Streptomyces olivaceus LGWZYYLX-160 and application thereof

Abstract

The application discloses Streptomyces olivaceus LGWZYYLX-160 and application thereof, and belongs to the technical field of biological control. The Streptomyces olivaceus LGWZYYLX-160 has double functions of immunity enhancement and disease resistance promotion on peppers. In addition, the Streptomyces olivaceus LGWZYYLX-160 has antagonistic effects on pathogenic bacteria of various crops such as peppers, potatoes, peanuts, tomatoes, eggplants, cucumbers, pines, strawberries, tobaccos and corns. Meanwhile, the strain can enhance root activity and peroxidase activity of peppers, increase proline content of the roots and reduce malondialdehyde content. In summary, the application of the Streptomyces olivaceus LGWZYYLX-160 can provide excellent strain resources for immunity enhancement of pepper roots and biological control of diseases, and provide technical support for green yield increase and quality improvement cultivation of peppers.

Description

Technical Field

[0001] This invention relates to the field of biocontrol technology, and more specifically to a Streptomyces oliveri LGWZYYLX-160 and its applications. Background Technology

[0002] Chili peppers are an important vegetable and cash crop in my country, and their yield and quality directly affect farmers' income and industrial development. However, under the long-term large-scale and intensive planting model, chili pepper producing areas generally suffer from problems such as prominent continuous cropping obstacles, soil nutrient imbalance, and deterioration of physical and chemical properties. In addition, some farmers overuse chemical fertilizers and neglect organic inputs, leading to disordered soil microbiota, enrichment of pathogens, and frequent occurrence of soil-borne diseases (such as bacterial wilt, blight, and root rot). This not only seriously affects the growth, development, and stress resistance of chili pepper plants, but also becomes a key bottleneck restricting sustainable chili pepper production and the improvement of industrial quality and efficiency.

[0003] In recent years, the research and application of plant growth-promoting rhizobacteria (PGPRs) have received increasing attention in order to alleviate the negative impacts of continuous cropping obstacles and excessive fertilization on agro-ecosystems. These microorganisms activate soil nutrients through nitrogen fixation, phosphorus solubilization, and potassium release, and promote plant growth and improve plant health by secreting growth regulators, inducing systemic resistance, and competitively inhibiting pathogens. Root immune-enhancing bacteria for peppers belong to a special functional strain of PGPRs. Their core mechanism lies in enhancing root vitality, optimizing root architecture, and activating root immune responses, thereby improving the plant's resistance to soil-borne diseases and achieving stable and high-quality yields.

[0004] However, research and application of Streptomyces strains that possess both significant broad-spectrum disease resistance and plant growth-promoting abilities still require further exploration. In particular, there are few reports on specific Streptomyces strains that can effectively control various plant diseases, such as soil-borne diseases of peppers, while simultaneously promoting the growth of crops like peppers, and their mature application technologies.

[0005] Therefore, how to isolate and identify a Streptomyces strain with a clear taxonomic position and broad-spectrum disease resistance is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the present invention provides a Streptomyces oliveri LGWZYYLX-160 and its application.

[0007] The biocontrol bacteria screened in this invention have antagonistic effects against a variety of plant pathogens and can effectively promote the growth of chili peppers and improve their disease resistance.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0009] A Streptomyces olivaceus strain, LGWZYYLX-160, was deposited on March 25, 2026, at the China Center for Type Culture Collection (CCTCC) with accession number CCTCC NO: M 2026509, located at Wuhan University, Wuhan, China.

[0010] The above-mentioned application of Streptomyces oliveii LGWZYYLX-160 in the prevention and control of plant diseases.

[0011] Furthermore, the plants mentioned include tomatoes, peppers, corn, potatoes, peanuts, eggplants, cucumbers, water chestnuts, strawberries, citrus fruits, pine trees, and tobacco.

[0012] Furthermore, the plant diseases mentioned are: pepper blight, pepper wilt, pepper anthracnose, corn leaf blight, potato early blight, peanut white mold, tomato early blight, eggplant wilt, cucumber wilt, water chestnut postharvest Fusarium rot, strawberry blight, citrus scab, pine resin canker, and tobacco wilt.

