Streptomyces xr001 strain and application thereof

Abstract

The application discloses a streptomyces XR001 strain and application thereof. The streptomyces XR001 strain is preserved in the China General Microbiological Culture Collection Center, and the preservation number is CGMCC No. 38856, and the preservation date is May 25, 2026. The streptomyces XR001 strain screened by the application has the abilities of nitrogen fixation and actinorhodin production, has a significant growth promoting effect on rice, and provides a microbial resource with the functions of growth promotion and biological prevention and control for agricultural production.

Description

Technical Field

[0001] This invention belongs to the field of microbial technology and relates to a Streptomyces strain XR001 and its applications. Background Technology

[0002] Nitrogen is a core element constituting the proteins and nucleic acids of living organisms, and it is also one of the key nutrients limiting agricultural production. Although nitrogen is abundant in the atmosphere (accounting for about 78%), most plants cannot directly utilize molecular nitrogen (N2). The long-term, large-scale application of chemical nitrogen fertilizers, while ensuring crop yields to some extent, has led to a series of ecological and economic problems, including soil acidification, water eutrophication, increased greenhouse gas emissions, and rising agricultural production costs. Therefore, exploring and utilizing microbial resources with highly efficient biological nitrogen-fixing capabilities, and developing green and sustainable bio-nitrogen fertilizer technologies, is of great significance for promoting the development of ecological agriculture.

[0003] Actinoxones belong to the benzonaphthoquinone class of antibiotics, characterized by their distinctive deep red pigment and broad bioactivity, including inhibition of Gram-positive bacteria, antifungal activity, antitumor activity, and antioxidant effects. Streptomyces is a representative genus that produces actinoxones and various other secondary metabolites, and has long been an important source for the development of novel natural products. However, the resources of most Streptomyces strains have not been fully explored, especially research on strains possessing multiple beneficial functions (such as biological nitrogen fixation and bioactive product synthesis) remains very limited.

[0004] Currently, research on Streptomyces mainly focuses on their single functions, such as antagonizing plant pathogens, producing enzymes, or producing specific antibiotics. Streptomyces with both highly efficient nitrogen-fixing capabilities and the ability to produce actinolite are rarely reported. Integrating nitrogen-fixing function and natural antibiotic production capacity into a single strain not only holds promise for providing agricultural production with microbial agents that combine growth-promoting and biocontrol functions, but also for providing new sources of microbial inoculum for the microbial synthesis of natural products.

[0005] Therefore, the targeted screening of Streptomyces strains that possess both nitrogen-fixing activity and cyclopurinic acid production capabilities from the natural environment, and the clarification of their application potential in the agricultural field, has significant theoretical value and application prospects. Summary of the Invention

[0006] To address the shortcomings of existing technologies and practical needs, this invention provides a Streptomyces XR001 strain and its application. The Streptomyces XR001 strain obtained by this invention has both nitrogen-fixing and cyclopurinic acid-producing capabilities, and exhibits a significant growth-promoting effect on rice, providing agricultural production with a microbial resource that combines growth promotion and biocontrol functions.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a Streptomyces sp. XR001 strain, which is deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 38856 and deposit date of May 25, 2026.

[0009] In a second aspect, the present invention provides the application of the Streptomyces sp. XR001 strain described in the first aspect in biological nitrogen fixation, production of actinomycin, or promotion of crop growth.

[0010] Preferably, the crop includes rice.

[0011] Thirdly, the present invention provides a method for culturing the Streptomyces sp. XR001 strain described in the first aspect, the method comprising: inoculating the Streptomyces sp. XR001 strain described in the first aspect onto Ashby nitrogen-free solid medium for culturing.

[0012] Preferably, the culture temperature is 25℃-30℃ (e.g., 25℃, 28℃ or 30℃) and the time is 3-8 days (e.g., 3 days, 5 days or 8 days).

