Bacillus licheniformis BL-C15 and application thereof

Abstract

The invention belongs to the technical field of microorganisms, and particularly relates to bacillus licheniformis BL-C15 and application thereof. The invention provides bacillus licheniformis BL-C15, which is characterized in that the bacillus licheniformis BL-C15 is preserved in the China General Microbiological Culture Collection Center on November 25, 2024, the preservation number is CGMCC No.32787, and the preservation address is No.3, Yard 1, Beichen West Road, Chaoyang District, Beijing. The strain has the characteristics of high alkali resistance, salt resistance and acid production, not only can effectively restore saline-alkali degraded soil, but also has a remarkable plant growth promoting effect, and has important application value in the field of saline-alkali soil restoration. The strain can also be used for preparing microbial products for repairing saline-alkali soil.

Description

Technical Field

[0001] The present invention belongs to the field of microbial technology, and particularly relates to a Bacillus licheniformis BL-C15 and its application. Background Art

[0002] Soil salinization is a global problem threatening land use and ecological environment. Currently, about 954 million hectares of land globally show varying degrees of salinization, accounting for about 7% of the total land area. As the third largest country with saline-alkali land distribution in the world, China has about 1.5 billion mu of saline-alkali land, which is equivalent to the existing cultivated land area in China. Currently, saline-alkali land is an important reserve resource in China, and its reasonable development and utilization is an important guarantee for China's food security. Therefore, it is urgent to find a method for improving and repairing saline-alkali soil.

[0003] After years of research and practical application, traditional measures for improving saline-alkali soil mainly include water drainage for salt removal, soil replacement for salt reduction, and chemical neutralization for salt removal. However, these measures mostly have problems such as being laborious and time-consuming, causing secondary pollution, or having a short long-term effect, and it is difficult to continuously improve the soil. Microbial soil remediation measures have a better long-term effect, and the application is time-saving and labor-saving, which is a saline-alkali soil improvement method with good development prospects. However, currently commonly used microbial strains mostly use salt tolerance as the primary screening condition, often ignoring the alkali tolerance characteristics of the strains. In addition to having a high salt content, the soil pH of saline-alkali land is often alkaline, especially the pH of severely saline-alkali land can reach above 9.5. Therefore, it has become very urgent to find a microbial strain that is salt-tolerant and also has alkali tolerance and growth-promoting effects. Summary of the Invention

[0004] In view of this, the present invention provides a Bacillus licheniformis BL-C15 and its application. The Bacillus licheniformis BL-C15 has good salt tolerance and alkali tolerance characteristics, can normally reproduce in saline-alkali soil with high alkali and salt content, and effectively improve the saline-alkali soil; at the same time, this strain also has a significant growth-promoting effect on plants, and can ensure the normal growth of plants in saline-alkali soil.

[0005] To solve the above technical problems, the first aspect of the present invention provides a Bacillus licheniformis BL-C15. This strain was deposited in the China General Microbiological Culture Collection Center on November 25, 2024, with the deposit number CGMCC No. 32787, and the deposit address is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing.

[0006] Compared with the prior art, the Bacillus licheniformis BL-C15 provided by the present invention not only has the characteristics of high alkali resistance and salt tolerance, and can still grow and reproduce normally in a medium with a pH of 12 and / or a salt content of 10 wt%, and can play an important role in the remediation of saline-alkali soil. At the same time, the Bacillus licheniformis BL-C15 can also effectively degrade inorganic phosphorus in the soil, has the function of potassium solubilization, and a large amount of indole-3-acetic acid (IAA) produced by it can also promote the growth of plants, and the extracellular polymeric substances (EPS) produced have the function of improving the salt tolerance of plants, so as to ensure that plants can grow rapidly in saline-alkali or compacted degraded soil. The Bacillus licheniformis BL-C15 can not only effectively improve the saline-alkali soil in coastal areas, but also has a significant plant growth promotion effect, and has important application value in the field of remediation of saline-alkali soil, especially in coastal areas.