[0013] The above-mentioned application of Streptomyces oliveii LGWZYYLX-160 in improving the resistance of chili peppers to Phytophthora blight.

[0014] The above-mentioned application of Streptomyces oliveii LGWZYYLX-160 in promoting pepper growth.

[0015] Furthermore, promoting chili pepper growth means increasing the plant height, stem diameter, SPAD, fresh biomass, and dry biomass of chili peppers.

[0016] The above-mentioned application of Streptomyces oliveii LGWZYYLX-160 in improving the root vigor, superoxide dismutase and peroxidase content of peppers.

[0017] The above-mentioned application of *Streptomyces oliveii* LGWZYYLX-160 in increasing proline content and reducing malondialdehyde content in pepper roots.

[0018] A root immune-enhancing bacterial agent for chili peppers, comprising the aforementioned Streptomyces oliveii LGWZYYLX-160.

[0019] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects:

[0020] The *Streptomyces olfur* LGWZYYLX-160 strain involved in this invention exhibits dual functions of immune enhancement and disease resistance promotion in chili peppers. Plate confrontation tests showed that its inhibition rate against *Phytophthora capsici* reached 60.18%. Furthermore, *Streptomyces olfur* LGWZYYLX-160 has antagonistic effects against pathogens of various crops, including chili peppers, potatoes, peanuts, tomatoes, eggplants, cucumbers, pine trees, and corn. Simultaneously, this strain can enhance root vigor and peroxidase activity in chili peppers, increase root proline content, and reduce malondialdehyde content. In conclusion, the application of *Streptomyces olfur* LGWZYYLX-160 can provide excellent strain resources for root immune enhancement and biological control of diseases in chili peppers, and provide technical support for green yield increase and quality improvement cultivation of chili peppers. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0022] Figure 1 This is a colony morphology diagram of strain LGWZYYLX-160 in Example 2 of the present invention.

[0023] Figure 2 This is a phylogenetic tree constructed based on the 16S rDNA sequence of strain LGWZYYLX-160 in Example 2 of the present invention. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1

[0026] Isolation and screening of strains

[0027] 1. Sample collection

[0028] Soil sample source: Rhizosphere soil from healthy, high-yielding, and disease-resistant chili pepper plants.

[0029] The chili pepper variety is Xiangyan 15.

[0030] 2. Pathogens used for screening antagonistic bacteria

[0031] The pathogen used for screening antagonistic bacteria was *Phytophthora capsici*, catalog number TS287888, purchased from testobio.com. This strain was originally isolated from chili pepper samples in Chengdu, Sichuan Province, by the Sichuan Academy of Agricultural Sciences.

[0032] 3. Culture medium preparation

[0033] Phytophthora inoculum culture medium: Potato glucose agar (PDA). Dissolve 200 g of potato, 20 g of glucose, and 18-20 g of agar powder in 1 L of distilled water by heating and sterilization. Add 1 mL of 0.1 g / mL chloramphenicol solution (prepared with sterile water) to each 1 L of medium to inhibit bacterial growth.

[0034] Bacterial culture medium: NB medium, peptone 10 g / L, sodium chloride 5 g / L, beef extract 3 g / L, agar powder 18~20 g / L, sterilized.

[0035] Sterilization procedure: After the agar powder is completely dissolved, the culture medium that has not yet solidified is dispensed into conical flasks and sterilized at 121°C for 20 min. Then, it is dispensed into petri dishes under aseptic conditions. After solidification, it is placed at 37°C for 24 h. The culture medium without the growth of contaminants is stored and used for the next step of the experiment.

[0036] 4. Preparation of soil suspension

[0037] After mixing the three soil samples thoroughly, 10 g of soil was randomly weighed into a 250 mL Erlenmeyer flask, 90 mL of sterile water was added, and the mixture was stirred on a magnetic stirrer at 190 r / min for 1 h to prepare a soil suspension.

[0038] 5. Antagonistic bacteria were isolated using the dilution plate coating method.

[0039] Dilute the soil suspension to 10% of the original solution. -4 10 -5 10 -6 For each concentration, 100 μL was plated onto NB medium, and each concentration was repeated three times. The culture was incubated at 30°C for 2 days. Single colonies were selected based on colony morphology for streak purification, numbered, and stored at 14°C.