[0013] Preferably, the Ashby nitrogen-free solid culture medium comprises: sucrose 5.0-15.0 g / L (e.g., 5.0 g / L, 10 g / L, or 15 g / L), KH₂PO₄ 0.1-0.5 g / L (e.g., 0.1 g / L, 0.3 g / L, or 0.5 g / L), MgSO₄·7H₂O 0.1-0.5 g / L (e.g., 0.1 g / L, 0.3 g / L, or 0.5 g / L), NaCl 0.1-0.5 g / L (e.g., 0.1 g / L, 0.3 g / L, or 0.5 g / L), CaSO₄·2H₂O 0.05-0.2 g / L (e.g., 0.05 g / L, 0.1 g / L, or 0.2 g / L), and CaCO₃ 2.0-8.0 g / L (e.g., 2 g / L, 5 g / L, or 8 g / L). The solvent is water.

[0014] Fourthly, the present invention provides a method for producing actinol, the method comprising: culturing the Streptomyces sp. XR001 strain described in the first aspect under nitrogen-free conditions and / or under conditions with an oxygen concentration of 3%-8% (e.g., 3%, 5% or 8%).

[0015] Fifthly, the present invention provides a method for promoting rice growth, the method comprising: culturing the Streptomyces sp. XR001 strain described in the first aspect under nitrogen-free conditions and / or under conditions with an oxygen concentration of 3%-8% (e.g., 3%, 5% or 8%).

[0016] In a sixth aspect, the present invention provides a microbial agent comprising the Streptomyces sp. XR001 strain described in the first aspect.

[0017] Preferably, the microbial agent further includes an acceptable carrier or excipient.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) The Streptomyces sp. XR001 strain screened in this invention can grow normally on nitrogen-free medium and has good biological nitrogen fixation ability, which can reduce the application of chemical nitrogen fertilizer.

[0020] (2) The Streptomyces sp. XR001 strain screened in this invention can produce actinolite, and the production of actinolite is significantly increased under conditions of 5% oxygen concentration and nitrogen deficiency.

[0021] (3) The Streptomyces sp. XR001 strain screened in this invention has a significant growth-promoting effect on rice. Under normal nitrogen levels, it can increase the weight of rice by 16.3%, and when nitrogen is insufficient, it preferentially promotes root growth, with an increase of up to 8%.

[0022] (4) This invention integrates nitrogen fixation function and actinol production capacity into the same strain, providing agricultural production with microbial resources that have both growth-promoting and biocontrol functions. Attached Figure Description

[0023] Figure 1 This is a colony diagram of the bacterial strain isolated from nitrogen-containing medium.

[0024] Figure 2 A graph showing the effect of Streptomyces sp. XR001 on rice growth.

[0025] Figure 3 Figure showing the secretion of actinopyroxin by nitrogen-free Streptomyces sp. XR001 strain;

[0026] Figure 4 Figure showing the anaerobic promotion of actinopyroxin secretion by Streptomyces sp. XR001 strain. Detailed Implementation

[0027] To further illustrate the technical means and effects of this invention, the following description, in conjunction with embodiments and accompanying drawings, provides a further explanation of the invention. It is understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it.

[0028] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.

[0029] The Streptomyces sp. XR001 strain mentioned below is classified as Streptomyces sp., with a deposit date of May 25, 2026, accession number CGMCC No. 38856, and is deposited at the China General Microbiological Culture Collection Center, located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing. Example 1

[0030] 1.1 Ashby medium

[0031] Prepare 1000 mL of the following: 10.0 g sucrose, 0.2 g KH2PO4, 0.2 g MgSO47H2O, 0.2 g NaCl (to maintain osmotic pressure), 0.1 g CaSO42H2O, 5.0 g CaCO3, and 15.0 g agar.

[0032] 1.2 Fungal Screening

[0033] (1) Soil collection: Soil was collected from peanut fields in Shenyang, Liaoning Province. Fresh soil was passed through a 20-mesh sieve to remove roots and debris.

