Bacillus subtilis subsp. Deserticola with selenium enrichment and disease bacterium inhibition effects

Abstract

The invention discloses a bacillus subtilis subsp. Deserticola with selenium-rich and disease bacterium inhibition effects, and belongs to the technical field of selenium-rich biocontrol bacteria. The bacillus subtilis subsp. Deserticola is preserved in the China General Microbiological Culture Collection Center (CGMCC), and the preservation number of the bacillus subtilis subsp. Deserticola is CGMCC No.34489. The bacillus subtilis subsp. Deserticola is a bacillus subtilis subsp. Deserticola strain. The strain has efficient selenium-rich conversion capability, and can convert inorganic selenium (such as sodium selenite) with relatively high toxicity into organic selenium or nano-selenium particles with low toxicity or no toxicity and high bioavailability. In addition, the strain also has a better antifungal effect, and has an excellent inhibition effect on fungi such as fusarium solani, arbuscular oryzae, fusarium equiseti, fusarium oxysporum and the like, so that the purpose of biological prevention and control can be achieved, plant diseases can be prevented, and healthy growth of plant crops is facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of selenium-enriched biocontrol bacteria, and particularly relates to a Bacillus subtilis deserticola strain that is selenium-enriched and has the function of inhibiting pathogenic bacteria. Background Art

[0002] Selenium enrichment in agriculture refers to the phenomenon of significantly increasing the selenium content of crops, soil, or agricultural products through natural or artificial means, thereby improving the nutritional value of the agricultural products and meeting human health needs. Selenium is a trace element crucial to human health, possessing numerous physiological functions, including antioxidant, immune-boosting, anti-cancer, and cardiovascular protection. The core goal of selenium enrichment in agriculture is to produce selenium-rich agricultural products and promote the development of healthy and functional agriculture. Selenium-enriched agricultural products have higher nutritional value and improved taste, such as rich flavor, comprehensive nutritional profile, and pleasant mouthfeel. Furthermore, selenium's antioxidant properties can extend the growing season of crops and enhance their absorption and utilization of other nutrients. In selenium-enriched agriculture, scientific planting and breeding techniques can optimize soil structure, increase soil selenium levels, and thus improve soil quality. Manure produced from selenium-enriched poultry and livestock farming can be used to make fertilizer, which in turn increases the selenium content of organic fertilizers, thereby contributing to a virtuous cycle of agricultural ecology.

[0003] In recent years, with the gradual improvement of people's health concepts and the continuous strengthening of environmental awareness, eco-friendly agricultural adjuvants such as selenium-enriched bacteria have received increasing attention. Research on selenium-enriched microorganisms has made significant progress in strain screening, mechanism analysis and application of microbial agents. However, there are still the following shortcomings: On the one hand, there is insufficient strain screening and functional diversity, which is specifically manifested in the limitations of screening specific strains and the imbalance between functional singleness and composite performance. Moreover, although some strains have the ability to enrich selenium, resist oxidation and degrade ethanol, most strains have a single function and are difficult to cope with the actual agricultural scenarios of multi-factor stress. On the other hand, the disconnection between the application of microbial agents and the actual agricultural environment is also an important factor that makes it difficult for many selenium-enriched bacteria to be put into large-scale agricultural production. Strains that are efficient under laboratory conditions often fail to colonize in field applications due to factors such as soil physical and chemical properties and microbial competition.

[0004] Furthermore, inorganic selenium in soil, such as sodium selenite, is highly toxic. Therefore, biotransformation is essential to convert inorganic selenium into less toxic organic selenium (such as selenoproteins and selenium nanoparticles) or elemental selenium. Furthermore, pathogenic bacteria in the soil can cause crop diseases, impacting not only yield but also selenium accumulation in crops. Therefore, it is essential to identify selenium-enriching biocontrol bacteria that can both efficiently enrich selenium and control a variety of plant diseases, thereby increasing the value of crop operations. Summary of the Invention

[0005] The present invention provides a Bacillus subtilis subsp. Inaquosorum strain, which is deposited in the General Microbiology Center of the China Culture Collection Administration of Microorganisms with a deposit number of CGMCC No. 34489.

