Bacillus velezensis SW-Env003 as well as water-retaining functional bacterial agent and application of bacillus velezensis SW-Env003

Abstract

The invention discloses bacillus velezensis SW-Env003 as well as a water-retaining functional bacterial agent and application thereof, and belongs to the technical field of microorganisms and soil improvement. The invention discloses a bacillus velezensis SW-Env003, and the preservation number of the bacillus velezensis SW-Env003 is CCTCC (China Center for Type Culture Collection) NO: M 20232005. The water-retention functional microbial agent disclosed by the invention can effectively improve the fertility of desertification soil, improve the maximum water-holding capacity and field water-holding capacity of soil, reduce the water conductivity of the soil and improve the quality of the soil, and is beneficial to the growth of crops.

Description

Technical Field

[0001] The present invention relates to the technical field of microorganisms and soil improvement, and more particularly to a Bacillus velezensis SW-Env003, its water-retaining functional bactericide and application. Background Art

[0002] Land desertification is the degradation of land in arid, semi-arid and semi-humid areas with drought disasters due to factors such as climate change and unreasonable economic activities of humans, which is one of the important problems seriously affecting the sustainable development of humans. The environmental and climate governance for preventing desertification is an important aspect of global environmental governance.

[0003] In response to problems such as land desertification, tending to desertification, poor and low-yielding, domestic and foreign scholars have carried out research on comprehensive treatment technologies, mainly including engineering physical sand control methods, chemical sand control methods and biological sand control methods. Engineering physical sand control is easily buried by exogenous sand due to the limitations of the protection height and short protection time. Chemical sand control technologies include sand fixatives and water retainers. The dosage and cost of sand fixatives are relatively high. Traditional chemically synthesized water retainers are not conducive to popularization and application due to disadvantages such as high cost, non-degradability, poor salt resistance, and easy soil compaction. High water-absorbing water retainers have great application potential. Biological sand control, also known as plant sand control, has little effect due to the limitations of water resources and soil conditions in desert areas. Therefore, the method of combining high water-absorbing water retainer treatment with plant sand control has become an important measure for desertification control.

[0004] Previous research on water retainers often only focused on one aspect of improving soil, retaining water, improving fertilizer efficiency, increasing the survival rate of afforestation, increasing crop yields, and wind prevention and sand fixation, without comprehensive consideration. In addition, due to the poor organic matter content and weak adsorption and exchange capacity of desertified soil, the soil is severely lacking in nutrient elements such as nitrogen, phosphorus, and potassium required for plant growth, and the comprehensive fertility quality of the soil is very low. Based on this, developing an environmentally friendly water retainer with excellent degradability, improving soil fertility, high performance, and prepared from natural renewable resources has great application potential in desertification restoration, broad market prospects, and great practical significance for the sustainable development of China's environment.

[0005] Therefore, providing a Bacillus velezensis SW-Env003, its water-retaining functional bactericide and application is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the present invention provides a strain of Bacillus velezensis SW-Env003, its water-retaining functional bactericide, and applications thereof. The water-retaining functional bactericide is prepared by adsorbing Bacillus velezensis SW-Env003 with a natural water-absorbing material as the matrix; it can effectively increase the water-holding capacity of desertified soil, degrade minerals in the soil, increase the available phosphorus and available potassium contents in the soil, thereby promoting plant growth, enhancing the ecological functions in ecologically fragile areas, and promoting the sustainable development of ecologically fragile areas.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A strain of Bacillus velezensis SW-Env003, with the preservation number of CCTCC NO: M 20232005, has been preserved in the China Center for Type Culture Collection, abbreviated as CCTCC, address: Wuhan University, Wuhan, China, and the preservation date is October 25, 2023, and the taxonomic name is Bacillus velezensis SW-Env003.

[0009] Furthermore, the application of the Bacillus velezensis SW-Env003 in phosphorus solubilization.