[0007] The second aspect of the present invention provides an application of the above-mentioned Bacillus licheniformis BL-C15 as a plant growth promoting product.

[0008] The third aspect of the present invention provides an application of the above-mentioned Bacillus licheniformis BL-C15 as a product for degrading inorganic phosphorus.

[0009] The fourth aspect of the present invention provides an application of the above-mentioned Bacillus licheniformis BL-C15 as a product for potassium solubilization.

[0010] The fifth aspect of the present invention provides an application of the above-mentioned Bacillus licheniformis BL-C15 in the production of indole-3-acetic acid (IAA).

[0011] The sixth aspect of the present invention provides an application of the above-mentioned Bacillus licheniformis BL-C15 in the production of extracellular polymeric substances (EPS).

[0012] The seventh aspect of the present invention provides an application of the above-mentioned Bacillus licheniformis BL-C15 as a product for improving saline-alkali soil.

[0013] Saline-alkali soil has a high salt content and strong alkalinity, and is prone to hardening or impoverishment after degradation.

[0014] Combined with the seventh aspect, the salt content of the saline-alkali soil is not less than 0.1 wt%.

[0015] Preferably, the salt content of the saline-alkali soil is 0.1 wt% to 10 wt%.

[0016] More preferably, the salt content of the saline-alkali soil is 3 wt% to 5 wt%.

[0017] Combined with the seventh aspect, the pH of the saline-alkali soil is 8 to 12.

[0018] Preferably, the pH of the saline-alkali soil is 9-12, and it can be 9, 10, 11, 12 or any value between any two of them.

[0019] The eighth aspect of the present invention provides a microbial inoculant, including the above-mentioned Bacillus licheniformis BL-C15.

[0020] Preferably, the microbial inoculant further includes a microbial carrier, and the microbial carrier can be at least one of biochar, diatomite or attapulgite.

[0021] Preferably, the microbial inoculant can be prepared by the following method: streak-activate the strain BL-C15 on an LB solid medium, culture for 46-50 h, pick the bacterial colonies and inoculate them into 100 mL of sterilized LB liquid medium, culture under the conditions of a shaker at 27-29 °C and 200 rpm / min for 24 h, expand the culture as a seed liquid until more than 80% of the spores are produced to obtain the BL-C15 bacterial liquid, adsorb the obtained bacterial liquid with a microbial carrier, and dry it to obtain the microbial inoculant. Description of the Drawings

[0022] Figure 1 It is the effect diagram of promoting the growth of wheat by Bacillus licheniformis BL-C15 in a petri dish;

[0023] Figure 2 It is the growth photo of Bacillus licheniformis BL-C15 in a saline-alkali medium. Among them, (a) is the growth photo of Bacillus licheniformis BL-C15 in a medium with a salt concentration of 10 wt%, and (b) is the growth photo of Bacillus licheniformis BL-C15 in a medium with a pH of 12;

[0024] Figure 3 It is the morphological characteristic diagram of Bacillus licheniformis BL-C15;

[0025] Figure 4 It is the phylogenetic tree of Bacillus licheniformis BL-C15 based on the gyrb gene;

[0026] Figure 5 It is the test result diagram of the inorganic phosphorus solubilization of Bacillus licheniformis BL-C15;

[0027] Figure 6 It is the test result diagram of the production of 3-indoleacetic acid (IAA) by Bacillus licheniformis BL-C15;

[0028] Figure 7 It is the photo of the growth promotion effect of Bacillus licheniformis BL-C15 on wheat. Detailed Embodiments

[0029] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0030] Unless otherwise specified, the experimental methods used in the following examples and comparative examples are all conventional methods in the art.

[0031] Unless otherwise specified, the raw materials, reagents, etc. used in the following examples and comparative examples are all obtained through commercial channels.

