A strain of Streptomyces and its application in controlling white rot

Abstract

The present invention relates to the field of biological control, and in particular to a strain of Streptomyces and its application in controlling white rot. The present invention provides a salt-alkali tolerant Streptomyces B0861 (Streptomyces sp.B0861) and its application in preventing and controlling white rot. Experiments show that the strain of the present invention has strong salt-alkali and drought resistance, and can grow under the conditions of 0%~6% NaCl salt concentration, pH 7.0~10.0 or PEG6000 concentration of 70%. In addition, the strain of the present invention can establish a good symbiotic relationship with peanut plants, and the in vitro inhibition rate of the white rot pathogen is as high as 68.24%, which can effectively prevent and control peanut white rot, and at the same time has a strong chitinase production ability.

Description

Technical Field

[0001] The invention relates to the field of biological control, and in particular to a Streptomyces strain adapted to a dry and hot valley environment and having the characteristics of preventing and controlling white rot and salt-alkali resistance, and an application thereof. Background Art

[0002] Soil microorganisms play an important role in material circulation, decomposition of insoluble substances, plant nutrient utilization and plant disease resistance. For example, some beneficial microorganisms colonizing in the rhizosphere or body of plants can not only improve the physical and chemical properties of the soil, but also produce substances that promote plant growth, such as auxin, cytokinin and gibberellin; some beneficial microorganisms can directly antagonize pathogens through heavy parasitism or competition (space, nutrients), or produce antagonistic substances (such as chitinase, ligninase, antibiotics, etc.), and can also directly induce systemic resistance and enhance plant immunity.

[0003] Peanut is an important oil crop and cash crop in my country. However, with the increase of unscientific soil cultivation and continuous cropping years, peanut soil-borne diseases are serious, mainly represented by white rot, root rot and fruit rot. Among them, peanut white rot is caused by Sclerotium rutinum. The pathogen can form dense sclerotia and survive in the soil, seeds and host residues for a long time. It can accumulate for many years and occur year after year, which has a huge impact on the yield and quality of peanuts. At present, the soil-borne diseases of peanuts are mainly sprayed with chemical agents multiple times, which leads to negative effects such as the reduction of beneficial microorganisms and the development of drug resistance by pathogens. Therefore, it is very important to find a method to replace traditional prevention and control methods. Among them, Streptomyces is an important part of the plant rhizosphere microbial community and also the most important source of biocontrol agents. The antibiotics and active metabolites produced by it show high potential in preventing plant diseases. In addition, its mycelial morphology is diverse and complex, which makes Streptomyces have super stress resistance and can survive in extreme environments. It is increasingly valued in the process of green prevention and control of plant diseases.

[0004] Therefore, it is of great significance to screen and isolate endophytic Streptomyces resources that can adapt to dry and hot environments and prevent the occurrence of soil-borne plant diseases from the roots of peanuts in the continuous cropping fields of the Yuanmou dry and hot valley, and to provide biocontrol microbial resources for the prevention and control of soil-borne peanut diseases in the Jinsha River dry and hot valley basin and similar climates. However, strains are selective for hosts and environments, and strains isolated from different environments can generally only exert their effects in their suitable environments. This is part of the reason why there is no biological agent on the market that can maintain its stability and effectiveness when used on all crops and regions, and the biocontrol microbial resources for dry and hot valley areas are still very limited. Summary of the invention

[0005] In view of this, the present invention provides a Streptomyces B0861 with the characteristics of preventing and controlling white rot and salt-alkali tolerance and application thereof, which can adapt to the dry and hot valley environment and prevent the occurrence of soil-borne plant diseases.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides Streptomyces B0861 (Streptomyces cess p. B0861) with a deposit number of CCTCC NO: M 2024599.

[0008] The present invention also provides a fermentation product of the Streptomyces sp. B0861.