[0010] Furthermore, the application of the Bacillus velezensis SW-Env003 in potassium solubilization.

[0011] The Bacillus velezensis of the present invention has high phosphorus and potassium solubilization performance, can regulate the soil nutrient structure, and transform substances in the soil that are difficult for plants to utilize, thereby promoting plant growth and improving the stress resistance of plants.

[0012] Furthermore, a water-retaining functional bactericide is composed of the Bacillus velezensis SW-Env003 and diatomite mixed in a mass ratio of 1:1.

[0013] Furthermore, the application of the water-retaining functional bactericide in increasing the soil moisture content.

[0014] Furthermore, the application of the water-retaining functional bactericide in increasing the available phosphorus content in the soil.

[0015] Furthermore, the application of the water-retaining functional bactericide in promoting the growth of wheat.

[0016] The water-retaining functional bactericide of the present invention uses natural high-water-absorbing material diatomite as a solid adsorbent to immobilize the Bacillus velezensis, which can play a role in increasing the soil water-holding capacity while ensuring the phosphorus and potassium solubilization performance of strain SW-Env003, and further ensure the healthy growth of plants.

[0017] Furthermore, the application of the water-retaining functional bactericide in the improvement of desertified soil.

[0018] As can be seen from the above technical solutions, compared with the prior art, the present invention discloses a strain of Bacillus velezensis SW-Env003, its water-retaining functional bacterium agent and application, which have the following beneficial effects:

[0019] (1) The Bacillus velezensis SW-Env003 provided by the present invention has good phosphorus and potassium solubilizing abilities. When applied to the soil, this strain can increase the contents of available nutrients such as P and K in the soil, improve soil fertility, and thus reduce the usage amount of chemical fertilizers.

[0020] (2) The Bacillus velezensis SW-Env003 provided by the present invention is a plant rhizosphere bacterium in kiwifruit orchards and apple orchards. Compared with many strains artificially cultivated by means of genetic engineering modification or induced mutation in the prior art, the Bacillus velezensis SW-Env003 has better soil and plant rhizosphere colonization abilities, which is more conducive to its continuous exertion of effects after application.

[0021] (3) The water-retaining functional bacterium agent provided by the present invention can effectively improve the fertility of desertified soil, increase the maximum water-holding capacity, field water-holding capacity of the soil and reduce the soil hydraulic conductivity, improve soil quality, and contribute to crop growth. Further research found that this water-retaining functional bacterium agent has a promoting effect on the growth of Jimai 44 seedlings. Compared with the control group, the seedling length of the treatment group increased by 29.41%, the seedling weight increased by 135.31%, and the root weight increased by 106.55%.

[0022] (4) The water-retaining functional bacterium agent provided by the present invention uses diatomite as the main raw material, which has the characteristics of wide raw material sources, low cost, and environmental friendliness; it has positive significance for environmental protection and sustainable development. Description of the Drawings

[0023] 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 use in 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, other drawings can be obtained according to the provided drawings without creative efforts.

[0024] Figure 1 The drawing is a single colony map of Bacillus velezensis SW-Env003 growing on an inorganic phosphorus solid medium in Example 1 of the present invention;

[0025] Figure 2 The drawing is a single colony map of Bacillus velezensis SW-Env003 growing on a potassium feldspar solid medium in Example 1 of the present invention;

[0026] Figure 3The accompanying figure is a phylogenetic tree of Bacillus velezensis SW-Env003 constructed in Example 1 of the present invention;

[0027] Figure 4 The accompanying figure is a graph showing the results of soil water holding capacity with different proportions of water retaining agent added in Example 4 of the present invention;

[0028] Figure 5 The accompanying figure is a graph showing the results of soil bulk density with different proportions of water retaining agent added in Example 4 of the present invention;

[0029] Figure 6 The accompanying figure is a graph showing the results of soil porosity with different proportions of water retaining agent added in Example 4 of the present invention;

[0030] Figure 7 The accompanying figure is an application effect diagram of the functional microbial inoculum in the pot experiment of desertified soil in Example 4 of the present invention; Figure A shows the growth of Jimai 44 seedlings and roots after turning the pot 20 days after potting; Figure B shows the growth of wheat seedlings before turning the pot. Detailed implementation manners

[0031] 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 shall fall within the protection scope of the present invention.