[0032] The formula of the LB solid medium in the following examples is: 10 g of tryptone, 5 g of yeast extract, 10 g of NaCl, 15 - 20 g of agar, made up to 1 L with distilled water, and the pH is adjusted to 7.0 - 7.2.

[0033] The formula of the LB solid medium containing 3% salt and with a pH of 9 is: 10 g of tryptone, 5 g of yeast extract, 30 g of NaCl, 15 - 20 g of agar, made up to 1 L with distilled water, and the pH is adjusted to 9 with NaOH solution.

[0034] The formula of the LB liquid medium in the following examples is: 10 g of tryptone, 5 g of yeast extract, 10 g of NaCl, made up to 1 L with distilled water, and the pH is adjusted to 7.0 - 7.2.

[0035] The formula of the inorganic phosphorus medium is: 10 g of glucose, 0.5 g of (NH4)2SO4, 0.5 g of yeast extract, 0.3 g of NaCl, 0.3 g of MgSO4, 0.3 g of KCl, 0.03 g of FeSO4, 0.03 g of MnSO4, 5 g of Ca3(PO4)2, 15 g of agar, made up to 1 L with distilled water, and sterilized at 115 °C for 30 min.

[0036] The formula of the organic phosphorus medium is: 10 g of glucose, 0.5 g of (NH4)2SO4, 0.5 g of yeast extract, 0.3 g of NaCl, 0.3 g of MgSO4, 0.3 g of KCl, 0.03 g of FeSO4, 0.03 g of MnSO4, 0.2 g of lecithin, 1 g of CaCO3, 15 g of agar, made up to 1 L with distilled water, and sterilized at 115 °C for 30 min.

[0037] The formula of the nitrogen-fixing medium is: 0.2 g of KH2PO4, 0.2 g of MgSO4, 0.2 g of NaCl, 5 g of CaCO3, 10 g of mannitol, 0.1 g of CaSO4, 15 g of agar, made up to 1 L with distilled water, and sterilized at 121 °C for 15 min.

[0038] The formula of the potassium-solubilizing medium is as follows: 5 g of sucrose, 2 g of Na2HPO4, 0.5 g of MgSO4, 0.005 g of FeCl3, 0.1 g of CaCO3, 1 g of potassium feldspar powder (300 mesh), 15 g of agar, and distilled water is added to make up to 1 L. Sterilize at 115 °C for 30 min.

[0039] The formula of the medium for producing 3-indoleacetic acid (IAA) is as follows: 1.15 g of K2HPO4, 20 g of peptone, 15 mL of glycerol, 0.1 g of L-tryptophan, 1.5 g of MgSO4, and distilled water is added to make up to 1 L. Sterilize at 115 °C for 30 min.

[0040] The formula of the medium for producing extracellular polymeric substances (EPS) is as follows: 20 g of sucrose, 0.2 g of K2HPO4, 0.5 g of KH2PO4, 100 g of NaCl, 0.5 g of MgSO4, 3 g of yeast powder, and distilled water is added to make up to 1 L. Sterilize at 121 °C for 15 min.

[0041] Example 1

[0042] Isolation and screening of Bacillus licheniformis BL-C15

[0043] Ten saline-alkali soil samples were collected from Wuyuan County, Inner Mongolia, Haixing County, Cangzhou, Hebei, and Huanghua City, Cangzhou, Hebei. The collected samples were placed in a pre-sterilized sterilization bag, cooled with an ice box and transported back to the laboratory, and stored in a 4 °C refrigerator. An LB medium with a salt content of 3 wt% and a pH of 9 was used for screening salt-tolerant and alkali-tolerant microorganisms. The specific steps were as follows: Weigh 5 g of the test soil sample and add it to a conical flask containing 45 mL of sterile water, shake at 200 r / min for 30 min to obtain a soil mixture. The soil mixture was diluted in gradients, and the soil mixtures with concentration gradients of 10 -4 、10 -5 and 10 -6 were selected. 100 μL of the soil mixture was respectively pipetted and spread on the saline-alkali LB solid medium (NaCl content 3 wt%, pH 9) for isolating salt-tolerant and alkali-tolerant microorganisms, with 3 plates for each dilution. The plates were inverted and placed in an incubator at 28 °C for 72 h. Colonies with different morphologies were picked and purified by streaking 3 times. The purified strains were stored in a -80 °C refrigerator with 50% glycerol for future use. Through the isolation on the saline-alkali LB medium, a total of 10 highly efficient salt-tolerant and alkali-tolerant strains were purified, named C-1, C-3, C-8, C-14, BL-C15, C-31, C-35, C-41, C-55, and L1-2 respectively.

