109").

[0076] In this example, soil samples were collected from the rhizosphere soil of a cypress group in Qinglong Village, Shangxueshan Town, Enyang District, Bazhong City, Sichuan Province, and the Streptomyces in the collected soil samples were separated by gradient dilution method, and finally a Streptomyces strain was obtained, and the strain was named BZ109. The detailed separation method is as follows:

[0077] Step 1: Weigh 10 g of soil, pour it into a conical flask filled with 90 ml of sterile water, and place it in a shaker at 28°C and 200 rpm for 30 minutes.

[0078] Step 2: Pipette 1 ml of soil suspension into a centrifuge tube containing 9 ml of sterile water and mix thoroughly.

[0079] Step 3: Dilute the soil suspension to 10-3, 10-4, and 10-5 in sequence, apply 100 μl of the soil suspension diluted to 10-3, 10-4, and 10-5 on a starch casein solid culture medium containing nalidixic acid (25 μg / ml), cycloheximide (25 μg / ml), and nystatin (25 μg / ml), and culture at 28°C for 5 to 7 days.

[0080] Step 4: Pick colonies with chalky color, rough and dry surface, and difficult-to-pick-up texture. Single colonies that produce hyphae in the late stage of culture and meet the culture characteristics of Streptomyces are placed in starch casein liquid culture medium containing nalidixic acid (25μg / ml), cycloheximide (25μg / ml) and nystatin (25μg / ml) at 28°C and 200rpm for 5-7 days.

[0081] Step 5: Use a 10 μl inoculation loop to inoculate into starch casein solid medium containing nalidixic acid (25 μg / ml), cycloheximide (25 μg / ml) and nystatin (25 μg / ml) for streak purification culture.

[0082] Step 6: Pick a single colony of the purified isolate for propagation, and use glycerol to preserve the isolate suspension. Mix the isolate suspension with 50% glycerol in a 1:1 ratio and store it in a -80°C ultra-low temperature refrigerator.

[0083] Embodiment 2,

[0084] For the identification of Streptomyces varsoviensis BZ109 (hereinafter referred to as "strain BZ109").

[0085] In this embodiment, the cultivated Streptomyces mutans was morphologically identified, and the strain BZ109 was inoculated into PDA and 7 culture media formulated in the International Streptomyces Program: ISP1-casein yeast extract agar; ISP2-yeast extract malt extract agar, ISP3-oatmeal agar, ISP4-inorganic salt starch agar, ISP5-glycerol asparagine agar, ISP6-peptone yeast extract iron agar, ISP7-tyrosine agar. After culturing at 28°C for 7 days, the growth of strain BZ109 on the test culture medium, the color of aerial hyphae, the color of intrabasal hyphae and the pigment production were recorded, and the spore and hyphae morphological characteristics of strain BZ109 were observed using a scanning electron microscope.

[0086] Figure 1 The morphology of Streptomyces mutans cultured on PDA medium in this example is shown; Figure 2 The morphology of Streptomyces mutans cultured on ISP1 medium in this example is shown; Figure 3 The morphology of Streptomyces mutans cultured on ISP2 medium in this example is shown; Figure 4 The morphology of Streptomyces mutans cultured on ISP3 medium in this example is shown; Figure 5 The morphology of Streptomyces mutans cultured on ISP4 medium in this example is shown; Figure 6 The morphology of Streptomyces mutans cultured on ISP5 medium in this example is shown; Figure 7 The morphology of Streptomyces mutans cultured on ISP6 medium in this example is shown; Figure 8 The form of Streptomyces mutans cultured on ISP7 medium in the present embodiment is shown. As can be seen from the above-mentioned accompanying drawings, strain BZ109 produces relatively abundant aerial hyphae and base hyphae on PDA medium, does not secrete pigment, aerial hyphae are white to gray, a circle around hyphae is light gray, and the edge of the colony is neat. In all other IPS mediums, it can grow normally, and except that the hyphae are chalky in color on IPS2 and IPS4, they are all light gray on other IPS mediums. Through the above morphological observations, BZ109 is identified as Streptomyces.

