Streptomyces alboflavin, bacterial agent and their application

Abstract

The present invention relates to the field of microbial technology, and discloses a white-flavour streptomyces, a bacterial agent and their applications. The white-flavour streptomyces provided by the present invention has good ability to degrade benzoic acid, decompose organic phosphorus, secrete auxin (IAA), produce siderophores and have broad-spectrum inhibition on a variety of pathogens. The strain and related preparations are applied in the rhizosphere of plants, which can effectively improve soil quality, prevent and control soil-borne diseases and promote plant growth. In addition, since the bacterium is derived from Wuliangshan Nature Reserve in Yunnan Province, it is a natural plant rhizosphere bacterium, so the bacterium has good colonization ability, and the bacterium is derived from virgin forest soil, and has the ability to adapt to complex environments compared with general strains, so that it can stably prevent and control the occurrence and spread of soil-borne diseases and promote the growth of plants.

Description

Technical Field

[0001] The invention relates to the technical field of microorganisms, and in particular to a strain of Streptomyces alboflavinus, a bacterial agent and applications thereof. Background Art

[0002] With the development of modern agriculture, which is large-scale, intensive and monoculture, continuous planting is very common, resulting in frequent continuous cropping problems such as suppressed crop growth, high incidence of soil-borne diseases and sharp decline in yield. The secretion of autotoxic substances by plant roots is one of the main factors leading to this phenomenon. With the development of society and economy, people are seeking green and environmentally friendly methods to solve the problem of continuous cropping problems in agriculture. Microbial fertilizers are used in production to improve the soil environment to achieve the effect of controlling the occurrence of soil-borne diseases of crops. However, the strains used have single functions and do not play a good role in the soil environment.

[0003] Beneficial rhizosphere microorganisms can provide plants with more available nutrients and effectively inhibit or even kill plant pathogens by solubilizing phosphorus, secreting plant hormones, and producing antibacterial active substances during their growth and metabolism. Beneficial rhizosphere microorganisms can also use self-toxic substances in the soil to reduce or eliminate the adverse effects of the accumulation of self-toxic substances on the soil or plants. Therefore, it has great application value and potential in the biological control of plant diseases. In addition, the application of beneficial rhizosphere microorganisms can reduce the use of pesticides and fertilizers, which can reduce production costs on the one hand, and meet the requirements of modern agriculture for sustainable development on the other hand, which is of great significance to the development and transformation of modern agricultural production.

[0004] However, the number of rhizosphere beneficial strains that can be used for actual production is still very limited, and the effects of existing strains need to be improved. Moreover, the development of most plant rhizosphere beneficial strains now relies on artificial mutagenesis and screening, and the obtained strains are prone to problems of being difficult to colonize or the effects far below the laboratory detection level in actual production. In order to meet the needs of agricultural production, it is urgent to develop new rhizosphere beneficial strains with better and more stable growth-promoting effects, which are easier to colonize and can be applied to actual production. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned problems existing in the prior art, and to provide a strain of Streptomyces alboflavin, a bacterial agent and their applications. The Streptomyces alboflavin provided by the present invention is a rhizosphere fungus collected from a primeval forest, which has good colonization ability after application, and after testing, the strain can efficiently degrade benzoic acid, and has good auxin secretion, siderophore production, and organic phosphorus decomposition ability, has a broad-spectrum antibacterial activity against a variety of pathogens, and has a significant promoting effect on plant growth.

[0006] In order to achieve the above-mentioned object, the present invention provides a first aspect of a Streptomyces alboflavinus strain, the deposit number of which is CCTCC NO:M 20231644.

[0007] The second aspect of the present invention provides the use of the Streptomyces alboflavin described in the first aspect in degrading benzoic acid and / or alleviating the inhibition of benzoic acid on crop seed germination.

[0008] The third aspect of the present invention provides use of the Streptomyces alboflavin described in the first aspect in producing siderophores and / or auxins.

[0009] The fourth aspect of the present invention provides the use of the Streptomyces alboflavin described in the first aspect in decomposing organic phosphorus.

[0010] The fifth aspect of the present invention provides a microbial agent, the microbial agent comprising the Streptomyces alboflavinus described in the first aspect and an optional carrier

[0011] The sixth aspect of the present invention provides the use of the Streptomyces alboflavin described in the first aspect, or the microbial agent described in the fifth aspect in preventing and controlling soil-borne plant diseases, and / or promoting plant growth, and / or improving soil.

[0012] The seventh aspect of the present invention provides a method for preventing and controlling soil-borne plant diseases and / or promoting plant growth, the method comprising applying the Streptomyces alboflavin and / or its metabolites described in the first aspect, or the bacterial agent described in the fifth aspect, to the rhizosphere soil of the plant.

[0013] Through the above technical solution, the present invention can at least achieve the following beneficial effects:

[0014] (1) The Streptomyces alboflavin provided by the present invention has excellent effects of degrading benzoic acid and degrading organic phosphorus, and can also produce growth hormone and siderophore. In addition, the bacteria can also have a broad-spectrum inhibitory effect on a variety of pathogens, thereby effectively improving soil quality and increasing the content of nutrients that can be used by plants in the soil, thereby having a good effect of promoting plant growth and preventing diseases.

[0015] (2) The Streptomyces alboflavin provided by the present invention is a natural forest rhizosphere fungus isolated from the unique habitat of the original forest. Compared with the strains screened by laboratory mutagenesis, it has better adaptability to the planting environment and can better colonize in the soil. Secondly, it is rich in functions, thereby more stably exerting the effect of promoting growth and preventing diseases. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is the colony morphology of strain YNK-FS0019 in Example 1.

[0017] Figure 2 It is the phylogenetic tree of strain YNK-FS0019 in Example 1.

[0018] Figure 3 This is a diagram showing the broad-spectrum antibacterial effect of strain YNK-FS0019 in Example 2.

[0019] Figure 4 This is a diagram showing the effect of strain YNK-FS0019 in Example 6 in alleviating the inhibition of seed germination by benzoic acid.

[0020] Biological Deposit

[0021] The Streptomyces alboflavus provided by the present invention is classified and named Streptomyces alboflavus YNK-FS0019, which has been preserved in the China Center for Type Culture Collection on September 7, 2023, with the address at No. 299, Bayi Road, Wuchang District, Wuhan City, Hubei Province, Wuhan University, and the preservation number is CCTCC NO: M 20231644.

[0022] The salt-tolerant spore-forming bacteria provided by the present invention are classified and named Bacillus halotolerans YNK-FB0022, and have been deposited in the China Center for Type Culture Collection on November 20, 2023, with the address at No. 299, Bayi Road, Wuchang District, Wuhan City, Hubei Province, Wuhan University, and the deposit number is CCTCC NO: M 20232276. DETAILED DESCRIPTION

[0023] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0024] In the present invention, unless otherwise specified, "Streptomyces alboflavin / strain CCTCC NO: M20231644", "Streptomyces alboflavin / strain YNK-FS0019", "Streptomyces alboflavin of the present invention (provided)" and the like all refer to the same strain, that is, the Streptomyces alboflavin strain with a deposit number of CCTCC NO: M 20231644. The above expressions have the same meaning and can be used interchangeably.