[0006] The present invention provides the application of the above-mentioned Bacillus subtilis subspecies desertificans in the conversion of inorganic selenium; the application refers to converting inorganic selenium into elemental selenium or organic selenium; the inorganic selenium is selected from one or more of sodium selenite, sodium selenate, and selenide.

[0007] The present invention provides the use of the above-mentioned Bacillus subtilis subspecies deserticola in the preparation of a bacterial agent for inhibiting pathogenic bacteria; the pathogenic bacteria are selected from plant pathogenic bacteria, specifically one or more of Fusarium solani, Erythrocera oryzae, Fusarium equisetum, and Fusarium stratum.

[0008] The present invention provides application of the above-mentioned Bacillus subtilis subspecies desertificans in selenium enrichment of plants.

[0009] The present invention provides application of the above-mentioned Bacillus subtilis subspecies desertificans in improving plant growth performance.

[0010] The present invention provides a microbial agent, which contains the above-mentioned Bacillus subtilis subspecies desertificans.

[0011] The above-mentioned microbial agent can be prepared by the following methods: Bacillus subtilis subspecies deserticola was added to LB bacterial culture solution, and then the culture was shaken and fermented in a shaker at 28° C. and 150 rpm for 24 hours to obtain a microbial agent.

[0012] The present invention provides a method for enriching plants with selenium, which comprises the following steps: irrigating the roots of plants with the microbial agent, or spraying the microbial agent on the leaves of plants to achieve a selenium-enriched effect on the plants.

[0013] In the above-mentioned method for enriching plants with selenium, preferably, inorganic selenium can be added to the microbial agent; the concentration of the inorganic selenium in the microbial agent is selected from 10 to 60 mg / L.

[0014] The beneficial effects of the present invention are: The strain BZY-KUYA-5, obtained through screening, possesses highly efficient selenium-rich conversion capabilities. It can convert highly toxic inorganic selenium (such as sodium selenite) into low- or non-toxic organic selenium or nano-selenium particles with high bioavailability. Within 24 hours, strain BZY-KUYA-5 achieved a conversion rate exceeding 70% for 40 mg / L sodium selenite. This conversion capability significantly reduces the environmental toxicity of selenium and increases its bioavailability.

[0015] In addition to its selenium-enriching effect, strain BZY-KUYA-5 also has good antifungal effects. It can have excellent inhibitory effects on fungi such as Fusarium solani, Fusarium oryzae, Fusarium equisetum, and Fusarium thunbergii, thereby achieving the purpose of biological control, preventing plant diseases, and promoting the healthy growth of plant crops. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a confrontation experiment diagram of BZY-KUYA-5; among them, a is Fusarium solani, b is Erythrocera oryzae, c is Fusarium equisetum, and d is Fusarium lamellifolium; Figure 2 This is a confrontation experiment diagram of BZY-BEI-8; among them, a is Fusarium solani, b is Erythrocera oryzae, c is Fusarium equisetifolia, and d is Fusarium lamellifolia; Figure 3 This is the concentration gradient diagram of the selenium enrichment experiment; A is BZY-KUYA-5, B is BZY-BEI-8; Figure 4 This is the phylogenetic tree of BZY-KUYA-5; Figure 5 This is the phylogenetic tree of BZY-BEI-8. DETAILED DESCRIPTION

[0017] In the present invention, the formula (1 L) of the liquid culture medium is as follows: 8.0 g of tryptone, 2.0 g of yeast powder, 10.0 g of sodium chloride, pH 7.2-7.4, and 0.1 g of sodium selenite.

[0018] In the present invention, the formula (1 L) of the solid culture medium is as follows: 10.0 g of tryptone, 5.0 g of yeast extract powder, 5.0 g of sodium chloride, 12.0 g of agar, and a pH value of 7.0±0.2.