[0040] 6. Antagonistic bacteria plate confrontation test

[0041] Using *Phytophthora capsici* as the target, an antagonistic bacterial screening method was employed. *Phytophthora capsici* was first inoculated into the center of a PDA medium. After a colony with a radius of 5 mm was formed, two perpendicular lines, each 5 cm long, were drawn with the center of the plate as the intersection. Isolated bacteria were then inoculated at the four endpoints. The control group was inoculated with only *Phytophthora capsici* without any isolated bacteria. Each treatment was repeated three times. The plates were incubated at 30°C. The antagonistic effect of the isolated bacteria was observed when the control group colonies had completely covered the plate.

[0042] Based on the above plate confrontation test, strains with antagonistic effects were selected, and the antagonistic strain with the best effect was obtained, with an inhibition rate of 60.18% against Phytophthora capsici, and named LGWZYYLX-160.

[0043] Example 2

[0044] Identification of strains

[0045] 1. Observation of colony morphology characteristics

[0046] Strain LGWZYYLX-160 appears as small, round colonies with smooth edges and a raised center on agar plates. The colonies have a smooth, white surface. Figure 1 ).

[0047] 2. Identification of physiological and biochemical characteristics of the strain

[0048] Microbial identification is one of the most crucial steps in the research and production of biocontrol bacteria. Antagonistic bacteria must undergo reliable identification before production and application. Traditional identification methods focus on colony shape, size, surface characteristics, and color, using a series of physiological and biochemical tests to determine the taxonomic position of a species. Different microorganisms have different enzyme systems and metabolic types, resulting in different metabolic products after utilizing various substances. Therefore, the physiological and biochemical reactions of microorganisms can be used to determine their metabolic products, thereby identifying microorganisms that are difficult to distinguish morphologically.

[0049] The physiological and biochemical identification results of strain LGWZYYLX-160 are shown in Table 1:

[0050] Table 1. Physiological and biochemical characteristics of antagonistic bacteria LGWZYYLX-160

[0051]

[0052] Note: "+" indicates a positive reaction; "-" indicates a negative reaction.

[0053] Based on the physiological and biochemical identification results (Table 1), the metabolic characteristics of strain LGWZYYLX-160 are as follows: The strain was positive for catalase (hydrogen peroxide) test, indicating its ability to decompose hydrogen peroxide. Both methyl red (MR) and VP tests were negative, indicating that it cannot ferment glucose to produce acid via the mixed acid pathway or butanediol pathway. This strain can hydrolyze starch and produce hydrogen sulfide, suggesting its potential to utilize starch as a carbon source and produce sulfur-containing metabolites. Detection confirmed that this strain can secrete the plant growth regulator indoleacetic acid and siderophores, and possesses a certain biofilm formation ability (OD). 590 (Value: 0.581). Furthermore, this strain cannot hydrolyze gelatin or reduce nitrates, but it can reduce litmus milk.

[0054] 3. Molecular biological identification of the strain

[0055] DNA was extracted from bacterial strain LGWZYYLX-160 using a bacterial genome extraction kit, and PCR amplification was performed using 16S universal primers. The PCR products were sequenced by Sangon Biotech (Shanghai) Co., Ltd., and the sequencing results are as follows.

[0056]

[0057] Sequencing revealed that the 16S rDNA gene sequence of strain LGWZYYLX-160 was 1464 bp in length. Comparison with the NCBI database showed that the 16S rDNA sequence of strain LGWZYYLX-160 had 100% similarity to that of Streptomyces olivaceus strain PT2IS (GenBank accession number: OR104999.1). The phylogenetic tree is shown below. Figure 2 .

[0058] Example 3

[0059] Preservation of strains

[0060] Streptomyces olivaceus LGWZYYLX-160 was deposited at the China Center for Type Culture Collection (CCTCC) on March 25, 2026, with accession number CCTCC NO: M 2026509, at Wuhan University, Wuhan, China.