[0087] The species status of strain BZ109 was then further determined by molecular identification.

[0088] Firstly, the genomic DNA of BZ109 was extracted using the Gram-positive bacteria genomic DNA extraction kit (catalog number ZP303-1) produced by Zhuangmeng International Biogene Technology Co., Ltd.

[0089] Then, the BZ109 16S ribosomal RNA sequence was amplified using the universal primers 16S-27F (5'-AGAGTTTGATCTGGCTCAG-3') and 16S-1492R (5'-TACGGCTACCTTGTTACGACTT-3'); the amplified sequence was purified and sequenced by Shanghai Sangon Biotechnology Co., Ltd., and the obtained BZ109 16S ribosomal RNA sequence is shown in SEQ ID NO.1.

[0090] Through the comparison analysis of EzBioCloud 16S database, it was found that the BZ109 16S ribosomal RNA sequence had the highest similarity with the Streptomyces varsoviensis 16S rRNA sequence, reaching 99.71%. Since the BZ109 16S ribosomal RNA sequence was also highly similar to other Streptomyces species besides Streptomyces varsoviensis, a phylogenetic analysis was performed on the top 15 Streptomyces species with the highest similarity in the comparison results of BZ109 16S ribosomal RNA in the EzBioCloud 16S database, and the phylogenetic tree was obtained as follows: Fig. 9 As shown in the figure, it can be seen that BZ109 is still clustered with Streptomyces varsoviensis, so BZ109 is identified as Streptomyces varsoviensis.

[0091] Embodiment 3,

[0092] In this example, the preparation process of a biological agent based on Streptomyces varsoviensis BZ109 (hereinafter referred to as "strain BZ109") and its effect in inhibiting mold are disclosed.

[0093] In this example, the plate confrontation method was used to conduct an antibacterial evaluation test on the isolated and purified strain BZ109. Specifically, it includes:

[0094] Pour the PDA culture medium into a sterile culture dish with a diameter of 9 mm to prepare a PDA solid culture medium plate.

[0095] The mycelial block (d = 8 mm) of pathogens (Fusarium oxysporum, Rhizoctonia solani, Fusarium graminearum and Phytophthora sojae) was placed in the center of the PDA plate. 5 μl of the Streptomyces isolate suspension was titrated 2.5 cm away from the mycelial block of the pathogens on the same plate. The plate was placed in a constant temperature incubator at 28°C for 3 to 7 days to observe the inhibition of pathogen mycelium. Fig.10 The experimental results in the present embodiment are shown, with a control group on the left and an experimental group comprising strain BZ109 on the right. As can be seen from the figure, strain BZ109 isolates show excellent antibacterial activity, and can significantly inhibit the mycelial growth of Phytophthora sojae, Rhizoctonia solani, Fusarium oxysporum, and Fusarium graminearum. Among them, especially for Phytophthora sojae, Rhizoctonia solani and Fusarium oxysporum, there is an excellent inhibitory effect, and it can be seen from the figure that strain BZ109 isolates have the best inhibition rate for Phytophthora sojae, Rhizoctonia solani and Fusarium oxysporum, and can reach an inhibition efficiency of nearly 100%.

[0096] Embodiment 4,

[0097] In this example, Phytophthora sojae was used as a model plant pathogen to further evaluate the antibacterial activity of strain BZ109.

[0098] This implementation specifically evaluates the effect of strain BZ109 on soybean phytophthora, and the evaluation method used is through the antibacterial activity of BZ109 fermentation liquid on soybean phytophthora. The specific steps include:

[0099] Step 1: Pick the cultivated BZ23 colonies and put them into 50 ml of sterilized Gao's No. 1 liquid culture medium, and culture them at 28°C and 180 rpm / min for 7 days to obtain BZ23 fermentation broth.

[0100] Step 2: Centrifuge the fermentation broth at 6000×g and 4°C for 10 min, and filter with a 0.22 μm filter membrane to obtain the BZ109 culture filtrate.

[0101] Step 3: Mix different volumes of culture filtrate with molten PDA to prepare culture filtrate PDA plates with concentrations of 1%, 5%, 10% and 20% (v / v).

