CN116179399A

CN116179399A - Rhizosphere growth promoting bacterium and application thereof

Info

Publication number: CN116179399A
Application number: CN202210911575.3A
Authority: CN
Inventors: 王亚玉; 刘欢
Original assignee: Shenzhen Huada Everything Technology Co ltd; BGI Shenzhen Co Ltd
Current assignee: Shenzhen Huada Everything Technology Co ltd; BGI Shenzhen Co Ltd
Priority date: 2022-07-22
Filing date: 2022-07-22
Publication date: 2023-05-30

Abstract

The invention provides a bacterial strain for promoting plant growth and application thereof, wherein the bacterial strain is selected from at least one of the following: strain 1 comprising the amino acid sequence of SEQ ID NO:1 or a complement thereof or a sequence complementary to the sequence set forth in SEQ ID NO:1 by at least 85% identity sequence; strain 2 comprising the amino acid sequence of SEQ ID NO:2 or a sequence comprising a sequence identical to SEQ ID NO:2 by at least 85% identity sequence; strain 3 comprising SEQ ID NO:3 or a sequence comprising a sequence identical to the sequence set forth in seq id NO:3 by at least 85% identity sequence; and strain 4 comprising SEQ ID NO:4 or a sequence comprising a sequence identical to SEQ ID NO:4 to at least 85% identity sequence.

Description

Rhizosphere growth promoting bacterium and application thereof

Technical Field

The application relates to the field of microorganisms, in particular to rhizosphere growth-promoting bacteria and application thereof.

Background

Microorganisms are a large group of organisms including bacteria, viruses, fungi and the like, have tiny individuals and close relationship with plants, and the roots, stems, leaves, flowers, seeds and other parts of the plants have the microorganisms. Various physiological functions of plant growth are affected by microorganisms, for example, microorganisms can promote plant growth and development, reduce heavy metal toxicity in soil, enhance plant resistance to extreme environments (drought, waterlogging and heat), prevent and treat plant diseases and insect pests, and the like.

Microorganisms have undergone a co-evolutionary history of over a hundred years with plant hosts, with the root microorganisms serving as hot spot areas for plant and microorganism energy and material exchange, and with 40% of the carbon source photosynthetically immobilized at the plant roots serving as a nutrient source for the root soil microorganisms, a source of signaling and antimicrobial actives.

Therefore, development of plant rhizosphere growth promoters to promote the growth of a broad spectrum of plants is needed.

Disclosure of Invention

To this end, embodiments of the present application provide rhizosphere growth-promoting bacteria and uses thereof.

Embodiments of the first aspect of the present application propose a bacterial strain for promoting plant growth, wherein the bacterial strain is selected from at least one of the following:

strain 1 comprising the amino acid sequence of SEQ ID NO:1 or a complement thereof or a sequence complementary to the sequence set forth in SEQ ID NO:1 by at least 85% identity sequence;

strain 2 comprising the amino acid sequence of SEQ ID NO:2 or a sequence comprising a sequence identical to SEQ ID NO:2 by at least 85% identity sequence;

strain 3 comprising SEQ ID NO:3 or a sequence comprising a sequence identical to SEQ ID NO:3 by at least 85% identity sequence; and

strain 4 comprising SEQ ID NO:4 or a sequence comprising a sequence identical to SEQ ID NO:4 to at least 85% identity sequence.

In some embodiments, the strain 1 is Arthrobacter (Arthrobacter). In some embodiments, the strain 1 has the amino acid sequence as set forth in SEQ ID NO:1, and a 16S rDNA sequence shown in the formula 1. In some embodiments, the strain 1 is Arthrobacter sp.Arth4 with accession number GDMCC No. 62566.

In some embodiments, the strain 2 is Bacillus. In some embodiments, the strain 2 is a strain of bacillus licheniformis (Bacillus paralicheniformis). In some embodiments, the strain 2 has the amino acid sequence as set forth in SEQ ID NO:2, and a 16S rDNA sequence shown in FIG. 2. In some embodiments, the strain 2 is Bacillus paralicheniformis Bacil9 having accession number GDMCC No. 62569.

In some embodiments, the strain 3 is listeria (Priestia). In some embodiments, the strain 3 is a species of listeria megaterium (Priestia megaterium). In some embodiments, the strain 3 has the amino acid sequence as set forth in SEQ ID NO:3, and a 16S rDNA sequence shown in the formula 3. In some embodiments, the strain 3 is Priestia megaterium Bacif4 with accession number GDMCC No. 62567.

In some embodiments, the strain 4 is Bacillus. In some embodiments, the strain 4 is bacillus belicus strain (Bacillus velezensis). In some embodiments, the strain 4 has the amino acid sequence as set forth in SEQ ID NO:4, and a 16S rDNA sequence shown in FIG. 4. In some embodiments, the strain 4 is Bacillus velezensis Baci having accession number GDMCC No. 62568.

Embodiments of the second aspect of the present application provide an agricultural formulation, wherein the agricultural formulation comprises a bacterial strain as described in any of the embodiments of the first aspect of the present application.

In some embodiments, the agricultural formulation further comprises an adjuvant.

In some embodiments, the agricultural formulation is in a dosage form selected from: wettable powder, water dispersible granules, suspending agents, aqueous emulsion, granules, seed coating agents or a combination thereof.

Embodiments of the third aspect of the present application provide the use of a bacterial strain according to any of the embodiments of the first aspect of the present application in the preparation of an agricultural formulation.

Embodiments of the fourth aspect of the present application provide a method of promoting plant growth, the method comprising applying to the plant a bacterial strain as described in any of the embodiments of the first aspect of the present application or an agricultural formulation as described in any of the embodiments of the second aspect of the present application.

The embodiment of the application realizes the following beneficial effects:

the application provides four strains of Arthrobacter sp.Arth4, bacillus paralicheniformis Bacil, priestia megaterium Bacif4 and Bacillus velezensis Baci and application thereof in improving agronomic characters of plants for the first time, particularly bacterial genus and species of the 4 strains can effectively promote growth of roots and stems of the plants, and nutrient absorption and accumulation of the plants are further improved, so that crop yield is improved. The rhizosphere growth promoting bacteria provided by the embodiment of the application have important significance for improving the crop yield. Meanwhile, the Arth4, the Bacil9, the Bacif4 and the Baci5 are prepared into the microbial fertilizer suitable for agricultural production, so that the use amount of the fertilizer can be reduced, and the agricultural green production can be promoted.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a cluster map of Arth4 according to example 2 of the present application;

FIG. 2 is a cluster map of Bacil9 according to example 2 of the present application;

FIG. 3 is a cluster map of Bacif4 according to example 2 of the present application;

FIG. 4 is a cluster map of Baci5 according to example 2 of the present application;

FIG. 5 is a plate growth map according to example 3 of the present application;

FIG. 6 is a plot of the growth of sterile soil for seedlings according to example 4 of the present application;

fig. 7 is a field growth map of the Huagu 12 according to example 5 of the present application;

fig. 8 is a further field growth map of the Huagu 12 according to example 5 of the present application.

