A Cajanus cajan growth-promoting mixed bacterium M1H for increasing the abundance of host microbial populations and reducing the abundance of pathogenic microorganisms

Abstract

The present invention discloses a Cajanus cajan growth-promoting mixed bacterium M1H (Serratia marcescens, Paenibacillus polymyxa partial) that can increase the abundance of host microorganisms and reduce the abundance of pathogenic microorganisms, belonging to the field of microbial technology. The mixed bacterium M1H enhances the consumption of soil nutrients by Cajanus cajan, increases the abundance of host microorganisms, and reduces the abundance of pathogenic bacteria, thereby promoting the growth and development of Cajanus cajan. Among them, the available potassium content in the soil decreased significantly by 40.75%, the hydrolyzable nitrogen content in the soil decreased significantly by 19.08%, and the organic matter content decreased significantly by 21.89%. The relative abundance of the host microorganism Cajanus in the rhizosphere soil of Cajanus cajan increased significantly, from 26.39% to 37.23%; the relative abundances of the pathogenic bacteria Zopfiella and Podospora decreased significantly. The relative abundance of Zopfiella decreased from 7.37% to 0.32%, and the relative abundance of Podospora decreased from 3.92% to 0.47%. The changes in the abundance of soil microbial populations jointly affect the growth and development of Cajanus cajan, but the size of the abundance of Cajanus is the main factor determining the promoting effect of the mixed bacterium M1H on Cajanus cajan.

Description

Technical Field

[0001] The present invention relates to the technical field of microorganisms, and more specifically to a Cajanus cajan growth-promoting mixed bacterium M1H (Serratia marcescens M1P, Paenibacillus polymyxa M45N) that can increase the abundance of host microbial populations and reduce the abundance of pathogenic microorganisms. Background Art

[0002] A large number of studies have shown that due to long-term traditional experience in planting and the one-sided pursuit of yield while ignoring quality, there is a phenomenon of blind fertilization, especially the excessive use of chemical fertilizers, which has caused soil compaction, a decrease in organic matter content, damage to microbial populations, and a serious impact on plant benefits. In recent years, with the increasing understanding of the disadvantages of chemical fertilizers, the application of microbial fertilizers has received extensive attention. Microorganisms play an important role in enhancing plant characteristics, regulating microbial growth, and plant growth, and have a positive impact on improving plant quality. Cajanus cajan is widely used in human life due to its rich nutrients such as a large amount of protein and amino acids. In addition, the excellent stress resistance quality of Cajanus cajan can be used as a pioneer tree species for afforestation. These qualities have enhanced the demand and economic returns of farmers and herdsmen worldwide. Therefore, screening Cajanus cajan-adapted microbial agents and understanding the Cajanus cajan growth-promoting mechanism have become current research hotspots. Currently, there have been studies using mineral-dissolving microorganisms to improve the growth quality of Indigofera pseudotinctoria by improving the soil environment.

[0003] Soil microorganisms are an important part of the soil ecosystem, and the richness of soil microorganisms is usually accompanied by the diversity of soil microbial functions. Blindly applying microorganisms to plant growth, whether plants can adapt to the characteristics of microorganisms and thrive in such an environment remains to be verified. Accordingly, can some rhizosphere bacteria be screened from the rhizosphere soil of Cajanus cajan to improve the adaptability between rhizosphere bacteria and Cajanus cajan, achieve the effect of "suitable trees for suitable land", and further explore the growth-promoting functional mechanism of rhizosphere bacteria on host plants, rather than blindly selecting microorganisms to match with Cajanus cajan.

[0004] If such rhizosphere bacteria exist, it first ensures the adaptability of the microorganisms themselves to the growth soil environment of Cajanus cajan, and then explores their important role in the Cajanus cajan growth-promoting mechanism.

