A salt-alkali resistant bacterial agent and its preparation method and application

Abstract

The invention discloses a salt-alkali tolerant bacterial agent and a preparation method and application thereof. The salt-alkali tolerant bacterial agent comprises Bacillus proteolyticus XZT198. The deposit number of the strain is CCTCC M 20232321. The strain has salt-alkali tolerance and can tolerate salt stress caused by sodium chloride concentration ≤10% and alkali stress caused by pH ≤9.0. The salt-alkali tolerant bacterial agent can significantly reduce the pH of saline-alkali soil, improve soil microbial activity, significantly improve salinized soil, enhance the stress resistance of crops in saline-alkali land, promote crop growth, and increase the germination rate and yield of crops. The preparation method comprises: grinding a corn fermentation liquid product and mixing it with the fermentation liquid of Bacillus proteolyticus XZT198 to obtain the salt-alkali tolerant bacterial agent. The preparation method is simple, can retain the activity of the salt-alkali tolerant bacterial agent to the greatest extent, and improve the use effect of the salt-alkali tolerant bacterial agent.

Description

Technical Field

[0001] The invention belongs to the field of green agricultural production, and specifically relates to a salt-alkali resistant bacterial agent and a preparation method and application thereof. Background Art

[0002] my country's saline-alkali land is large in area, diverse in types and widely distributed. Irrational fertilizer application and irrigation methods have led to soil compaction and decreased fertility in some areas, exacerbating the trend of soil salinization. Traditional technologies for improving saline-alkali land include physical improvement technology and chemical improvement technology. However, these two improvement methods have many problems such as large labor volume, high investment cost, short maintenance time and even secondary pollution. With the continuous deepening of agricultural microbial research, it has been found that salt-alkali-tolerant bacteria combined with corn fermentation products are an effective way to achieve saline-alkali land improvement and resource recycling.

[0003] In saline-alkali environments, directly applying bacterial liquid to soil improvement often leads to colonization failure. However, the introduction of carriers such as crushed corn cobs, zeolite or biogas slurry can significantly improve the survival of salt-alkali tolerant functional bacteria in the soil, thereby reducing the adverse stress of saline-alkali conditions on plants. A large amount of fermentation products are produced during the deep processing of corn, and these fermentation products are ideal raw materials for the production of microbial agents. Practice has shown that appropriate raw material selection and ratio, temperature and pH control during the fermentation stage are the key to accelerating the microbial fermentation process and improving the biological activity of microbial agents. By exploring excellent salt-alkali tolerant functional bacteria, introducing excellent fermentation carriers such as corn fermentation liquid products, and controlling raw material ratios and fermentation conditions to create salt-alkali tolerant bacterial agents, it is possible to effectively improve the structure of saline-alkali soils, promote the growth of saline-alkali crops, increase crop yields and improve the quality of agricultural products, which is beneficial to the protection of the ecological environment, thereby creating considerable economic and environmental benefits, and has a guiding role in the cultivation of saline-alkali crops.

[0004] Therefore, the salt-alkali tolerant bacterial agent made by combining the salt-alkali tolerant bacteria screened from saline-alkali soil with corn fermentation products is of great significance for improving soil salinization, optimizing the growth conditions of crops in saline-alkali land, and achieving high yield and high quality of crops. Summary of the invention

[0005] One of the purposes of the present invention is to provide a strain of Bacillus proteolyticus XZT198 and its application, wherein the strain has excellent salt-alkali resistance.

[0006] The second object of the present invention is to provide a salt-alkali tolerant bacterial agent, which aims to improve soil conditions, enhance crop stress resistance, increase crop germination rate, and promote crop growth.

[0007] The third object of the present invention is to provide a preparation method and application of the above-mentioned salt-alkali resistant bacterial agent, aiming to retain the activity of the salt-alkali resistant bacterial agent to the greatest extent and improve the use effect of the salt-alkali resistant bacterial agent.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] The present invention first provides a strain of Bacillus proteolyticus XZT198, which was deposited in the China Type Culture Collection in Wuhan, Hubei on November 24, 2023, with a deposit number of CCTCC M20232321. The strain has salt-alkali tolerance and has a good effect on improving the salt-alkali tolerance of plants.

[0010] Furthermore, the strain tolerates salt stress caused by sodium chloride concentration ≤ 10%; and the strain tolerates alkali stress caused by pH ≤ 9.0.