Strain preservation description:

arthrobacter sp.Arth4: the deposit accession number is GDMCC No. 62566, and the deposit institution is: the collection of microorganism strains in Guangdong province; deposit unit address: first, the middle road 100 # college experiment building 5 in the View area of Guangzhou City in Guangdong province; the preservation time is 2022, 6 and 28 days.

Bacillus paralicheniformis Bacil9: the deposit registration number is GDMCC No. 62569, and the deposit institution is: the collection of microorganism strains in Guangdong province; deposit unit address: first, the middle road 100 # college experiment building 5 in the View area of Guangzhou City in Guangdong province; the preservation time is 2022, 6 and 28 days.

Priestia megaterium Bacif4: the deposit accession number is GDMCC No. 62567, and the deposit institution is: the collection of microorganism strains in Guangdong province; deposit unit address: first, the middle road 100 # college experiment building 5 in the View area of Guangzhou City in Guangdong province; the preservation time is 2022, 6 and 28 days.

Bacillus velezensis Baci5: the deposit accession number is GDMCC No. 62568, and the deposit institution is: the collection of microorganism strains in Guangdong province; deposit unit address: first, the middle road 100 # college experiment building 5 in the View area of Guangzhou City in Guangdong province; the preservation time is 2022, 6 and 28 days.

Detailed Description

The invention will now be described in further detail with reference to the following specific embodiments, which are given by way of illustration only and are not intended to limit the scope of the invention. The examples provided below are intended as guidelines for further modifications by one of ordinary skill in the art and are not to be construed as limiting the invention in any way.

The present application is made based on the following knowledge of the inventors:

soil serves as a treasury of microorganism resources, and microorganisms among the treasury are complex in composition and various in variety, and about 2000-18000 microorganisms are contained in 1g of soil. Root microorganisms are extremely susceptible to plant hosts, soil types, nutritional conditions, and climatic factors. The choice of microorganisms by the plant host seems not to be completely random, as it appears by secreting specific small molecule nutrients, attracting some beneficial, potential plant probiotic values around it, modifying the pH of the soil, improving the quality of the soil, etc. However, it is not known how microorganisms can help plants grow to increase crop yield.

Research has shown that plant-related microorganisms (rhizosphere microorganisms, root surface microorganisms, etc.) have evolved a large number of functional genetic elements to adapt to plant environments such as plant nodules, nitrogen fixation reactions, phytohormone synthesis, T3SS and T6SS secretion systems, and flagella exercise, etc., as compared to non-plant-related microorganisms.

Knowing the microorganism composition around the plant, analyzing the interrelation between the microorganism, the plant growth and the environmental condition, finding the optimal microorganism composition required by the plant growth, establishing a controllable model for assisting the crop health, the efficient growth and the high yield by the microorganism, and promoting the maximization of the grain production. This requires the finding of these potential plant probiotics and functional properties by correlating the information on microbial composition and functional genes associated with large-scale plants with crop growth, yield phenotypes. The potential probiotics with application value can be purposefully screened under the guidance of the big data analysis result, and the potential can be provided for agricultural application.

The examples herein collect millet growth and yield phenotype data by sequencing studies on the microbial composition of the different lines Gu Zigen. Key microbiota (marker bacteria) associated with millet growth and yield phenotypes were identified by constructing a linear model. By isolating single bacterial strains in the rhizosphere soil of millet and comparing the 16S rRNA sequences, 4 marker strains with obvious correlation between the growth and the yield of the millet are found. Further, the growth promoting function of the strains is verified through a series of experiments such as a flat plate growth promoting experiment, a sterile soil experiment and a field experiment.

In a first aspect, embodiments of the present application provide a bacterial strain for promoting plant growth, wherein the bacterial strain is selected from at least one of the following:

In the examples of the present application, the percentage of identity generally describes the degree to which two sequences are identical, i.e. it generally describes the percentage of nucleotides at their sequence positions that correspond to the same nucleotides of the reference sequence. In the examples herein, the "sequence of at least 85% identity" refers to a sequence having any number (inclusive) of identity between 85% and 100% compared to the sequences shown in SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:3, and SEQ ID NO:4, for example, may have sequence identity of 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%, and countless decimal numbers between two adjacent integers, for example, sequence identity of at least 98.57%, 99.64%, 99.7%, 99.8% or 99.9% compared to the sequences shown in SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:3, and SEQ ID NO:4, respectively.

In the examples herein, strain 1 is Arthrobacter (Arthrobacter). In some embodiments, strain 1 has the amino acid sequence as set forth in SEQ ID NO:1, and a sequence shown in 1. In some embodiments, strain 1 may be Arthrobacter sp.Arth4 with accession number GDMCC No. 62566.

The genus Arthrobacter is a gram-positive bacterium, and has a distinct rod-like-globular growth cycle on a complex medium, a typical species of which is Arthrobacter globosus. By tree analysis, the Arth4 set forth in the examples of the present application is a new species under the genus Arthrobacter. Arth4 is an Arthrobacter belonging to the genus Arthrobacter, which is designated Arthrobacter sp.Arth4; the deposit accession number is GDMCC No. 62566, and the deposit institution is: the collection of microorganism strains in Guangdong province; deposit unit address: first, the middle road 100 # college experiment building 5 in the View area of Guangzhou City in Guangdong province; the preservation time is 2022, 6 and 28 days.

In the examples herein, the strain Arth4 having the sequence shown in SEQ ID NO. 1 can be understood by those skilled in the art as the original strain. Strains having a genomic sequence with at least 85% identity to the sequence shown in SEQ ID No. 1 can be understood by a person skilled in the art as variant strains of the strain Arth4 having the sequence shown in SEQ ID No. 1. It will be appreciated that strains such as strain Arth4 may undergo spontaneous mutation or undergo artificial culture to form variant strains, for example, nucleotide deletions, nucleotide additions, or nucleotide substitutions. The "variant strain" has a highly identical gene sequence to the "strain Arth4" and very similar biological functions, and the mutated gene does not substantially affect the conserved sequence of the strain Arth4 and thus does not affect the genetic stability of the strain Arth4. More specifically, the "variant strain" is also a strain of Arth4, and exhibits the physiological activity characteristics of Arth4. The specific genus of strain 1 and all species under it are also within the scope of protection of the present application.

In the examples herein, strain 2 is Bacillus. In some embodiments, strain 2 is a strain of bacillus licheniformis (Bacillus paralicheniformis). In some embodiments, strain 2 has the amino acid sequence as set forth in SEQ ID NO:2, and a sequence shown in seq id no. In some embodiments, strain 2 may be Bacillus paralicheniformis Bacil9 having accession number GDMCC No. 62569.