[0005] Therefore, screening highly efficient growth-promoting rhizosphere microorganisms is the key to promoting plant growth and development and the green development of agriculture. Studying the growth-promoting ability and mechanism of rhizosphere bacteria on plants, clarifying how the soil fungal community evolves under long-term rhizosphere bacteria application conditions, and the relationship with soil nutrients provide a theoretical basis and practical guide for the development of green agriculture and animal husbandry. Summary of the Invention

[0006] In view of this, the present invention provides a mixed bacterium M1H for promoting the growth of pigeon pea, which can increase the abundance of host microbial populations and reduce the abundance of pathogenic microorganisms.

[0007] The mixed bacterium M1H is composed of M1P (Serratia marcescens) and M45N (Paenibacillus polymyxa). The component strains are both preserved in the China Center for Type Culture Collection, address: Wuhan University, Wuhan, China. Among them, the preservation number of M1P is CCTCC NO: M 20221841; the preservation number of M45N is CCTCC NO: M 20221840. The preservation date is November 29, 2022.

[0008] The highly efficient pigeon pea growth-promoting bacterium M1H of the present invention is screened from the rhizosphere soil of pigeon pea, and the growth-promoting ability of the strain on pigeon pea is studied through pot experiments. Combining high-throughput sequencing technology, the characteristics of the change in the soil fungal community structure and its relationship with soil nutrients under the condition of short-term application of microbial inoculants are studied. The research results will provide a theoretical basis and practical guide for the pigeon pea planting industry and the development of green agriculture and animal husbandry, and provide a beneficial basis for strains.

[0009] In order to achieve the above object, the present invention adopts the following technical scheme:

[0010] A method for promoting the growth of pigeon pea, the mixed bacterium M1H is composed of M1P (Serratia marcescens, the same below) and M45N (Paenibacillus polymyxa, the same below), and the mixed bacterium M1H is used as an inoculant for application. Among them, the preservation number of M1P is CCTCC NO: M 20221841; the preservation number of M45N is CCTCC NO: M 20221840..

[0011] The present invention also provides a method for increasing the relative abundance of host microorganisms, using the mixed bacterium M1H as an inoculant for application. Among them, the preservation number of M1P is CCTCC NO: M 20221841; the preservation number of M45N is CCTCC NO: M 20221840.

[0012] The present invention also provides a method for reducing the relative abundance of pathogenic microorganisms, using the mixed bacterium M1H as an inoculant for application. Among them, the preservation number of M1P is CCTCC NO: M 20221841; the preservation number of M45N is CCTCC NO: M 20221840.

[0013] The present invention also provides an application of the mixed bacteria M1H in promoting the production of pigeon pea plants, using the mixed bacteria M1H as a microbial agent. Among them, the preservation number of M1P is CCTCC NO: M 20221841; the preservation number of M45N is CCTCC NO: M20221840.

[0014] The present invention also provides an application of the mixed bacteria M1H in promoting the consumption of soil nutrients by pigeon pea, increasing the abundance of host microbial populations and reducing the abundance of pathogenic microbial populations, using the mixed bacteria M1H as a biofertilizer.

[0015] Preferably: After being treated with the mixed bacteria M1H, the consumption of pigeon pea growth significantly reduced the available potassium content in the soil by 40.75%, the hydrolyzable nitrogen content in the soil by 19.08%, and the organic matter content by 21.89%.

[0016] Preferably: After being treated with the mixed bacteria M1H, at the family and genus level, the abundance of the host microbial population increased significantly. The relative abundance of the genus Cajanus (Cajanus genus, Fabaceae family) increased from 26.39% to 37.23%; the abundance of the pathogenic microbial population decreased significantly. The relative abundance of the genus Zopfiella (Zopfiella genus, Chaetomiaceae family) decreased from 7.37% to 0.32%, and the relative abundance of the genus Podospora (Podospora genus, Lasiosphaeriaceae family) decreased from 3.92% to 0.47%.