[0044] Example 2

[0045] Growth promotion effect of salt-tolerant and alkali-tolerant strains

[0046] The 10 strains screened in Example 1 were activated on an LB plate, and then the activated strains were inoculated into an LB liquid medium (10 g tryptone, 5 g yeast extract, 10 g NaCl, supplemented with distilled water to 1 L, pH adjusted to 7.0 - 7.2), and cultured at 28 °C for 24 h. The bacterial solution was centrifuged at 10,000 rpm for 10 min, the supernatant was removed and 10 mL of sterile water was added and shaken to resuspend the bacteria, and then it was centrifuged again at 10,000 rpm for 10 min. The supernatant was poured off, and the bacteria were resuspended with sterile water and the OD 600 was adjusted to 0.1 to obtain a bacterial solution. 10 wheat seeds of uniform size were evenly placed in a sterilized petri dish lined with double-layer filter paper. After adding 5 mL of the bacterial solution correspondingly, vermiculite that had been sterilized and rinsed with water was covered, and 5 mL of water with a NaCl concentration of 1 wt% and a pH of 9 was poured in respectively. It was cultured under the conditions of 25 °C and a 12 h / 12 h light-dark cycle. After one week, the plant height, root length and fresh weight of the wheat were measured respectively, and the growth promotion rate was calculated (using the wheat growth plate with the same batch of equal-volume clear water replacing the bacterial solution as the blank control). The specific growth promotion of wheat by the bacterial solutions of different strains is shown in Table 1. The growth conditions of wheat corresponding to strain BL-C15 and the control group are as Figure 1 shown.

[0047] Table 1 Growth promotion effect of salt- and alkali-tolerant growth-promoting strains on wheat

[0048] Strain Plant height growth rate Root length growth rate Fresh weight growth rate C-1 12.52％ -0.7％ 11.11％ C-3 0.92％ -2.3％ 5.56％ C-8 5.49％ 2.14％ 5.56％ C-14 12.33％ 7.02％ 11.15％ BL-C15 16.42％ 21.95％ 25％ C-31 -7.91％ 2.92％ 5.56％ C-35 5.58％ 8.82％ 13.89％ C-41 8.95％ 2.61％ 16.67％ C-55 18.83％ 10.49％ 11.08％ L1-2 2.25％ 8.18％ 11.13％

[0049] As can be seen from Table 1, under the above saline-alkali conditions, strain BL-C15 has the best growth promotion effect on wheat. Therefore, this strain was used as the object of subsequent research.

[0050] Example 3

[0051] Determination of the saline-alkali tolerance range of the salt- and alkali-tolerant strain BL-C15

[0052] The screened salt- and alkali-tolerant strain BL-C15 was inoculated into the above LB solid media with salt content (NaCl concentration) gradients of 3 wt%, 5 wt%, and 10 wt% and LB solid media with pH gradients of 9, 10, 11, and 12 respectively, and cultured at 28 °C for 48 h. Observe the growth of the strain on the media corresponding to different salt contents and different pH values on the LB plate to determine its saline-alkali tolerance range. The results showed that the strain could still grow well on the medium with a salt content of 10% and a pH of 12, indicating that the strain has strong salt and alkali tolerance capabilities, especially strong alkali tolerance characteristics, and can grow normally in a high-alkali environment. The growth photos of strain BL-C15 in the medium with a salt content of 10 wt% and the medium with a pH of 12 are respectively as Figure 2 (a) and Figure 2 (b) shown.