In the examples herein, strain 3 is a listeria (Priestia). In some embodiments, strain 3 is a species of listeria megaterium (Priestia megaterium). In some embodiments, strain 3 has the amino acid sequence as set forth in SEQ ID NO: 3. In some embodiments, strain 3 may be Priestia megaterium Bacif4 with accession number GDMCC No. 62567.

In the examples herein, strain 4 is Bacillus. In some embodiments, strain 4 is bacillus belicus (Bacillus velezensis). In some embodiments, strain 4 has the amino acid sequence as set forth in SEQ ID NO: 4. In some embodiments, strain 4 may be Bacillus velezensis Baci with accession number GDMCC No. 62568.

Bacil9 is a bacillus paralicheniformis belonging to the genus bacillus, named Bacillus paralicheniformis Bacil9; the deposit registration number is GDMCC No. 62569, and the deposit institution is: the collection of microorganism strains in Guangdong province; deposit unit address: first, the middle road 100 # college experiment building 5 in the View area of Guangzhou City in Guangdong province; the preservation time is 2022, 6 and 28 days.

Bacif4 is a large species of Listeria, belonging to the genus Listeria, designated Priestia megaterium Bacif; the deposit accession number is GDMCC No. 62567, and the deposit institution is: the collection of microorganism strains in Guangdong province; deposit unit address: first, the middle road 100 # college experiment building 5 in the View area of Guangzhou City in Guangdong province; the preservation time is 2022, 6 and 28 days.

Baci5 is a bacillus beleiensis belonging to the genus bacillus, which is named Bacillus velezensis Baci5; the deposit accession number is GDMCC No. 62568, and the deposit institution is: the collection of microorganism strains in Guangdong province; deposit unit address: first, the middle road 100 # college experiment building 5 in the View area of Guangzhou City in Guangdong province; the preservation time is 2022, 6 and 28 days.

Bacillus belongs to the bacillus family and the genus bacillus, is a gram positive bacterium capable of generating resistance endospores, and cells are in a rod shape and are covered with a large amount of calcium dipicolinate. The cortex is positioned between the core and the spore shell, and contains abundant peptidoglycan; the core is a highly concentrated, inert chromosome; the outer wall of the outermost layer is a layer of peptidoglycan wall, and one or more layers of spore coat is/are protein. Bacillus also has broad-spectrum bacillus activity, can produce bacteriocin and inhibit pathogenic bacteria. An important property of this genus of bacteria is the ability to produce spores that are particularly resistant to adverse conditions. At present, bacillus is widely applied to bacillus types such as bacillus subtilis, bacillus licheniformis and bacillus cereus. In the examples of the application, strains 2-4 all belong to the genus bacillus, wherein the bacterial 9 isolated in the examples of the application is a new strain under the strain Bacillus licheniformis (Bacillus paralicheniformis) by further analysis of the evolutionary tree; the Bacif4 isolated in the examples of this application is a new strain under the species Listeria megaterium (Priestia megaterium); the bacillus 5 isolated in the examples of the present application is a new strain under bacillus belicus strain (Bacillus velezensis).

It will be appreciated that as discussed above for strain 1 variants, there are variants that are identical to SEQ ID NOs: 2. SEQ ID NO: 3. SEQ ID NO:4, and the corresponding species and species corresponding thereto, which also have similar physiological activity characteristics as those of the strains 2-4, and all species corresponding to the specific genus and genus of the strains 2-4, which also fall within the scope of the present application.

When the four novel strains Arth4, bacil9, bacil 4 and Bacil 5 separated in the embodiment are used singly or in a mixed mode, the novel four strains Arth4, bacil9, bacil 4 and Bacil 5 can be effectively used for improving the agronomic characters of plants, particularly the bacterial genus of the 4 strains and the species of the 4 strains can effectively promote the elongation of roots and the growth of stems of the plants, and further the nutrient absorption and accumulation of the plants are improved, so that the crop yield is improved. The rhizosphere growth promoting bacteria provided by the embodiment of the application have important significance for improving the crop yield.

The second aspect of the embodiments of the present application also proposes an agricultural formulation comprising a bacterial strain as described in any of the embodiments of the first aspect of the present application.

In embodiments of the present application, the agricultural formulation may comprise any of the bacterial strains described above, wherein the bacterial strain comprises: strain 1 comprising the amino acid sequence of SEQ ID NO:1 or a complement thereof or a sequence complementary to the sequence set forth in SEQ ID NO:1 by at least 85% identity sequence; strain 2 comprising the amino acid sequence of SEQ ID NO:2 or a sequence comprising a sequence identical to SEQ ID NO:2 by at least 85% identity sequence; strain 3 comprising SEQ ID NO:3 or a sequence comprising a sequence identical to SEQ ID NO:3 by at least 85% identity sequence; and strain 4 comprising SEQ ID NO:4 or a sequence comprising a sequence identical to SEQ ID NO:4 to at least 85% identity sequence. Thus, the agricultural formulation in the examples herein may be either strain 1-4 alone or any combination between strains 1-4; meanwhile, since the above strain also contains mutant strains of the same genus as the strain 1-4, the specific genus of the strain 1-4 and all species under it are also within the scope of protection of the agricultural formulation of the present application.

In the examples herein, strain 3 is a listeria (Priestia). In some embodiments, strain 3 is listeria megaterium (Priestia megaterium). In some embodiments, strain 3 has the amino acid sequence as set forth in SEQ ID NO: 3. In some embodiments, strain 3 may be Priestia megaterium Bacif4 with accession number GDMCC No. 62567.

In an embodiment of the present application, the agricultural preparation further includes an auxiliary material, wherein the auxiliary material may be organic and/or inorganic. In the embodiment of the present application, the organic matter may be other additional bacterial manure capable of promoting plant growth besides the bacterial strains 1 to 4, for example: bacterial fertilizers for increasing soil nitrogen and crop nitrogen nutrition, such as rhizobium fertilizers, nitrogen fixing bacterial fertilizers, nitrogen fixing blue algae fertilizers and the like; bacterial manure for decomposing soil organic matters, such as organic phosphorus bacterial manure and comprehensive bacterial manure; bacterial fertilizers for decomposing soil insoluble minerals, such as phosphorus bacterial fertilizers, potassium bacterial fertilizers and mycorrhizal fungi fertilizers; bacterial fertilizers for stimulating plant growth, such as growth promoting bacterial fertilizers; bacterial fertilizers for increasing the stress resistance of crop root systems, such as antibiotic fertilizers and stress-resistant fungus fertilizers. In the embodiment of the application, the organic matter can also be an organic fertilizer required for plant growth, such as manure and the like. It is understood that the organic matters in the embodiments of the present application alone or in combination are only required to ensure the promotion effect on plant growth, and the present application is not limited thereto.