[0017] The beneficial effects are as follows: The growth indexes of pigeon pea plants treated with the mixed bacteria M1H, such as plant height, breast diameter, and dry weight, have all been significantly improved, promoting the growth and development of pigeon pea. Specifically, the average plant height of pigeon pea is 128.37 cm, which is significantly increased by 31.93%; the average breast diameter is 7.61 mm, which is significantly increased by 23.74%; the average dry weight is 827.65 g, which is significantly increased by 26.41%. After being treated with the mixed bacteria M1H, the nutrients in the rhizosphere soil of pigeon pea changed, and the total nitrogen and total potassium contents in the soil both decreased. The total potassium content decreased from 2.87 g·kg -1 to 2.32 g·kg -1, it was significantly reduced by 19.16%; the available potassium, hydrolyzable nitrogen and organic matter contents in the soil were significantly reduced by 40.75%, 19.08% and 21.89% respectively, and the soil was alkalized to a certain extent, with the pH increasing from 6.34 to 6.67. The mixed bacteria M1H reduced the total nitrogen and total potassium contents in the soil, increasing the possibility of the conversion of total nitrogen and total potassium in the soil into available nutrients. However, the results showed that the hydrolyzable nitrogen and available potassium contents in the pigeon pea soil were significantly reduced. The treatment with the mixed bacteria M1H enhanced the consumption of hydrolyzable nitrogen and available potassium nutrients in the soil by pigeon pea, thus promoting the growth of pigeon pea; in addition, after treatment with the mixed bacteria M1H, at the family level, the relative abundance of Fabaceae increased from 26.39% to 37.23%, and the relative abundances of Chaetomiaceae and Lasiosphaeriaceae in the family Chaetomiaceae decreased from 9.13% to 2.14% and from 3.92% to 0.48% respectively; at the genus level, the relative abundance of Cajanus increased from 26.39% to 37.23%, while the abundances of pathogenic microbial populations were significantly reduced. The relative abundance of Zopfiella decreased from 7.37% to 0.32%, and the relative abundance of Podospora decreased from 3.92% to 0.47%. The dominant position of Cajanus did not change, but its relative abundance changed.

[0018] As can be seen from the above analysis of the technical solutions, compared with the traditional technology, the present invention provides a growth-promoting mixed bacteria M1H for pigeon pea that can increase the abundance of host microbial populations and reduce the abundance of pathogenic microorganisms.

[0019] The technical effects achieved are as follows: after the application of the mixed bacteria M1H provided by the present invention, it effectively promoted the conversion of total nitrogen and total potassium in the soil into hydrolyzable nitrogen and available potassium in the soil, enhanced the consumption ability of pigeon pea for available nutrients in the soil, significantly increased the relative abundance of the optimal genus Cajanus in the soil, and significantly reduced the relative abundances of pathogenic bacteria (Zopfiella and Podospora), improving the soil microenvironment and being beneficial to the growth and development of pigeon pea. At the same time, the present invention explored the internal relationship between the soil fungal community and soil nutrients under the condition of short-term application of microbial inoculants through high-throughput sequencing technology, providing a theoretical basis and practical guide for the pigeon pea industry and the development of green agriculture and animal husbandry, and providing a beneficial basis for strains. Brief Description of the Drawings

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0021] Figure 1 is a schematic diagram of the changes in the plant height, diameter at breast height, and dry weight of pigeon pea provided by the present invention for the strains to be screened. Among them, from left to right are CK, M45N, M1P, and M1H in sequence. Figure 1(a) is a schematic diagram of the changes in the plant height and diameter at breast height of pigeon pea for the strains to be screened; Figure 1(b) is a schematic diagram of the changes in the dry weight of pigeon pea for the strains to be screened;

[0022] Figure 2 The attached figure is a schematic diagram of the changes in the content of hydrolyzable nitrogen and available potassium in the soil provided by the present invention for the strains to be screened. From left to right are CK, M45N, M1P, and M1H in sequence.

[0023] Figure 3 The attached figure is a schematic diagram of the changes in the content of soil organic matter and pH provided by the present invention for the strains to be screened. From left to right are CK, M45N, M1P, and M1H in sequence.