[0025] In the present invention, "phosphorus solubilization" means that the P content available to plants in the soil is increased through the action of the strain provided by the present invention, for example, organic phosphorus components in the soil (such as phosphatidylcholine, inositol hexaphosphate, etc.) are converted into forms that can be used by plants, thereby promoting the absorption and utilization of phosphorus in the soil by plants; for example, after continuous planting of crops such as tomatoes, tobacco, and cucumbers, phenolic acid self-toxic substances such as benzoic acid are secreted. These phenolic acid self-toxic substances accumulate in the soil and easily cause seed germination, growth and other inhibition problems for crops, which is not conducive to the continued planting of crops. "Benzoic acid degradation" means that the benzoic acid self-toxic substances secreted by plant roots can be degraded through the action of the strain provided by the present invention, thereby reducing or eliminating the adverse effects of the accumulation of self-toxic substances on the soil or plants; microorganisms secrete iron carriers to chelate Fe in the environment 3+ It is considered to be one of the main sources of effective iron for plants, which has the effect of promoting plant growth. Secondly, the strains that can secrete siderophores compete with plant pathogens for iron ions, and can also inhibit the growth of pathogens, thereby preventing and controlling crop diseases. "Secreting siderophores" means that the strains provided by the present invention can secrete siderophores under iron-deficient conditions, helping microorganisms absorb Fe from the environment. 3+ , increase Fe in the environment 3+ Move and promote crops to absorb Fe 3+ absorption.

[0026] The inventor of the present invention accidentally isolated a strain of Streptomyces alboflavus from the rhizosphere soil of trees in Wuliangshan National Nature Reserve during the research process. It was found through testing that the strain has the functions of efficiently degrading benzoic acid, dissolving phosphorus (especially organic phosphorus, such as lecithin, etc.), producing long element, producing iron carriers and antagonizing multiple pathogens. The strain can not only degrade phenolic acid autotoxic substances secreted by plant roots, but also convert organic phosphorus into effective phosphorus that can be absorbed by plants. After further research, the inventor also found that applying the fermentation liquid of the strain to the rhizosphere soil of plants can effectively promote plant growth, prevent and control the occurrence of soil-borne diseases such as tomato wilt, improve the soil environment, increase agricultural productivity, and promote the green and sustainable development of ecological agriculture.

[0027] Based on the above findings, the present invention provides a first aspect of a Streptomyces alboflavus strain, the deposit number of which is CCTCC NO: M 20231644.

[0028] The second aspect of the present invention provides the use of the Streptomyces alboflavin described in the first aspect in degrading benzoic acid and / or alleviating the inhibition of benzoic acid on crop seed germination.

[0029] The present invention further provides a method for degrading benzoic acid, which comprises contacting benzoic acid with Streptomyces alboflavinus CCTCC NO:M 20231644.

[0030] According to some preferred embodiments of the present invention, the method may include evenly sprinkling Streptomyces alboflavin CCTCCNO:M 20231644 (bacterial agent or culture solution) into the soil to alleviate the problem of benzoic acid accumulation caused by continuous cropping or soil pollution, thereby adversely affecting the continued planting of crops.

[0031] The present invention further provides a method for alleviating the inhibition of benzoic acid on crop seed germination, which comprises contacting the seeds with Streptomyces alboflavinus CCTCC NO: M 20231644 during the germination process.

[0032] According to a preferred embodiment of the present invention, the method may include:

[0033] i. Soak the seeds in water for 2-4 hours to obtain soaked seeds;

[0034] ii. contacting Streptomyces alboflavinus CCTCC NO:M 20231644 with the soaked seeds obtained in step i to obtain soaked seeds with alleviated germination inhibition.

[0035] Preferably, in step ii, the contacting method comprises immersing the soaked seeds in a culture solution of Streptomyces alboflavinus CCTCC NO: M20231644. Preferably, the concentration of Streptomyces alboflavinus CCTCC NO: M 20231644 in the culture solution is 10 7 -10 8 CFU / mL (i.e., the content of Streptomyces alboflavin in the culture medium reaches 10 7 -10 8 CFU / mL level, that is, the content of Streptomyces alboflavin in the culture medium can be greater than or equal to 1×10 7 CFU / mL to less than 1×10 9 CFU / mL range).

[0036] Preferably, the method may further include:

[0037] iii. placing the soaked seeds with alleviated germination inhibition obtained in step ii under seed germination conditions to germinate them.

[0038] More preferably, step iii can be carried out by soaking the soaked seeds with relieved germination inhibition in water to make them germinate. Step iii can also be carried out by burying the soaked seeds with relieved germination inhibition in soil to make them germinate.

[0039] In the above method provided by the present invention, "immersion" refers to a process in which the seeds are contacted with water or a culture solution of Streptomyces alboflavinus CCTCC NO: M20231644 so that the seeds are in a moist state to promote seed germination. In order to prevent the seeds from germinating due to lack of oxygen, the "immersion" treatment can usually be performed by not completely immersing the seeds in the immersion liquid, or placing the seeds on a paper material such as absorbent paper, and then soaking the paper material with the immersion liquid.

[0040] According to a preferred embodiment of the present invention, the crop is at least one of tomato, pepper and cucumber.

[0041] The third aspect of the present invention provides use of the Streptomyces alboflavin described in the first aspect in producing siderophores and / or auxins.

[0042] The present invention further provides a method for preparing auxin and / or siderophore, the method comprising (fermentation) culturing the Streptomyces alboflavin described in the first aspect, and collecting the culture product.

[0043] Any method and conditions that can ferment and culture Streptomyces alboflavin and make it produce auxin / siderophore can be applied to the present invention.

[0044] According to a preferred embodiment of the present invention, the (fermentation) culture conditions include: culture temperature 28-32°C, culture time 72-96h.

[0045] According to a preferred embodiment of the present invention, when the (fermentation) culture is carried out in a shake flask fermentation manner, a shaking culture at a rotation speed of 100-200 rpm can be used during the fermentation process.

[0046] The fourth aspect of the present invention provides use of the Streptomyces alboflavinus described in the first aspect in decomposing organic phosphorus.

[0047] Preferably, the organic phosphorus comprises lecithin.

[0048] The present invention further provides a method for degrading organic phosphorus, which comprises contacting the Streptomyces alboflavin described in the first aspect with organic phosphorus.

[0049] Preferably, the organic phosphorus comprises lecithin.

[0050] The fifth aspect of the present invention provides a microbial agent, which comprises the Streptomyces alboflavinus as described in the first aspect and an optional carrier. "Optional" means that in the microbial agent, the carrier can be added or not according to actual conditions and needs, and is not a necessary component of the microbial agent.

[0051] The microbial agent provided by the present invention can be used for degrading benzoic acid, alleviating the inhibition of benzoic acid on the germination of crop seeds (preferably at least one of tomatoes, peppers and cucumbers), solubilizing phosphorus (especially organic phosphorus), producing iron carriers, producing auxins, etc.