[0034] (2) Strain screening: Under aseptic conditions, 1 g of soil was added to a test tube containing 9 mL of sterile water and continuously diluted. 0.2 mL of the supernatant diluted 100 times and 1000 times was taken and plated using the spread plate method. The culture was carried out at 28℃ for 5 days, and the growth of the strains was observed. The screened strains were streaked and then purified and cultured.

[0035] 1.3 Strain Identification

[0036] 1.3.1 Culture medium and solution

[0037] (1) 10×TBE buffer (pH 8.3): Tris 108 g, boric acid 55 g, Na2EDTA•2H2O 7.44 g, diluted to 1 L with deionized water and stored at room temperature.

[0038] (2) Agarose gel (1%): 100 mL of 1×TBE buffer, 1 g of agarose, 5 μL of 10 mg / mL EB.

[0039] 1.3.2 Molecular identification methods

[0040] (1) Bacterial genomic DNA was extracted using the MiniBEST Universal Genomic DNA Extraction Kit from Takara Bio Inc.

[0041] (2) The extracted DNA was detected by agarose gel electrophoresis.

[0042] (3) PCR amplification of 16S rRNA sequence:

[0043] (4) Primer pairs:

[0044] 27F (SEQ ID NO: 1): 5'-AGRGTTYGATYMTGGCTCAG-3';

[0045] 1492R (SEQ ID NO:2): 5'-RGYTACCTTGTTACGACTT-3'.

[0046] Primers 27F and 1492R were diluted to 10 pmol / μL with TE buffer and set aside. Then, 10 μL of 5×FastPfu buffer, 2 μL of 2.5 mM dNTPs, 1 μL of each primer, 0.5 μL of FastPfu DNA polymerase, and 10 ng of template DNA were added sequentially, followed by ddH2O to a final volume of 50 μL. PCR amplification conditions: 95℃ for 5 min; 95℃ for 0.5 min, 55℃ for 0.5 min, 72℃ for 0.75 min, 27 cycles; 72℃ for 10 min, and stored at 10℃. PCR products were sent to Shanghai Ling'en Biotechnology Co., Ltd. for sequencing.

[0047] 1.3.3 Results of strain identification

[0048] like Figure 1As shown, the isolated strain belongs to the genus *Streptomyces*. The colonies are white, with a rough, uneven surface, and are circular in shape, with filamentous hyphae on the surface. It appears blue on nitrogen-free Ashby medium. The 16S rRNA gene sequence of the strain is shown in SEQ ID NO:3. Based on morphological characteristics and 16S rRNA sequence analysis, it was identified as *Streptomyces* sp., named XR001, and deposited on May 25, 2026, at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 38856.

[0049] SEQID NO:3:

[0050] Example 2

[0051] The growth-promoting effect of Streptomyces XR001 strain on rice.

[0052] The experimental design of this embodiment included low-nitrogen treatment without Streptomyces sp. XR001 strain (LN-S), low-nitrogen treatment with Streptomyces sp. XR001 strain (LN+S), high-nitrogen treatment without Streptomyces sp. XR001 strain (HN-S), and high-nitrogen treatment with Streptomyces sp. XR001 strain (HN+S). The rice variety was "Dongdao 4". Nitrogen was provided by Kimura nutrient solution (formulation shown in Table 1). The nitrogen content of the low-nitrogen treatment was 1 / 3 of that of the high-nitrogen treatment. Each treatment was repeated 3 times.

[0053] Table 1

[0054] ;

[0055] Streptomyces sp. XR001 strain was cultured in liquid Ashby medium, and the bacterial concentration was determined by OD00. 600 = 0.01. The agent was applied once on day 7 and day 10 after rice emergence, with liquid Ashby medium containing Streptomyces sp. XR001 as a control. Seedling height, root length, and weight were measured 15 days after emergence, and the results are as follows: Figure 2 As shown in Table 2. From Figure 2 It was found that 15 days after rice emergence, compared with the uninoculated control group, the rice plants inoculated with Streptomyces sp. XR001 (HN+XR) were significantly taller and had more developed root systems. Under low nitrogen conditions, the root length of plants inoculated with Streptomyces sp. XR001 (LN+XR) increased significantly. Table 2 shows that 15 days after emergence, the addition of Streptomyces sp. XR001 significantly increased the weight of rice with normal nitrogen levels, reaching 16.3%. Under nitrogen deficiency, it promoted root growth in rice, with an increase of 8%. This indicates that under sufficient nitrogen, Streptomyces sp. XR001 promotes rice growth, exhibiting a growth-promoting function. Under nitrogen deficiency, Streptomyces sp. XR001 preferentially promotes root growth, demonstrating a plant-friendly interaction effect.