[0009] The present invention also provides the use of the above-mentioned Streptomyces sp. B0861 or the above-mentioned fermentation product in at least one of the following:

[0010] (i) producing chitinase;

[0011] (ii) producing ACC deaminase;

[0012] (iii) amylase production;

[0013] (iv) producing cellulase;

[0014] (v) catalase production;

[0015] (vi) producing biofilm;

[0016] (vii) inhibiting or antagonizing pathogens;

[0017] The pathogenic bacteria include Sclerotium rolfsii.

[0018] The present invention also provides the use of the above-mentioned Streptomyces sp. B0861 or the above-mentioned fermentation product in preventing, reducing or eliminating plant diseases:

[0019] The plant diseases include white rot.

[0020] The present invention also provides the use of the Streptomyces sp. B0861 or the fermentation product in helping plants resist abiotic stress;

[0021] The abiotic stress includes at least one of drought stress, salt stress or alkaline stress.

[0022] In some specific embodiments of the present invention, the plant used is peanut.

[0023] The present invention also provides use of the Streptomyces sp. B0861 or the fermentation product in preparing products for planting.

[0024] The present invention also provides a biocontrol agent, comprising:

[0025] (I) the above-mentioned Streptomyces sp. B0861; or

[0026] (II) The above fermentation products.

[0027] The present invention also provides a culture method, comprising: inoculating the above-mentioned Streptomyces sp. B0861 into a culture medium, culturing, and obtaining a culture.

[0028] In some specific embodiments of the present invention, the culture conditions of the above culture method include at least one of the following:

[0029] (a) The salt concentration is 0% to 6%, which can be 1%, 3% or 5%;

[0030] (b) pH 7.0-10.0, which can be 7.5, 8.5 or 9.5;

[0031] (c) The concentration of PEG6000 is 0%~70%, which can be 5%, 15%, 25%, 35%, 45%, 55% or 65%.

[0032] The present invention also provides a method for planting crops, based on any of the following planting:

[0033] (I) the above-mentioned Streptomyces sp. B0861; or

[0034] (II) the above fermentation products; or

[0035] (III) The above-mentioned biocontrol agents.

[0036] The present invention has the following effects:

[0037] (1) The strain of the present invention is an endophytic fungus isolated from the root system of seven-color peanuts in a continuous peanut field in the dry and hot valley of Yuanmou, Yunnan. The strain can establish a good symbiotic relationship with the peanut plant, and the strain has strong salt-alkali and drought resistance;

[0038] (2) The strain of the present invention is the first reported to be used for the prevention and treatment of soil-borne fungal diseases (scalyrical rot), with an in vitro inhibition rate of up to 68.24%, and has a strong ability to produce chitinase;

[0039] (3) The roots of colorful peanut plants were colonized in the bacterial solution of the strain Streptomyces B0861 of the present invention for 6 hours, which had a good control rate against peanut white rot;

[0040] (4) The strain of the present invention can grow under alkaline conditions of 0% to 6% NaCl salt concentration and pH 7.0 to 10.0;

[0041] (5) The strain of the present invention can grow under simulated drought conditions with a PEG6000 concentration of 70%.

[0042] Biological Deposit Description

[0043] Biological material: Streptomyces B0861, classification name: Streptomyces sp. B0861, deposited in China Center for Type Culture Collection on April 1, 2024, the address of the collection center is: Wuhan University, Wuhan, China; the collection number is CCTCC NO: M 2024599. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] 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 are briefly introduced below.

[0045] Figure 1 The colony morphology of 8 strains of Streptomyces from different genera is shown;

[0046] Figure 2 The figure shows 8 strains of Streptomyces from different genera confronted with uniform Sclerotium in vitro;

[0047] Figure 3 The inhibition rates of 8 strains of Streptomyces from different genera on Sclerotium sclerotiorum are shown;

[0048] Figure 4 The detection of chitinase produced by Streptomyces is shown;

[0049] Figure 5 The morphological effect diagram of the plant of Streptomyces B0861 against Sclerotium truncatum is shown, wherein A shows no inoculation of any strain, B shows only inoculation of Sclerotium truncatum, and C shows simultaneous inoculation of Sclerotium truncatum and Streptomyces B0861;