[0053] Example 4

[0054] Identification of Bacillus licheniformis BL-C15

[0055] Morphological identification:

[0056] Take out the strain BL-C15 from the low-temperature refrigerator and inoculate it on the LB solid medium, and culture it in an incubator at 28°C for 48 h to observe the colony growth. Its morphological characteristics are as Figure 3 shown. It can be seen that this strain grows relatively fast, and the colonies are flat, with irregular edges, white, and opaque.

[0057] Molecular biology identification:

[0058] Inoculate the activated strain BL-C15 into the LB liquid medium and culture it on a shaker at 28°C for 24 h. Send the obtained bacterial liquid to Sangon Biotech (Shanghai) Co., Ltd. for amplification and sequencing with the primer pair of gyrB-FUP-1 (5′-GAAGTCATCATGACCGTTCTGCAYGCNGGNGGNAARTTYGA-3′, SEQ ID NO.1) and gyrB-RUP-2r (5′-AGCAGGGTACGGATGTGCGAGCCRTCNACRTCNGCRTCNGTCAT-3′, SEQ ID NO.2) to obtain the 16S rDNA sequence (as shown in SEQ ID NO.3). Compare and analyze the sequencing results on NCBI by BLAST. According to the BLAST results, the similarity between the BL-C15 strain and the gyrb gene sequence of Bacillus licheniforms is 99%. The phylogenetic tree of BL-C15 constructed is as Figure 4 shown.

[0059] Based on the above characteristics, it is determined that the strain BL-C15 belongs to Bacillus licheniforms. This strain BL-C15 was deposited in the China General Microbiological Culture Collection Center on November 25, 2024, with the deposit number CGMCC No. 32787, and the deposit address is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, and the taxonomic name is Bacillus licheniforms.

[0060] Among them, the reaction system used for PCR amplification is: 94°C, 5 min; 94°C, 30 s, 55°C,

[0061] 45 s, 72°C, 1 min, for a total of 30 cycles; 72°C, 10 min.

[0062] Example 5

[0063] In this example, the growth-promoting characteristics of strain BL-C15 were tested, and the performance test methods are as follows:

[0064] The strain BL-C15 obtained in Example 1 was inoculated on an LB solid medium for streaking and incubated in an inverted position in an incubator at 28°C for 1-3 days for standby. The activated strain was inoculated into 50 mL of LB liquid medium and cultured on a shaker at 28°C for 24 h to obtain the bacterial solution required for the test. The following tests were carried out using this bacterial solution:

[0065] (1) Test for the ability to dissolve inorganic phosphorus: 5 μL of the obtained bacterial solution was inoculated on an inorganic phosphorus medium and cultured at 28°C for 7 days. A transparent circle appeared around the strain, indicating that the strain has the ability to dissolve inorganic phosphorus. The results are shown in Table 2 and Figure 5 as follows.

[0066] (2) Test for the ability to dissolve organic phosphorus: 5 μL of the obtained bacterial solution was inoculated on an organic phosphorus medium and cultured at 28°C for 7 days. No turbidity spots appeared around the strain, indicating that the strain does not have the ability to dissolve organic phosphorus.

[0067] (3) Test for the ability to produce indole-3-acetic acid (IAA): The bacterial solution was inoculated into the IAA medium at an inoculation amount of 5%, cultured on a shaker at 28°C for 48 h, centrifuged at 10000×g for 10 min, 1 mL of the supernatant was taken, mixed with 2 mL of Salkowski reagent (15 mL of concentrated sulfuric acid, 25 mL of double-distilled water, 0.75 mL of 0.5 mol / L FeCl3), and incubated in the dark for 30 min. It was observed that the color of the IAA medium inoculated with the bacterial solution turned pink, while the IAA medium without the inoculated bacterial solution (recorded as the control group CK) remained colorless, indicating that the strain has the ability to produce IAA. The results are shown in Table 2 and Figure 6 as follows.