[0056] Table 2

[0057] ; Example 3

[0058] Improve the production conditions of purpuric acid.

[0059] Actinoporin is an important antioxidant. The cells were cultured for 5 days in both nitrogen-containing and nitrogen-free liquid Ashibyl medium.

[0060] The effects of nitrogen-free conditions on actinolite production are as follows: Figure 3 As shown, after culturing in Ashby nitrogen-free liquid medium for 5 days, the fermentation broth turned a distinct blue color, indicating a large amount of actinolite secreted; while in nitrogen-containing medium (Ashby with added nitrogen), the fermentation broth was lighter in color, and the actinolite production was significantly reduced. The results indicate that nitrogen-free conditions can significantly promote the secretion of actinolite by Streptomyces sp. XR001.

[0061] Under nitrogen-free conditions, experiments simulating different O2 concentrations (0% and 5%) were conducted by evacuating the vacuum and adding O2. The effect of 5% hypoxia on actinolite production was shown in the results. Figure 4 As shown, the production of actinol can be significantly increased under conditions of 5% oxygen concentration and nitrogen deficiency.

[0062] In summary, the Streptomyces sp. XR001 strain screened in this invention possesses both nitrogen-fixing and cyclopurinic acid-producing capabilities, exhibiting a significant growth-promoting effect on rice and providing agricultural production with a microbial resource that combines growth promotion and biocontrol functions.

[0063] The applicant declares that the detailed method of the present invention is illustrated by the above embodiments, but the present invention is not limited to the above detailed method, that is, it does not mean that the present invention must rely on the above detailed method to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A Streptomyces sp. XR001 strain, characterized in that, The Streptomyces p. XR001 strain is deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 38856 and deposit date of May 25, 2026.

2. The application of the Streptomyces sp. XR001 strain according to claim 1 in biological nitrogen fixation, production of actinol, or promotion of crop growth.

3. The application according to claim 2, characterized in that, The crop mentioned includes rice.

4. The method for culturing Streptomyces sp. XR001 strain according to claim 1, characterized in that, The cultivation method includes: inoculating the Streptomyces sp. XR001 strain of claim 1 onto Ashby nitrogen-free solid medium for cultivation.

5. The cultivation method according to claim 4, characterized in that, The culture temperature is 25℃-30℃, and the time is 3-8 days.

6. The cultivation method according to claim 4 or 5, characterized in that, The Ashby nitrogen-free solid culture medium comprises: sucrose 5.0-15.0 g / L, KH2PO4 0.1-0.5 g / L, MgSO4·7H2O 0.1-0.5 g / L, NaCl 0.1-0.5 g / L, CaSO4·2H2O 0.05-0.2 g / L, CaCO3 2.0-8.0 g / L, and agar 10.0-20.0 g / L, with water as the solvent.

7. A method for producing actinolite, characterized in that, The method comprises: culturing the Streptomyces sp. XR001 strain of claim 1 under nitrogen-free conditions and / or under conditions with an oxygen concentration of 3%-8%.

8. A method for promoting rice growth, characterized in that, The method comprises: culturing the Streptomyces sp. XR001 strain of claim 1 under nitrogen-free conditions and / or under conditions with an oxygen concentration of 3%-8%.

9. A microbial inoculant, characterized in that, The microbial agent includes the Streptomyces sp. XR001 strain as described in claim 1.

10. The microbial agent according to claim 8, characterized in that, The microbial agent also includes acceptable carriers or excipients.

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