[0050] Figure 6 The morphological diagram of mycelium of Streptomyces B0861 is shown; among them, A shows mycelium at 200 times magnification, and B shows mycelium at 300 times magnification;

[0051] Figure 7 Shown is the gel detection image of Streptomyces B0861 16S rDNA extraction and amplification;

[0052] Figure 8The results of the alignment of 16S rDNA homologous sequences of Streptomyces B0861 are shown;

[0053] Fig. 9 The physical and chemical properties of Streptomyces B0861 are shown, among which A shows the production of ACC deaminase, B shows the production of amylase, C shows the production of cellulase, and D shows the production of H 2 O 2 enzyme, E indicates biofilm;

[0054] Fig.10 Shown is the salt tolerance test of Streptomyces B0861 strain;

[0055] Fig.11 The alkali resistance test of Streptomyces B0861 strain is shown;

[0056] Fig.12 Shown is the drought tolerance test of Streptomyces B0861 strain. DETAILED DESCRIPTION

[0057] The present invention discloses the isolation, identification and application of a strain of Streptomyces B0861 having the characteristics of preventing and controlling white rot and salt-alkali tolerance. Those skilled in the art can refer to the content of this article and appropriately improve the process parameters for implementation. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art, and they are all considered to be included in the present invention. The method and application of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the method and application described herein without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0058] The present invention provides the isolation, identification and application of a salt-alkali tolerant Streptomyces B0861 having the ability to prevent and treat white rot. The crown-mycin Streptomyces B0861 provided by the present invention has strong salt-alkali tolerance and can help plants resist biological and abiotic stresses.

[0059] The present invention screened out a salt-alkali and stress-resistant Streptomyces B0861, whose preservation number is CCTCC NO: M2024599, belonging to the order Actinomycetales, the family Streptomyces, and the Streptomyces coronarius. The Streptomyces B0861 is deposited in the China Center for Type Culture Collection (CCTCC) of Wuhan University, and the preservation date is April 1, 2024.

[0060] The strain was constructed according to its 16S rDNA sequence using R software to construct a phylogenetic tree. Figure 8 Combining morphological characteristics and homologous sequence analysis results, it was shown that it was closest to Streptomyces chrestomyceticus in classification and was named Streptomyces B0861.

[0061] The Streptomyces B0861 described in the present invention is a strain isolated from the roots of seven-color peanuts collected from the dry-hot valley of Yuanmou, Yunnan, and is obtained by a plate dilution method.

[0062] The Streptomyces B0861 of the present invention has strong salt-alkali resistance and drought resistance capabilities.

[0063] The Streptomyces B0861 described in the present invention is reported for the first time to have good disease resistance to peanuts.

[0064] The present invention provides application of the Streptomyces B0861 in preventing and treating the white rot of colorful peanut caused by Sclerotium sclerotiorum and a method thereof.

[0065] The sequence information involved in the present invention is as follows:

[0066] Sequencing results of Streptomyces sp. B0861:

[0067]

[0068] Primer 799F:

[0069] 5'-AACMGGATTAGATACCCKG-3' (SEQ ID NO: 2);

[0070] Primer 1193R:

[0071] 5'-ACGTCATCCCCCACCTTCC-3' (SEQ ID NO: 3);

[0072] Primer 27F:

[0073] 5'-AGAGTTTGATCCTGGCTCAG-3' (SEQ ID NO: 4);

[0074] Primer 1492R:

[0075] 5'-TACGGCTACCTTGTTACGACTT-3' (SEQ ID NO: 5).

[0076] Unless otherwise specified, the raw materials, reagents, consumables and instruments involved in the present invention are all common commercial products and can be purchased from the market.

[0077] The Gaoshi No. 1 solid culture medium of the present invention has a formula of: 20 g soluble starch, 1 g KNO 3 , 0.5 g NaCl, 0.5 g K 2 HPO 4 ·3H 2 O, 0.5 g MgSO 4 7H 2 O, 0.01 g FeSO 4 7H 2 O, 16 g agar, adjust to pH 7.5 ± 0.1 with NaOH, then make up to 1.0 L, and sterilize at 121 °C for 15 min.