[0024] Figure 4 is a schematic diagram of the microbial community composition at the family level in the potted soil treated with the control group, single strain M1P, and mixed strain M1H provided by the present invention. Figure 4(a) shows the difference in the species richness of the top ten soil fungal communities at the family level under different treatments; Figure 4(b) shows the difference in the richness of the soil Chaetomiaceae (Chaetomiaceae and Lasiosphaeriaceae) under different treatments;

[0025] Figure 5 is a schematic diagram of the microbial community composition at the genus level in the potted soil treated with the control group, single strain M1P, and mixed strain M1H provided by the present invention. Figure 5(a) shows the difference in the species richness of the top ten soil fungal communities at the genus level under different treatments; Figure 5(b) shows the difference in the richness of the pathogens (Zopfiella and Podospora) under different treatments;

[0026] Figure 6 The attached figure is a schematic diagram of the heat map distribution of sample species at the genus level using Spearman correlation analysis provided by the present invention.

[0027] Figure 7 is a schematic diagram of the relationship between the sample, microbial community, and soil nutrients provided by the present invention. Figure 7(a) shows the relationship between the soil physical and chemical properties and the soil fungal community at the genus level based on RDA correlation analysis; Figure 7(b) shows the differential relationship between the soil physical and chemical properties and the soil fungal community at the genus level based on Spearman correlation heat map analysis;

[0028] Figures 8(a) and 8(b) are colony diagrams of Paenibacillus polymyxa M45N (NA solid medium) and Serratia marcescens M1P (PDA solid medium) provided by the present invention respectively; Detailed implementation manners

[0029] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0030] An embodiment of the present invention discloses that the present invention provides a Cajanus cajan growth-promoting mixed bacterium M1H that can increase the abundance of host microbial populations and reduce the abundance of pathogenic microorganisms.

[0031] The raw materials and reagents involved in the embodiments are all obtained through commercial channels, and there are no requirements for their brands. The methods not mentioned are all common experimental methods. For example, Excel software is used for data processing and sequencing registration for drawing and data analysis, SPSS software is used for statistical analysis, R language (ggplot2 package and vegan package) is used to make microbial community structure diagrams and RDA diagrams, and STAMP software is used for species difference analysis and drawing, etc. Details are not elaborated here one by one.

[0032] Example 1

[0033] 1 Sample source

[0034] Strains were screened from the rhizosphere soil of Cajanus cajan. The Cajanus cajan soil samples were from the Cajanus cajan experimental field in Bagua Zhou, Qixia District, Nanjing City, Jiangsu Province, China. The five-point sampling method was used to collect Cajanus cajan rhizosphere soil samples, which were then taken back to the laboratory for processing and used for microbial screening.

[0035] 2 Isolation and screening

[0036] (1) Strain isolation medium: 0.3 g of NaCl, 0.3 g of KCl, 0.5 g of (NH4)SO2, 0.3 g of MgSO4·7H2O, 0.03 g of FeSO4·7H2O, 0.3 g of MnSO4·4H2O, 5.0 g of Ca3(PO4)2, 10 g of sucrose, 15 - 20 g of agar, 1000 mL of deionized water, pH 7.0 - 7.5.

[0037] (2) PDA solid medium for culturing fungi: 6.0 g of potato, 20.0 g of glucose, 18.0 g of agar, 1000 mL of distilled water, pH 7.0 - 7.2.

[0038] (3) NA solid medium for culturing bacteria: 10.0 g of peptone, 3.0 g of beef extract powder, 5.0 g of sodium chloride; 15.0 g of agar, 1000 mL of distilled water, pH 7.2 - 7.4.

[0039] (4) LB liquid medium: 10 g of peptone, 5 g of yeast extract powder, 5 g of sodium chloride, 1000 mL of deionized water, pH 7.2.

[0040] 2.2 Screening

[0041] Take 0.1 g of rhizosphere soil of pigeon pea and place it in a conical flask containing 100 ml of LB liquid medium, then place it on a shaker. After 3 days, using the plate dilution method, spread the serially diluted 10-fold soil samples on NA plates to isolate bacteria M45N and M1P respectively. Incubate in a 28 °C incubator on NA solid medium for about 2 - 5 days, pick single colonies, repeatedly streak and purify colonies with different morphologies, and inoculate the obtained strains onto solid medium plates respectively, then store them in a 4 °C refrigerator to obtain pure strains. Based on the main biological characteristics, ITS and rRNA analyses, bacteria M45N and M1P are obtained.