[0052] According to a preferred embodiment of the present invention, the bacterial agent is a liquid bacterial agent.

[0053] Preferably, the content of Streptomyces alboflavin in the liquid bacterial agent is not less than 1×10 6 CFU / mL.

[0054] More preferably, in the liquid bacterial agent, the content of Streptomyces alboflavin is 1×10 7 -1×10 10 CFU / mL. More preferably 1×10 8 -1×10 9 CFU / mL.

[0055] Preferably, the carrier may be a liquid culture medium. Any culture medium that can be used for culturing and / or preserving Streptomyces alboflavin in the art may be applicable to the present invention.

[0056] The sixth aspect of the present invention provides the use of the Streptomyces alboflavin described in the first aspect, or the microbial agent described in the fifth aspect in preventing and controlling soil-borne plant diseases, and / or promoting plant growth, and / or improving soil.

[0057] According to some preferred embodiments of the present invention, the soil-borne plant diseases include diseases caused by at least one of tomato wilt pathogen (Fusarium oxysporum), corn leaf spot pathogen (Exserohilum turcicum), tobacco anthracnose pathogen (Colletotrichum micotianae), grass fruit stem spot pathogen (Phoma matteuciicola), tobacco black shank pathogen (Phytophthora parasitica) and banana wilt pathogen (Fusarium oxysporum fsp.Cubenserace4 (Foc4)).

[0058] Preferably, the soil-borne plant diseases include tomato wilt.

[0059] The present invention further provides a method for inhibiting plant pathogens, which comprises contacting the Streptomyces alboflavin described in the first aspect or the microbial agent described in the fifth aspect with plant pathogens.

[0060] Preferably, the plant pathogen is selected from at least one of tomato wilt pathogen, corn leaf blight pathogen, tobacco anthracnose pathogen, tsaoko leaf spot pathogen, tobacco black shank pathogen and banana wilt pathogen.

[0061] In the present invention, "soil improvement" refers to increasing the content of nutrients in the soil that can be absorbed and utilized by plants, thereby improving soil quality and making the soil more suitable for plant growth. The soil quality can be determined by measuring the physical and chemical properties of the soil, such as the pH value of the soil, the content of nutrients, etc. The conversion of effective nutrients in the soil (i.e., nutrients that can be absorbed and utilized by plants, such as effective phosphorus, effective nitrogen, effective potassium, etc.) can also be determined by measuring the content of enzymes such as soil sucrose invertase, urease, acid phosphatase, and catalase in the soil, thereby determining the change in soil quality. Generally, the higher the content of nutrients in the soil, especially effective nutrients, the higher the content of the above enzymes in the soil, which means that the soil quality is better.

[0062] In the present invention, "promoting plant growth" refers to promoting the absorption of nutrients in the soil by plants and increasing the growth rate of plants, such as increasing the plant height, diameter, root length, plant weight, fruit weight and quality, etc., or shortening the plant growth cycle and promoting the growth and development of the plant root system.

[0063] In the present invention, "preventing and controlling soil-borne plant diseases" means that in potted plant experiments, the invention has a preventive and control effect on soil-borne plant diseases (such as tomato wilt), which can significantly reduce the incidence of soil-borne plant diseases and ensure the healthy growth of plants.

[0064] The seventh aspect of the present invention provides a method for preventing and controlling soil-borne plant diseases and / or promoting plant growth, the method comprising applying the Streptomyces alboflavin and / or its metabolites described in the first aspect, or the bacterial agent described in the fifth aspect, to the rhizosphere soil of the plant.

[0065] According to a preferred embodiment of the present invention, the application amount of Streptomyces alboflavinus is not less than 1×10 8 CFU / strain / time, preferably 1×10 9 -1×10 12 CFU / strain / time.

[0066] According to a preferred embodiment of the present invention, the dosage of the bacterial agent is such that the dosage of Streptomyces alboflavinus is not less than 1×10 8 CFU / strain / time, preferably 1×10 9 -1×10 12 CFU / strain / time.

[0067] Preferably, the application frequency of the Streptomyces alboflavin or the bacterial agent is 1-3 times per crop.

[0068] According to a preferred embodiment of the present invention, the dosage of the metabolite is not less than 100 mL / plant / time, preferably 100-200 mL / plant / time.

[0069] Preferably, the frequency of application of the metabolite is 1 to 3 times per crop.

[0070] More preferably, the metabolites include auxins and / or siderophores.

[0071] According to a preferred embodiment of the present invention, the metabolites are provided by the fermentation broth of the Streptomyces alboflavinus. The fermentation broth can be obtained by the fermentation culture method as described above, and the specific method and conditions are not repeated here.

[0072] Preferably, the content of auxin in the metabolites may be 20-40% (w / v), preferably 30-37% (w / v).

[0073] More preferably, the content of auxin (indoleacetic acid) in the metabolites may be 10-30 μg / mL. Preferably, it may be 20-30 μg / mL. For example, it may be 20 μg / mL, 21 μg / mL, 22 μg / mL, 23 μg / mL, 24 μg / mL, 25 μg / mL, 26 μg / mL, 27 μg / mL, 28 μg / mL, 29 μg / mL, 30 μg / mL, or it may be a range consisting of any two of the above values, or any intermediate value within the range.

[0074] Preferably, the content of iron carrier in the metabolite may be 10-30%, preferably 15-25%.

[0075] In the present invention, the fermentation broth can be directly applied (after dilution / concentration so that the auxin / siderophore content reaches the above-mentioned level), or the auxin / siderophore in the fermentation broth can be purified and then prepared into a preparation for application. The purification method can be any method in the art that can be used to separate and purify auxin / siderophore.

[0076] Preferably, the plant is selected from the Solanaceae family, genus Solanum, most preferably tomato.

[0077] Preferably, the seeds are selected from the Solanaceae family, the genus Solanum, most preferably tomato; and / or, selected from the Solanaceae family, the genus Capsicum, most preferably pepper; and / or, selected from the Cucurbitaceae family, the genus Cucumis, most preferably cucumber.

[0078] According to some preferred embodiments of the present invention, the soil-borne plant diseases include diseases caused by at least one of tomato wilt pathogen (Fusarium oxysporum), corn leaf spot pathogen (Exserohilum turcicum), tobacco anthracnose pathogen (Colletotrichum micotianae), grass fruit stem spot pathogen (Phoma matteuciicola), tobacco black shank pathogen (Phytophthora parasitica) and banana wilt pathogen (Fusarium oxysporum fsp.Cubenserace4 (Foc4)).

[0079] Preferably, the soil-borne plant diseases include tomato wilt.

[0080] The present invention further provides a method for inhibiting plant pathogens, which comprises contacting the Streptomyces alboflavin described in the first aspect or the microbial agent described in the fifth aspect with plant pathogens.

[0081] Preferably, the plant pathogen is selected from at least one of tomato wilt pathogen, corn leaf blight pathogen, tobacco anthracnose pathogen, tsaoko leaf spot pathogen, tobacco black shank pathogen and banana wilt pathogen.