[0019] The other materials used in the present invention, unless otherwise stated, can be obtained through commercial channels. Unless otherwise specified, other terms used in the present invention generally have the meanings commonly understood by those of ordinary skill in the art. The present invention will be further described in detail below with reference to specific examples and data. The following examples are merely for illustration of the present invention and are not intended to limit the scope of the present invention in any way.

[0020] 1. Screening and identification of selenium-rich biocontrol bacteria 1. Initial screening of selenium-resistant strains In Binzhou, Shandong Province, eight samples were collected according to the soil microbial collection method. These included two samples of selenium mine slag, two samples of plant rhizosphere soil near the surface water flow of the selenium mine tailings, two samples of bottom sediment from the surface water flow of the selenium mine tailings, and two samples of farmland soil near the selenium mine. At each sampling point, surface debris was removed. Soil samples were collected at a depth of 10 to 20 cm, free of rocks, plants, rhizomes, and fallen leaves. After multiple mixing, the samples were placed in sterile ziplock bags, labeled, stored at low temperatures, and promptly brought back to the laboratory for screening for selenium-resistant bacteria.

[0021] The collected samples were subjected to microbial isolation. Weigh 5 g of soil sample and place it in a sterilized conical flask containing 45 mL of deionized water. Oscillate at 28°C and 150 rpm for 1 hour and let it rest for 30 minutes. Take 2 mL of soil suspension supernatant and add it to liquid culture medium containing 100 μg / mL of selenium for enrichment culture. The enriched bacterial liquid was separated by dilution plate method and 10 -4 , 10 -5 , 10 -6 , 10 -7 Spread 100 μL of the diluted solution onto a solid culture medium without selenium and incubate in a constant-temperature incubator for 3 days to obtain single colonies. Observe the growth and species of the strain, and select well-growing single colonies with distinct morphological characteristics. Repeat the plate streak method to isolate and purify the culture until multiple single colonies appear on the culture medium, thus obtaining a pure culture. Inoculate the purified strain onto a slant culture medium in a test tube and store in a refrigerator at 4°C.

[0022] The isolated and purified strains were inoculated into liquid culture medium for expansion and cultured at 28°C and 150 rpm for 48 hours. Ten μL of the culture was then inoculated onto solid culture medium containing varying selenium concentrations for a gradient acclimation. Initial screening was performed using a 10 μg / mL selenium gradient. Strains that could tolerate 1000 μg / mL of selenium were then tested for their ability to tolerate higher concentrations. The selenium concentration on the plates was increased exponentially along the selenium gradient. The growth and colony characteristics of the strains were observed, and strains with poor selenium tolerance were gradually eliminated. Once the most tolerant strains were identified, they were purified to obtain pure selenium-tolerant strains. Five selenium-tolerant strains were obtained and designated as follows: BZY-KUYA-5, BZY-BEI-8, BZY-3-KU-B, BZY-3-KU-BSYK-2, and BZY-2-CEBAODUAN.

[0023] The five strains obtained from the initial screening were subjected to selenium enrichment experiments and antifungal confrontation experiments to further screen selenium-rich biocontrol bacteria with both selenium-rich and disease-resistant properties.

[0024] 2. Antifungal confrontation experiment A confrontation experiment was conducted between Fusarium solani, Nectria cinnabarina, Fusarium equiseti, and Fusarium proliferatum and the above five initially screened bacteria to screen out biocontrol bacteria that can effectively prevent and control multiple pathogens.

[0025] Prepare a potato dextrose medium (PDA-medium) in a clean bench. Inoculate the center of the medium with pathogenic fungi, seal the medium, and incubate in a constant-temperature incubator for 24–48 hours. Once colonies with a radius greater than 1 cm appear, remove the medium. Inoculate 6 μL of biocontrol bacteria in the surrounding blank areas, reseal the medium, and incubate in a constant-temperature incubator for 48 hours for morphological observation. Each experiment should include at least one control group and three replicate experimental groups. Post-experimental waste should be sterilized by autoclaving.

[0026] The test results showed that BZY-KUYA-5 and BZY-BEI-8 had good inhibitory effects on Fusarium solani, Fusarium oryzae, Fusarium equisetifolia, and Fusarium thunbergii, while the effects on other strains were poor.