[0068] (4) Test for the ability to produce extracellular polymeric substances (EPS): The strain was inoculated into the EPS medium at an inoculation amount of 5% and cultured on a shaker at 28°C for 48 h. 10 mL of the culture solution was centrifuged at 10000 r / min for 10 min to remove the supernatant. The cells were dried and weighed. 30 mL of 95% ethanol was added to the supernatant for alcohol precipitation, and it was placed in a refrigerator at 4°C overnight. The mixture was centrifuged at 10000 r / min for 10 min to remove the supernatant, and the precipitate was dried and weighed. The ratio of the dry weight of EPS to the dry weight of the cells is the EPS yield of the strain. The results are shown in Table 2, indicating that the strain can produce extracellular polymeric substances EPS, and the production amount is 2.38 g / g.

[0069] (4) Test for the ability to dissolve potassium: 5 μL of the bacterial solution was inoculated on a potassium-dissolving medium and cultured at 28°C for 7 days. A transparent circle appeared around the strain, indicating that the strain has the ability to dissolve potassium. The results are shown in Table 2.

[0070] (5) Nitrogen fixation ability test: 5 μL of the bacterial solution was inoculated onto the nitrogen fixation medium and cultured at 28 °C for 7 days. It was observed that the strain did not grow, indicating that the strain does not have nitrogen fixation ability.

[0071] Table 2 Summary of the growth-promoting characteristics of strain BL-C15

[0072] Types of growth-promoting characteristics Growth-promoting effect Potassium solubilization +(1.98) Nitrogen fixation - Inorganic phosphorus solubilization (D / d) +(1.21) Organic phosphorus solubilization (D / d) - IAA production (ug / mL) +(7.06) EPS production (g / g) +(2.38)

[0073] Note: In Table 2, "+" indicates having this function; "-" indicates not having this function.

[0074] As can be seen from Table 2, strain BL-C15 has the abilities of potassium solubilization, inorganic phosphorus solubilization, IAA production, and EPS production. The above abilities ensure the salt tolerance, alkali tolerance, and growth-promoting performance of the strain.

[0075] Example 6

[0076] This example explores the growth-promoting effect of strain BL-C15 on wheat in saline-alkali soil.

[0077] In the following pot experiment, the saline-alkali soil used was the saline-alkali soil in Inner Mongolia. The specific physical and chemical indexes are shown in Table 3.

[0078] Table 3 Basic physical and chemical properties of the saline-alkali soil used in the pot experiment

[0079]

[0080] Preparation of bacterial suspension: Strain BL-C15 was streaked and activated on LB solid medium and cultured for 48 h. The bacterial colonies were picked and inoculated into 100 mL of sterilized LB liquid medium, cultured at 28 °C and 200 rpm / min on a shaker for 12 h. The bacterial solution was centrifuged at 10000 rpm for 10 min, the supernatant was removed and 10 mL of sterile water was added and shaken to resuspend the bacterial cells. Then it was centrifuged again at 10000 rpm for 10 min, the supernatant was poured off, and the bacterial cells were resuspended with sterile water and the OD 600 was adjusted to 0.1 to obtain the bacterial suspension.

[0081] A simulation experiment was carried out in flowerpots with a diameter of about 12 cm and a height of 12 cm: The bacterial suspension was mixed with the above-mentioned tested saline-alkali soil (the ratio was 10 kg of saline-alkali soil: 100 mL of bacterial suspension). At the same time, the treatment with an equal amount of sterile water added was used as the control group (CK). The washed wheat seeds of the same size were evenly planted in the flowerpots, 20 seeds per pot. After 4 weeks of cultivation, the plant height, root length, fresh weight, and chlorophyll content of the wheat were measured. The test results are shown in Table 4, and the growth conditions are as Figure 7 shown.