In embodiments of the present application, the inorganic substance may be an agriculturally acceptable chemical component, such as an agriculturally acceptable carrier, excipient, diluent, adjuvant, vehicle, excipient, carrier, or combination thereof, and/or an inorganic fertilizer having a concentration that does not affect the microbial activity in the agricultural formulation, as the application is not limited in this regard.

In embodiments of the present application, the dosage form of the agricultural formulation may be selected from: wettable powder, water dispersible granules, suspending agents, aqueous emulsion, granules, seed coating agents or a combination thereof. It will be appreciated that the dosage form of the agricultural formulation in the examples of the present application is not limited to this as long as it is ensured that it can be applied to plants in a certain form.

The agricultural preparation provided by the embodiment of the application can be effectively used for improving the agronomic characters of plants by using Arth4, bacil9, bacil 4 and Bacil 5 singly or in combination, especially the bacterial genus and species of 4 strains can effectively promote the elongation of roots and the growth of stems of the plants, and further improve the nutrient absorption and accumulation of the plants, thereby improving the crop yield. The rhizosphere growth promoting bacteria provided by the embodiment of the application have important significance for improving the crop yield. In addition, the application amount of the fertilizer can be reduced and the green agricultural production can be promoted by preparing the Arth4, the Bacil9, the Bacil 4 and the Bacil 5 into the microbial fertilizer suitable for the agricultural production.

The third aspect of the embodiments also provides a use of a bacterial strain according to any of the embodiments of the first aspect of the application for the preparation of an agricultural formulation.

A fourth aspect of embodiments of the present application also provides a method of promoting plant growth comprising administering to a bacterial strain as described in any of the embodiments of the first aspect of the present application or an agricultural formulation as described in any of the embodiments of the second aspect of the present application.

The experimental methods in the following examples, unless otherwise specified, are conventional methods, and are carried out according to techniques or conditions described in the literature in the field or according to the product specifications. Materials, reagents and the like used in the examples described below are commercially available unless otherwise specified.

Unless otherwise indicated, the quantitative tests in the examples below were all performed in triplicate, and the results averaged.

Example 1: isolation of strains

Rhizosphere soil samples of millet planted in Shaanxi Yang Ling were collected, diluted into a soil solution with sterile PBS-S buffer, and then centrifuged at 1200rpm for 5 minutes to collect the supernatant. Respectively diluting the supernatant into 10 ^-1 To 10 ^-7 Gradient concentration of 10 ^-4 And 10 ^-6 2 μl of the diluted solution was inoculated into a 96-well microtiter plate containing LB medium, cultured at 28℃for 48-72 hours, and then the culture solution was aspirated and passaged three times on LB solid medium to obtain a strain monoclonal. The 16S rRNA gene of the monoclonal strain was sequenced, and the microorganism strain 1-4 having the growth promoting function was found, with the following specific information.

Strain 1: arth4, whose 16S rDNA gene sequence is shown below in SEQ ID NO: 1.

AACGATGATCTCCAGCTTGCTGGGGGGATTAGTGGCGAACGGGTGAGTAACACGTGAGTAACCTGCCCTTGACTCTGGGATAAGCCTGGGAAACTGGGTCTAATACCGGATATGACCATTCCACGCATGTGGTGGTGGTGGAAAGCTTTTGCGGTTTTGGATGGACTCGCGGCCTATCAGCTTGTTGGTGGGGTAATGGCCTACCAAGGCGACGACGGGTAGCCGGCCTGAGAGGGTGACCGGCCACACTGGGACTGAGACACGGCCCAGACTCCTACGGGAGGCAGCAGTGGGGAATATTGCACAATGGGCGGAAGCCTGATGCAGCGACGCCGCGTGAGGGATGACGGCCTTCGGGTTGTAAACCTCTTTCAGTAGGGAAGAAGCGTAAGTGACGGTACCTGCAGAAGAAGCGCCGGCTAACTACGTGCCAGCAGCCGCGGTAATACGTAGGGCGCAAGCGTTATCCGGAATTATTGGGCGTAAAGAGCTCGTAGGCGGTTTGTCGCGTCTGCTGTGAAAGACCGGGGCTCAACTCCGGTTCTGCAGTGGGTACGGGCAGACTAGAGTGCAGTAGGGGAGACTGGAATTCCTGGTGTAGCGGTGAAATGCGCAGATATCAGGAGGAACACCGATGGCGAAGGCAGGTCTCTGGGCTGTAACTGACGCTGAGGAGCGAAAGCATGGGGAGCGAACAGGATTAGATACCCTGGTAGTCCATGCCGTAAACGTTGGGCACTAGGTGTGGGGGACATTCCACGTTTTCCGCGCCGTAGCTAACGCATTAAGTGCCCCGCCTGGGGAGTACGGCCGCAAGGCTAAAACTCAAAGGAATTGACGGGGGCCCGCACAAGCGGCGGAGCATGCGGATTAATTCGATGCAACGCGAAGAACCTTACCAAGGCTTGACATGGACTGGAAAGATCTGGAGACAGGTCCCCCGCTTGCGGTCGGTTCACAGGTGGTGCATGGTTGTCGTCAGCTCGTGTCGTGAGATGTTGGGTTAAGTCCCGCAACGAGCGCAACCCTCGTTCTATGTTGCCAGCGCGTTATGGCGGGGACTCATAGGAGACTGCCGGGGTCAACTCGGAGGAAGGTGGGGACGACGTCAAATCATCATGCCCCTTATGTCTTGGGCTTCACGCATGCTACAATGGCCGGTACAAAGGGTTGCGATACTGTGAGGTGGAGCTAATCCCAAAAAGCCGGTCTCAGTTCGGATTGGGGTCTGCAACTCGACCCCATGAAGTCGGAGTCGCTAGTAATCGCAGATCAGCAACGCTGCGGTGAATACGTTCCCGGGCCTTGTACACACCGCCCGTCAAGTCACGAAAGTTGGTAACACCCGAAGC(SEQ ID NO：1)

Strain 2: bacil9, whose 16S rDNA gene sequence is as follows SEQ ID NO: 2.