[0027] Figure 1 and Figure 2 The confrontation test pictures of BZY-KUYA-5 and BZY-BEI-8 with the above five pathogenic fungi are shown respectively; among them, a is Fusarium solani, b is Aspergillus oryzae, c is Fusarium equisetum, and d is Fusarium solani.

[0028] 3. Selenium enrichment test Weigh 0.2g of sodium selenite using a weighing balance and place it into an Erlenmeyer flask. Then, weigh 100mL of deionized water using a graduated cylinder and add it to the Erlenmeyer flask, stirring evenly. Filter the solution in a clean bench using a bacterial filter and a disposable sterile filter tip (0.22μm) with a syringe. Filter the prepared 2g / L sodium selenite solution, pour it into two 50mL centrifuge tubes, and store it in a refrigerator at 4°C. When using, dilute the selenium solution with sterilized deionized water.

[0029] In a clean bench, LB bacterial culture solutions with selenium contents of 0 mg / L, 10 mg / L, 20 mg / L, 40 mg / L, and 60 mg / L were prepared using a sodium selenite stock solution. BZY-KUYA-5, BZY-BEI-8, BZY-3-KU-B, BZY-3-KU-BSYK-2, and BZY-2-CEBAODUAN were added to 30 mL of LB bacterial culture solutions containing different selenium concentrations. The cultures were shaken at 28°C and 150 rpm for 24 hours. Suitable biocontrol bacteria were screened based on the color differences of the selenium-enriched bacterial solutions obtained at different selenium concentrations.

[0030] The test results showed that BZY-KUYA-5 and BZY-BEI-8 had better selenium conversion capabilities, while other strains had poorer effects.

[0031] Figure 3 The concentration gradient diagram of the selenium-enrichment experiment is shown; among them, A is BZY-KUYA-5 and B is BZY-BEI-8.

[0032] Depend on Figure 3 Compared to the turbid yellow color of the CK group, the selenium-enriched bacterial cultures at selenium concentrations of 20 mg / L, 40 mg / L, and 60 mg / L all turned red. The red color of the 40 mg / L and 60 mg / L selenium-enriched bacterial cultures was essentially the same, and both were darker than the 20 mg / L selenium-enriched bacterial culture. This demonstrates that the bacterial culture efficiently converts colorless sodium selenite into red nano-selenium. Therefore, both strains exhibited efficient selenium conversion capabilities in LB culture broth containing 40 mg / L and 60 mg / L selenium, indicating that these concentrations are suitable.

[0033] The converted bacterial broth (initial inorganic selenium concentration: 40 mg / L) was sent to the Science Compass testing platform for selenium content measurement. The selenium conversion efficiency of the selected strain was determined based on the different valence states of the sample. The results showed that the conversion rate of inorganic selenium in the BZY-KUYA-5 bacterial broth was 72.3%, and that in the BZY-BEI-8 bacterial broth was 76.5%.

[0034] Based on the above selenium-enrichment test and antifungal confrontation experiment, it can be seen that strains BZY-BEI-8 and BZY-KUYA-5 have both significant selenium-enrichment effect and good antifungal effect, and finally both were screened as selenium-enriched biocontrol bacteria.

[0035] 4. Identification of bacterial species Morphological observations and physiological and biochemical tests revealed the strain characteristics of BZY-KUYA-5 and BZY-BEI-8, including colony color, shape, size, cell morphology, Gram staining results, and various enzyme activity reactions. Molecular biological identification results were also presented, and a phylogenetic tree was constructed to clarify the taxonomic status of the strains.

[0036] (1) Morphological identification Identification showed that the surface of strain BZY-KUYA-5 was rough (wrinkled), milky white, and the colonies were opaque with irregular edges; the colonies of strain BZY-BEI-8 were smoother and moister, milky white (occasionally with light yellow).

[0037] (2) Physiological and biochemical identification The results of physiological and biochemical identification are shown in Table 1: Table 1 Physiological and biochemical characteristics Note: “+” indicates a positive reaction result; “-” indicates a negative reaction result.