[0082] Table 4 Effects of strain BL-C15 on wheat growth

[0083] Different treatments Plant height (mm) Root length (mm) Fresh weight (g) Chlorophyll CK 197.23±15.48b 134.07±11.35b 0.20±0.02c 3.94±0.35b BL-C15 212.78±9.61a 143.39±13.16b 0.22±0.02b 4.00±0.31b

[0084] Note: The above data are expressed as "mean ± standard deviation (SD)", and different lowercase letters indicate significant differences at the p < 0.05 level.

[0085] Example 7

[0086] This example explores the effect of strain BL-C15 on the growth of sunflowers in saline-alkali soil. The test site is Wuyuan County, Bayannur, Inner Mongolia, and the soil texture is shown in Table 5.

[0087] Table 5 Basic physical and chemical properties of the soil in the test plot

[0088]

[0089] Preparation of saline-alkali soil improvement product (microbial inoculant): Streak and activate strain BL-C15 on LB solid medium, culture for 48 h, pick the bacterial colonies and inoculate them into 100 mL of sterilized LB liquid medium, culture under the conditions of 28 °C and 200 rpm / min on a shaker for 24 h, and use it as the seed liquid to expand the culture until more than 80% of the spores are produced to obtain the BL-C15 bacterial liquid. The obtained bacterial liquid is adsorbed by biochar to prepare a microbial inoculant with a viable count of 200 million / g. The obtained microbial inoculant is evenly spread on the soil surface at a dosage of 100 kg / mu before land cultivation and then plowed and leveled. Sunflowers are planted, and at the same time, sunflowers are planted in the same way in the soil without applying the microbial inoculant (as the control group). The growth conditions of sunflowers, the soil conductivity and pH in the saline-alkali soil applied with the microbial inoculant and the control group are shown in Table 6. It can be seen that compared with the control group, applying the microbial inoculant can significantly promote the growth of sunflowers, and the improvement amplitudes of the stem diameter, plant height and yield of sunflowers are 38.10%, 28.12% and 32.59% respectively. At the same time, it can also reduce the soil conductivity and pH, indicating that this strain can not only promote the growth of sunflowers, but also has an improvement effect on saline-alkali soil.

[0090] Table 6 Effects of microbial inoculant containing BL-C15 on the growth of sunflowers and soil physical and chemical properties

[0091]

[0092] The above is only the preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A strain of Bacillus licheniformis BL-C15, characterized in that: It was deposited in the General Microbiology Center of China Culture Collection Administration on November 25, 2024, with the deposit number CGMCC No.32787, and the deposit address is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing.

2. Use of the Bacillus licheniformis BL-C15 according to claim 1 as a plant growth promotion product.

3. Use of the Bacillus licheniformis BL-C15 according to claim 1 in degrading inorganic phosphorus products.

4. Use of the Bacillus licheniformis BL-C15 according to claim 1 as a potassium-solubilizing product.

5. Use of the Bacillus licheniformis BL-C15 according to claim 1 in the production of indole-3-acetic acid IAA.

6. Use of the Bacillus licheniformis BL-C15 according to claim 1 in producing extracellular polymers (EPS).

7. Use of the Bacillus licheniformis BL-C15 according to claim 1 as a saline-alkali soil improvement product.

8. The use of Bacillus licheniformis BL-C15 as a saline-alkali soil improvement product according to claim 7, characterized in that: The salt content of the saline-alkali soil is not less than 0.1 wt %.

9. The use of Bacillus licheniformis BL-C15 as a saline-alkali soil improvement product according to claim 7, characterized in that: The pH of the saline-alkali soil is 8-12.

10. A microbial agent, characterized in that: The invention comprises the Bacillus licheniformis BL-C15 according to claim 1.

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