Salt-tolerant planococcus FY231025 and application thereof

Abstract

The present application belongs to the technical field of microbial application, and more particularly relates to a salt and alkali tolerant planococcus FY231025 and application thereof. The planococcus FY231025 provided by the present application is preserved in the China General Microbiological Culture Collection Center, and the preservation time is May 13, 2025, and the preservation number is CGMCC NO: 34534. The bacteria have the functions of salt and alkali tolerance, phosphorus dissolution, IAA production and plant growth promotion, can be used for improving the salt and alkali tolerance of plants, slowing down the degree of soil salinization, protecting plants from active oxygen damage and promoting plant growth, and the strain can be prepared into a fertilizer with plant growth promotion and salt and alkali land improvement effects.

Description

Technical Field

[0001] This invention belongs to the field of microbial application technology, and more specifically, relates to a salt-tolerant zoococcus FY231025 and its applications. Background Technology

[0002] With global climate change and inadequate agricultural irrigation, soil salinization has become a significant problem affecting global agricultural production. As soil salinization intensifies, related environmental problems such as soil desertification and land degradation are emerging, leading to a rapid deterioration of the agricultural production environment. These environmental problems not only hinder the long-term application of crops but also pose a serious threat to the overall coordination and stability of the ecosystem. Therefore, effectively developing methods for improving and managing saline-alkali land, and seeking new utilization pathways, has become a major scientific and technological challenge that agricultural production must address in the new era. Research on the application of microbial improvement technologies, particularly the role of halophilic bacteria in the improvement of saline-alkali soil, is of positive significance for achieving the long-term utilization of saline-alkali land resources.

[0003] Microorganisms play a crucial role in the improvement of saline-alkali soils. They can improve soil structure, reduce salinity, and enhance soil fertility through various mechanisms, thereby promoting plant growth. With the advancement of science and technology, microbial improvement technology for saline-alkali land, as a new and continuously effective improvement technique, has received increasing attention from researchers. This technology primarily utilizes the power of microorganisms to improve saline-alkali land by enhancing soil microbial activity and diversity, demonstrating its low pollution, high ecological and environmental benefits, and sustainability. This process mainly involves the action of animals, plants, and other microorganisms, transforming salt and other harmful substances in saline-alkali land into harmless or low-toxicity substances, increasing organic matter content, and creating an environment suitable for plant growth, thus establishing a complete and sustainable soil ecological environment. Therefore, it is essential to develop functional microorganisms and their products that can enhance crop salt stress tolerance and improve soil conditions in saline-alkali lands. Summary of the Invention

[0004] In order to solve the above-mentioned technical problems, the purpose of this invention is to provide a salt-tolerant zoococcus FY231025 and its application.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] This invention provides a zoococcus FY231025, which is classified and named as follows: Planococcus rhizosphaeraeIt is deposited at the China General Microbiological Culture Collection Center, located at No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing, on May 13, 2025, with accession number CGMCCNO.34534.

[0007] The Zoococcus FY231025 provided by this invention has the functions of salt and alkali tolerance, phosphorus solubilization, IAA production and plant growth promotion. It can be used to improve the salt and alkali tolerance of plants, slow down the degree of soil salinization, protect plants from reactive oxygen species damage and promote plant growth. Furthermore, the strain provided by this invention can be prepared into fertilizer with plant growth promotion and saline-alkali soil improvement effects.

[0008] The present invention also provides a microbial fertilizer, with Zoococcus FY231025 as the active ingredient.

[0009] The present invention also provides the application of the aforementioned Zoococcus FY231025 in the production of IAA.

[0010] The present invention also provides the application of the aforementioned Zoococcus FY231025 or the aforementioned microbial fertilizer in the improvement of saline-alkali soil.

[0011] Furthermore, the improvement is achieved through the phosphate-solubilizing function of Zoococcus FY231025.

[0012] The present invention also provides the application of the Zoococcus FY231025 or the microbial fertilizer in improving the salt and alkali tolerance of corn.

[0013] Furthermore, the improvement of corn's salt and alkali tolerance is achieved by soaking corn seeds in a bacterial solution of Zoococcus FY231025.

[0014] The present invention also provides the application of the Zoococcus FY231025 or the microbial fertilizer in promoting corn growth.

[0015] Furthermore, the promotion of maize growth includes increasing maize root length, fresh weight, plant height, stem diameter, and leaf thickness. This invention has the following beneficial effects:

[0016] The Zoococcus FY231025 provided by this invention possesses salt and alkali tolerance, phosphorus solubility, and IAA production characteristics. It can effectively improve the soil microenvironment of plant roots, reduce the stress caused by salt and alkali on plants, provide nutrients for plant growth, and ultimately promote plant growth. Therefore, FY231025 of this invention has significant application value in saline-alkali land improvement, enhancing plant tolerance to salt and alkali stress, and promoting plant growth. It can be used in the preparation of fertilizers with plant growth-promoting and saline-alkali land improvement effects. Attached Figure Description

[0017] Figure 1This is a colony morphology diagram of FY231025.