[0038] As shown in Table 1, strains BZY-KUYA-5 and BZY-BEI-8 are both Gram-positive bacteria, with positive VP tests. They can utilize sugars such as glucose and trehalose, reduce nitrates, and hydrolyze starch and casein to liquefy gelatin. Strain BZY-KUYA-5 cannot grow in 7% NaCl, while strain BZY-BEI-8 can grow in 7% NaCl. Furthermore, strain BZY-KUYA-5 can produce acid from mannose, while strain BZY-BEI-8 cannot. Therefore, it can be preliminarily determined that strain BZY-KUYA-5 belongs to the genus Bacillus subtilis, while strain BZY-BEI-8 belongs to the genus Bacillus Velezii. To further confirm this, 16s rRNA sequencing and phylogenetic tree construction are required.

[0039] (3) Gene identification 16S rRNA gene sequencing was assisted by Qingke Biotechnology Co., Ltd. Using the assembled gene fragments provided by Qingke Biotechnology Co., Ltd., we were able to quickly locate the taxonomic status of the selected strain using BLAST (Basic Local Alignment Search Tool) and construct a phylogenetic tree of its 16S sequence.

[0040] The 16S rRNA gene sequence of BZY-KUYA-5 is as follows: The 16S rRNA gene sequence of BZY-BEI-8 is as follows: CGTACGAGCTGAGGAGCGAAGCGTGGGGAGCGAACAGGATTAGATACCCTGGTAGTCCACGCCGTAAACGATGAGTGCTAAGTGTTAGGGGGTTTCCGCCCCTTAGTGCTGCAGCTAACGCATTAAGCACTCCGCCTGGGGAGTACGGTCGCAAGACTGAAACTCAAAGGAATTGACGGGGGCCCGCACAAGCGGTGGAGCATGTGGTTTAATTCGAAGCAACGCGAAGAACCTTACCAGGTCTTGACATCCTCTGACAATCCTAGAGATAGGACGTCCCCTTCGGGGGCAGAGTGACAGGTGGTGCATGGTTGTCGTCAGCTCGTGTCGTGAGATGTTGGGTTAAGTCCCGCAACGAGCGCAACCCTTGATCTTAGTTGCCAGCATTCAGTTGGGCACTCTAAGGTGACTGCCGGTGACAAACCGGAGGAAGGTGGGGATGACGTCAAATCATCATGCCCCTTATGACCTGGGCTACACACGTGCTACAATGGACAGAACAAAGGGCAGCGAAACCGCGAGGTTAAGCCAATCCCACAAATCTGTTCTCAGTTCGGATCGCAGTCTGCAACTCGACTGCGTGAAGCTGGAATCGCTAGTAATCGCGGATCAGCATGCCGCGGTGAATACGTTCCCGGGCCTTGTACACACCGCCCGTCACACCACGAGAGTTTGTAACACCCGAAGTCGGTGAGGTAACCTTTATGGAGCCAGCCGCCGAAGGTGGGACAGATGATTGGGGTGAGCGAAAAGGGGAGC Perform a BLAST alignment on the NCBI website. Based on the Gen-Bank sequence homology comparison, construct the phylogenetic trees of BZY-KUYA-5 and BZY-BEI-8, as shown respectively in Figure 4 and Figure 5 the following figures. <X

[0041] Sequencing and phylogenetic tree analysis of the strain identified strain BZY-KUYA-5 as Bacillus subtilis subsp. Inaquosorum. The strain was deposited on May 9, 2025, at the China General Microbiology Culture Collection Center (CGMCC, Institute of Microbiology, Chinese Academy of Sciences, No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, 100101, China) under the accession number CGMCC No. 34489.

[0042] Sequencing and phylogenetic tree analysis of the strain identified strain BZY-BEI-8 as Bacillus velezensis. The strain was deposited with the China General Microbiology Center (CGMCC) at the Institute of Microbiology, Chinese Academy of Sciences, No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, 100101, China, on May 9, 2025, under the accession number CGMCC No. 34490.