[0042] Example 2

[0043] Explore the effect of the growth-promoting effect of the strains. Combining with pot experiments, apply the screened pigeon pea rhizosphere bacteria to the soil of pigeon pea seedlings to explore their potential effects in production applications.

[0044] Preparation of microbial inoculum

[0045] To prepare the microbial inoculum, inoculate the purified isolates on NA plates until their derivatives cover half of the plate. After activating the screened strains, inoculate them into a 250 ml conical flask containing 100 ml of LB liquid, ferment at 25 °C and 200 rpm for 3 - 5 days, measure the concentration of the cultured microorganisms in the suspension with a UV-visible spectrophotometer at OD600, ensure the OD600 value of the bacterial liquid is in the range of 0.8 - 1.2 by dilution or continuous fermentation, and then seal and store it in a 4 °C refrigerator for later use. Dilute the culture 100 times when using to prepare the microbial inoculum.

[0046] In the pot experiment, dilute the stored strains 100 times, put 60 mL of the diluted bacterial liquid into each pot, set 3 parallels for each treatment, and use sterile culture solution as the blank control.

[0047] Planting of pigeon pea seedlings

[0048] The potted plants used leguminous plant Cajanus cajan as the experimental object. After soaking the Cajanus cajan seeds in pure water for 12 h, filtering the water, the seeds were soaked in 5% sodium hypochlorite solution for 10 min for disinfection, then washed with pure water until odorless, placed in a seedling cup to germinate for one week. When the seeds germinated into seedlings, the seedlings with similar growth height were transplanted into the potted plants, and one seedling was planted in each pot. The soil used for the potted plants was taken from the farmland soil in Bagua Zhou, Qixia District, Jiangsu Province, China. After the Cajanus cajan seedlings grew well, the prepared microbial inoculum was applied. Taking the day of applying the microbial inoculum as the first day, samples were taken by destruction three months later for experiments.

[0049] Determination and methods of potted plant indexes

[0050] For the plants: A vernier caliper and a tape measure were used to measure the ground diameter and plant height of the seedlings; and the Cajanus cajan was dried and killed by baking to measure its dry weight.

[0051] For the potted soil: The total potassium in the soil was determined by the NaOH alkali fusion-flame photometer method; the total nitrogen in the soil was measured by an elemental analyzer; the soil organic matter was determined by the potassium dichromate volumetric method; the hydrolyzable content in the soil was measured by the alkali diffusion method; the available potassium content was determined by the flame photometry method after extraction with ammonium acetate.

[0052] The results showed that:

[0053] Effects of microbial inoculum treatment on the growth characteristics of Cajanus cajan

[0054] As shown in Table 1, compared with the control group, the M1P and M1H treatments significantly increased the plant height of Cajanus cajan (P < 0.05, the same below), and their plant heights increased by 21.45% and 31.92% respectively, and there was no significant difference between the M1P treatment and the control group. From the perspective of the ground diameter of Cajanus cajan, the M1H was the optimal treatment, and it significantly increased by 23.74% compared with the control group. From the perspective of the dry weight of Cajanus cajan. Overall, all microbial inoculum treatments could increase the plant height, ground diameter and dry weight of Cajanus cajan, but the promotion effects were different. The order of the growth promotion benefits of each treatment was: mixed bacteria M1H > single bacteria M1P > single bacteria M45N > CK.