[0082] According to some preferred embodiments of the present invention, the method further comprises applying halotolerant Bacillus CCTCC NO: M20232276 in the rhizosphere soil of the plant.

[0083] Preferably, the application amount of the salt-tolerant Bacillus CCTCC NO: M20232276 is not less than 1×10 8 CFU / strain / time, preferably 1×10 9 -1×10 12 CFU / strain / time.

[0084] More preferably, the application frequency of the halodurable Bacillus CCTCC NO: M20232276 is 1-3 times per crop.

[0085] In the method provided by the present invention, the Streptomyces alboflavinus and the halotolerant Bacillus CCTCCNO: M20232276 provided by the present invention can be applied to the rhizosphere soil of the plant together, or they can be applied in batches one by one.

[0086] Furthermore, the present invention also provides a composite bacterial agent comprising the aforementioned Streptomyces alboflavinus and Bacillus halodurans CCTCCNO: M20232276.

[0087] Furthermore, the present invention also provides the use of the above-mentioned bacterial agent in promoting plant growth, improving soil (improving soil quality), enhancing plant disease resistance, preventing and controlling plant diseases (especially soil-borne diseases), and promoting plant growth.

[0088] The present invention will be described in detail below by way of examples. It should be understood that the following examples are only used to further explain and illustrate the content of the present invention by way of example, and are not intended to limit the present invention.

[0089] In the following examples, unless otherwise specified, the reagents and materials used were all commercial products purchased from regular chemical / biological reagent or material suppliers, and the reagents were all analytical grade.

[0090] In the following examples, unless otherwise specified, the operating temperature is room temperature (25±5° C.).

[0091] Example 1

[0092] This example is used to illustrate the acquisition, identification and preservation of Streptomyces albicans CCTCC NO: M 20231644.

[0093] (I) Strain isolation and purification

[0094] Gao's medium No. 1 was used in the process of strain isolation and purification. The preparation method was as follows: weigh soluble starch (20.00 g), KNO 3 (1.00g), K 2 HPO 4 (1.00 g), MgSO 4 7H 2 O (0.50 g), NaCl (0.50 g), FeSO 4 7H 2 O (0.50 g), add it into 1000 mL of water to dissolve, adjust the pH to 7.3 ± 0.1, add 20.00 g of agar, sterilize it with high pressure steam at 121 ° C for 20 min, and set aside.

[0095] An actinomycete was isolated and purified from the rhizosphere soil samples of Pinus armandii collected from Wuliangshan National Nature Reserve by using the dilution spread plate method and the plate streak method, and was named YNK-FS0019.

[0096] (II) Strain identification

[0097] 1. Identification of bacterial morphological, physiological and biochemical characteristics

[0098] Physiological and biochemical tests were performed on strain YNK-FS0019 according to the Bergey's Manual of Bacterial Identification and the Manual of Identification of Common Bacterial Systems, and the colony morphology characteristics were described.

[0099] Colony & Cell Morphology: Figure 1 The colony morphology of strain YNK-FS0019 on Gao's medium No. 1 is shown. It can be seen from the figure that the colony of this strain is round, with neat edges, orange-yellow white, and a bulge in the middle of the colony with white spore hyphae.

[0100] Physiological and biochemical characteristics: The strain YNK-FS0019 is Gram-positive, with a salt tolerance range of 0-5% (w / v) and a pH tolerance range of 4-8, indicating that the strain has a certain degree of salt and acid resistance. The colony of YNK-FS0019 is orange-yellow-white with slight protrusions. It is a Gram-positive bacterium, and starch hydrolysis, protease hydrolysis, citric acid reaction, catalase, lactose utilization, etc. are all positive.

[0101] 2. Molecular identification

[0102] The total DNA of strain YNK-FS0019 was extracted by Chelex extraction method as a template, 27F (5'-AGAGTTTGATCCTGGCTCAG-3') was used as the upstream primer, 1492R (5'-TAC GGCTACCTTGTTACGACTT-3') was used as the downstream primer, and 16S rRNA was amplified using the reaction system and conditions in Table 1.

[0103] Table 1 PCR system and conditions

[0104]

[0105] The amplified product was purified and recovered by 1% agarose gel electrophoresis using a gel recovery and purification kit produced by Guangzhou Meiji Biotechnology Co., Ltd., and then sent to Beijing Qingke Biotechnology Co., Ltd. for sequencing. The sequencing results were compared and analyzed in the NCBI database (https: / / www.ncbi.nlm.nih.gov / ) and the EZBiocloud database (https: / / www.ezbiocloud.net / ). The phylogenetic analysis method was used, and the 16S rRNA sequence of the model strain with high homology was selected as the reference object. The Clustal X 1.8 software was used for multiple sequence alignment to calculate the similarity between the test strain and the reference strain sequence. The base deletion sites were excluded during the phylogenetic analysis, and the neighbor-joining analysis was used to construct the phylogenetic tree between the test strain and the reference strain using MEGA 7.0. Among them, the Bootstrap value was set to 1000, and the rest were the default values.

[0106] Figure 2The phylogenetic tree of strain YNK-FS0019 is shown, from which it can be seen that YNK-FS0019 has the highest homology with Streptomyces alboflavus NRRLB-5480.

[0107] 3. Identification results

[0108] Combining the molecular detection results of strain YNK-FS0019 with the bacterial morphological characteristics and physiological and biochemical characteristics, the strain was identified as Streptomyces alboflavus.

[0109] 3. Strain preservation

[0110] The Streptomyces alboflavus YNK-FS0019 obtained above was deposited in the China Center for Type Culture Collection on September 7, 2023, at 299 Bayi Road, Wuchang District, Wuhan City, Hubei Province, Wuhan University, with the deposit number CCTCC NO: M 20231644.

[0111] Example 2

[0112] This example is used to illustrate the effects of Streptomyces alboflavinus CCTCC NO: M 20231644 in degrading organic phosphorus and antagonizing pathogens.

[0113] Phosphate solubilization effect test

[0114] (I) Solution of organic phosphorus

[0115] Preparation method of organophosphorus solid culture medium: weigh 10g glucose, 0.5g ammonium sulfate, 0.5g yeast extract powder, 0.3g sodium chloride, 0.3g potassium chloride, 0.3g magnesium sulfate, 0.03g ferrous sulfate, 0.03g manganese sulfate, 0.2g lecithin, 1g calcium carbonate, add to 1000mL water to dissolve, adjust pH to 7.3±0.2, add 18±2g agar, and sterilize at 121℃ for 20min.

[0116] The strain YNK-FS0019 obtained in Example 1 was inoculated on an organophosphate culture plate using the four-point plate inoculation method, and the inoculation was repeated for 3 plates. After the inoculation was completed, the plate was placed in a 30°C constant temperature incubator for 5 days, and the bacterial growth and the formation of transparent circles around the colonies were observed every day during the incubation period.