[0078] The Gaoshi No. 1 liquid culture medium of the present invention comprises: 20 g soluble starch, 1 g KNO 3 , 0.5 g NaCl, 0.5 g K 2 HPO 4 ·3H 2 O, 0.5 g MgSO 4 7H 2 O, 0.01 g FeSO 4 7H 2O, adjust the pH to 7.5±0.1 with NaOH, then make up to 1.0 L, and sterilize at 121°C for 15 min.

[0079] The PDA culture medium formula involved in the present invention is: 6 g potato flour, 20 g glucose, 20 g agar, adjusted to pH 5.6 with NaOH, then fixed to 1.0 L, and sterilized at 121°C for 15 min.

[0080] The chitinase screening medium of the present invention: K 2 HPO 4 0.7 g, KH 2 PO 4 0.5 g, MgSO 4 7H 2 O0.5 g, FeSO 4 10 mg, ZnSO 4 1 mg, 5 g of colloidal chitin, 15 g of agar powder, then dilute to 1.0 L, pH 7.0, and sterilize at 121°C for 15 min.

[0081] The ISP2 liquid culture medium of the present invention has a formula of: 4.0 g yeast extract powder, 10.0 g malt extract powder, 4.0 g glucose, adjusted to pH 7.2±0.2 with NaOH, then fixed to 1.0 L, and sterilized at 121°C for 15 min.

[0082] The present invention will be further described below in conjunction with the embodiments.

[0083] Example 1: Isolation, purification and preliminary identification of Streptomyces from the roots of colorful peanuts

[0084] 1. Isolation and purification of Streptomyces

[0085] In 2023, diseased seven-color peanut root samples were collected from a continuous peanut field in the dry-hot valley of Yuanmou, Chuxiong Prefecture, Yunnan Province. The root samples were rinsed with sterile water, clamped with tweezers and quickly burned under an alcohol lamp for 3 to 4 times, and then fully ground in a mortar. The grinding liquid was diluted to 10 -1 , 10 -2 , 10 -3 Take 100 μL of different gradient dilutions and evenly spread them on Gao's No. 1 solid culture medium. Repeat each dilution twice and culture them upside down in a constant temperature incubator at 30℃ for 4-6 days. Pick out single colonies with actinomycete characteristics and purify the strains 2-3 times by conventional plate streaking method to obtain pure Streptomyces.

[0086] 2. Preliminary identification of Streptomyces 16S rDNA

[0087] Using V5-V7 primers (799F and 1193R) with labels (Barcodes) and adapters required for sequencing, the labels and sequences required for Illumina sequencing were added to the 3' and 5' ends of the target fragments, and the isolated and purified Streptomyces were preliminarily identified. PCR amplification conditions: 94℃ 5 min; 94℃ 30 s; 55℃ 45 s; 72℃ 10 min; 30 cycles in total; 72℃ 10min; stored at 4℃. The PCR products were detected by 1% agarose gel electrophoresis, marked with 100~5000 bp marker; the bands with a molecular weight of 500 bp and 1 cm above and below were cut and purified and recovered. According to the DNA recovery concentration of each sample, they were combined into one sample at the same concentration and sent to Shenzhen BGI Co., Ltd. for first-generation gene sequence sequencing. The sequencing results were analyzed, and 8 strains of Streptomyces of different genera were selected for disease resistance screening, such as Figure 1 shown.

[0088] Example 2: Application of Streptomyces in the prevention and treatment of soil-borne diseases of colorful peanuts

[0089] 1. Preparation of test bacterial culture

[0090] The test strain was streaked in Gao's solid medium No. 1 for 4 days, and a single colony was picked with an inoculation loop and inoculated into 20 mL of Gao's liquid medium No. 1. The culture was shaken at 30°C and 150 rpm / min for 5 days, centrifuged at 4000 rpm for 10 min, and the supernatant was discarded. The culture medium was washed with 10 mmol / L sterile MgCl 2 After resuspension, dilute the bacterial solution to OD 600 Value 0.2, store at 4℃ for later use.