[0011] Further preferably, the strain tolerates salt stress and alkali stress caused by a sodium chloride concentration of 10% and a pH of 9.0.

[0012] The invention provides an application of the Bacillus proteolyticus XZT198 as a crop growth promoter.

[0013] The Bacillus proteolyticus XZT198 is used as a growth promoter for crops planted in saline-alkali land.

[0014] Further preferably, the crops are rice and pepper.

[0015] The present invention also provides a salt-alkali resistant bacterial agent, which comprises the Bacillus proteolyticus XZT198.

[0016] The salt-alkali tolerant bacterial agent comprises the fermentation broth of the proteolytic Bacillus XZT198 and a corn fermentation broth product.

[0017] In some specific embodiments, the fermentation broth of Bacillus proteolyticus XZT198 is an unconcentrated original fermentation broth of Bacillus proteolyticus XZT198, and the effective viable count of Bacillus proteolyticus XZT198 in the original fermentation broth is 15 to 20 billion CFU / mL.

[0018] In some specific embodiments, the corn fermentation broth product comprises the following components: organic acids, polypeptides, plant stimulants, soluble sugars, mineral elements, soluble amino acids and growth factors.

[0019] Furthermore, the organic acid comprises the following concentration components: oxalic acid 6.5-7.6 mg / ml, tartaric acid 5.1-6.8 mg / ml, formic acid 9.5-10.6 mg / ml, malonic acid 1.2-1.6 mg / ml, lactic acid 102.1-113.6 mg / ml, acetic acid 5.6-7.1 mg / ml, citric acid 55.1-59.4 mg / ml, succinic acid 12.6-14.5 mg / ml, propionic acid 123.5-136.7 mg / ml, and the organic acid causes the pH value of the corn fermentation broth product to be 3.8-5.0.

[0020] Furthermore, the soluble amino acids contain the following concentration components: aspartic acid 4.5-6.6 mg / ml, threonine 3.5-4.5 mg / ml, serine 3.6-5.6 mg / ml, glutamate 7.5-8.4 mg / ml, glycine 2.8-3.1 mg / ml, alanine 5.1-5.7 mg / ml, cysteine ​​0.2-0.5 mg / ml, valine 3.6-4.8 mg / ml, methionine 2.1-3.8 mg / ml, isoleucine 2.5-3.2 mg / ml, leucine 6.5-7.0 mg / ml, tyrosine 3.9-4.8 mg / ml, phenylalanine 3.7-4.8 mg / ml, histidine 1.6-2.7 mg / ml, lysine 2.6-4.9 mg / ml, arginine 3.0-3.9 mg / ml, and proline 6.5-7.0 mg / ml.

[0021] Furthermore, the plant stimulant contains the following concentration components: salicylic acid 1108.6-1206.7ng / ml, gibberellin A31.8-2.7ng / ml, gibberellin A12.8-3.7ng / ml, indoleacetic acid 6237.8-6453.7ng / ml, abscisic acid 125.7-135.6ng / ml, jasmonic acid-isoleucine 13.5-14.7ng / ml, gibberellin A40.2-0.3ng / ml, and jasmonic acid 3.5-4.5ng / ml.

[0022] Further, the growth factor comprises the following concentration components: 45-50 mg / L of pyrroloquinoline quinone. Further, the polypeptide is a small peptide of 300-2000 Daltons.

[0023] In some specific embodiments, in the salt-alkali tolerant bacterial agent, the volume ratio of the fermentation broth of Bacillus proteolyticus XZT198 to the corn fermentation broth product is 1:1, and the effective viable count of Bacillus proteolyticus XZT198 is 7.5 to 10 billion CFU / mL.

[0024] The preparation of the fermentation broth of the Bacillus proteolyticus XZT198 comprises the following steps:

[0025] 1) Strain activation: inoculate Bacillus proteolyticus XZT198 on LB solid culture medium, and culture at a constant temperature of 28-30° C. for 22-24 hours to obtain activated Bacillus proteolyticus XZT198;

[0026] 2) Primary fermentation: inoculating the activated Bacillus proteolyticus XZT198 into a seed culture medium, with a liquid volume of 60-70%, an inoculation amount of 7%-10%, a culture temperature of 35-37° C., and a shaking culture at 170-190 rpm for 18-20 hours to obtain a primary seed solution of Bacillus proteolyticus;

[0027] 3) Secondary fermentation: inoculate the primary seed liquid of Bacillus proteolyticus into the culture medium, with the liquid volume of 60-70%, the inoculation amount of 7%-10%, the culture temperature of 35-37° C., and the shaking culture of 170-190 rpm for 18-20 hours to obtain the secondary seed liquid of Bacillus proteolyticus;

[0028] 4) Tertiary fermentation: inoculate the secondary seed liquid of Bacillus proteolyticus into the culture medium, with a liquid volume of 60-70%, an inoculation amount of 7%-10%, a culture temperature of 35-37° C., and a shaking culture at 170-190 rpm for 22-24 hours to obtain the fermentation liquid of the Bacillus proteolyticus XZT198.