[0102] Step 4: Using the PDA plate without culture filtrate as the control, place the mycelium block (8 mm in diameter) containing soybean Phytophthora in the center of the PDA plate and culture it at 28°C for 3 days.

[0103] Step 5: Then measure the radial growth diameter of mycelium and calculate the antibacterial activity of the culture filtrate. The formula is: inhibition rate (%) = [(growth diameter of control group - growth diameter of treatment group) / growth diameter of control group] × 100%.

[0104] The results are as follows Fig.11 As shown, Fig.11 The inhibitory effect of different concentrations of BZ109 culture filtrate on the growth of soybean phytophthora hyphae in this embodiment is shown. As can be seen from the figure, the inhibition rate of soybean phytophthora in the fermentation liquid containing 1% BZ109 reaches more than 12%, the inhibition rate of soybean phytophthora in the fermentation liquid containing 5% BZ109 reaches 40%, the inhibition rate of soybean phytophthora in the fermentation liquid containing 10% BZ109 reaches more than 78%, and the inhibition rate of soybean phytophthora in the fermentation liquid containing 20% ​​BZ109 reaches more than 98%. As the concentration of BZ109 fermentation liquid in the PDA medium increases, the efficiency of inhibiting the growth of soybean phytophthora hyphae is higher.

[0105] Embodiment 5,

[0106] In this example, a pot experiment was used to evaluate the inhibitory effect of the fermentation liquid of strain BZ109 on soybean phytophthora. The specific steps include:

[0107] Step 1: Select 4 pepper plants with a height of about 10 cm and uniform growth, and divide them into two groups, one as the control group and the other as the treatment group. Fig.12 Four pepper plants selected in this example are shown, with the control group on the left and the pepper plants inoculated with strain BZ109 on the right.

[0108] Step 2: Dilute the BZ109 fermentation liquid 5 times and spray it on the leaves and irrigate the roots of the plants in the treatment group. The spraying amount should be such that a layer of water mist forms on the pepper leaves and the fermentation liquid does not drip from the leaves. The root irrigation amount is 50ml per pepper plant.

[0109] The control plants were sprayed and irrigated with clean water, and the spraying and root irrigation amounts were consistent with those of the treatment group.

[0110] Step 3: After 24 hours, the middle leaves of the pepper plants were inoculated with soybean phytophthora mycelium (diameter = 8 mm), and at the same time, soybean phytophthora mycelium (diameter = 8 mm) was also inoculated at four locations on the nutrient matrix 2 cm away from the base of the pepper stem.

[0111] The above plants were subjected to a moisturizing treatment, and the disease occurrence of the peppers was observed after 7 days.

[0112] The final result is Fig.13 As shown, no obvious disease symptoms were observed in plants sprayed with the fermentation liquid of strain BZ109 and irrigated with roots, while the control group showed symptoms of leaf yellowing, wilting and falling, indicating that the fermentation liquid of strain BZ109 can effectively inhibit the infection of soybean Phytophthora to the host.

[0113] Embodiment 6,

[0114] In this example, the antibacterial activity of the fermentation broth of strain BZ109 against gray mold was tested. The specific steps include:

[0115] Step 1: Select 8 pepper plants with a height of about 10 cm and uniform growth, and divide them into two groups, one as the control group and the other as the treatment group.

[0116] Step 2: Dilute the BZ109 fermentation liquid 5 times and spray it on the leaves and irrigate the roots of the plants in the treatment group. The spraying amount should be such that a layer of water mist forms on the pepper leaves and the fermentation liquid does not drip from the leaves. The root irrigation amount is 50ml per pepper plant.

[0117] The control plants were sprayed and irrigated with clean water, and the spraying and root irrigation amounts were consistent with those of the treatment group.

[0118] Step 3: After 24 hours, each pepper plant in the treatment group and the control group was inoculated with 5 ml of 10 7 spores / ml of Botrytis cinerea spores (the pathogen of gray mold). The above plants were treated with moisture retention, and the disease status of the plants was observed after 7 days.