[0091] 2. Peanut seedling cultivation

[0092] The potting medium was a mixture of vermiculite and organic matrix in a ratio of 4:1, which was sterilized at 121℃ for 90 min. The colorful peanut seeds with full morphology were selected, sterilized by soaking in 75% anhydrous ethanol for 30 s, rinsed with sterile water three times, and then soaked in 2.5% hydrogen peroxide silver ion disinfectant + 0.01% Tween-20 for 48 h, rinsed with sterile water four times, and sown in the sterile matrix. The day and night mode was 16 h / 8 h, the temperature was 30℃ / 25℃, and the light quantum flux was 200 μmol·m -2 ·s -1 Grow it in a greenhouse and you will get peanut seedlings after about a week.

[0093] 3. Disease resistance testing

[0094] The common soil-borne disease of peanut, white rot (pathogen: Sclerotium rolfsii) was selected as the disease resistance target. The pathogen was isolated from the root system of peanuts in the early stage, and the incidence rate of peanuts after inoculation under experimental conditions was 100%. In order to test the disease resistance of the test strains to pathogens, plate confrontation, chitinase production and plant disease resistance tests were carried out respectively.

[0095] (1) Initial screening of disease resistance in vitro

[0096] Activation preparation of Sclerotium uniformis: The preserved Sclerotium uniformis strain was activated on PDA culture medium. When the mycelium covered the plate, it was cultured in the dark for more than 45 days to obtain Sclerotium uniformis covered with sclerotia.

[0097] The pathogen strain was inoculated in the middle of Gao's No. 1 solid medium, and the test strain was inoculated about 2 cm on both sides of the pathogen. The plate inoculated with sterile water was used as the CK treatment. When the CK just covered the entire plate, the antagonistic activity of the test strain was evaluated. The inhibition efficiency percentage was calculated using the following formula:

[0098] Inhibition efficiency percentage = (radius of uniform sclerotium in CK - radius of uniform sclerotium in test strain) / radius of uniform sclerotium in CK × 100%;

[0099] After 2 days of confrontation culture on the plate, the results are as follows Figure 2 and Figure 3 As shown, it was shown that Streptomyces B0861, B2186 and B2338 had an inhibitory effect on Sclerotium sclerotiorum on the plate, and the inhibition rates were 68.24%, 61.3% and 32.28%, respectively.

[0100] (2) Chitinase production test

[0101] Most crop diseases are mainly caused by fungi, among which chitin is an important component of fungal cell walls. Chitinase is a glycoside hydrolase widely present in microorganisms and plants. It can effectively degrade chitin in the cell walls of pathogenic fungi, inhibit the germination of pathogenic fungal spores and the growth of mycelium, and has a certain targeted prevention and control effect. Studies have shown that antagonistic bacteria with high chitinase production show broad-spectrum disease resistance to different plant pathogenic fungi. Therefore, the chitinase screening medium was used to test the chitinase production ability of three strains of Streptomyces B0861, B2168 and B2338 with good in vitro antagonistic effects. The fermentation liquid of the test strain was inoculated on the chitinase screening medium, and 3 points were inoculated on each plate, with 5 μL at each point. It was placed in a constant temperature incubator at 30℃ for 7 days and the formation of transparent circles in the culture medium was observed. The larger the transparent circle, the more chitinase the strain produced. The results are shown in the figure. Figure 4As shown, Streptomyces B0861 has a larger transparent zone and produces the most chitinase.

[0102] (3) Disease resistance test of Streptomyces B0861 plants

[0103] Peanut seedlings of uniform shape and size were selected, 20 seeds were used for each treatment, and the roots were immersed in the test bacterial solution for 12 h (the control was treated with 10 mmol / L sterile MgCl 2 The plants were then transplanted into a 18 × 35 cm round glass pot and sealed with a 0.45 μm filter membrane. The day and night mode was 16 h / 8 h, the temperature was 30 °C / 25 °C, the humidity was above 90%, and the light quantum flux was 200 μmol·m -2 ·s -1 After growing in a greenhouse for about 3 days, neat sclerotia or fungus cakes were inoculated, and the incidence of the plants was observed and counted.