[0055] Table 1 Effects of microbial inoculum treatment on the growth indexes of Cajanus cajan

[0056]

[0057] Effects of strain treatment on the physical and chemical properties of the soil

[0058] As can be seen from Table 2, the contents of total nitrogen and total potassium in the rhizosphere soil of the potted plants treated with the mixed bacteria M1H decreased significantly (P < 0.05, the same below). The total soil nitrogen and total soil potassium decreased by 23.71% and 1.32% respectively. However, after treatment with the mixed bacteria M1H, the contents of hydrolyzable nitrogen, available potassium and organic matter in the soil decreased significantly, by 19.08%, 40.75% and 21.89% respectively, alleviating soil acidification, and the pH increased from 6.34 to 6.67. The potted plant experiment showed that the mixed bacteria M1H could convert the total nitrogen and total potassium nutrients in the soil into corresponding forms of available nutrients, and enhance the consumption of available soil nutrients by pigeon pea, thus promoting the growth of pigeon pea.

[0059] The potted plant experiment showed that the mixed bacteria M1H could significantly reduce the contents of total nitrogen and total potassium in the soil. However, the contents of hydrolyzable nitrogen and available potassium in the soil did not increase, but decreased significantly, and the corresponding growth indexes of pigeon pea also increased significantly, indicating that the treatment with the mixed bacteria M1H enhanced the consumption of hydrolyzable nitrogen and available potassium in the soil by pigeon pea. At the same time, the soil organic matter also showed the same trend. Therefore, through the availability of nitrogen source and potassium source, the mixed bacteria M1H significantly improved the soil environment, strengthened the consumption of soil nutrients by pigeon pea, and promoted the growth and development of pigeon pea, and could be used as a functional strain of growth-promoting microbial fertilizer.

[0060] Table 2 Effects of inoculant treatments on soil physical and chemical properties

[0061]

[0062] Example 3

[0063] Explore the effects of the mixed bacteria M1H on the composition of soil fungal communities.

[0064] Send the collected and sorted rhizosphere soil samples of pigeon pea to Guangzhou Keydi Biotechnology Co., Ltd. for high-throughput sequencing using the Omicsmart platform.

[0065] Detection and analysis of fungal diversity and fungal community structure in pigeon pea potting soil by high-throughput sequencing. As can be seen from Figure 5, compared with the control group, there was no significant change in the fungal community structure composition at the genus level in the rhizosphere soil of the potted plants after the treatment with the mixed bacteria M1H. However, significant changes occurred in the relative abundances of Cajanus, Zopfiella, and Podospora in the soil after the treatment with the mixed bacteria M1H (P < 0.05, the same below). The experiment showed that after the treatment with the mixed bacteria M1H, Cajanus, as the most dominant genus in the rhizosphere soil of pigeon pea, had its relative abundance increased from 26.39% to 37.23%; while the relative abundance of Zopfiella decreased from 7.38% to 0.32%, and the relative abundance of Podospora decreased from 3.92% to 0.47%. After consulting the literature, Zopfiella and Podospora belong to the Sordariomycetes, Sordariales, Chaetomiaceae and Lasiosphaeriaceae, and mainly contain important plant pathogens, which have a certain pathogenicity to plant growth and development. The Student's T-test method was used to conduct a significance test of species differences at the genus level, and the results are shown in Figure 5. There were significant differences in Cajanus, Zopfiella, and Podospora between the two groups.

[0066] Spearman analysis was carried out at the genus level to reflect the internal relationship between the bacterial community and soil environmental factors. The relationship is shown in Figure 7(b). At the genus level, OC, AK, AWN, and NN were the main environmental factors affecting Cajanus. AWN was significantly positively correlated with Cajanus (R2 = 0.738, P = 0.037), and AK was extremely significantly negatively correlated with Cajanus (P < 0.01); except for AWN, the remaining environmental factors had a positive correlation with Zopfiella, and AP and AN significantly affected the relative abundance of Zopfiella.