[0018] Figure 2 This is a transmission electron microscope (TEM) image of FY231025.

[0019] Figure 3 This is a growth statistics chart for FY231025.

[0020] Figure 4 The bar charts show the growth of FY231025 under different NaCl concentrations. In the bar chart, A is the growth of FY231025 under NaCl concentrations ranging from 0 g / mL to 12 g / mL, and B is the growth of FY231025 under NaCl concentrations ranging from 13 g / mL to 22 g / mL.

[0021] Figure 5 The bar chart shows the growth of FY231025 under different pH conditions.

[0022] Figure 6 The graph shows the results of the phosphorus dissolution test for FY231025.

[0023] Figure 7 The image shows the growth-promoting effect of FY231025 on corn.

[0024] Figure 8 The bar chart shows the growth-promoting effect of FY231025 on maize. In the bar chart, A is the maize root length, B is the maize stem diameter, C is the maize fresh weight, and D is the maize plant height.

[0025] Figure 9 This is a statistical chart of corn leaf thickness, where * indicates P<0.05 and ** indicates P<0.01. Detailed Implementation

[0026] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments, but this should not be construed as limiting the invention. Unless otherwise specified, the technical means used in the following embodiments are conventional means well known to those skilled in the art, and the materials, reagents, etc. used in the following embodiments are commercially available unless otherwise specified.

[0027] Example 1: Isolation, identification and application of FY231025.

[0028] I. Separation of FY231025.

[0029] Rhizosphere soil samples of *Suaeda salsa* from Wuhai area, Inner Mongolia Autonomous Region, were selected, placed in sterile bags, and brought back to the laboratory at low temperature for processing. The rhizosphere soil was gently shaken off, and 0.1g of the saline-alkali soil from the rhizosphere was added to 900μL of sterile water to form a mixture. The mixture was vortexed for 2 minutes to ensure thorough dispersion of the rhizosphere soil in the sterile deionized water. After standing for 5 minutes, a suspension was obtained. 1mL of the suspension was added to 9mL of sterile deionized water to obtain a concentration of 10%. -1 A soil suspension of g / mL was successively diluted to obtain 10 g / mL. -2 g / mL, 10 -3 g / mL, 10 -4 g / mL, 10 -5 Prepare gradient suspensions of g / mL, vortex to mix, and spread each dilution gradient onto LB solid medium. Repeat each gradient three times and incubate upside down in a 30°C incubator. Pick single colonies and inoculate them onto LB liquid medium to obtain pure cultures of FY231025 single colonies.

[0030] II. Identification of FY231025.

[0031] 1. Morphological identification: such as Figure 1 As shown, after two days of cultivation on LB agar at 32°C, strain FY231025 formed round, low-convex colonies, which is consistent with the colony morphology characteristics of the genus *Zoococcus*. Figure 2 As shown in the transmission electron microscope image, strain FY231025 has a spherical shape and flagella.

[0032] 2. Whole Genome Analysis: Genomic DNA was extracted using the cetyltrimethylammonium bromide method. All genome sequencing tasks were performed by Shanghai Paisenno Biotechnology Service Co., Ltd. using the Illumina Novaseq platform. The whole genome sequence results showed that the genome length of FY231025 was 3798726 bp, with a G+C content of 50.2%. The ANI value was calculated using the JSpeciesWS online ANI tool (http: / / jspecies.ribohost.com / jspeciesws / ). Planococcus antioxidants Y74T, Planococcus chinensis DX3-12T, Planococcus glaciei 0423T and Planococcus halotolerans SCU63T was used as the reference strain. The ANI value used was calculated based on the BLAST method and is referred to as the ANIb value. The dDDH value was calculated using the Genome-to-Genome Distance CalcuLator (https: / / ggdc.dsmz.de / ggdc.php).

[0033] The results are shown in Table 1. FY231025 and four Zoococcus spp. reference strains Planococcus antioxidants Y74T, Planococcus chinensis DX3-12T, Planococcus glaciei 0423T and Planococcus halotolerans The ANIb values ​​for SCU63T are 77.5%, 77.1%, 84.4%, and 78.2%, all significantly lower than the species threshold of 95%. The dDDH values ​​are 22.6%, 21.3%, 39.2%, and 22.4%, also far below the 70% species threshold. Therefore, these values ​​confirm the unique taxonomic position of FY231025 within the genus *Zoococcus*.