AGCGGACAGATGGGAGCTTGCTCCCTGATGTTAGCGGCGGACGGGTGAGTAACACGTGGGTAACCTGCCTGTAAGACTGGGATAACTCCGGGAAACCGGGGCTAATACCGGATGCTTGATTGAACCGCATGGTTCAATTATAAAAGGTGGCTTTTAGCTACCACTTACAGATGGACCCGCGGCGCATTACCTAGTTGGTGAGGTAACGGCTCACCAAGGCAACAATGCGTACCCAACCTGAAAGGGTGATCGGCCACACTGGGACTGAAACACGGCCCAAACTCCTACGGGAGGCAGCAGTAGGGAATCTTCCGCAATGGACAAAAGTCTGACGGAGCAACGCCGCGTGAGTGATGAAGGTTTTCGGATCGTAAAACTCTGTTGTTAGGGAAAAACAAGTACCGTTCGAATAGGGCGGTACCTTGACGGTACCTAACCAAAAAGCCACGGCTAACTACGTGCCACCAGCCGCGGTAATACGTAGGTGGCAAGCGTTGTCCGGAATTATTGGGCGTAAAGCGCGCGCAGGCGGTTTCTTAAGTCTGATGTGAAAGCCCCCGGCTCAACCGGGGAGGGTCATTGGAAACTGGGGAACTTGAGTGCAAAAAAGGAGAGTGGAATTCCACGTGTAGCGGTGAAATGCGTAAAGATGTGGAGGAACACCAGTGGCGAAGGCGACTCTCTGGTCTGTAACTGACGCTGAGGCGCGAAAGCGTGGGGAGCGAACAGGATTAGATACCCTGGTAGTCCACGCCGTAAACGATGAGTGCTAAGTGTTAGAGGGTTTCCGCCCTTTAGTGCTGCAGCAAACGCATTAAGCACTCCGCCTGGGGAGTACGGTCGCAAGACTGAAACTCAAAGGAATTGACGGGGGCCCGCACAAGCGGTGGAGCATGTGGTTTAATTCGAAGCAACGCGAAGAACCTTACCAGGTCTTGACATCCTCTGACAACCCTAGAGATAGGGCTTCCCCTTCGGGGGCAGAGTGACAGGTGGTGCATGGTTGTCGTCAGCTCGTGTCGTGAGATGTTGGGTTAAGTCCCGCAACGAGCGCAACCCTTGATCTTAGTTGCCAGCATTCAGTTGGGCACTCTAAGGTGACTGCCGGTGACAAACCGGAGGAAGGTGGGGATGACGTCAAATCATCATGCCCCTTATGACCTGGGCTACACACGTGCTACAATGGGCAGAACAAAGGGCAGCGAAGCCGCGAGGCTAAGCCAATCCCACAAATCTGTTCTCAGTTCGGATCGCAGTCTGCAACTCGACTGCGTGAAGCTGGAATCGCTAGTAATCGCGGATCAGCATGCCGCGGTGAATACGTTCCCGGGCCTTGTACACACCGCCCGTCACACCACGAGAGTTTGTAACACCCG(SEQ ID NO：2)

Strain 3: bacif4, the 16S rDNA gene sequence of which is shown in SEQ ID NO: 3.

AGCGAACTGATTAGAAGCTTGCTTCTATGACGTTAGCGGCGGACGGGTGAGTAACACGTGGGCAACCTGCCTGTAAGACTGGGATAACTTCGGGAAACCGAAGCTAATACCGGATAGGATCTTCTCCTTCATGGGAGATGATTGAAAGATGGTTTCGGCTATCACTTACAGATGGGCCCGCGGTGCATTAGCTAGTTGGTGAGGTAACGGCTCACCAAGGCAACGATGCATAGCCGACCTGAGAGGGTGATCGGCCACACTGGGACTGAGACACGGCCCAGACTCCTACGGGAGGCAGCAGTAGGGAATCTTCCGCAATGGACGAAAGTCTGACGGAGCAACGCCGCGTGAGTGATGAAGGCTTTCGGGTCGTAAAACTCTGTTGTTAGGGAAGAACAAGTACGAGAGTAACTGCTTGTACCTTGACGGTACCTAACCAGAAAGCCACGGCTAACTACGTGCCAGCAGCCGCGGTAATACGTAGGTGGCAAGCGTTATCCGGAATTATTGGGCGTAAAGCGCGCGCAGGCGGTTTCTTAAGTCTGATGTGAAAGCCCACGGCTCAACCGTGGAGGGTCATTGGAAACTGGGGAACTTGAGTGCAGAAGAGAAAAGCGGAATTCCACGTGTAGCGGTGAAATGCGTAGAGATGTGGAGGAACACCAGTGGCGAAGGCGGCTTTTTGGTCTGTAACTGACGCTGAGGCGCGAAAGCGTGGGGAGCAAACAGGATTAGATACCCTGGTAGTCCACGCCGTAAACGATGAGTGCTAAGTGTTAGAGGGTTTCCGCCCTTTAGTGCTGCAGCTAACGCATTAAGCACTCCGCCTGGGGAGTACGGTCGCAAGACTGAAACTCAAAGGAATTGACGGGGGCCCGCACAAGCGGTGGAGCATGTGGTTTAATTCGAAGCAACGCGAAGAACCTTACCAGGTCTTGACATCCTCTGACAACTCTAGAGATAGAGCGTTCCCCTTCGGGGGACAGAGTGACAGGTGGTGCATGGTTGTCGTCAGCTCGTGTCGTGAGATGTTGGGTTAAGTCCCGCAACGAGCGCAACCCTTGATCTTAGTTGCCAGCATTTAGTTGGGCACTCTAAGGTGACTGCCGGTGACAAACCGGAGGAAGGTGGGGATGACGTCAAATCATCATGCCCCTTATGACCTGGGCTACACACGTGCTACAATGGATGGTACAAAGGGCTGCAAGACCGCGAGGTCAAGCCAATCCCATAAAACCATTCTCAGTTCGGATTGTAGGCTGCAACTCGCCTACATGAAGCTGGAATCGCTAGTAATCGCGGATCAGCATGCCGCGGTGAATACGTTCCCGGGCCTTGTACACACCGCCCGTCACACCACGAGAGTTTGTAACACCCGAAGTCGGTGGAGTA(SEQ ID NO：3)

Strain 4: baci5, the 16S rDNA gene sequence of which is as follows SEQ ID NO: 4.