[0104] The results are as follows Figure 5 As shown, Streptomyces B0861 showed good control effect on colorful peanut plants. The control peanuts showed obvious necrosis at the base of the stems and the plants wilted. After inoculation with Streptomyces B0861, there were no obvious symptoms of invasion of Sclerotium in the roots and stems of the plants, and the plants grew well.

[0105] Example 3: Identification of Streptomyces B0861

[0106] 1. Morphological identification of Streptomyces B0861

[0107] The strain was cultured on Gao's solid medium No. 1 at 30°C for 5-6 days. The colonies were dense and difficult to pick up. The center was convex, the surface was wrinkled, and there were radiating white villi around it. It was grayish white. Figure 1 After culturing Streptomyces B0861 in Gao's No. 1 liquid medium for 5 days, crown-shaped colonies with a diameter of about 0.5-1.0 cm can be seen. Under the microscope, the hyphae and spores can be clearly seen. The colony is dense in the middle, and the hyphae around it are branched and irregularly and spirally distributed. The hyphae contain spores, such as Figure 6 shown.

[0108] 2. Molecular identification

[0109] The bacterial genomic DNA of B0861 was extracted using a bacterial fungal genome extraction kit. The 16S rDNA sequence was amplified using bacterial universal primers 27F and 1492R. PCR amplification conditions: 96℃ 5 min; 96℃ 30 s; 56℃ 30 s; 72℃ 1 min; 30 cycles in total; 72℃ 10 min; stored at 4℃. The PCR product was detected by 1% agarose gel electrophoresis with a 100~5000 bp marker as a marker. The results are as follows Figure 7 The gene sequence was sent to Shenzhen BGI Co., Ltd. for sequencing. Basic BLAST on the NCBI website was used to compare the homology of the 16S rDNA sequence of strain B0861, and the phylogenetic tree was constructed using the R software using the NJ method, as shown in the figure. Figure 8 The strain B0861 and Streptomyces sp. were in the same branch in the evolutionary tree. Based on the morphological characteristics and physiological and biochemical properties, it was identified as Streptomyces chrestomyceticus and named Streptomyces B0861.

[0110] 3. Physiological and biochemical identification

[0111] The strains were tested according to the test methods in the Manual of Identification of Common Bacterial Systems and the Manual of Identification of Streptomyces. The strain B0861 was Gram-positive and could produce cellulase, ACC deaminase, amylase, H 2 O 2 Enzymes, biofilms, e.g. Fig. 9 As shown; but it cannot produce hydrogen sulfide and use tyrosine to produce melanin; it can grow on conventional carbon source culture media such as glucose, fructose, rhamnose, mannose, lactose, etc.

[0112] Example 4: Abiotic stress test of Streptomyces B0861 strain

[0113] 1. Salt tolerance test of strains

[0114] The test strain was streaked and cultured in Gao's solid medium No. 1 for 4 days, and the bacterial suspension was made with sterile water. Based on ISP2 liquid medium, liquid culture media containing 0%, 2%, 4%, 6%, 8%, and 10% NaCl were prepared respectively. Each salt gradient was divided into 3 200 mL shake flasks, 30 mL per bottle, and each shake flask was inoculated with 100 μL of bacterial suspension and cultured in a shaker at 30°C and 150rpm / min for 3 days. Centrifuge at 12000 rpm for 10 min, discard the supernatant, and weigh the wet bacteria. If the strain can still grow normally at a certain salt concentration, it means that the strain has the ability to tolerate the salt concentration.

[0115] The results are as follows Fig.10As shown in the figure, the biomass of the strain gradually decreases with the increase of salt concentration. According to the tolerance to NaCl, microorganisms can be divided into: non-halophilic microorganisms (NaCl concentration <0.2 mol / L), mildly halophilic microorganisms (NaCl concentration 0.2~0.5 mol / L), moderately halophilic microorganisms (NaCl concentration 0.5~2.5 mol / L) and extremely halophilic microorganisms (NaCl concentration 2.5~5.2 mol / L). Streptomyces B0861 grows under 6% (about 1 mol / L) NaCl salt, and the growth in 0.5~2.5 mol / L NaCl solution is the salt tolerance standard. This strain belongs to the salt-tolerant bacteria.