[0117] From the results, it can be seen that strain YNK-FS0019 can produce transparent circles when cultured on organophosphate culture plates. The size of the transparent circle was measured by the cross method, and the ratio of the transparent circle diameter (D) to the colony diameter (d) was calculated to be D / d = 2.925 ± 0.87. This shows that the strain has a good ability to degrade organophosphates. (II) Broad-spectrum antibacterial activity of YNK-FS0019

[0118] Use an inoculation needle to pick up the mycelium block of the pathogen, place it in a PDA culture dish and culture it for 5 days, use a puncher to punch a 0.50 cm pathogen cake on the edge of the pathogen, place it in the center of a new PDA culture dish, use an inoculation needle to pick up the activated YNK-FS0019 from the culture dish, cross-inoculate the strain 2.50 cm away from the pathogen, use the culture dish inoculated with only the pathogen as a control, and culture it in a 28°C incubator for 3-5 days (the specific culture time is determined according to the growth of the pathogen and YNK-FS0019, and the culture can be stopped when the plate inoculated with only the pathogen is full of mycelium). The inhibitory effect on pathogens is expressed by the inhibition rate, and the calculation method is as follows. Table 2 and Figure 3 The figure shows the inhibitory effect of strain YNK-FS0019 on various pathogens.

[0119] Inhibition rate (%) = [(control colony diameter - treated colony diameter) / control colony diameter] × 100%.

[0120] Table 2 Inhibition rate of YNK-FS0019 against different pathogens

[0121] Pathogens YNK-FS0019 antibacterial rate (%) Tomato wilt pathogen Fusarium oxysporum 75.42 Exserohilum turcicum 81.03 Tobacco Anthracnose Pathogen Colletotrichum micotianae 74.23 Phoma matteuciicola 85.15 Phytophthora parasitica 83.03 Banana wilt pathogen Fusarium oxysporum fsp. Cubense race4 (Foc4) 68.21

[0122] From the data in the table, it can be seen that the inhibition rate of YNK-FS0019 against pathogens is as high as over 65%, among which the inhibition rate against the leaf spot pathogen of the genus Amomi is as high as 85.15%, indicating that this Streptomyces alboflavin strain has a good application prospect in biological control.

[0123] Example 3

[0124] This example is used to illustrate the effect of Streptomyces alboflavinus CCTCC NO: M 20231644 in secreting auxin.

[0125] The activated Streptomyces alboflavinus YNK-FS0019 was inoculated into KB medium and cultured at 30°C and 180 rpm / min for 24 h. 1 mL of the fermentation liquid was aseptically pipetted into a centrifuge tube and quickly mixed with 4 mL of Sackowcki's colorimetric reagent. The tube was incubated at room temperature in the dark for 40 min to develop color. The color change was observed and recorded. If pink appeared, it was positive, indicating that the strain could secrete IAA.

[0126] After the strain was cultured in Gao's medium No. 1 for 1 day, the seed solution was prepared and inoculated into KB liquid medium containing L-tryptophan at a 1% inoculum (the initial content of YNK-FS0019 in the culture system after inoculation was about 1.2×10 6 CFU / mL), placed in a 30°C constant temperature shaker with 180r / min shaking culture, 4mL of supernatant was taken every day and mixed with 4mL of Sackowcki's colorimetric reagent, and after standing for 40min in a dark environment, the OD value was measured at a wavelength of 535nm. The obtained absorbance value was substituted into the standard curve for calculation to obtain the indoleacetic acid content of the strain. It was determined that the indoleacetic acid content of strain YNK-FS0019 was the highest on the 4th day, which was 22.21±0.32μg / mL.

[0127] Example 4

[0128] This example is used to illustrate the effect of Streptomyces alboflavinus CCTCC NO: M 20231644 in degrading benzoic acid.

[0129] Benzoate Inorganic Salt Medium: MgSO 4 7H 2 O 0.20g; (NH4) 2 SO 4 1g; KH 2 PO 4 0.50g; NaCl 0.50g; K 2 HPO 4 1.50g, benzoic acid 0.1g, distilled water 1000mL, pH natural; sterilize at 121℃ for 20min.

[0130] After the activation of YNK-FS0019 screened in Example 1, it was inoculated into 20 mL of Gao's No. 1 liquid medium and cultured in a shaker at 30°C and 180 rpm for 24 hours as a seed solution. 1 mL of the seed solution was inoculated into 50 mL of benzoic acid inorganic salt liquid medium. The samples at zero time and the end time of 4 days of shaking culture at 37°C and 180 rpm were taken respectively, and the substrate amount was detected by HPLC after filtration, so as to calculate the substrate degradation efficiency.

[0131] The conditions of high performance liquid chromatography were as follows: the fermentation broth to be tested was added into a 50 mL centrifuge tube, centrifuged at 4°C and 8000 rpm for 10 min, 1.00 mL of the supernatant was filtered through a 0.22 μm microporous filter membrane as the input sample, the chromatographic column used was an Agillent C18 column (250 mm × 4.0 mm × 5 μm); the column temperature was 35°C; the UV detection wavelength was 230 nm; the mobile phase was methanol: 0.02 mol / L, ammonium acetate = 5:95; the flow rate was 1.00 mL / min; the injection volume was 10.00 μL, and the elution was isocratic.

[0132] Degradation rate = [(substrate amount at zero time - substrate amount at the end of time) / substrate amount at zero time] × 100%

[0133] The results showed that after four days of cultivation of YNK-FS0019 in benzoic acid inorganic salt medium, very little benzoic acid content was detected, indicating that the strain could efficiently degrade and utilize benzoic acid, with a calculated degradation rate of 99.83%.

[0134] Example 5

[0135] This example is used to illustrate the effect of Streptomyces alboflavinus CCTCC NO: M 20231644 in producing siderophore.

[0136] CAS color developer preparation method:

[0137] Solution A: Add 60.5 mg of Chrome Azurol S (CAS) to 50 mL of deionized water and then mix with 10 mL of Fe 3+ Solution (1 mM FeCl 3 6H 2 Mix the above solution A and solution B, and filter through a 0.2 μm filter membrane to obtain the CAS color developer.

[0138] Preparation method of CAS color double-layer culture medium: add 1.5g agar to 100mL distilled water, sterilize at 121℃ for 20min, and obtain water agar. When the water agar is cooled to 50-60℃, add 10% CAS detection solution evenly to the culture medium, and pour a larger amount of culture medium as the lower culture medium. After the water agar culture medium is cooled and solidified, pour iron-free Czapek culture medium to form a double-layer plate.

[0139] Qualitative testing:

[0140] The test strain was inoculated into CAS color double-layer culture medium by 4-point inoculation method, and each treatment was repeated 3 times. The culture medium was placed in a 30°C incubator to continuously observe whether a color circle was formed around the colony. The ratio between the diameter (D) of the color circle and the diameter (d) of the colony was measured, and the D / d value of strain YNK-FS0019 was 2.72 (±0.21).