[0029] Furthermore, in step 1), the formula of the LB solid culture medium is: 8-10 g / L tryptone, 5-6 g / L yeast extract, 8-10 g / L sodium chloride, 15-18 g / L agar, and pH 7.2-7.3.

[0030] Furthermore, in step 2), the formula of the seed culture medium is: 18-20 g / L peptone, 8-10 g / L sodium chloride, 8-10 g / L yeast extract powder, 45-50 mmol / L zinc sulfate, and pH is 7.2-7.3.

[0031] Furthermore, in step 3), the formula of the culture medium is: 18-20 g / L peptone, 8-10 g / L sodium chloride, 8-10 g / L yeast extract, 45-50 mmol / L zinc sulfate, 800-1000 nmol / L PQQ (pyrroloquinoline quinone), and pH is 7.2-7.3.

[0032] Furthermore, in step 4), the formula of the culture medium is: 2-3% soybean meal, 0.8-1.0% yeast extract powder, 0.8-1.0% ammonium sulfate, 0.8-1.0% glucose, 1.0-2.0% starch, 1.0-1.5% magnesium sulfate heptahydrate, 1.0-1.5% sodium chloride, 0.5-0.8% potassium dihydrogen phosphate, and 25-30 mmol / L zinc sulfate heptahydrate solution.

[0033] Furthermore, the volume ratio of the primary fermentation, secondary fermentation and tertiary fermentation fermentation tanks is 50L:500L:50t.

[0034] The preparation of the corn fermentation liquid product comprises: adsorbing corn soaked water through a resin column, collecting effluent, subjecting the effluent to fermentation treatment with a fermentation agent to obtain a fermentation product, separating the fermentation product, collecting a filtrate, filtering the filtrate through a nanofiltration membrane with a molecular weight cutoff of 300 to 2000 Daltons, and collecting the retentate to obtain the corn fermentation liquid product.

[0035] Furthermore, during the preparation of the corn fermentation liquid product, the fermentation treatment conditions are: pH 4.5-7.5, fermentation temperature 28-37° C., and fermentation time 7-8 days.

[0036] The present invention also provides a method for preparing the salt-alkali resistant bacterial agent, comprising the steps of: grinding a corn fermentation liquid product with a sand mill and mixing the mixture with a fermentation liquid of proteolytic Bacillus subtilis XZT198 in a volume ratio of 1:1 to obtain the salt-alkali resistant bacterial agent.

[0037] Furthermore, the sanding time is 2 to 3 hours.

[0038] The application of the salt-alkali resistant bacterial agent in at least one of the following:

[0039] (1) Improve soil salinization;

[0040] (2) Promote plant growth;

[0041] (3) Improve plant quality;

[0042] (4) Improve the ability of plants to resist salt and alkali.

[0043] Beneficial effects of the present invention:

[0044] 1. The present invention finds that Bacillus proteolyticus XZT198 improves the salt-alkali tolerance of plants. The salt-alkali tolerant bacterial agent prepared by using Bacillus proteolyticus and corn fermentation liquid products has the effect of enhancing plant stress resistance and promoting crop growth. In particular, Bacillus proteolyticus has a significant effect on improving the germination rate and germination potential of rice and pepper under saline-alkali conditions.

[0045] 2. The present invention combines Bacillus proteolyticus XZT198 with corn fermentation broth to produce a bacterial agent with high activity concentration and strong timeliness, which can reduce the loss and function reduction during the shelf life.