[0034] Table 1: ANIb and dDDH values ​​between FY231025T and the reference strain

[0035]

[0036] Note: 1 represents Planococcus antioxidans Y74T, 2 is Planococcus chinensis DX3-12T, 3 is Planococcus glaciei 0423T, 4 is Planococcus halotolerans SCU63T.

[0037] Based on morphological and molecular biological identification results, FY231025 exhibits morphological characteristics similar to the Salinecoccus type strain and has low levels of ANI and dDDH values, proving that FY231025 is a new species of the genus *Aggregatibacter*.

[0038] III. Study on the function of the strain.

[0039] 1. Growth curve determination: A single colony of FY231025 was placed on LB liquid medium and incubated on a constant temperature shaking incubator at 30℃ and 170 r / min. The absorbance (OD) was measured every 12 hours using a UV spectrophotometer. 600 The experiment was repeated three times at each time point, and the average value was taken to plot the growth curve. The experimental results are as follows: Figure 3 As shown, FY231025 reached the logarithmic growth phase between 24 and 36 hours.

[0040] 2. Salt tolerance test: Single colonies of FY231025 in the logarithmic growth phase were inoculated into LB liquid medium with NaCl concentrations ranging from 0 g / mL to 20 g / mL, and then incubated on a constant temperature shaking incubator at 30℃ and 170 r / min for 36 h. The absorbance (OD) was measured using a UV spectrophotometer. 600 The result is as follows Figure 4 As shown, FY231025 can tolerate salt concentrations ranging from 1 g / mL to 18 g / mL, indicating that this strain has good salt tolerance.

[0041] 3. Alkali tolerance test: Single colonies of FY231025 in the logarithmic growth phase were inoculated into LB liquid medium with pH 3-12, and then incubated on a constant temperature shaking incubator at 30℃ and 170r / min for 36h. The absorbance (OD) was measured using a UV spectrophotometer. 600 The result is as follows Figure 5 As shown, FY231025 grows normally within the pH range of 7 to 10, indicating that this strain has good alkali resistance.

[0042] 4. IAA Production Capacity Determination: IAA content was determined using the Salkowski colorimetric method. FY231025 cells in logarithmic growth phase were inoculated into 50 mL of LB liquid medium containing 100 mg / L tryptophan and cultured at 30°C with shaking at 170 rpm for 48 h. 2 mL of the bacterial suspension was centrifuged at 8000 rpm for 10 min, and 0.5 mL of the supernatant was collected. An equal volume of Salkowski colorimetric solution was added, and the mixture was incubated in the dark for 30 min. The absorbance at 530 nm was measured, and the IAA content was calculated based on the absorbance. The calculation formula is: y = 104.2x - 3.8341, where x represents the absorbance at 530 nm and y represents the IAA content.

[0043] The results are shown in Table 2. The fermentation broth of FY231025 contained 3.12±0.032 mg / L of IAA. This result indicates that FY231025 plays an important role in promoting plant growth in saline-alkali land. This is because IAA is the most important form of natural auxin in plants, which can increase plant roots and promote root elongation, thereby increasing the absorption of nutrients from the soil and promoting plant growth.

[0044] Table 2: IAA Results for FY231025T

[0045]

[0046] 5. Phosphorus solubility test of FY231025: FY231025 in the logarithmic growth phase was inoculated onto inorganic phosphorus medium, such as... Figure 6 As shown, a transparent ring appeared around the colony after 72 hours, indicating that FY231025 has the ability to decompose inorganic phosphorus, convert insoluble phosphates into soluble phosphates, and improve the soluble phosphate content in the soil.

[0047] IV. The impact of FY231025 on maize growth.

[0048] 1. Seed Treatment: Plump corn seeds were selected. These seeds were provided by Inner Mongolia Xingfeng Seed Industry Co., Ltd., and the tested variety was Xingke 5. The experimental group seeds were treated with OD... 600Seeds were soaked in FY231025 bacterial solution (1.0) for 24 hours, while control group seeds were soaked in deionized water for 24 hours.

[0049] 2. Experimental soil: Saline-alkali soil was taken from the Yellow River Equestrian Park in Jiuyuan District, Baotou City, Inner Mongolia Autonomous Region, with coordinates E109.811645, N40.515128. Soil from 3cm below the surface was taken and placed in a sealed bag.

[0050] 3. Experimental Treatments: CK was the control group, with potted plants grown in saline-alkali soil and containing three seeds soaked in deionized water. T was the experimental group, with potted plants grown in saline-alkali soil and containing three seeds soaked in bacterial solution. After 27 days of cultivation, the plants were harvested. The root length, stem diameter, plant height, leaf thickness, and fresh weight of the corn seedlings were measured using a ruler and a balance.