[0141] Quantitative testing:

[0142] The strain YNK-FS0019 was cultured in iron-free Czapek liquid medium at 30°C and 150rpm on a constant temperature shaker for 96 hours. After the culture was completed, about 5 mL of the culture solution was filtered with a 0.22um sterile filter membrane and an equal volume of CAS detection solution was added. After standing for 1 hour, the OD of the inoculated bacterial solution was measured using a full-wavelength microplate reader. 630The OD of the uninoculated liquid culture medium was determined by the same method. 630 As a reference value (denoted as "Ar"), the siderophore concentration was expressed as siderophore activity unit (SU), SU = [(Ar-As) / Ar] × 100%, the measurement was repeated 3 times, and the siderophore concentration in the culture solution of strain YNK-FS0019 was 24%.

[0143] Example 6

[0144] This example is used to illustrate the effect of Streptomyces alboflavinus CCTCC NO: M 20231644 on alleviating the inhibition of seed germination by benzoic acid.

[0145] The experiment set up three treatments: 1) clean water control (CK1); 2) 1.00 g / L benzoic acid treatment (CK2); 3) YNK-FS0019 bacterial suspension (experimental group).

[0146] Preparation method of bacterial suspension in experimental group: YNK-FS0019 strain was inoculated into Gao's liquid medium No. 1 at an inoculum volume of 1%, and cultured in a constant temperature shaker at 30°C and 180 rpm for 48 h. Then, the suspension was centrifuged at 4°C and 8000 rpm for 10 min, the supernatant was discarded, and the suspension was resuspended in sterile water and diluted to 1.2×10 8 CFU / mL concentration was used.

[0147] Tomato, pepper and cucumber seeds were selected as experimental objects. The seeds were soaked in 70% alcohol for 10 minutes and then washed with sterile water for 3 times to complete disinfection. Take the seeds that have settled under the water, soak them in water at room temperature for 12 hours, then take each group of seeds and place them in a 9.00cm transparent culture dish with 2-3 layers of sterilized filter paper. Each dish has 10 seeds for each treatment, and repeat 3 times. Treatment 3) First, use 2.00mL of bacterial suspension to inject into the culture dish, soak the sterilized paper and culture the seeds on the moist sterilized paper for 24 hours, then continue to inject 2.00mL of benzoic acid into the culture dish to culture the seeds on the sterilized paper containing benzoic acid solution for 24 hours, and then inject 2.00mL of sterile water into the culture dish every 24 hours to keep the sterilized paper moist. For other treatments, inject 2.00mL of the required liquid into the culture dish, and add 2.00mL of sterile water every 24 hours to keep the sterilized paper moist. The seeds were germinated in an artificial climate box at 26°C, with alternating light and dark periods of 16 h and 8 h, and the germination rate and plant length were measured 7 days after the bacterial suspension treatment. Figure 4 The figure shows the alleviating effect of strain YNK-FS0019 on the inhibition of seed germination by benzoic acid.

[0148] Germination index determination: whether the seeds have germinated after treatment is determined by the standard of whitening>1 / 2 seed length, seed germination rate (%) = (number of germinated seeds / number of test seeds) × 100%.

[0149] Table 3 Results of YNK-FS0019 alleviating benzoic acid inhibition of seed germination

[0150]

[0151] From the data in Table 3, it can be seen that benzoic acid inhibited the germination rate of tomato, pepper and cucumber seeds, but after treatment with strain YNK-FS0019, the seed germination rate increased, and the germination rate of tomato and pepper seeds in the experimental group was also improved compared with the water control, indicating that YNK-FS0019 can degrade benzoic acid, alleviate the inhibition of benzoic acid on seeds, and promote seed germination. In addition, the full length of tomatoes, cucumbers and peppers was increased compared with the control, indicating that YNK-FS0019 not only promoted seed germination, but also promoted seedling growth.

[0152] Example 7

[0153] This example is used to illustrate the control effect of Streptomyces fulvicinus CCTCC NO: M 20231644 on tomato wilt.

[0154] Preparation of bacterial agent: The strain YNK-FS0019 obtained in Example 1 was inoculated into Gao's liquid medium No. 1 and cultured at 30°C and 180 rpm for 72 h. The resulting fermentation liquid was the bacterial agent of strain YNK-FS0019 (the viable count was about 6×10 8 CFU / mL).

[0155] Plant planting: Add the same weight of soil to each pot, randomly group 10 pots per treatment, and plant one tomato seedling of similar growth in each pot.

[0156] Verification of the effect of preventing and controlling wilt disease: On the third day after the tomato seedlings were transplanted into the pots, the tomato seedlings were irrigated with tomato wilt bacteria (Fusarium oxysporum), and a small hole was pierced at the root of the seedlings during the root irrigation. After three days of root irrigation with tomato wilt bacteria to allow the pathogen to colonize, the tomato seedlings were irrigated with the above-mentioned bacterial agent, and the same amount of sterile water was used as the control group (CK).

[0157] After the root irrigation treatment, the tomato seedlings were placed in a greenhouse to grow naturally. After 45 days of root irrigation with the bacterial agent, the incidence rate and disease index of the tomato plants were measured. The results are shown in Table 4.

[0158] The disease conditions of each treatment were graded according to the tomato wilt disease classification standard: 0: no symptoms; 1: one or two leaves turn yellow; 2: three or four true leaves turn yellow and wilt and droop; 3: five or six true leaves turn yellow or wilt and droop; 4: the whole plant wilts severely and dies.

[0159] Disease index = (number of diseased plants at each level × value of the disease level) / (total number of plants × highest level value) × 100.

[0160] Preventive effect = (disease index of control group - disease index of treatment group) / disease index of control group × 100.

[0161] Table 4 The efficacy of YNK-FS0019 against tomato wilt

[0162] Measurement indicators CK Experimental Group Disease index 25.83±0.21a 6.67±0.07b Prevention effect (%) - 74.18±0.23

[0163] In Table 4, data with different letters represent significant differences, and “-” represents no protective effect.

[0164] It can be seen from the above data that after applying the YNK-FS0019 fungicide, the disease index of tomato wilt disease decreased significantly and the incidence rate was significantly controlled, indicating that this strain has great application potential in the prevention and control of tomato wilt disease.

[0165] Example 8

[0166] This example is used to illustrate the growth-promoting effect and soil-improving effect of Streptomyces alboflavinus CCTCC NO: M 20231644.

[0167] (I) Verification of growth-promoting effect

[0168] The same weight of soil was added to each flower pot, and 10 pots were randomly divided into groups according to each treatment, and one tomato seedling with similar growth was planted in each pot. On the third day after the tomato seedlings were transplanted into the flower pots, the tomato seedlings were root-irrigated with 100 mL / plant of the microbial agent in Example 7, and the same amount of sterile water was used for the same treatment as control group 1 (CK1), and the same amount of Gao's No. 1 medium was used for the same treatment as control group 2 (CK2).

[0169] After the root irrigation treatment, the tomato seedlings were placed in a greenhouse to grow naturally. After 45 days of root irrigation treatment, the aboveground fresh weight and dry weight, underground (root) fresh weight and dry weight, stem diameter, root length and plant height of the tomato plants were measured. The results are shown in Table 5.