GAGCGGACAGATGGGAGCTTGCTCCCTGATGTTAGCGGCGGACGGGTGAGTAACACGTGGGTAACCTGCCTGTAAGACTGGGATAACTCCGGGAAACCGGGGCTAATACCGGATGGTTGTTTGAACCGCATGGTTCAGACATAAAAGGTGGCTTCGGCTACCACTTACAGATGGACCCGCGGCGCATTAGCTAGTTGGTGAGGTAACGGCTCACCAAGGCGACGATGCGTAGCCGACCTGAGAGGGTGATCGGCCACACTGGGACTGAGACACGGCCCAGACTCCTACGGGAGGCAGCAGTAGGGAATCTTCCGCAATGGACGAAAGTCTGACGGAGCAACGCCGCGTGAGTGATGAAGGTTTTCGGATCGTAAAGCTCTGTTGTTAGGGAAGAACAAGTGCCGTTCAAATAGGGCGGCACCTTGACGGTACCTAACCAGAAAGCCACGGCTAACTACGTGCCAGCAGCCGCGGTAATACGTAGGTGGCAAGCGTTGTCCGGAATTATTGGGCGTAAAGGGCTCGCAGGCGGTTTCTTAAGTCTGATGTGAAAGCCCCCGGCTCAACCGGGGAGGGTCATTGGAAACTGGGGAACTTGAGTGCAGAAGAGGAGAGTGGAATTCCACGTGTAGCGGTGAAATGCGTAGAGATGTGGAGGAACACCAGTGGCGAAGGCGACTCTCTGGTCTGTAACTGACGCTGAGGAGCGAAAGCGTGGGGAGCGAACAGGATTAGATACCCTGGTAGTCCACGCCGTAAACGATGAGTGCTAAGTGTTAGGGGGTTTCCGCCCCTTAGTGCTGCAGCTAACGCATTAAGCACTCCGCCTGGGGAGTACGGTCGCAAGACTGAAACTCAAAGGAATTGACGGGGGCCCGCACAAGCGGTGGAGCATGTGGTTTAATTCGAAGCAACGCGAAGAACCTTACCAGGTCTTGACATCCTCTGACAATCCTAGAGATAGGACGTCCCCTTCGGGGGCAGAGTGACAGGTGGTGCATGGTTGTCGTCAGCTCGTGTCGTGAGATGTTGGGTTAAGTCCCGCAACGAGCGCAACCCTTGATCTTAGTTGCCAGCATTCAGTTGGGCACTCTAAGGTGACTGCCGGTGACAAACCGGAGGAAGGTGGGGATGACGTCAAATCATCATGCCCCTTATGACCTGGGCTACACACGTGCTACAATGGACAGAACAAAGGGCAGCGAAACCGCGAGGTTAAGCCAATCCCACAAATCTGTTCTCAGTTCGGATCGCAGTCTGCAACTCGACTGCGTGAAGCTGGAATCGCTAGTAATCGCGGATCAGCATGCCGCGGTGAATACGTTCCCGGGCCTTGTACACACCGCCCGTCACACCACGAGAGTTTGTAACACCCGAAGTCGGTGAGGTAACCTTTA(SEQ ID NO：4)

Example 2: identification of isolated strains

The inventors have further identified the isolated strains 1-4 of example 1 by aligning the 16S rRNA sequences of strains 1-4 with a database.

2.1 Arth4 (Strain 1)

The sequence of about 1.4Kb of the obtained Arth4 (Arth4_16S_rRNA_gene, SEQ ID NO: 1) was aligned in the 16S rRNA gene database of EzBioCloud to primarily obtain species classification information of strain 1. According to the comparison, the two strains with the highest homology to the 16S rRNA gene of Arth4 in the database were Arthrobacter bambusae GM (SEQ ID NO: KF 150696) and Paenarthrobacter aurescens NBRC 12136 (SEQ ID NO: BJMD 01000050), with similarities of 98.57% and 98.50%, respectively. From the information of 16S rRNA, it could be preliminarily determined that Arth4 is a new species belonging to the genus Arthrobacter.

Further, the phylogenetic tree was constructed using MAGA for the sequence of the related strain of Arth4 in the orthotopic fusion method, and the results are shown in FIG. 1. From FIG. 1 it can be seen that Arth4 is not clustered with other species of bacteria, which also demonstrates that strain 1 isolated in example 1 is a new species under the genus Arthrobacter.

Meanwhile, arth4 was subjected to whole genome sequencing, and genomes of Arthrobacter_bambusae (Genebank sequence number: GCA_ 022606295.1) and Paenarthrobacter aurescens NBRC 12136 (Genebank sequence number: GCA_ 006538985.1) strains, the genomic sequences of which were most similar thereto, were subjected to whole genome average nucleotide similarity (Average Nucleotide Identity, ANI) analysis using FastANI software. ANI is an index comparing two genome relatedness at nucleotide levels, and is defined as the average base similarity between homologous fragments of two microbial genomes, characterized by a higher degree of discrimination between closely related species. Analysis showed that the genome ANI of the entire genome of Arth4 and Arthrobacter_bacteria and Paenarthrobacter aurescens NBRC 12136 was 80.5% and 84.4% and was far lower than that of the same species (see Jain C, rodriguez-RLM, phillippy A M, et al high throughput ANI analysis of 90K prokaryotic genomes reveals clear speciesboundaries[J ]. Nature Communications,2018,9 (1): 5114, 95% was considered as the threshold for determining whether or not the same species) and thus further determined that Arth4 was a new strain under the genus Arthrobacter, designated Arthrobacter sp. Arth4, and deposited with the Guangdong province microorganism collection under the accession number GDMCC No. 62566.

2.2 Baci9 (Strain 2)

Similarly, the sequence of approximately 1.4Kb of the obtained Bacil9 (Bacil 9-16S_rRNA_gene, SEQ ID NO: 2) was aligned in the 16S rRNA gene database of EzBioCloud to obtain species classification information of strain 2 in the preliminary. According to the comparison result, the strain with the highest homology with the 16S rRNA gene of Bacil9 in the database is Bacillus paralicheniformis (sequence number: KY 694465), the sequence similarity is 98.98%, and the Bacil9 can be primarily judged to belong to Bacillus paralicheniformis species according to the information of the 16S rRNA.

Further, the phylogenetic tree was constructed using MAGA for the sequence of the proximal strain of Bacil9 in the orthotopic fusion method, and the results are shown in FIG. 2. From FIG. 2, it can be seen that Bacil9 clusters together with Bacillus paralicheniformis KJ-16 (Genebank Serial number: GCA_ 001042485.2), which also verifies that the strain 2 isolated in example 1 belongs to the species Bacillusparalicheiformis.

Meanwhile, bacil9 was subjected to whole genome sequencing, and the genome of the Bacillus paralicheniformis KJ-16 (Genebank SEQ ID NO: GCA_ 001042485.2) strain, the genomic sequence of which was the most similar thereto, was subjected to ANI analysis using FastANI software as well. Analysis showed that the genome ANI of Bacil9 whole genome and Bacillus paralicheniformis KJ-16 (Genebank serial number: GCA_ 001042485.2) reached 99.24% (more than 95%), thereby further judging that Bacil9 was a new strain under Bacillus paralicheniformis, designated Bacillus paralicheniformis Bacil9, and deposited with the Guangdong province microorganism strain deposit center under the accession number GDMCC No. 62569.

2.3 Bacif4 (Strain 3)

Similarly, the nearly 16S rDNA full-length sequence of 1.4Kb of Bacif4 obtained by sequencing (Bacif4_16S_rRNA_gene, SEQ ID NO: 3) was aligned in the 16S rRNA gene database of EzBioCloud, and species classification information of strain 3 was obtained preliminarily. According to the comparison result, the strain with the highest homology with the 16S rRNA gene of Bacif4 in the database is Priestia megaterium NBRC15308 (sequence number: JJMH 01000057), and the similarity is 99.93%. Based on the information of 16S rRNA, it was possible to preliminarily determine that Bacif4 belongs to Priestia megaterium species.