[0032] Inorganic phosphorus liquid medium: Sucrose 10.0 g, (NH 4 ) 2 SO 4 0.5 g, MgSO 4 ·7H 2 O 0.3 g, NaCl 0.3 g, KCl 0.3 g, FeSO 4 ·7H 2 O 0.03 g, MnSO 4 ·7H 2 O 0.03 g, Ca 3 (PO 4 ) 2 5.0 g, made up to 1.0 L with distilled water, pH 7.2 - 7.5, sterilized at 121 °C for 20 min.

[0033] Inorganic phosphorus solid medium: On the basis of the inorganic phosphorus liquid medium, 20 g of agar powder is added.

[0034] Mengjina organic phosphorus liquid medium: Sucrose 10.0 g, (NH 4 ) 2 SO 40.5 g, 0.3 g of NaCl, MgSO 4 ·7H 2 O 0.3 g, FeSO 4 ·7H 2 O 0.03 g, 0.3 g of NaCl, MnSO 4 ·7H 2 O 0.03 g, CaCO 3 5.0 g, 1.0 g of lecithin, made up to 1 L with deionized water, pH 7.2 - 7.4, sterilized at 121 °C for 20 min.

[0035] Mengjina Organophosphorus Solid Medium: Based on Mengjina Organophosphorus Liquid Medium, 20 g of agar powder was added.

[0036] Potassium Feldspar Inorganic Salt Liquid Medium: 5.0 g of sucrose, MgSO 4 ·7H 2 O 0.5 g, CaCl 2 0.1 g, FeCl 3 0.005 g, 1.0 g of potassium feldspar powder, made up to 1.0 L with deionized water, pH 7.2 - 7.5, sterilized at 121 °C for 20 min.

[0037] Potassium Feldspar Inorganic Salt Solid Medium: Based on Potassium Feldspar Inorganic Salt Liquid Medium, 20 g of agar powder was added.

[0038] Screening, Identification and Preservation of Functional Strains in Example 1

[0039] 1) Sampling: The sampling sites were orchards in Zhouzhi County, Shaanxi Province: kiwifruit orchards and apple orchards that had been applied with organic fertilizer. At the above sampling sites, soil samples with a depth of 5 - 20 cm were collected by the five-point sampling method. The samples were collected and stored in sterile plastic bags and brought back to the laboratory for the isolation and screening of functional strains in the soil.

[0040] 2) Isolation of Strains

[0041] Take 1 g of soil sample and add it to 10 ml of sterile physiological saline to make a soil suspension. Four dilution gradients (10 -3 、10 -4 、10 -5 and 10 -6) 100 μL was separately aspirated and spread on LB medium (tryptone 10 g / L, yeast extract 5 g / L, NaCl 10 g / L, pH 7.0), incubated at 30 °C for 24 h. Single colonies were picked and streaked on a new LB medium, incubated at 30 °C for 24 h. Single colonies were picked and purified by continuous streaking 5 times in this way. The isolated single colonies were punched, and the bacterial cakes were placed in cryotubes containing 2 ml of 15% glycerol and stored in an ultra-low temperature freezer (-80 °C) for later use.