[0046] 3. The salt-alkali tolerant bacterial agent provided by the present invention can significantly improve the salt-alkali resistance of crops. By applying the salt-alkali tolerant bacterial agent of the present invention, the yield of rice and pepper in saline-alkali land can be significantly increased, and the production efficiency can be improved by more than 40%. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 The colony morphology of the front side of the plate of Bacillus proteolyticus XZT198;

[0048] Figure 2 Phylogenetic tree analysis of Bacillus proteolyticus XZT198. DETAILED DESCRIPTION

[0049] Example 1 Isolation and screening of bacteria

[0050] The separation and screening method of Bacillus proteolyticus XZT198 of the present invention comprises the following steps: collecting saline-alkali soil from the Tibetan Plateau, separating and purifying bacteria in the soil by using LB culture medium combined with a dilution plate method, and screening strains that are resistant to saline-alkali under saline-alkali adversity. Figure 1 This is the colony morphology of Bacillus proteolyticus XZT198 on the front side of the plate.

[0051] Example 2 Identification of bacteria

[0052] (1) The morphological, cultural, physiological and biochemical characteristics of the strain are as follows:

[0053] Strain XZT198 is a Gram-positive bacterium. After being cultured on LB medium for 3 days, the strain is off-white in color, opaque, moist, with radial edges, a shiny surface without wrinkles, and can be easily picked up by an inoculation loop. Strain XZT198 can liquefy gelatin, reduce nitrates, and hydrolyze glucose, maltose, and starch, while the indole test is negative.

[0054] The results of the strain 16S rRNA gene sequence determination are shown in SEQ ID NO.1.

[0055] The strain was streaked and purified on an LB plate, and the 16S rRNA gene was amplified using bacterial universal primers (sequences shown in SEQ ID NO.2 and SEQID NO.3). The gene sequence obtained after the PCR product was sent for sequencing was compared and analyzed in NCBI. The results showed that the strain XZT198 had a similarity of 99.93% with Bacillus proteolyticus, and its morphological characteristics and physiological and biochemical properties were closest to those of Bacillus proteolyticus. Therefore, based on the 16S rRNA gene sequence determination and the morphological characteristics and physiological and biochemical characteristics, the strain can be classified as Bacillus proteolyticus.

[0056] The strain was named Bacillus proteolyticus XZT198, with the preservation number CCTCC M 20232321, and was deposited in the China Center for Type Culture Collection in Wuhan, Hubei on November 24, 2023.

[0057] Example 3 Preparation of corn fermentation broth product

[0058] The corn soaking water is adsorbed from bottom to top through a resin column (filler is weak alkaline ion exchange resin) at 1BV / h. The collected effluent is fermented. Bacillus Velezii is added according to the volume ratio of effluent to fermentation agent of 100:1, pH is adjusted to 7.0, temperature is 32°C, and fermentation is carried out in an open fermentation tank for 7 days. The fermentation product is separated by a microfiltration membrane with a molecular weight cutoff of 10,000 to obtain a filtered clear liquid and a retained mother liquor. The retained mother liquor is recycled and enters the fermentation tank for further fermentation. The collected filtrate is filtered by an organic nanofiltration membrane with a molecular weight cutoff of 300, and the retained liquid is collected to obtain the corn fermentation liquid product.

[0059] The corn fermentation broth product obtained in this example was tested and found to contain the following components: organic acids, polypeptides, plant stimulants, soluble sugars, mineral elements, soluble amino acids and growth factors.

[0060] The organic acid comprises the following concentration components: oxalic acid 7.1 mg / ml, tartaric acid 6.2 mg / ml, formic acid 10.2 mg / ml, malonic acid 1.4 mg / ml, lactic acid 107.4 mg / ml, acetic acid 6.1 mg / ml, citric acid 56.2 mg / ml, succinic acid 12.8 mg / ml, propionic acid 135.2 mg / ml, and the pH value of the corn fermentation broth product caused by the organic acid is 5.0;

[0061] Soluble amino acids include the following concentration components: aspartic acid 6.6 mg / ml, threonine 4.4 mg / ml, serine 5.3 mg / ml, glutamic acid 8.1 mg / ml, glycine 2.9 mg / ml, alanine 5.6 mg / ml, cystine 0.4 mg / ml, valine 4.6 mg / ml, methionine 3.2 mg / ml, isoleucine 3.1 mg / ml, leucine 6.9 mg / ml, tyrosine 4.6 mg / ml, phenylalanine 4.4 mg / ml, histidine 2.6 mg / ml, lysine 4.7 mg / ml, arginine 3.7 mg / ml, proline 6.8 mg / ml;

[0062] The plant stimulant contains the following concentration components: salicylic acid 1202.8 ng / ml, gibberellin A 32.3 ng / ml, gibberellin A 13.6 ng / ml, indoleacetic acid 6421.2 ng / ml, abscisic acid 130.3 ng / ml, jasmonic acid-isoleucine 14.5 ng / ml, gibberellin A 40.27 ng / ml, jasmonic acid 4.2 ng / ml;

[0063] The polypeptide is a small peptide of 300 Daltons; the content of pyrroloquinoline quinone is 45 mg / L.