[0051] 4. Experimental Index Detection: Root length measurement is the straight-line length of the entire root system from the base to the tip of the longest root. The target plant, along with the surrounding soil, is dug up, keeping the root system intact. The roots, still with soil, are placed in a large basin filled with clean water. Gently shake the plant to rinse away the soil adhering to the roots, changing the water repeatedly until the roots are clean and free of soil. Drain the water, and lay the cleaned roots flat on absorbent paper or suspend them in the air to drain briefly to remove excess moisture. Arrange the roots carefully, using tweezers to spread and straighten them as much as possible, laying them flat on a measuring table or clean surface. Use a measuring tape to measure the straight-line distance from the base of the stem to the end of the longest root. Record the measurement in centimeters.

[0052] The stem diameter is measured at the base of the corn stalk, specifically the diameter of the first distinct internode above ground. Using vernier calipers, gently clamp the measuring jaws on both sides of the selected internode, ensuring the calipers are perpendicular to the stalk axis. Gently close the calipers, ensuring they contact the stalk surface without compressing or deforming it. Read and record the data. The unit of measurement is centimeters.

[0053] Plant height is measured vertically from the rootstock to the highest point of the plant, specifically the tip of the last fully unfolded leaf. Place the plant upright on a flat surface and measure vertically from the root collar to the highest point using a measuring tape. Record the measurement in centimeters.

[0054] Leaf thickness is measured at the midpoint of a fully unfolded leaf, avoiding the midrib. In the central area of ​​the leaf, avoiding the midrib and large lateral veins, choose a flat spot, specifically the middle section between the midrib and the leaf margin. Place the measuring point between the caliper jaws. Close the calipers extremely gently until they just touch both sides of the leaf, being absolutely careful not to squeeze or deform the leaf. Record the data in centimeters.

[0055] Fresh weight measurement measures the weight of the entire plant while it is fresh and still moist. Dig up the target plant along with the surrounding soil, keeping the root system intact. Rinse the roots thoroughly with running water, changing the water repeatedly until the roots are clean and free of soil. Gently absorb any remaining water droplets from the washed roots with absorbent paper. Quickly and steadily place the plant on the weighing container. Record the weight immediately after the balance reading stabilizes. The unit of measurement is grams.

[0056] 5. Experimental Results: In Figure 7 The results clearly show that inoculation with the bacterial strain significantly promotes corn growth. Corn roots are responsible for absorbing nutrients, providing energy, anchoring the plant, and preventing lodging. The growth of corn roots is an important indicator of corn growth quality. The stem diameter of corn seedlings affects later plant growth; therefore, the stem diameter of corn seedlings can be used as an important indicator of corn growth. Corn fresh weight reflects the robustness of the corn plant. The growth characteristics of inoculated and uninoculated corn, including root length, stem diameter, plant height, leaf thickness, and fresh weight, are shown in the figures. Figure 8 and Figure 9 As shown in the figure, the root length, stem diameter, and fresh weight of corn treated with FY231025 were all higher than those of the control group without the strain. Increased root length improved the plant's ability to absorb water and nutrients and reduced salt accumulation. Significance analysis showed a significant increase in the differential bacterial count between the FY231025-treated corn experimental group and the control group without the strain. Increased plant height reduced soil surface evaporation and salt accumulation; increased stem diameter enhanced plant resistance and reduced soil erosion; increased leaf thickness reduced water evaporation and thus salt accumulation; and increased fresh weight indicated good plant growth and better adaptation to saline-alkali environments. Therefore, FY231025 has a promoting effect on corn growth.

[0057] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

Claims

1. Application of Planococcus sp. FY231025 in improving salt and alkali tolerance of corn, wherein the Planococcus sp. FY231025 is classified as Planococcus rhizosphaerae , and is preserved in the China General Microbiological Culture Collection Center on May 13, 2025, with a preservation number of CGMCC NO. 34534.

2. Use according to claim 1, characterized in that, The improvement of the salt and alkali tolerance of the corn is achieved by soaking the corn seeds in the Planococcus rhizosphaerae FY231025 bacterial solution.

3. Use according to claim 1, characterized in that, The improvement of the salt and alkali tolerance of the corn is to promote the growth of the corn in the salt and alkali environment.

4. Use according to claim 3, characterized in that, The promotion of the growth of the corn in the salt and alkali environment is to improve the root length, fresh weight, plant height, stem diameter and leaf thickness of the corn. The promotion of the growth of the corn in the salt and alkali environment is to improve the root length, fresh weight, plant height, stem diameter and leaf thickness of the corn.

Images