[0061] Example 4

[0062] Investigation of the optimal growth environment for Streptomyces oliveri LGWZYYLX-160

[0063] 1. Optimal Temperature Test

[0064] Streptomyces oliveri LGWZYYLX-160 was inoculated into NB medium and cultured at different temperatures (20℃, 30℃, 37℃, 41℃, 45℃, 60℃) for 24 h. The OD of the culture medium was then measured. 600 The results showed that OD values ​​were higher at 20℃, 30℃, 37℃, 41℃, 45℃, and 60℃. 600 The values ​​were 0.48, 1.55, 1.52, 1.20, 0.38, and 0.04, respectively. The OD at 30℃ was... 600 The highest value was 1.55, indicating that the optimal growth temperature for this strain is 30℃.

[0065] 2. Optimal pH test

[0066] NB medium was adjusted to different pH values ​​(5, 6, 7, 8, 9), and after inoculation with *Streptomyces oliveri* LGWZYYLX-160, it was incubated at 30℃ for 24 h. The OD values ​​of the culture medium were then measured. 600 The results showed that the OD values ​​at pH 5, 6, 7, 8, and 9 were... 600 The values ​​were 0.28, 1.60, 1.58, 1.20, and 0.72, respectively. The OD at pH 6 was... 600The highest value was 1.60, and it was 1.58 at pH 7, indicating that the optimal growth pH for this strain is 6-7.

[0067] 3. Optimal Inorganic Salt Test

[0068] Different inorganic salts (calcium chloride, potassium dihydrogen phosphate, potassium chloride, sodium chloride, and magnesium sulfate) were added to NB medium at 10 g / L. After inoculating *Streptomyces oliveri* LGWZYYLX-160, the medium was incubated at 30℃ for 24 h, and the OD of the culture medium was measured. 600 NB medium without added inorganic salts was used as a control. The results showed that the OD values ​​of the control group and the conditions with added calcium chloride, potassium dihydrogen phosphate, potassium chloride, sodium chloride, and magnesium sulfate were significantly different. 600 The values ​​were 0.98, 0.82, 1.28, 1.15, 1.58, and 1.45, respectively. The OD values ​​were highest when sodium chloride (10 g / L) was added. 600 The highest value was 1.55, indicating that sodium chloride is the optimal inorganic salt for this strain.

[0069] 4. Optimal carbon source test

[0070] Different carbon sources (glucose, sucrose, xylose, cellobiose, fructose, mannose, lactose, sorbitol, and rhamnose) were added to inorganic salt culture medium at 10 g / L. After inoculation with *Streptomyces oliveri* LGWZYYLX-160, the medium was incubated at 30°C for 24 h, and then the OD of the culture medium was measured. 600 The results showed that the OD values ​​of the control group and those added with glucose, sucrose, xylose, cellobiose, fructose, mannose, lactose, sorbitol, and rhamnose were significantly different. 600 The values ​​were 0.06, 1.52, 1.68, 1.10, 0.88, 1.45, 1.30, 1.18, 0.90, and 0.75, respectively. The OD values ​​were as follows: when sucrose (10 g / L) was added... 600 The highest value was 1.68, indicating that sucrose is the optimal carbon source for this strain.

[0071] 5. Optimal Nitrogen Source Test

[0072] Different nitrogen sources (urea, yeast extract, peptone, tryptone, beef extract, potassium nitrate, and ammonium sulfate) were added to NB medium at 10 g / L. After inoculating with *Streptomyces oliveri* LGWZYYLX-160, the medium was incubated at 30°C for 24 h, and then the OD of the culture medium was measured. 600 NB medium without added nitrogen source was used as a control. Results showed that the OD values ​​of the control group and the culture medium supplemented with urea, yeast extract, peptone, tryptone, beef extract, potassium nitrate, and ammonium sulfate were significantly different. 600 The values ​​were 0.30, 0.95, 1.65, 1.55, 1.60, 1.48, 1.05, and 0.88, respectively. The OD values ​​were highest when yeast powder (10 g / L) was added.600 The highest value was 1.65, indicating that yeast extract was the optimal nitrogen source for this strain.

[0073] In summary, the optimal growth environment for *Streptomyces oliveri* LGWZYYLX-160 is shown in Table 2.

[0074] Table 2 Results of the investigation into the optimal growth environment conditions

[0075]

[0076] Example 5

[0077] Antagonistic effect of Streptomyces oliveii LGWZYYLX-160 against other crop diseases

[0078] A confrontation experiment was conducted using Streptomyces oliveii LGWZYYLX-160 against pathogens causing diseases in crops such as eggplant, cucumber, and tomato.