[0064] Example 4 Acid resistance test of Bacillus proteolyticus XZT198

[0065] Since the corn fermentation broth product is an acidic liquid with a pH of 5.0, the following experiment was designed to test the change in the effective viable count of Bacillus proteolyticus after mixing with the corn fermentation broth product: the pH of the conventional LB culture medium was adjusted to 5.0, 6.0, and 7.0 using an acid-base regulator, and three treatments were set up, each with three replicates. After 24 hours of shaking culture on a shaker, the microscopic counting method was used to detect the effective viable count of each treatment group.

[0066] Table 1 Growth of Bacillus proteolyticus XZT198 at different acidic pH

[0067]

[0068] The experimental data in Table 1 show that there is no significant difference in the effective viable count of Bacillus proteolyticus XZT198 under pH values ​​of 5.0, 6.0, and 7.0. This shows that the acidic corn fermentation broth product will not have a negative impact on the viable count of Bacillus proteolyticus XZT198.

[0069] Example 5 Salt and alkali resistance test of Bacillus proteolyticus XZT198

[0070] The salt-alkali tolerant culture medium is prepared by adding 4%, 6%, 8%, 10% and 12% sodium chloride solution to the conventional LB culture medium, adjusting the pH to 8.0, 9.0 and 10.0, sterilizing with high pressure steam at 121°C for 20 min, pouring the plate, and after the plate solidifies, picking a single colony with a sterilized inoculation loop for three-zone marking. After culturing at 37°C for 3 days, observe whether bacteria grow on the plate.

[0071] Table 2 Growth of Bacillus proteolyticus XZT198 under different saline and alkali concentrations

[0072]

[0073] Note: "*" in the table indicates strain growth, and "-" indicates strain no growth.

[0074] The experimental results in Table 2 show that Bacillus proteolyticus XZT198 can tolerate a sodium chloride concentration of 10%, and the highest tolerable pH is 9.0.

[0075] Example 6 Preparation of salt-alkali resistant bacterial agent

[0076] This embodiment will introduce the preparation of salt-alkali resistant bacteria agent, and the specific process is as follows:

[0077] 1. Preparation of fermentation broth of Bacillus proteolyticus XZT198:

[0078] 1) Strain activation: inoculate Bacillus proteolyticus XZT198 with a deposit number of CCTCC M 20232321 on LB solid medium, and culture at 28° C. for 24 h to obtain activated Bacillus proteolyticus;

[0079] The formula of LB solid medium is: tryptone 10g / L, yeast extract 5g / L, sodium chloride 10g / L, agar 15g / L, pH 7.2-7.3;

[0080] 2) Primary fermentation (50 L): inoculating the activated Bacillus proteolyticus XZT198 into a seed culture medium, with a liquid volume of 65%, an inoculum size of 8%, a culture temperature of 37° C., and a shaking culture at 180 rpm for 18 h to obtain a primary seed solution of Bacillus proteolyticus; wherein the formula of the seed culture medium is: 18 g / L peptone, 10 g / L sodium chloride, 10 g / L yeast extract powder, 50 mmol / L zinc sulfate, and a pH of 7.2-7.3;

[0081] 3) Secondary fermentation (500 L): liquid volume 65%, inoculation size 8%, culture temperature 37°C; shaking culture at 180 rpm for 18 hours to obtain secondary seed solution of Bacillus proteolyticus; wherein the formula of the culture medium is: 20 g / L peptone, 10 g / L sodium chloride, 10 g / L yeast extract powder, 50 mmol / L zinc sulfate, 1000 nmol / L PQQ, pH 7.2-7.3;

[0082] 4) Tertiary fermentation (50t): liquid volume 70%, inoculation volume 10%, culture temperature 37°C, shaking culture at 190rpm for 24h, to obtain an unconcentrated original bacterial liquid of Bacillus proteolyticus XZT198, wherein the effective viable count is 20 billion CFU / mL; wherein the formula of the culture medium is: 2% soybean meal, 0.9% yeast extract powder, 1.0% ammonium sulfate, 1.0% glucose, 1.5% starch, 1.0% magnesium sulfate heptahydrate, 1.5% sodium chloride, 0.5% potassium dihydrogen phosphate, and 25mmol / L zinc sulfate heptahydrate solution.