[0042] 3) Screening of strains

[0043] (1) Screening of inorganic phosphorus-solubilizing strains: Take a strain preserved in a cryotube, thaw it and add it to 100 ml of LB liquid medium, incubate at 30 °C on a shaker for 24 h; Place the Oxford cup on the inorganic phosphorus solid medium, use a pipette to aspirate 20 μl of the bacterial liquid and add it to the Oxford cup, incubate at 30 °C for 5 d ( Figure 1 ), take out the Oxford cup, observe whether there is a phosphorus-solubilizing circle on the plate. If there is a phosphorus-solubilizing circle, measure the diameter (D) of the phosphorus-solubilizing circle and the diameter (d) of the colony produced by the strain on the solid plate on the fifth day, and calculate the solubility index (D / d). Preliminarily judge the phosphorus-solubilizing ability of the strain according to the solubility index. The results show that the strain SW-Env003 has good inorganic phosphorus degradation ability, and the D / d value reaches 1.73 (D = 1.21 cm, d = 0.70 cm). The phosphorus-solubilizing ability of the strain was re-screened by the shake flask method. The strain with obvious phosphorus-solubilizing effect was inoculated into 100 ml of LB liquid medium, incubated at 30 °C on a shaker for 24 h, and adjusted to a bacterial suspension of 1×10 8 cfu / mL with sterile water, inoculated into 50 mL of sterilized inorganic phosphorus liquid medium at an inoculation amount of 1%, with three replicates for each strain. Then, the non-inoculated medium was used as the control group, and it was placed in a shaker and incubated at 30 °C and 180 r / min for 5 d. Aspirate 10 mL of the culture solution of each strain and centrifuge. The supernatant was used to determine the inorganic phosphorus-solubilizing ability by the molybdenum blue colorimetric method, and the phosphorus-dissolving amount of the strain was calculated through the phosphorus standard curve y = 0.026x + 0.0139 (R 2 = 0.9924).

[0044] (2) Screening of organophosphorus-degrading bacterial strains: Take a strain stored in a cryopreserved tube, thaw it and add it to 100 ml LB liquid culture medium, and culture it on a shaking table at 30°C for 24 hours; Place an Oxford cup on the Mongina organophosphorus solid culture medium, pipette 20 μl of bacterial solution into the Oxford cup, and culture it at 30°C for 7 days. Observe whether a phosphorus-dissolving ring appears on the plate. If a phosphorus-dissolving ring appears, measure the diameter (D) and colony diameter (d) of the phosphorus-dissolving ring produced by the strain on the solid plate on the fifth day, and calculate the solubility index (D / d). The phosphorus-dissolving ability of the strain is preliminarily judged based on the solubility index. The results show that the strain SW-Env003 has a certain organophosphorus degradation ability, and the D / d value reaches 1.28 (D = 0.64 cm, d = 0.50 cm). The phosphorus-dissolving ability of the strain was rescreened by the shake flask method. The strain with obvious phosphorus-dissolving effect was inoculated into 100 ml LB liquid culture medium, cultured on a shaking table at 30°C for 24 hours, and adjusted to 1×10 8 cfu / mL of bacterial suspension was inoculated into 50mL of sterilized Mengina organophosphorus liquid medium at a 1% inoculation amount, and each strain was repeated three times. Then, the medium without bacteria was used as the control group and cultured in a shaker at 30°C and 180r / min for 7 days. 10mL of the culture medium of each strain was centrifuged, and the supernatant was used to determine the ability to degrade organophosphorus by molybdenum blue colorimetry. The phosphorus standard curve y=0.0829x+0.0137(R 2 =0.9937) to calculate the phosphate solubilization capacity of the strain.

[0045] (3) Screening of potassium-solubilizing strains: Take a strain stored in a cryopreserved tube, thaw it, add it to 100 ml of LB liquid culture medium, and culture it in a shaking incubator at 30°C for 24 h. Use a pipette to transfer 1 ml of the bacterial solution to a solid culture medium containing potassium feldspar inorganic salts, and culture it at 30°C for 3 days. When colonies appear ( Figure 2 ) and then transfer the single colony to 100 ml LB liquid medium, culture at 30 °C in a shaking incubator for 24 h, and adjust the concentration to 1 × 10 8 cfu / mL of bacterial suspension was inoculated into 100ml of sterilized potassium feldspar inorganic salt liquid medium at a 1% inoculation rate, with three replicates for each strain, and then the medium without bacteria was used as the control group, which was placed in a shaker at 30℃ and 180r / min for 3 days. 10mL of the culture solution of each strain was centrifuged, the supernatant was taken, and the volume was fixed to 100ml. The available potassium content was measured by flame spectrophotometry with the uninoculated treatment as the control.