[0043] 2. Effects of bacterial strains on plant selenium enrichment capacity A potted experiment was conducted using cream cabbage as the test object.

[0044] Preparation of bacterial solution: strain BZY-KUYA-5 or strain BZY-BEI-8 was added to LB bacterial culture medium, and then the culture was shaken and fermented in a shaker at 28°C and 150 rpm for 24 hours to obtain bacterial solution.

[0045] Preparation of selenium-containing bacterial solution: Sodium selenite was added to the bacterial solution to prepare a selenium-containing bacterial solution with a selenium concentration of 40 mg / L.

[0046] A total of 9 processing settings: (1) Control group without vaccination (CK group); (2) BZY-BEI-8 plus selenium irrigated the roots 50 mL / time (SY 1 group); (3) BZY-BEI-8 plus selenium foliar spray (SY 2 group); (4) BZY-KUYA-5 plus selenium irrigated the roots with 50 mL / time (SY 3 group); (5) BZY-KUYA-5 plus selenium foliar spray (SY 4 group); (6) BZY-BEI-8 root irrigation 50 mL / time (SY 5 group); (7) BZY-BEI-8 foliar spray (SY 6 group); (8) BZY-KUYA-5 root irrigation 50 mL / time (SY 7 group); (9) BZY-KUYA-5 foliar spray (SY 8 group); Each treatment had 5 replicates.

[0047] Each root irrigation and foliar spray was applied seven days apart, for a total of three treatments. Potted plants were pakchoy (cream-colored pakchoy), grown from seeds of the four-season pakchoy variety cultivated by Huayu Company. One seedling was planted per pot. The pakchoy were grown in a constant-temperature incubator at 24°C. During their growth period, they were uniformly managed and watered regularly to maintain consistent soil moisture within each pot (60% of field capacity). Pots were randomly rotated weekly, and harvested after 21 days.

[0048] Collection of Chinese cabbage and determination of biomass: When harvesting, the Chinese cabbage was harvested with roots, washed repeatedly with tap water and distilled water for 3 times, and the water was absorbed with absorbent paper. The leaves and roots were separated and set aside for use. The leaf length, root length, fresh weight and other indicators were measured and set aside.

[0049] The prepared pakchoy samples to be tested were sent to Qingke Biotechnology Co., Ltd. for selenium content determination. The selenium conversion efficiency of the selected strain was determined based on the selenium content of the samples. The prepared selenium-enriched bacteria samples to be tested were sent to Qingke Biotechnology Co., Ltd. for selenium content determination. The selenium enrichment efficiency of the selected strain was determined based on the selenium content of the samples.

[0050] The bacterial sample was centrifuged at 4000 r / min for 30 min. The precipitate after solid-liquid separation was dried to a constant weight and weighed to represent the biomass of the bacteria. The calculation formula is as follows: Biomass (g / L) = dry weight of bacteria (g) / volume of fermentation liquid (L).

[0051] The precipitate was digested with HNO3 and HClO4 (4:1), and then the selenium content was determined by hydride generation-atomic fluorescence spectrometry. The selenium content was calculated according to the following formula: Bacterial selenium content (mg / L) = bacterial selenium content (mg) / fermentation liquid volume (L).

[0052] The test results are shown below: (1) Effects of microbial agents on the biomass of pakchoy The effects of the inoculant on the biomass of pakchoi are shown in Table 2. The data in Table 2 are based on the CK group, which was set to 1. Specifically, in the CK group, the aboveground fresh weight was 42.21 g, the aboveground dry weight was 4.55 g, the underground fresh weight was 4.53 g, and the underground dry weight was 0.48 g.

[0053] Table 2 Biomass indexes of Chinese cabbage Table 2 shows that compared with the CK treatment, treatments SY 1, SY 2, SY 3, SY 4, SY 5, SY 6, SY 7, and SY 8 all significantly increased the aboveground and underground biomass of pakchoi. The results were as follows: SY 3 > SY 4 > SY 7 > SY 8; and SY 1 > SY 2 > SY 5 > SY 6. This indicates that the increase in the aboveground and underground dry weight of pakchoi varies significantly depending on the application location of the inoculant and whether or not selenium is added. Root irrigation treatment was significantly more effective than foliar spraying. Furthermore, the selenium content of pakchoi in all treatments met the requirements of the national standard for "Selenium-Enriched Agricultural Products" (GH / T 1135-2017).