[0119] The final result is Fig.14 As shown in the figure, it can be seen that the control group had lesions, while the leaves of the plants treated with BZ109 fermentation liquid had no obvious symptoms, indicating that BZ109 also has a good prevention and control effect on gray mold.

[0120] Embodiment 7,

[0121] In this example, Ralstonia persica was selected as a model bacterium of plant bacterial wilt to evaluate the inhibitory activity of BZ109 against the pathogen of plant bacterial wilt. The specific steps are:

[0122] Add 4% OD to molten LB solid medium (about 40-50℃) 600 = 0.6, poured into the plate and cooled, placed an Oxford cup on the LB solid medium containing Ralstonia peach, and added 5-fold diluted BZ109 fermentation filtrate to the Oxford cup, cultured overnight at 37°C, and observed the size of the inhibition zone the next day. Fig.15 As shown in the figure, it can be seen that the 5-fold diluted BZ109 fermentation broth has a significant inhibitory effect on Ralstonia persica.

[0123] Embodiment 8,

[0124] In this example, the effect of strain BZ109 on plant growth was tested.

[0125] Eight cucumber seedlings at the four-leaf stage with consistent growth were selected and divided into two groups, one as the control group and the other as the treatment group.

[0126] After diluting the BZ109 fermentation liquid 5 times, spray the leaves and irrigate the roots of the plants in the treatment group. The spraying amount should be such that a layer of water mist forms on the pepper leaves and the fermentation liquid does not drip from the leaves. The root irrigation amount is 50ml per plant. The control plants are sprayed and irrigated with clean water. One week later, spray the leaves and irrigate the roots again, and the spraying and root irrigation amount are the same as the first time.

[0127] Starting from the second treatment, the growth of cucumber seedlings was observed every week. Fig.16 As shown in the figure, it can be seen that the height of cucumber seedlings treated with BZ109 fermentation liquid was significantly higher than that of the control group, and the cucumber tendrils in the treatment group grew earlier than those in the control group.

[0128] The growth condition on the 21st day after treatment was as follows Fig.17 As shown in the figure, it can be seen that the flowering time of cucumber plants treated with BZ109 fermentation liquid is earlier than that of the control group, indicating that BZ109 fermentation liquid treatment has a significant effect on promoting cucumber growth and early flowering.

[0129] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A strain of Streptomyces mutans, characterized in that The classification name of the Streptomyces varsoviensis BZ109 was deposited in the China Center for Type Culture Collection on August 5, 2024, and its deposit number is CCTCC NO: M 20241749.

2. The Streptomyces mutans according to claim 1, characterized in that The 16S rRNA sequence of the Streptomyces mutans is shown as SEQ ID NO.

1.

3. The Streptomyces mutans according to claim 1, characterized in that After the Streptomyces mutans was cultured on a potato dextrose agar medium at 28° C. for 7 days, aerial hyphae and intrabasal hyphae were produced on the medium without secreting pigments. The aerial hyphae are chalky white, the circle around the hyphae is light grey, and the edges of the colony are relatively neat.

4. A biological agent, characterized in that: The biological preparation comprises the Streptomyces mutans as claimed in claim 1, or a bacterial suspension thereof, or a culture solution thereof, or a fermentation product thereof, or a dry powder bacterial agent thereof.

5. Use of the Streptomyces mutans according to claim 1 or the biological preparation according to claim 4 in inhibiting soybean Phytophthora pathogen.

6. Use of the Streptomyces mutans according to claim 1 or the biological preparation according to claim 4 in inhibiting Rhizoctonia solani.

7. Use of the Streptomyces mutans according to claim 1 or the biological preparation according to claim 4 in inhibiting Fusarium oxysporum.

8. Use of the Streptomyces mutans according to claim 1 or the biological preparation according to claim 4 in inhibiting Fusarium oxysporum in Fusarium graminearum.

9. The role of the Streptomyces mutans according to claim 1 or the biological agent according to claim 4 in preventing and controlling plant diseases, wherein the plant diseases include plant gray mold and plant bacterial wilt.

10. Use of the Streptomyces mutans according to claim 1 or the biological preparation according to claim 5 in promoting plant growth.

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