[0046] The results showed that the strain SW-Env003 had good inorganic phosphorus degradation performance, and the phosphorus solubilization amount reached 79.38 mg / L. It also had a certain organic phosphorus degradation performance, with a degradation amount of 3.27 mg / L. The degradation amount of potassium feldspar by the strain SW-Env003 reached 6.3 mg / L. Combining with the previous experimental test results, it was found that the available phosphorus content in the desertified soil in northern Shaanxi was relatively low. Therefore, as a strain for subsequent research, the strain SW-Env003 could achieve better soil improvement effects.

[0047] 3) Strain identification: The DNA of the strain was extracted using a DNA extraction kit (TaKaRa). The 16s rDNA universal primers 27F (5’-AGAGTTTGATCMTGGCTCAG-3’; SEQ ID NO.1) and 1492R (5’-TACGGYTACCTTGTTACGACTT-3’; SEQ ID NO.2) were selected to establish a PCR amplification system for amplification. After the product was purified, the gene sequence was determined by a sequencing company (BGI), and the determination results were spliced by the sequencing company (BGI). The splicing result of the 16s rDNA gene sequence of the strain SW-Env003 is shown in SEQ ID NO.3.

[0048]

[0049] Sequence alignment was performed using Blast, and the sequences of model strains with relatively high similarity were selected. The homology was compared using the Neighbor-Joining method in MEGA 5.1 to construct a phylogenetic tree. The results are shown in Figure 3 . The results showed that the similarity between strain SW-Env003 and Bacillus velezensis was as high as 100%. Combining the colony and cell morphological characteristics, SW-Env003 was identified as Bacillus velezensis.

[0050] 4) Strain preservation

[0051] The preservation number of Bacillus velezensis SW-Env003 is CCTCC NO: M20232005, which has been preserved in the China Center for Type Culture Collection, abbreviated as CCTCC, address: Wuhan University, Wuhan, China. The preservation date is October 25, 2023, and the taxonomic name is Bacillus velezensis SW-Env003.

[0052] Example 2 Water retention experiment of adsorption materials

[0053] 1) Water absorption rate experiment of water retention materials

[0054] The water absorption rate of the water retention material was measured by the natural filtration method. The measurement steps were as follows: Weigh 0.20 g (accurate to 0.01 g) of the sample (particle size 0.2 - 0.4 mm), place it in a 2000 mL beaker, add 1000 mL of deionized water, stir well, and let it stand after the sample has absorbed enough water. Use a 200-mesh standard sieve with known mass to filter out the excess water through static filtration and inclined filtration, weigh the standard sieve and the water-saturated sample, and perform the same steps without adding the sample to measure the blank value. Calculate the water absorption rate of the water retention material through the formula: Water absorption rate of water retention material (%) = (Mass of water-saturated water retention material - Mass of dry water retention material) / Mass of dry water retention material * 100%. The results showed that diatomite had good water absorption performance, and the water absorption rate reached 230.8%.