[0079] First, *Streptomyces oliveri* LGWZYYLX-160 was streaked onto NB plates and incubated at 30°C for 24 h for later use. Then, single strains of each pathogen were incubated on PDA plates at 27°C for 5 days for later use. All 13 pathogen strains used in this experiment were purchased from domestic strain preservation centers or commercial platforms; specific information is shown in Table 3.

[0080] Table 3. Source and catalog number of strains

[0081]

[0082] In the treatment group, a fungal cake was punched from the center of the pathogen colony using a 5 mm diameter punch and inoculated into the center of a new PDA plate medium. At the same time, a single colony of Streptomyces oliveri LGWZYYLX-160 was picked up with a bamboo stick and streaked on both sides of the PDA plate medium (each treatment was repeated three times).

[0083] The control group consisted of PDA culture plates inoculated only with each pathogen.

[0084] Antibacterial rate (%) = (diameter of control group - diameter of treatment group) / diameter of control group × 100%.

[0085] The antagonistic effects of Streptomyces oliveii LGWZYYLX-160 on other crop diseases are shown in Table 4:

[0086] Table 4 Antagonistic effects on other crop diseases

[0087]

[0088] The results showed that *Streptomyces oliveri* LGWZYYLX-160 exhibited varying degrees of antagonistic effects against diseases in a variety of crops, including tobacco, pepper, tomato, eggplant, cucumber, water chestnut, strawberry, corn, potato, citrus, peanut, and pine. Among these, the inhibitory effect on peanut white mold was the most significant, with an inhibition rate of 60.56%. It also showed good inhibitory effects on wilt diseases of pepper, cucumber, and corn, with inhibition rates of 54.31%, 51.65%, and 50.77%, respectively.

[0089] Therefore, it can be seen that Streptomyces oliveri LGWZYYLX-160 has a broad antibacterial spectrum and is a strain with good biocontrol potential.

[0090] Example 6

[0091] Application of Streptomyces oliveii LGWZYYLX-160 in promoting growth and disease resistance of peppers

[0092] This experiment was a pot experiment, with two treatments, each with three replicates, and 20 pots per replicate.

[0093] ①CK: Add sterile water and inoculate only with Phytophthora capsici (product number TS287888, Taisto Bio).

[0094] ②PR160: Inoculate with Streptomyces oliveii LGWZYYLX-160 and Phytophthora capsici.

[0095] In all the above treatments, the application rates of N, P, and K fertilizers remained consistent: N was 0.81 g / kg dry soil, P2O5 was 0.94 g / kg dry soil, and K2O was 0.17 g / kg dry soil.

[0096] The chili pepper variety used in this experiment was Xiangyan 15. The substrate for the experimental potted plants was sterilized by high temperature and high pressure, and the chili pepper seedlings came from the Hunan Academy of Agricultural Sciences.

[0097] Inoculation method for Phytophthora capsici: Treat the roots with a root drench at 28, 35, and 49 days after transplanting, using 20 mL of pathogen spore solution per plant (concentration of pathogen spores is 1×10⁻⁶). 6 Conidia / mL).

[0098] Preparation method of Streptomyces oliveri LGWZYYLX-160 bacterial suspension: Take 100 μL of a single strain of glycerol bacteria, add 250 mL of LB liquid medium, incubate at 30℃ and 220 rpm for 24 h, centrifuge at 4000 r / min for 10 min, suspend the bacterial cells in sterile deionized water, and then... 600 Adjust the value to 1.2, incubate in a 30℃ constant temperature incubator for 7 days, then remove and dilute with sterile distilled water to a viable count of 1×10⁻⁶. 7CFU mL -1 Prepare the bacterial solution for later use.

[0099] Application method of Streptomyces oliveri LGWZYYLX-160 bacterial solution: Take the time when peppers are transplanted as day 0, and perform root irrigation treatment at 7, 14, 28, 35, 49 and 63 days respectively, with a dosage of 40 mL per plant.

[0100] The incidence of pepper blight was recorded 75 days after transplanting, and the disease control efficacy was calculated using the following formula:

[0101] Disease control efficacy = (incidence rate of control group - incidence rate of treatment group) / incidence rate of control group.