Further, the phylogenetic tree was constructed using MAGA for the sequence of the proximal strain of Bacif4 in the orthotopic fusion method, and the results are shown in FIG. 3. From FIG. 3, it can be seen that the relationship between Bacif4 and Priestia megaterium NBRC15308 (Genebank sequence number: GCA_ 009935415.1) is close, which also verifies that the isolated strain 3 of example 1 belongs to the Priestiamerium species.

Meanwhile, bacif4 was subjected to whole genome sequencing, and the genome of the Priestia megaterium NBRC15308 strain (Genebank sequence number: GCA_ 009935415.1) with which the genomic sequence was most similar thereto was also subjected to ANI analysis using FastANI software. Analysis showed that the genome ANI of Bacif4 whole genome and Priestia megaterium NBRC15308 (Genebank serial number: GCA_ 009935415.1) reached 99.18% (more than 95%), and thus a new strain of Bacif4 was further judged as Priestia megaterium, designated Priestia megateriumBacif4, and deposited with the Guangdong province microorganism strain deposit center under accession number GDMCC No. 62567.

2.4Baci5 (Strain 4)

Similarly, the nearly 16S rDNA full-length sequence of 1.4Kb of the obtained Bacillus 5 (Bac5_16S_rRNA_gene, SEQ ID NO: 4) was aligned in the 16S rRNA gene database of EzBioCloud to preliminarily obtain species classification information of strain 4. According to the comparison, the strains with the highest homology to the 16S rRNA gene of Bacillus 5 in the database are Bacillus siamensis KCTC 13613 (SEQ ID NO: AJVF 01000043) and Bacillus velezensis CR-502 (SEQ ID NO: AY 603658), and the similarity is 99.93%. Based on the information of 16S rRNA, it can be preliminarily determined that Bacillus 5 belongs to the genus Bacillus.

Further, the phylogenetic tree was constructed using MAGA for the sequence of the proximal strain of Bacillus 5 in the orthotopic fusion method, and the results are shown in FIG. 4. From FIG. 4, it can be seen that Bacillus 5 clusters together with Bacillus siamensis KCTC 13613 (Genebank sequence number: GCA_ 000262045.1) and Bacillus velezensis CR-502 (Genebank sequence number: GCA_ 001461825.1), which also verifies that isolated strain 4 of example 1 belongs to the genus Bacillus.

Meanwhile, bacillus 5 was subjected to whole genome sequencing, and the genomes of the Bacillus siamensis KCTC 13613 (Genebank SEQ ID NO: GCA_ 000262045.1) and Bacillus velezensis (Genebank SEQ ID NO: GCA_ 001461825.1) strains, the genomic sequences of which were most similar thereto, were also subjected to ANI analysis using FastANI software. The analysis results showed that the genome ANI of the Baci5 and Bacillus siamensis KCTC 13613 (Genebank sequence number: GCA_ 000262045.1) and Bacillus velezensis (Genebank sequence number: GCA_ 001461825.1) strains were 93.88% and 97.97%, respectively, and thus, it was further judged that Baci5 was not Bacillus siamensis but a new strain under Bacillus velezensis species, which was named Bacillus velezensis Baci5, and deposited with the Guangdong province microorganism strain deposit under the accession number GDMCC No. 62568.

Example 3: plate growth-promoting experiment

3.1 after the strain 1-4 is activated, inoculating into NY culture medium, and vibrating and fermenting at 28 ℃ and 180 r/min. Then, the bacterial liquid OD ₆₀₀ Adjusting to 0.5, collecting bacterial liquid, centrifuging at 5000rpm for 10min, removing supernatant, and re-suspending thallus with sterile water.

3.2 surface disinfection of Hua Gu seeds with 1% sodium hypochlorite for 5min, and rinsing with sterile water for 5 times after disinfection. In a sterile culture dish, seeds are respectively sown on sterile double-layer filter paper, and 15-20 seeds are uniformly placed on each filter paper. 2ml of the bacterial liquid 1-4 obtained in the step 3.1 is sprayed on seeds respectively, and the seeds are taken out after 7 days. Counting the number of germinated seeds, and recording the root length and plant height of seedlings. Each treatment was set up with 3 parallel experimental groups. The control group was sprayed with sterile water.

3.3 root length and plant height of seedlings were measured after 25 days of cultivation, and specific measured values (average values) are shown in tables 1 and 2, respectively. The growth of the treated and control groups is shown in figure 5.

TABLE 1

Strain	Root length (average value: cm)	Corrected P value
			Control group	3.63	/
Bacif4	3.41	4.07E-01
			Bacil9	3.95	2.12E-01
Baci5	3.96	2.12E-01
			Arth4	4.30	2.40E-02

TABLE 2

Strain	Plant height (average value: cm)	Corrected P value
			Control group	2.13	/
Bacif4	2.83	1.10E-01
			Bacil9	3.40	1.02E-08
Baci5	2.23	2.34E-03
			Arth4	2.82	4.34E-06

Tables 1 and 2 show root length and plant height of seedlings after treatment with the microbial inoculum in the plate experiments, respectively. As can be seen from table 1, the root length of seedlings treated with the microbial inoculum 1 (i.e. Arth 4) was significantly longer at the 5% level than that of the control group in plate culture (p < 0.05). Meanwhile, as can be seen from table 2, compared with the control group, the seedlings treated with microbial agents 1 to 4 all had longer average root lengths than the control group, and microbial agent 1 (i.e., arth 4) and microbial agent 2 (i.e., bacil 9) exhibited extremely significant differences (x, p < 0.001), and microbial agent 4 (i.e., baci 5) exhibited significant differences at the level of 0.1% (x, p < 0.01). Thus, it was confirmed that the strains 1 to 4 have a good promoting effect on root length, particularly plant height, of plants.

Example 4: sterile soil growth-promoting experiment

The surface of the millet seeds was sterilized with 1% sodium hypochlorite solution for 5min and rinsed with sterile distilled water for 5 times. The sterilized seeds are planted into a sterile soil basin, wherein the sterile soil is obtained by sterilizing the soil growing in the millet field at the high temperature of 120 ℃. 5-10 plants were grown in each pot. After the seeds germinate for 5 days, 5ml of bacterial liquid 1-4 is respectively poured around the root of the germinated plants in each pot, 3 parallel groups are arranged for each treatment, and the control group is poured with sterile water. Irrigating every 5 days for 3 times. After 25 days, the plants in the pot were removed and their root length and plant height were measured, and specific measured values (average values) are shown in tables 3 and 4 below. The growth of the treated and control groups is shown in figure 6.