[0055] 2) Water retention experiment of soil with different proportions of diatomite added

[0056] Take the sandy soil collected from the desertified area in northern Shaanxi, pass it through a 1 mm sieve, add different proportions of diatomite, set treatment 1 as CK without adding diatomite; the remaining treatments add 10% - 100% of diatomite, denoted as treatment 2 to treatment 11, with three replicates for each treatment. Measure the water holding capacity and soil bulk density and calculate the porosity. The soil bulk density, minimum water holding capacity, capillary water holding capacity, and maximum water holding capacity were measured by the core cutter method, and the soil porosity was calculated using the empirical formula:

[0057] Soil bulk density (g / cm 3 ) = Dry soil weight in the core cutter (g) / Core cutter volume (cm 3 )

[0058] Soil maximum water holding capacity = Water content (g) in the core cutter after the soil is saturated with water / Dry soil weight (g) in the soil sample in the core cutter * 100%

[0059] Soil capillary water holding capacity = (Wet soil weight in the core cutter (g) - Dry soil weight of the soil sample in the core cutter (g)) / Dry soil weight of the soil sample in the core cutter (g) * 100%

[0060] Soil minimum water holding capacity = (Wet soil sample mass (g) - Oven-dried soil mass (g)) / Oven-dried soil mass (g) * 100%

[0061] Capillary porosity = Capillary water holding capacity × Bulk density

[0062] Total porosity = Water content (g) in the core cutter after the soil is saturated with water / Core cutter volume (cm 3 ) * 100% Non-capillary porosity = Total porosity - Capillary porosity

[0063] The results are as Figures 4 - 6 shown. The results show that with the increase in the content of diatomite, the soil water holding capacity shows an upward trend, while the soil bulk density shows a downward trend, and the total porosity and capillary porosity increase. Considering the above factors and economic cost factors, the diatomite addition amount is selected to be 10%.

[0064] Example 3 Strain adsorption experiment

[0065] 1) Strain activation: Take a strain preserved in a cryopreservation tube, thaw it and add it to 50 mL of LB liquid medium, and culture it at 30 °C and 180 r / min under the condition of pH = 7 for 16 h for standby.

[0066] 2) Bacterial count determination: Inoculate the activated Bacillus velezensis SW-Env003 into LB liquid medium at an inoculation amount of 1% of the volume of the liquid medium, set the rotation speed at 180 r / min and the temperature at 30 °C, culture for 48 h, and measure the bacterial count and spore count. The test results show that after culturing the strain SW-Env003 for 48 h, the bacterial count reaches 1.79×10 9 cfu / mL, the spore count is 1.57×10 9 cfu / mL, and the spore rate is 87.7%.

[0067] 3) Strain adsorption: The cultured bacterial liquid (1.79×10 9(cfu / mL) and the selected adsorbent material diatomite were mixed evenly according to a mass ratio of 1:1, spread out flat in a tray, air-dried at room temperature, and the number of bacteria was measured. The results showed that diatomite had a good adsorption effect on the strain SW-Env003. The initial viable bacteria count of the strain SW-Env003 after diatomite adsorption reached 1.19×10 8 cfu / g. After being placed in the dark at room temperature for 30 days, the viable bacteria count of the strain SW-Env003 still reached 3.2×10 7 cfu / g. Combining the experimental results of Example 2, diatomite also had good water absorption performance. Therefore, diatomite was selected as the adsorbent material, and a water-retaining functional bacterial agent was prepared with a mass ratio of diatomite to bacterial liquid of 1:1 for standby.

[0068] Application of the water-retaining functional bacterial agent in Example 4

[0069] According to the results of Examples 2 and 3, it was confirmed that the addition amount of the water-retaining functional bacterial agent was 10% of the mass of the potted soil, and a potted experiment was carried out. Four treatment groups were set up, denoted as A1, A2, A3, and A4 respectively. Treatment A1 was the blank group (without adding any reagents, and the addition amount of sandy soil was 200 g); A2 was added with 0.2 g of calcium phosphate + 199.8 g of sandy soil; A3 was added with 20 g of the water-retaining functional bacterial agent (the bacterial liquid with a concentration of 1.79×10 9 cfu / mL was mixed evenly with diatomite according to a mass ratio of 1:1 and naturally air-dried) + 180 g of sandy soil; A4 was added with 0.2 g of calcium phosphate + 20 g of the water-retaining functional bacterial agent + 179.8 g of sandy soil; each group had three replicates.