[0083] 2. Preparation of corn fermentation broth product: The corn fermentation broth product was prepared according to the method of Example 3, wherein the fermentation treatment conditions were: pH 6.5, fermentation temperature 35° C., and fermentation time 7 days.

[0084] 3. Preparation of salt-alkali resistant bacterial agent: After the corn fermentation broth product is passed through a sand mill for 2.5 hours, the sand-milled corn fermentation broth product is added to the unconcentrated original bacterial liquid of Bacillus proteolyticus XZT198 at a volume ratio of 1:1, and a stirrer is used to mix at high speed to obtain a salt-alkali resistant bacterial agent with an effective live bacterial count of 10 billion CFU / mL.

[0085] Application Example 1

[0086] The soil nutrition of the experimental saline-alkali land is as follows: organic matter content is 28.18g / kg, salt content is 9.53g / kg, pH value is 8.3, soil bulk density is 1.59g / cm 3 Rice is planted in saline-alkali soil in June and harvested in mid-September.

[0087] Treatment 1: The original bacterial solution of Bacillus proteolyticus prepared according to the method of Example 6 was diluted 200 times to obtain a bacterial solution with an effective viable count of 100 million CFU / mL, and mixed with saline-alkali soil. The usage amount was 100 L per mu, and the treatment was repeated 3 times, with a planting area of ​​1 mu each time.

[0088] Treatment 2: The corn fermentation liquid product prepared according to the method of Example 6 was diluted 200 times and mixed with saline-alkali soil. The usage amount was 100 L per mu, and it was repeated 3 times, with a planting area of ​​1 mu each time.

[0089] Treatment 3: The salt-tolerant alkali bacterial agent obtained in Example 6 was diluted 100 times to obtain an effective viable bacterial count of 100 million CFU / mL and mixed with saline-alkali soil. The usage amount per mu was 100 L, and repeated 3 times, with a planting area of ​​1 mu each time.

[0090] Blank control: Use clean water mixed with saline-alkali soil, the usage is 100L per mu, repeat 3 times, and the planting area is 1 mu each time.

[0091] The other conditions of each treatment were the same during the growth of rice. The field soil was sampled after rice planting to measure the soil pH and microbial composition. The results are shown in Table 3. The rice germination rate and germination potential were tested during the germination period, and the rice yield was measured at harvest. The results are shown in Table 4.

[0092] Table 3 Effects of different treatments on soil microbial composition and pH of rice

[0093]

[0094] Table 3 shows the effects of different treatments on the composition of rice soil microorganisms and pH. According to the analysis of the table, each treatment can effectively reduce the pH of rice soil, among which treatment 3 (salt-alkali tolerant bacteria agent) has the most significant effect on improving soil pH, and the soil pH has dropped from 8.3 to 6.9, effectively reducing the degree of salinization of rice soil. In addition, each treatment has an effect on the composition of microorganisms such as bacteria, fungi, and actinomycetes in the soil. The content of bacteria, fungi, and actinomycetes in the soil of each treatment is significantly higher than that of the control group, among which treatment 3 has the most significant improvement effect. It can be seen that the salt-alkali tolerant bacteria agent treatment has the function of significantly enhancing the activity of rice soil microorganisms.

[0095] Table 4 Effects of different treatments on rice germination rate, germination potential and yield

[0096] Germination rate (%) Germination potential (%) Yield (kg / mu) Process 1 65.1±0.5c 43.2±0.35c 377.8±1.0c Process 2 79.3±0.32b 57.6±0.75b 400.7±1.6b Process 3 86.8±0.64a 65.5±0.13a 434.7±4.1a Blank control 46.5±0.85d 34.6±0.72d 184.3±3.8d

[0097] The data in Table 4 show that each treatment has a certain effect on the growth of rice in saline-alkali land. Treatment 3, i.e., the salt-alkali tolerant bacteria agent treatment, can significantly improve the germination rate and germination potential of rice in saline-alkali land, and the rice yield reaches 434.7 kg / mu, an increase of 135.9% over the control group. It can be seen that the salt-alkali tolerant bacteria agent can significantly improve the salt-alkali resistance of rice in saline-alkali land and promote rice growth.

[0098] Application Example 2

[0099] The soil nutrition of the experimental saline-alkali land is as follows: organic matter content is 20.25g / kg, salt content is 7.45g / kg, pH value is 8.5, soil bulk density is 1.52g / cm 3 Peppers are planted in saline-alkali soil in late May and harvested in late September.