TABLE 3 Table 3

Strain	Root length (average value: cm)	Corrected P value
			Control group	3.39	/
Bacif4	4.73	5.06E-04
			Bacil9	4.43	1.33E-03
Baci5	4.13	3.29E-02
			Arth4	3.95	6.86E-02

TABLE 4 Table 4

Strain	Plant height (average value: cm)	Corrected P value
			Control group	7.56	/
Bacif4	9.20	2.71E-02
			Bacil9	9.12	1.09E-02
Baci5	8.83	2.35E-02
			Arth4	10.81	9.60E-07

Tables 3 and 4 show root length and plant height of seedlings after bacterial liquid treatment in the aseptic soil experiment. As is clear from Table 3, the seedlings treated with the microbial agents 1 to 4 were longer in average root length than the control group in comparison with the control group in the culture with the sterile soil as the substrate, indicating that the microbial agents 1 to 4 have the promoting effect on the growth of plant roots. Moreover, bacterial agent 4 (i.e. Baci 5) and bacterial agent 3 (i.e. Bacif 4) exhibited a very significant difference (x, p < 0.001), and bacterial agent 2 (i.e. Bacil 9) exhibited a significant difference at the level of 0.1% (x, p < 0.01), thus demonstrating that strain 2-4 was able to significantly promote plant root growth.

As is clear from Table 4, the average plant height of seedlings treated with the microbial agents 1 to 4 was greater than that of the control group in the culture with the sterile soil as a substrate, indicating that the strains 1 to 4 had the promoting effect on the growth of the plant height. And the plant height of seedlings treated by the microbial inoculum 2-4 is significantly higher than that of the control group (x, p < 0.05), and the microbial inoculum 1 (i.e. Arth 4) shows extremely significant difference (x, p < 0.001) compared with the control group, thereby proving that the strain 1-4 has significant promotion effect on the high growth of plants.

In summary, the strains 1 to 4 proposed in the examples of the present application can be effectively used for promotion of plant growth.

Example 5: field experiment

Hua Gu 12 is planted in a large basin filled with field soil, and is irrigated with bacterial liquid 1-4 respectively, and after the plant grows up, the growth character of the plant is measured. 3 replicates were set for each treatment and the control group was irrigated with sterile water. The specific measurement data (average) are shown in tables 5 to 7. The growth of the treated and control groups is shown in figures 7 and 8.

TABLE 5

TABLE 6

Strain	Main stalk spike diameter (average value: mm)	Corrected P value
			Control group	14.36	/
Arth4	17.64	0.0145
			Bacil9	18.74	0.0116
Bacif4	15.45	0.3889
			Baci5	14.77	0.7299

TABLE 7

Strain	Plant height (average value: cm)	Corrected P value
			Control group
	86	/
			Arth4	92.18	0.0852
Bacil9	90	0.3464
			Bacif4	85.54	0.9036
Baci5	78.97	0.0637

As can be seen from fig. 7 and 8, in the field test, the plants after the application of the microbial inoculum 1-4 grow more luxuriantly than the control group, the plants are generally higher, stronger and straighter, and the leaves are greenish, which indicates that the strain 1-4 in the embodiment of the application has good promotion effect on the growth of the stems and leaves of the plants. Meanwhile, as can be seen from the millet setting condition in fig. 7, compared with the control group, the millet plants using the microbial inoculum 1-4 have more ears and large and full ears, which means that the strain 1-4 can realize more nutrient absorption and accumulation for the plants, and the setting condition of the plants is improved after the whole growth of the plants is promoted, so that the crop yield is improved.

Tables 5-7 are specific measurements of the main stem and plant height of the plants of the treatment and control groups, respectively, i.e., specific quantification of the growth of the plants. As can be seen from Table 5, the average of the main stems of the plants to which Bacil 4 strain was applied was comparable to that of the control group, and the plants to which other microbial agents (Arth 4, bacil9 and Bacil 5) were applied were larger than those of the control group, demonstrating that strains 1 to 4 can promote the growth of stems of plants, and that Bacil9 (i.e., strain 2) was the most robust, indicating that Bacil9 can effectively promote the growth of stems of plants. In terms of plant height, as can be seen from table 7, in the field test, the average plant height of the treated group to which the Baci5 strain was applied was smaller than that of the control group, the average plant height of the plant to which the Bacif4 strain was applied was comparable to that of the control group, and the average plant height of the plant to which the Arth4 and Bacil9 strain were applied was higher than that of the control group. In the aspect of the diameter of the main stem ear, the average diameter of the main stem ear of the applied microbial inoculum 1-4 is larger than that of a control group, and the nutrient absorption and accumulation conditions of plants can be visually reflected due to the fruiting condition, so the data in the table 6 prove that the microbial inoculum 1-4 can effectively promote the nutrient absorption conditions of the plants.

Therefore, the rhizosphere growth promoting strain 1-4 newly separated and identified in the embodiment of the application has good promoting effect on plant growth, and further, the growth promotion of the strain 1-4 on plant roots can effectively improve nutrient absorption of plant rhizosphere, so that crop yield is improved.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.

While embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the invention.

Claims

1. A bacterial strain for promoting plant growth, wherein the bacterial strain is selected from at least one of the following:

2. Bacterial strain according to claim 1, wherein said strain 1 is of the genus Arthrobacter (Arthrobacter), preferably said strain 1 has the amino acid sequence as set forth in SEQ ID NO:1, more preferably, said strain 1 is Arthrobacter sp.Arth4 having accession number GDMCC No. 62566.

3. Bacterial strain according to claim 1, wherein said strain 2 is Bacillus (Bacillus), preferably said strain 2 is a strain of Bacillus licheniformis (Bacillus paralicheniformis), more preferably said strain 2 has the amino acid sequence as set forth in SEQ ID NO:2, most preferably, said strain 2 is Bacillus paralicheniformis Bacil having accession number GDMCC No. 62569.

4. The bacterial strain according to claim 1, wherein said strain 3 is of the genus listeria (Priestia), preferably said strain 3 is of the species listeria megaterium (Priestia megaterium), more preferably said strain 3 has the amino acid sequence as set forth in SEQ ID NO:3, most preferably, said strain 3 is Priestia megaterium Bacif4 having accession number GDMCC No. 62567.

5. Bacterial strain according to claim 1, wherein said strain 4 is Bacillus (Bacillus), preferably said strain 4 is Bacillus besseyi (Bacillus velezensis), more preferably said strain 4 has the amino acid sequence as set forth in SEQ ID NO:4, most preferably, said strain 4 is Bacillus velezensis Baci5 having accession number GDMCC No. 62568.

6. An agricultural formulation, wherein the agricultural formulation comprises the bacterial strain of any one of claims 1 to 5.

7. The agricultural formulation of claim 6, wherein the agricultural formulation further comprises an adjuvant.

8. The use according to claim 6 or 7, wherein the agricultural formulation is in a dosage form selected from: wettable powder, water dispersible granules, suspending agents, aqueous emulsion, granules, seed coating agents or a combination thereof.

9. Use of a bacterial strain according to any one of claims 1 to 5 for the preparation of an agricultural formulation.

10. A method of promoting plant growth, the method comprising applying to the plant a bacterial strain according to any one of claims 1 to 5 or an agricultural formulation according to any one of claims 6 to 8.