[0070] 10 seeds of Jimai 44 were planted for each treatment. At the beginning of the experiment, 200 mL of water was added, and no more water was added afterwards. After 20 d, the pots were turned over, and the wheat seedlings were separated from the soil and the flower pots. The excess soil blocks at the roots were gently removed by hand, and then they were placed in water and gently shaken to allow the soil at the roots to fall off freely after soaking. The application effect is shown in Figure 7 . After turning over the pots, 1 part of the soil sample was taken by the quartering method, and the soil moisture content was measured by the aluminum box weighing method; the remaining soil was passed through a 1 mm sieve, air-dried, and the available phosphorus and available potassium contents of the soil were measured. The wheat seedlings were taken out, the root length and seedling length were measured, dried at 60 °C for 2 h, and the root weight (dry weight of the underground part) and seedling weight (dry weight of the aboveground part) were tested. The results are shown in Table 1. The results showed that the soil moisture content of A3 was 51.47% higher than that of the A1 group, the available phosphorus content of the soil increased by 80.63%, the seedling length increased by 37.78%, the dry weight of the aboveground part increased by 155.38%, and the dry weight of the underground part increased by 107.56%. The soil moisture content of the A4 group was 67.89% higher than that of the A2 group, the available phosphorus content of the soil increased by 80.60%, the seedling length increased by 29.41%, the dry weight of the aboveground part increased by 135.31%, and the dry weight of the underground part increased by 106.55%. In addition, from Figure 7It can be seen that in the treatments of groups A3 and A4 with the addition of microbial agents, the crop roots are short and thick, and the growth of wheat seedlings is more vigorous in part, while in the treatments of groups A1 and A2 without the addition of microbial agents, the roots are long and thin, and the growth of wheat seedlings is slow. Combining the results in Table 1, the dry weights of both the above-ground and underground parts in the group with the addition of microbial agents have increased. Thus, it can be seen that the water-retaining functional microbial agent can effectively increase the water content of desertified soil. Secondly, the water-retaining functional microbial agent can also effectively increase the available phosphorus content in desertified soil, so as to achieve the purpose of promoting the growth of wheat seedlings.

[0071] Table 1 Application of water-retaining functional microbial agent

[0072] A1 A2 A3 A4 Soil moisture content (%) 11.58±1.95 9.25±3.15 17.54±1.14 15.53±2.91 Available phosphorus content in soil (mg / kg) 30.26±1.24 302.65±12.39 54.66±8.23 546.58±82.29 Available potassium content in soil (mg / kg) 22.33±1.25 26.67±2.05 21.67±1.70 25.33±1.25 Seedling length (cm) 22.5 25.5 31.0 33.0 Root length (cm) 52.5 49.5 13.5 12.5 Aboveground dry weight (g) 0.251 0.320 0.641 0.753 Underground dry weight (g) 0.225 0.229 0.467 0.473

[0073] 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, and 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 these embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A strain of Bacillus velezensis SW-Env003, characterized in that: Its deposit number is CCTCC NO: M 20232005.

2. Use of the Bacillus Velezii SW-Env003 described in claim 1 in phosphate solubilization.

3. Use of the Bacillus Velez subtilis SW-Env003 according to claim 1 in potassium solubilization.

4. A water-retaining functional bacterial agent, characterized in that: The Bacillus Velez SW-Env003 described in claim 1 is mixed with diatomaceous earth in a mass ratio of 1:

1.

5. Use of the water-retaining functional bacterial agent according to claim 4 in improving soil moisture content.

6. Use of the water-retaining functional bacterial agent according to claim 4 in increasing the available phosphorus content in soil.

7. Use of the water-retaining functional bacterial agent according to claim 4 in promoting wheat growth.

8. Use of the water-retaining functional bacterial agent according to claim 4 in improving desertified soil.

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