[0170] The specific measurement method is as follows:

[0171] Aboveground fresh weight & dry weight: Cut the part above the root base of the tomato plant and weigh the aboveground fresh weight on an analytical balance, retaining one decimal place. Put the aboveground part of the plant weighed fresh weight into a paper bag and put it into an oven at 100±5℃ for 10 minutes, then lower the temperature of the oven to 75±5℃, dry to constant weight, and weigh the aboveground dry weight on an analytical balance, retaining one decimal place.

[0172] Underground fresh weight & dry weight: Cut the part below the root base of the tomato plant and weigh the fresh weight of the underground part on an analytical balance, retaining one decimal place. Put the underground part of the plant weighed fresh weight into a paper bag and put it into an oven at 100±5℃ for 10 minutes, then lower the temperature of the oven to 75±5℃, dry it to constant weight, and weigh it on an analytical balance to obtain the dry weight of the underground part, retaining one decimal place.

[0173] Stem Diameter: Use a caliper to measure the diameter of the thickest stem part of the plant.

[0174] Root length: Straighten the roots and measure the root length using a ruler.

[0175] Plant height: Straighten the plant and use a ruler to measure the length of the above-ground part from the highest point of the leaves.

[0176] Table 5 Growth status of tomato seedlings

[0177] Growth indicators CK1 CK2 Experimental Group Fresh weight above ground (g) 31.93±1.78c 39.45±1.32b 44.99±1.55a Above ground dry weight (g) 5.71±0.33c 6.15±0.21a 6.52±0.70a Root weight (g) 7.07±0.12c 9.20±0.07b 11.11±0.14a Stem diameter (mm) 5.24±0.07b 5.31±0.04c 6.12±0.68a Root length (cm) 12.03±0.60c 13.56±0.46b 15.20±0.46a Plant height (cm) 84.23±3.43c 99.17±4.23b 103.63±4.78a

[0178] *The data in the table with different letters indicate significant differences

[0179] From the data in the table above, it can be seen that after the root irrigation treatment with YNK-FS0019 bacterial agent, the plant height, stem diameter, aboveground fresh weight, root length, and root dry fresh weight of tomato plants were significantly improved compared with the control group (CK1) with water and the control group (CK2) with Gao's medium No. 1. According to calculations, the net increase in plant height of tomatoes in the experimental group compared with CK1 reached 23%, the stem diameter increased by 16.8%, the aboveground fresh weight increased by 40.9%, the aboveground dry weight increased by 14%, the root length increased by 26.3%, and the root weight increased by 57%, indicating that the strain YNK-FS0019 can effectively promote plant growth. There was a significant difference between the control group and the control group except for the stem diameter (P<0.05). It shows that the inoculation of rhizosphere strain YNK-FS0019 has a significant promoting effect on the growth of tomatoes.

[0180] 2. Verification of soil improvement effect

[0181] After the tomato (45 days) cultivation was completed, the rhizosphere soil of each group of tomatoes was collected, and the soil samples were tested for soil physical and chemical properties such as pH, organic matter, total nitrogen, total phosphorus, total potassium, alkaline nitrogen, available phosphorus, and effective potassium to verify the soil improvement effect of strain YNK-FS0019. The test results are detailed in Table 6.

[0182] The specific detection methods are as follows:

[0183] Organic matter was determined by chromic acid redox titration, pH was determined by potentiometric method, total nitrogen was determined by Kjeldahl method, total phosphorus was determined by sodium hydroxide alkali fusion-molybdenum antimony colorimetry, total potassium and available potassium were determined by flame photometry, alkaline nitrogen was determined by diffusion absorption method, and available phosphorus was determined by 0.5 mol / L NaHCO 3 -Molybdenum antimony colorimetry.

[0184] Table 6 Test results of soil sample physical and chemical properties

[0185] Detection indicators CK1 CK2 Experimental Group pH 7.1 7.4 7.1 Organic matter (g / kg) 163.8 179.6 92 Total nitrogen (g / kg) 3.75 3.78 3.68 Total phosphorus (g / kg) 1.09 1.12 1.29 Total potassium (g / kg) 6.35 6.78 7.27 Hydrolyzable nitrogen (mg / kg) 289 302 261 Available phosphorus (mg / kg) 115.6 124.7 79.4 Available potassium (mg / kg) 216 289 336

[0186] From the data in the table, it can be seen that there is no significant difference in pH value, total phosphorus and total nitrogen among the three treatments, but the total potassium and available potassium contents of the experimental group are higher than those of the two control groups, and the contents of organic matter, total nitrogen, available phosphorus and hydrolyzable nitrogen are lower than those of the control group. When analyzed together with the tomato plant growth data in Table 5, it can be inferred that the strain YNK-FS0019 has the function of decomposing organic phosphorus, converting the nutrients in the soil into available phosphorus that can be absorbed by plants, and fully absorbed by the tomato root system, so that the organic matter content of tomato plants increases and nutrients accumulate, thereby reducing the phosphorus content in the soil environment after planting. At the same time, it is speculated that under the influence of the growth-promoting effect of the strain YNK-FS0019, the total potassium and available potassium contents of the soil have increased, and the contents of hydrolyzable nitrogen and total nitrogen have decreased, indicating that the presence of the strain may promote the transformation and utilization of nitrogen elements by other microorganisms, proving that the strain YNK-FS0019 has a good improvement effect on the soil, and can have a significant growth-promoting effect on tomato growth.

[0187] (III) Verification of soil enzyme activity improvement effect

[0188] After the tomato (45 days) cultivation was completed, the rhizosphere soil of each group of tomatoes was collected, and the soil samples were tested for soil physical and chemical properties such as urease, sucrase, acid phosphatase, and catalase to verify the soil improvement effect of strain YNK-FS0019. The test results are shown in Table 7.

[0189] The specific detection methods are as follows:

[0190] The urease activity was determined by indophenol colorimetry; the sucrose invertase activity was determined by 3,5-dinitrosalicylic acid colorimetry; the acid phosphatase activity was determined by disodium phenyl phosphate colorimetry; and the catalase activity was determined by potassium permanganate titration.

[0191] Table 7 Soil enzyme activity test results

[0192] Detection indicators CK1 CK2 Experimental Group <![CDATA[Invertase (mg inversion -1 ·1 -1 )]]> 4.39 5.21 6.27 <![CDATA[Urease (μg·g -1 ·1 -1 )]]> 286.31 305.44 319.55 <![CDATA[Acid phosphatase (μmol·m -1 ·1 -1 )]]> 8.56 9.85 12.87 Catalase (mg / g·d) 2.13 3.08 4.56

[0193] It can be seen from the data in the table that soil sucrose invertase, urease, acid phosphatase and catalase are all improved compared with the two controls. Combined with the changes in the soil physical and chemical index data in Table 6, it shows that strain YNK-FS0019 increases the content of these enzymes in the soil, thereby promoting the conversion of available phosphorus, available nitrogen and available potassium in the soil, providing plants with more nutrients, thereby promoting the healthy growth of plants.

[0194] Example 9

[0195] This example is used to illustrate the growth-promoting effect of the composite bacterial agent of Streptomyces alboflavinus CCTCC NO: M 20231644 and Bacillus halodurans CCTCC NO: M20232276.