[0100] Treatment 1: The original bacterial solution of Bacillus proteolyticus prepared according to the method of Example 6 was diluted 200 times and mixed with saline-alkali soil. The usage amount was 100 L per mu, and the method was repeated 3 times. The planting area was 1 mu each time.

[0101] Treatment 2: The corn fermentation liquid product prepared according to the method of Example 6 was diluted 200 times and mixed with saline-alkali soil. The usage amount was 100 L per mu, and it was repeated 3 times, with a planting area of ​​1 mu each time.

[0102] Treatment 3: The salt-tolerant alkali bacterial agent obtained in Example 6 was diluted 100 times to obtain an effective viable bacterial count of 100 million CFU / mL and mixed with saline-alkali soil. The usage amount per mu was 100 L, and repeated 3 times, with a planting area of ​​1 mu each time.

[0103] Blank control: Use clean water mixed with saline-alkali soil, the usage is 100L per mu, repeat 3 times, and the planting area is 1 mu each time.

[0104] The other conditions of each treatment were the same during the growth of peppers. The field soil was sampled after pepper planting to measure the soil pH and microbial composition. The results are shown in Table 5. The germination rate and germination potential of peppers were tested during the germination period, and the yield of peppers was measured during the maturity period. The results are shown in Table 6.

[0105] Table 5 Effects of different treatments on soil microbial composition and pH of pepper

[0106]

[0107] Table 5 shows the effects of different treatments on the soil microbial composition and pH of pepper. According to the analysis of the table, each treatment can effectively reduce the pH of pepper soil, among which treatment 3 (salt-alkali tolerant bacteria agent) has the most significant effect on improving soil pH, and the soil pH drops from 8.5 to 7.0, effectively reducing the degree of soil salinization. In addition, each treatment has an effect on the composition of microorganisms such as bacteria, fungi, and actinomycetes in the soil. The content of bacteria, fungi, and actinomycetes in the soil of each treatment is significantly higher than that of the control group, among which treatment 3 has the most significant improvement effect. It can be seen that the treatment of salt-alkali tolerant bacteria agent has the function of significantly enhancing the activity of microorganisms in pepper soil.

[0108] Table 6 Effects of different treatments on pepper germination rate, germination potential and yield

[0109] Germination rate (%) Germination potential (%) Yield (kg / mu) Process 1 72.2±0.42c 58.3±0.67c 810.8±5.9c Process 2 80.8±1.08b 67.3±0.98b 880.2±3.2b Process 3 88.2±1.81a 74.4±0.71a 960.5±7.3a Blank control 52.1±1.21d 42.8±0.80d 550.0±2.9d

[0110] From the data in Table 6, we can see that each treatment has a certain effect on the growth of pepper in saline-alkali land. Among them, treatment 3, namely the salt-alkali tolerant bacteria agent treatment, can significantly improve the germination rate and germination potential of pepper in saline-alkali land, and the pepper yield reaches 960.5kg / mu, an increase of 74.6% over the control group. It can be seen that the salt-alkali tolerant bacteria agent can significantly improve the salt-alkali resistance of pepper in saline-alkali land and promote the growth of pepper.

Claims

1. A strain of Bacillus proteolyticus ( Bacillus proteolyticus )XZT198, characterized in that, The strain was deposited in the China Center for Type Culture Collection on November 24, 2023, with the deposit number CCTCC M 20232321; the strain is salt- and alkali-tolerant; the strain is tolerant to salt stress caused by a sodium chloride concentration of ≤10%; the strain is tolerant to alkaline stress caused by a pH of ≤9.0; the strain is tolerant to salt stress and alkaline stress caused by a sodium chloride concentration of 10% and a pH of 9.

0.

2. Use of the strain as claimed in claim 1 as a growth promoter for rice or pepper in saline-alkali land.

3. A salt-alkali tolerant bacterial agent, characterized in that: The salt-alkali tolerant bacterial agent comprises the Bacillus proteolyticus XZT198 as claimed in claim 1.

4. The salt-alkali resistant bacterial agent according to claim 3, characterized in that The salt-alkali resistant bacterial agent comprises the fermentation broth of the Bacillus proteolyticus XZT198 and a corn fermentation broth product; wherein the volume ratio of the fermentation broth of the Bacillus proteolyticus XZT198 to the corn fermentation broth product is 1:1, and the effective live bacterial count of the Bacillus proteolyticus XZT198 in the salt-alkali resistant bacterial agent is 7.5 to 10 billion CFU / mL.