[0116] 2. Alkali resistance test of strains

[0117] The test strain was streaked and cultured in Gao's solid medium No. 1 for 4 days, and the bacterial suspension was made with sterile water. Based on ISP2 liquid medium, the pH of the medium was adjusted with NaOH to 7.0, 8.0, 9.0, 10.0, 11.0, and 12.0, respectively. Each alkaline gradient was divided into 3 200 mL shake flasks, 30 mL per bottle, and each shake flask was inoculated with 100 μL of bacterial suspension and cultured in a shaker at 30°C and 150 rpm / min for 4 days. Centrifuge at 12000 rpm for 10 min, discard the supernatant, and weigh the wet bacteria. If the strain can still grow normally at a certain pH, it means that the strain has the ability to tolerate the pH.

[0118] The results are as follows Fig.11 As shown in the figure, with the increase of pH value, the biomass of the strain first increases and then gradually decreases. When the pH value is 8, the biomass reaches 28.85 g / L. According to the pH tolerance, microorganisms can be divided into: alkali-tolerant microorganisms (pH 7~9, pH>9.5 cannot grow) and alkaliphilic microorganisms (pH 10~12). Streptomyces B0861 can grow at pH 10. According to the standard that strains growing at pH 7~12 are alkali-tolerant bacteria, this strain belongs to alkali-tolerant bacteria.

[0119] 3. Drought tolerance test of strains

[0120] The test strains were streaked and cultured in Gao's solid medium No. 1 for 3 days, and the bacterial suspension was made with sterile water. Polyethylene glycol (PEG) 6000 was used to artificially simulate drought conditions to test the drought resistance of the test strains. Based on ISP2 liquid medium, 9 drought gradients containing 0%, 50%, 100%, 15%, 20%, 25%, 30%, 35%, and 40% PEG6000 were set. Each drought gradient was divided into 3 200 mL shake flasks, 30 mL per bottle, and each shake flask was inoculated with 100 μL of bacterial suspension and cultured in a shaker at 30℃ and 150 rpm / min for 5 days. The growth of the test strains was observed, and the supernatant was discarded at 12000 rpm for 10 min, and the weight of the wet bacteria was weighed. If the strain can still grow normally under a certain drought degree, it means that the strain has the ability to tolerate the drought degree.

[0121] The results are as follows Fig.12 As shown in the figure: the test strain first increased and then decreased with the increase of PEG6000 concentration, indicating that the strain has a certain degree of drought-philicity. At a concentration of 60%, the strain biomass dropped sharply, but the test strain was still able to grow at a concentration of 70% PEG6000, proving that the strain has a strong drought-resistant ability.

[0122] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. Streptomyces ( Streptomyces sp.) B0861, characterized in that The deposit number is CCTCC NO: M 2024599.

2. Use of Streptomyces B0861 as claimed in claim 1 in at least one of the following: (i) producing chitinase; (ii) producing ACC deaminase; (iii) amylase production; (iv) producing cellulase; (v) catalase production; (vi) producing biofilm; (vii) inhibit or antagonize Sclerotium sclerotiorum ( Sclerotium rolfsii ).

3. Use of Streptomyces B0861 as claimed in claim 1 in preventing, reducing or eliminating peanut white rot.

4. A biocontrol agent, characterized in that: Including the Streptomyces B0861 described in claim 1.

5. A method for culturing Streptomyces B0861 according to claim 1, characterized in that: The method comprises the step of inoculating the Streptomyces B0861 according to claim 1 into a culture medium.

6. A method for planting peanuts, characterized in that: The method uses any of the following: (I) the Streptomyces B0861 of claim 1; or (II) The biocontrol agent according to claim 4.

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