[0067] After treatment with the mixed bacteria M1H, the dominant position of Cajanus in the soil was not changed at the genus level, but the genus status of the pathogenic bacteria Zopfiella and Podospora was changed. After treatment with the mixed bacteria M1H, the relative abundance of the optimal genus Cajanus was significantly increased, and the relative abundances of the pathogenic bacteria Zopfiella and Podospora were significantly decreased. In addition, by combining the growth indexes of pigeonpea after treatment with the microbial agent, it can be found that the growth of pigeonpea was positively correlated with Cajanus and negatively correlated with Zopfiella and Podospora. Moreover, when comparing the mixed bacteria M1H with the single bacteria M1P, there was no significant difference in the relative abundances of Zopfiella and Podospora, but there was a significant difference in Cajanus. And the growth indexes of pigeonpea after treatment with the mixed bacteria M1H were better than those after treatment with the single bacteria M1P. This also indicates that the mixed bacteria have a stronger ability to promote the growth of pigeonpea than the single bacteria, and the relative abundance of Cajanus is the key factor affecting the growth promotion ability. Therefore, M1H can be used as a pigeonpea growth-promoting mixed microbial agent, providing a theoretical basis and practical guidance for the development of the pigeonpea industry.

[0068] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same and similar parts among the various embodiments, reference can be made to each other.

[0069] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for promoting the growth of pigeon pea, characterized in that, The mixed bacteria M1H is used as a microbial agent for application. M1H is composed of Serratia marcescens. M1P and Paenibacillus polymyxa. M45N; among them, the preservation number of M1P is CCTCC NO: M20221841; the preservation number of M45N is CCTCC NO: M20221840.

2. A method for increasing the relative abundance of host microorganisms in the rhizosphere soil of pigeon pea and decreasing the relative abundance of pathogenic microorganisms in the rhizosphere soil of pigeon pea, characterized in that, The mixed bacteria M1H is used as a microbial agent for application to the rhizosphere soil of pigeon pea. M1H is composed of Serratia marcescens. M1P and Paenibacillus polymyxa. M45N, which increases the relative abundance of the host microorganism Cajanus in the rhizosphere soil of pigeon pea and decreases the relative abundances of two pathogenic microorganisms, Zopfiella and Podospora, in the rhizosphere soil of pigeon pea; among them, the preservation number of M1P is CCTCC NO: M20221841; the preservation number of M45N is CCTCC NO: M20221840.

3. Use of the mixed bacterium M1H in promoting the production of pigeon pea plants, characterized in that, The mixed bacteria M1H is used as a microbial agent for application. M1H is composed of Serratia marcescens. M1P and Paenibacillus polymyxa. M45N; among them, the preservation number of M1P is CCTCC NO: M20221841; the preservation number of M45N is CCTCC NO: M20221840.

4. Use of a mixed bacterium M1H in enhancing the consumption of soil nutrients by pigeon pea, increasing the abundance of host microbial populations and reducing the abundance of pathogen populations, characterized in that, The mixed bacteria M1H is used as a biofertilizer for application. M1H is composed of Serratia marcescens. M1P and Paenibacillus polymyxa. M45N, which significantly reduces the contents of organic matter, hydrolyzable nitrogen and available potassium in the rhizosphere soil of pigeon pea, significantly increases the relative abundance of the host microorganism Cajanus in the rhizosphere soil of pigeon pea, and significantly decreases the relative abundances of the rhizosphere soil pathogens Zopfiella and Podospora; among them, the preservation number of M1P is CCTCC NO: M20221841; the preservation number of M45N is CCTCC NO: M20221840.

5. The application according to claim 4, wherein: After being treated with the mixed bacteria M1H, the content of available potassium in the rhizosphere soil of pigeon pea is significantly reduced by 40.75%, the content of hydrolyzable nitrogen in the soil is significantly reduced by 19.08%, and the content of soil organic matter is significantly reduced by 21.89%.

6. The application according to claim 4, characterized in that: After treatment with the mixed bacteria M1H, at the family level, the abundance of the host microbial population increased significantly. Among them, the relative abundance of Fabaceae increased from 26.39% to 37.23%, and the relative abundances of Chaetomiaceae and Lasiosphaeriaceae decreased from 9.13% to 2.14% and from 3.92% to 0.48% respectively; at the genus level, the relative abundance of Cajanus increased from 26.39% to 37.23%; the abundance of the pathogenic microbial population decreased significantly. The relative abundance of Zopfiella decreased from 7.37% to 0.32%, and the relative abundance of Podospora decreased from 3.92% to 0.47%.

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