[0102] Meanwhile, agronomic traits of chili peppers (plant height, stem diameter, SPAD, aboveground fresh biomass, and dry biomass) were measured. The agronomic traits of chili peppers 75 days after transplanting were measured according to the standard method of NY / T 2234-2012. The SPAD value of the leaf tip of the fifth true leaf from the top of the chili pepper plant in each treatment was measured using SPAD-502 (Konica Minolta). The results were repeated three times and the average value was calculated.

[0103] The disease resistance and growth-promoting effects of the experiment are shown in Tables 5-10:

[0104] Table 5 Disease incidence and control efficacy

[0105]

[0106] Table 6 Plant height

[0107]

[0108] Table 7 Stem Diameter

[0109]

[0110] Table 8 SPAD

[0111]

[0112] Table 9 Aboveground biomass

[0113]

[0114] Table 10 Aboveground dry biomass

[0115]

[0116] Tables 5-10 show that the *Streptomyces oliveii* strain LGWZYYLX-160 involved in this invention exhibits significant dual effects of disease resistance and growth promotion on chili pepper plants. Experimental data indicate that, compared to the sterile water control, treatment with this strain significantly reduced the incidence of blight in chili peppers from 58.61% to 37.50%, achieving a control efficacy of 36.03%. Simultaneously, it comprehensively optimized the agronomic traits of chili peppers. After treatment, plant height, stem diameter, and relative chlorophyll content (SPAD value) of leaves significantly increased by 25.78%, 23.82%, and 7.96% respectively compared to the control, and ultimately greatly promoted efficient biomass accumulation, increasing the fresh weight and dry weight of the aboveground parts by 30.16% and 53.11%, respectively. These results confirm that this strain not only effectively controls blight in chili peppers but also synergistically enhances the growth vigor and yield potential of chili peppers by promoting plant morphology and enhancing photosynthesis.

[0117] Example 7

[0118] Root enzyme activity assay of potted peppers after application of Streptomyces oliveri LGWZYYLX-160

[0119] To investigate the effects of *Streptomyces oliveii* LGWZYYLX-160 on root enzyme activity, root activity, superoxide dismutase (SOD), peroxidase (POD), proline (PRO), and malondialdehyde (MDA) were measured in peppers. The experiment consisted of two treatments, with three replicates per treatment and 20 pots per replicate.

[0120] ①CK: Add sterile water and inoculate only with Phytophthora capsici (product number TS287888, Taisto Bio).

[0121] ②PR160: Inoculate with Streptomyces oliveii LGWZYYLX-160 and Phytophthora capsici.

[0122] In all the above treatments, the application rates of N, P, and K fertilizers remained consistent: N was 0.81 g / kg dry soil, P2O5 was 0.94 g / kg dry soil, and K2O was 0.17 g / kg dry soil.

[0123] The chili pepper variety used in this experiment was Xiangyan 15. The substrate for the experimental potted plants was sterilized by high temperature and high pressure, and the chili pepper seedlings came from the Hunan Academy of Agricultural Sciences.

[0124] Inoculation method for Phytophthora capsici: Treat the roots with a root drench at 28, 35, and 49 days after transplanting, using 20 mL of pathogen spore solution per plant (concentration of pathogen spores is 1×10⁻⁶). 6 Conidia / mL).

[0125] Preparation method of Streptomyces oliveri LGWZYYLX-160 bacterial suspension: Take 100 μL of a single strain of glycerol bacteria, add 250 mL of LB liquid medium, incubate at 30℃ and 220 rpm for 24 h, centrifuge at 4000 r / min for 10 min, suspend the bacterial cells in sterile deionized water, and then... 600 Adjust the value to 1.2, incubate in a 30 ℃ constant temperature incubator for 7 days, then remove and dilute with sterile distilled water to a viable count of 1×10⁻⁶. 7 CFU mL -1 Prepare the bacterial solution for later use.

[0126] Application method of Streptomyces oliveri LGWZYYLX-160 bacterial solution: Take the time when peppers are transplanted as day 0, and perform root irrigation treatment at 7, 14, 28, 35, 49 and 63 days respectively, with a dosage of 40 mL per plant.