[0196] (I) Verification of growth-promoting effect

[0197] Add the same weight of soil to each flower pot, randomly group 10 pots per treatment, and plant a tomato seedling of similar growth in each pot. Set up the treatment groups as follows:

[0198] 1) T1: On the third day after the tomato seedlings were transplanted into the pots, 100 mL / plant of the culture medium with a bacterial count of 1.2×10 8 CFU / mL white and yellow Streptomyces inoculant was used to irrigate the roots of tomato seedlings. Three days later, the inoculant containing 7×10 8 CFU / mL of salt-tolerant Bacillus CCTCC NO: M 20232276 was used for root irrigation; 2) T2: 100 mL / strain was used with a bacterial content of 1.2×10 8 CFU / mL white yellow Streptomyces inoculant was used to irrigate the tomato seedlings; 3) T3: 100mL / plant was used with a bacterial content of 6×10 8 CFU / mL of Bacillus halodurans CCTCC NO: M 20232276 was used to irrigate the tomato seedlings; 4) CK: The same amount of sterile water was used as the control group. The tomato seedlings after root irrigation were placed in a greenhouse for natural growth.

[0199] After 45 days of root irrigation treatment (for root irrigation with two kinds of bacterial agents, the time of the first root irrigation treatment was used for calculation), the aboveground fresh weight and dry weight, underground (root) fresh weight and dry weight, stem diameter, root length and plant height of tomato plants were measured. The results are shown in Table 8. The specific measurement method is as follows:

[0200] Aboveground fresh weight & dry weight: Cut the part above the root base of the tomato plant and weigh the aboveground fresh weight on an analytical balance, retaining one decimal place. Put the aboveground part of the plant weighed fresh weight into a paper bag and put it into an oven at 100±5℃ for 10 minutes, then lower the temperature of the oven to 75±5℃, dry to constant weight, and weigh the aboveground dry weight on an analytical balance, retaining one decimal place.

[0201] Underground fresh weight & dry weight: Cut the part below the root base of the tomato plant and weigh the fresh weight of the underground part on an analytical balance, retaining one decimal place. Put the underground part of the plant weighed fresh weight into a paper bag and put it into an oven at 100±5℃ for 10 minutes, then lower the temperature of the oven to 75±5℃, dry it to constant weight, and weigh it on an analytical balance to obtain the dry weight of the underground part, retaining one decimal place.

[0202] Stem Diameter: Use a caliper to measure the diameter of the thickest stem part of the plant.

[0203] Root length: Straighten the roots and measure the root length using a ruler.

[0204] Plant height: Straighten the plant and use a ruler to measure the length of the above-ground part from the highest point of the leaves.

[0205] Table 8 Growth status of tomato seedlings

[0206] Growth indicators CK T1 T2 T3 Fresh weight above ground (g) 31.93±1.78c 51.26±1.07a 44.99±1.55b 46.21±0.60b Above ground dry weight (g) 5.71±0.33c 8.31±0.25a 6.52±0.70b 7.22±0.15b Root weight (g) 7.07±0.12b 13.67±0.13a 11.11±0.14a 12.39±0.41a Stem diameter (mm) 5.24±0.07b 5.78±0.10a 6.12±0.68a 5.71±0.03a Root length (cm) 12.03±0.60bc 19.16±0.52a 15.20±0.46b 22.83±1.46a Plant height (cm) 84.23±3.43b 108.85±0.45a 103.63±4.78a 104.90±1.61a

[0207] *The data in the table with different letters indicate significant differences

[0208] From the data in the table above, it can be seen that after the combined root irrigation treatment with YNK-FS0019 and CCTCC NO: M20232276 microbial agents, the aboveground fresh and dry weight, plant height, and root weight were all improved compared to the treatment of adding any of the microbial agents alone and the control group (CK) of water, indicating that the combined application of the two microbial agents has a better growth-promoting effect. According to calculations, the aboveground fresh weight of tomatoes in T1 increased by 13.93% and 10.93% compared to T2 and T3, respectively; the aboveground dry weight increased by 27.45% and 15.1%, respectively; and the root weight increased by 23.04% and 10.33%, respectively.

[0209] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A strain of Streptomyces alboflavinus ( Streptomyces alboflavus ), characterized in that The deposit number of this strain is CCTCC NO: M 20231644.

2. Use of the Streptomyces alboflavinus according to claim 1 in degrading benzoic acid and / or alleviating the inhibition of benzoic acid on crop seed germination.

3. The use according to claim 2, wherein: The crop is at least one of tomato, pepper and cucumber.

4. Use of the Streptomyces alboflavinus according to claim 1 in producing siderophores and / or auxins.

5. Use of the Streptomyces alboflavinus described in claim 1 in decomposing organic phosphorus.

6. The use according to claim 5, wherein: The organic phosphorus is lecithin.

7. A microbial agent, characterized in that: The microbial agent comprises the Streptomyces alboflavinus according to claim 1 and an optional carrier.

8. Use of the Streptomyces alboflavinus according to claim 1 or the microbial agent according to claim 7 in preventing and controlling soil-borne plant diseases, and / or promoting plant growth, and / or improving soil.

9. The use according to claim 8, wherein: The soil-borne plant diseases include tomato wilt.

10. The use according to claim 8, wherein: In the bacterial agent, the content of Streptomyces alboflavin is not less than 1×10 6 CFU / mL.

11. The use according to claim 10, wherein: In the bacterial agent, the content of Streptomyces alboflavin is 1×10 7 -1×10 10 CFU / mL.

12. A method for preventing and controlling soil-borne plant diseases and / or promoting plant growth, characterized in that: The method comprises applying the Streptomyces alboflavinus described in claim 1 or the bacterial agent described in claim 7 to the rhizosphere soil of the plant.

13. The method according to claim 12, wherein: The amount of Streptomyces alboflavin applied is not less than 1×10 8 CFU / strain / time; or The dosage of the bacterial agent is such that the dosage of Streptomyces alboflavinus is not less than 1×10 8 CFU / strain / time.

14. The method according to claim 13, wherein: The application amount of the white and yellow Streptomyces is 1×10 9 -1×10 12 CFU / strain / time; or The dosage of the bacterial agent is such that the dosage of Streptomyces alboflavinus is 1×10 9 -1×10 12 CFU / strain / time.

15. The method according to claim 12, wherein: The application frequency of the Streptomyces alboflavinus or the bacterial agent is 1-3 times per crop; And / or, the plant is selected from the Solanaceae family.

16. The method according to claim 15, wherein: The plant is tomato.

17. The method according to claim 12, wherein: The method further comprises applying halotolerant Bacillus CCTCC NO: M20232276 in the rhizosphere soil of the plant.

18. The method according to claim 17, wherein: The application amount of the salt-tolerant Bacillus CCTCC NO: M20232276 is not less than 1×10 8 CFU / strain / time, And / or, the application frequency of the halodurable Bacillus CCTCC NO: M20232276 is 1 to 3 times per crop.

19. The method according to claim 18, wherein: The application amount of the halodurogenic Bacillus CCTCC NO: M20232276 is 1×10 9 -1×10 12 CFU / strain / time.

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