5. The salt-alkali resistant bacterial agent according to claim 4, characterized in that: The preparation of the fermentation broth of the Bacillus proteolyticus XZT198 comprises the following steps: 1) Strain activation: inoculate Bacillus proteolyticus XZT198 on LB solid medium and culture at a constant temperature of 28-30°C for 22-24 hours to obtain activated Bacillus proteolyticus XZT198; 2) Primary fermentation: inoculate the activated Bacillus proteolyticus XZT198 into the seed culture medium, with a liquid volume of 60-70%, an inoculation amount of 7%-10%, a culture temperature of 35-37°C, and a shaking culture at 170-190 rpm for 18-20 hours to obtain a primary seed solution of Bacillus proteolyticus; 3) Secondary fermentation: inoculate the primary seed liquid of Bacillus proteolyticus into the culture medium, with a liquid volume of 60-70%, an inoculation amount of 7%-10%, a culture temperature of 35-37°C, and a shaking culture at 170-190 rpm for 18-20 hours to obtain the secondary seed liquid of Bacillus proteolyticus; 4) Tertiary fermentation: inoculating the secondary seed liquid of Bacillus proteolyticus into the culture medium, with a liquid volume of 60-70%, an inoculation amount of 7%-10%, a culture temperature of 35-37° C., and a shaking culture at 170-190 rpm for 22-24 hours to obtain the fermentation liquid of the Bacillus proteolyticus XZT198; The preparation of the corn fermentation liquid product comprises the following steps: adsorbing corn soaked water through a resin column, collecting effluent, subjecting the effluent to fermentation treatment with a fermentation agent to obtain a fermentation product, separating the fermentation product, collecting a filtrate, filtering the filtrate through a nanofiltration membrane with a molecular weight cutoff of 300 to 2000 Daltons, and collecting the retentate to obtain the corn fermentation liquid product.

6. The salt-alkali resistant bacterial agent according to claim 5, characterized in that: In step 1), the formula of the LB solid medium is: 8-10 g / L tryptone, 5-6 g / L yeast extract, 8-10 g / L sodium chloride, 15-18 g / L agar, and pH 7.2-7.3; In step 2), the formula of the seed culture medium is: 18-20 g / L peptone, 8-10 g / L sodium chloride, 8-10 g / L yeast extract powder, 45-50 mmol / L zinc sulfate, pH 7.2-7.3; In step 3), the formula of the culture medium is: 18-20 g / L peptone, 8-10 g / L sodium chloride, 8-10 g / L yeast extract powder, 45-50 mmol / L zinc sulfate, 800-1000 nmol / L PQQ, pH 7.2-7.3; In step 4), the formula of the culture medium is: 2-3% soybean meal, 0.8-1.0% yeast extract powder, 0.8-1.0% ammonium sulfate, 0.8-1.0% glucose, 1.0-2.0% starch, 1.0-1.5% magnesium sulfate heptahydrate, 1.0-1.5% sodium chloride, 0.5-0.8% potassium dihydrogen phosphate, and 25-30 mmol / L zinc sulfate heptahydrate solution; During the preparation of the corn fermentation broth product, the fermentation treatment conditions are: pH 4.5~7.5, fermentation temperature 28~37°C, and fermentation time 7~8d.

7. A method for preparing the salt-alkali resistant bacterial agent as claimed in any one of claims 4 to 6, comprising the following steps: grinding the corn fermentation broth product with a sand mill and mixing it with the fermentation broth of Bacillus proteolyticus XZT198 in a volume ratio of 1:1 to obtain the salt-alkali resistant bacterial agent.

8. Use of the salt-alkali tolerant bacterial agent according to any one of claims 4 to 6 or the salt-alkali tolerant bacterial agent prepared by the preparation method according to claim 7 in improving soil salinization.

9. Use of the salt-alkali tolerant bacterial agent according to any one of claims 4 to 6 or the salt-alkali tolerant bacterial agent prepared by the preparation method according to claim 7 in promoting the growth of rice or pepper in saline-alkali land.

10. Use of the salt-alkali tolerant bacterial agent according to any one of claims 4 to 6 or the salt-alkali tolerant bacterial agent prepared by the preparation method according to claim 7 in improving the salt-alkali resistance of rice or pepper.

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