[0127] 75 days after transplanting, the root vigor of mature chili plants was determined by the TTC colorimetric method, the contents of superoxide dismutase (SOD) and peroxidase (POD) were determined by the microplate method, and the contents of proline (PRO) and malondialdehyde (MDA) were determined by the micro-method.

[0128] The results are shown in Tables 11-15.

[0129] Table 11 Root Vigor of Chili Peppers

[0130]

[0131] Table 12 Superoxide dismutase

[0132]

[0133] Table 13 Peroxidases

[0134]

[0135] Table 14 Proline

[0136]

[0137] Table 15 Malondialdehyde

[0138]

[0139] As shown in Tables 10 to 14, application of *Streptomyces oliveri* LGWZYYLX-160 of the present invention significantly improved the physiological activity and stress resistance of pepper plants. Compared with the control (CK), treatment with *Streptomyces oliveri* LGWZYYLX-160 reduced pepper root activity from 4.90 mg / g. -1 ·h -1FW increased to 5.91 mg·g -1 ·h -1 The FW (free radical) content increased by 20.61% (Table 11). Simultaneously, this strain effectively activated the plant's antioxidant defense system, with superoxide dismutase (SOD) activity increasing by 11.91% (Table 12) and peroxidase (POD) activity significantly increasing by 41.89% (Table 13). Regarding osmotic regulators, treatment with *Streptomyces oliveri* LGWZYYLX-160 induced proline (PRO) accumulation of 125.35 μg·g⁻¹. -1 The FW level increased by 40.07% compared to the control (Table 14). Most importantly, the malondialdehyde (MDA) content, a marker of the degree of membrane lipid peroxidation damage, decreased significantly by 25.63%, from 39.09 nmol·g⁻¹. -1 FW decreased to 29.07 nmol·g -1 FW (Table 15). The synergistic changes in the above indicators indicate that Streptomyces oliveii LGWZYYLX-160 can effectively reduce the damage of reactive oxygen species to cell membranes (manifested as a decrease in MDA content) by enhancing root metabolic activity, increasing the activity of antioxidant enzyme systems (SOD, POD), and accumulating osmotic regulators (proline), thereby systematically enhancing the stress resistance of pepper plants and improving their adaptation and tolerance to environmental stress.

[0140] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0141] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A Streptomyces oliveii strain LGWZYYLX-160, characterized in that, Its classification is named Streptomyces olivaceus It was deposited on March 25, 2026, at the China Center for Type Culture Collection (CCTCC) with accession number CCTCC NO: M2026509, and the deposit address is Wuhan University, Wuhan, China.

2. The application of Streptomyces oliveii LGWZYYLX-160 as described in claim 1 in the prevention and control of plant diseases.

3. The application as described in claim 2, characterized in that, The plants mentioned are tomatoes, peppers, corn, potatoes, peanuts, eggplants, cucumbers, water chestnuts, strawberries, citrus fruits, pine trees, and tobacco.

4. The application as described in claim 2, characterized in that, The plant diseases mentioned are: pepper blight, pepper wilt, pepper anthracnose, corn leaf blight, potato early blight, peanut white mold, tomato early blight, eggplant wilt, cucumber wilt, water chestnut postharvest rot, strawberry blight, citrus scab, pine resin canker, and tobacco wilt.

5. The application of the *Streptomyces oliveii* LGWZYYLX-160 as described in claim 1 in improving the resistance of chili peppers to blight.

6. The application of the *Streptomyces oliveii* LGWZYYLX-160 as described in claim 1 in promoting chili pepper growth.

7. The application as described in claim 6, characterized in that, The promotion of chili pepper growth refers to increasing the plant height, stem diameter, SPAD, fresh biomass, and dry biomass of chili peppers.

8. The application of the *Streptomyces oliveii* LGWZYYLX-160 as described in claim 1 in improving the root vigor, superoxide dismutase, and peroxidase content of chili peppers.

9. The application of the *Streptomyces oliveii* LGWZYYLX-160 as described in claim 1 in increasing the proline content and reducing the malondialdehyde content in pepper roots.

10. A bacterial agent for enhancing the immune function of chili pepper roots, characterized in that, Includes Streptomyces oliveii LGWZYYLX-160 as described in claim 1.

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