[0054] (2) Effect of microbial agents on selenium enrichment in pakchoy The effect of the inoculant on the selenium content of pakchoy is shown in Table 3. The data in Table 3 are compared with the CK group, which has a content of 1. Specifically, in the CK group, the aboveground selenium content was 6.53 μg / kg, and the underground selenium content was 5.98 μg / kg.

[0055] Table 3 Selenium content of Chinese cabbage Table 3 shows that compared with the CK treatment, treatments SY 1, SY 2, SY 3, SY 4, SY 5, SY 6, SY 7, and SY 8 all increased selenium enrichment in both the aboveground and underground parts of pakchoi. However, treatments SY 1, SY 3, SY 5, and SY 7 significantly increased selenium enrichment in the underground part, while treatments SY 2, SY 4, SY 6, and SY 8 significantly increased selenium enrichment in the aboveground part. Selenium concentrations in the underground part of pakchoi grown in treatments SY 1, SY 3, SY 5, and SY 7 were 1.53–1.64 times higher than those in the aboveground part. Furthermore, selenium contents in the underground and aboveground parts were 2.54–3.13 and 2.21–2.33 times higher than those in treatments CK, respectively. Treatments SY 3 and SY 1 were significantly higher than those in treatments SY 7 and SY 5. The selenium concentration in the aboveground part of pakchoy treated with SY 2, SY 4, SY 6, and SY 8 was 1.34-1.52 times that in the underground part, and the selenium content in the aboveground and underground parts was 2.34-2.87 times and 2.26-2.91 times that in the CK group, respectively. The selenium concentrations in the SY 4 and SY 2 groups were greater than those in the SY 8 and SY 6 groups.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other manner. Any person skilled in the art may utilize the above-disclosed technical content to modify or modify the present invention into equivalent embodiments. However, any simple modifications, equivalent variations, and modifications to the above embodiments that do not depart from the technical content of the present invention and are based on the technical essence of the present invention remain within the scope of protection of the present invention.

Claims

1. A Bacillus subtilis subsp. Inaquosorum, characterized in that: The strain is deposited in the General Microbiology Center of China Culture Collection Administration of Microorganisms with the deposit number CGMCC No. 34489.

2. Use of the Bacillus subtilis subspecies desertificans according to claim 1 in inorganic selenium conversion.

3. The use according to claim 2, characterized in that The application refers to converting inorganic selenium into elemental selenium or organic selenium; the inorganic selenium is selected from one or more of sodium selenite, sodium selenate, and selenide.

4. Use of the Bacillus subtilis subspecies deserticola described in claim 1 in the preparation of a bacterial agent for inhibiting pathogenic bacteria.

5. The use according to claim 4, characterized in that The pathogenic fungus is a plant pathogenic fungus, specifically one or more selected from the group consisting of Fusarium solani, Erythrocera oryzae, Fusarium equisetifolia, and Fusarium laminarum.

6. Use of the Bacillus subtilis subspecies desertificans according to claim 1 in selenium enrichment of plants.

7. Use of the Bacillus subtilis subspecies desertificans according to claim 1 in improving plant growth performance.

8. A microbial agent, characterized in that: The bacterial agent contains the Bacillus subtilis subspecies desertificans according to claim 1.

9. The microbial agent according to claim 8, characterized in that The bacterial agent is prepared by the following method: Bacillus subtilis subspecies deserticola was added to LB bacterial culture solution, and then the culture was shaken and fermented in a shaker at 28° C. and 150 rpm for 24 hours to obtain a microbial agent.

10. A method for enriching plants with selenium, characterized in that: The method comprises the following steps: irrigating the roots of plants with the microbial agent according to claim 8, or spraying the microbial agent on the leaves of plants to achieve the selenium-enriched effect of the plants.

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