Streptomycete for promoting straw to synthesize biochemical fulvic acid and application of streptomycete

Abstract

The invention discloses streptomyces for promoting straw to synthesize biochemical fulvic acid and application of the streptomyces. The streptomyces is named as Streptomyces sp.X184FX, is preserved in the China Center for Type Culture Collection, and has the preservation number of CCTCC (China Center for Type Culture Collection) NO: M 20242611. The streptomyces X184FX provided by the invention can improve the degradation rate of cellulose, hemicellulose and lignocellulose in straws, promote the formation of reducing sugar, amino acid, soluble protein and tannin, and further promote the synthesis of biochemical fulvic acid. The invention provides a new technical means for resource utilization of agricultural and forestry wastes and production of biochemical fulvic acid.

Description

Technical Field

[0001] The present invention relates to a strain for promoting the synthesis of biochemical fulvic acid from straw and its application, in particular to a Streptomyces strain for promoting the synthesis of biochemical fulvic acid from straw and its application in efficiently degrading corn straw and promoting the synthesis of biochemical fulvic acid. The present invention belongs to the technical field of agricultural production. Background Art

[0002] Straw has become an important biomass resource due to its rich lignocellulose and essential trace elements (such as nitrogen, phosphorus, potassium, etc.). However, the lignocellulose structure in straw is stable and not easily degraded, resulting in the difficulty of directly using straw resources. At present, the main treatment method for crop straw is incineration, which not only causes waste of straw resources but also imposes a heavy burden on the environment. Therefore, how to effectively utilize crop straw has become an urgent problem to be solved.

[0003] Previous research reports have shown that biochemical fulvic acid (BFA) with higher added value can be produced from the organic matter in straw. BFA has the characteristics of low condensation degree, small molecular weight, and rich active groups, and is easily absorbed and utilized by plant and animal tissues. In agricultural production, the application of BFA has the effects of promoting plant growth, improving plant stress resistance, increasing yield, and improving quality. The complex macromolecular aromatic colloid formed by the further aggregation of lignocellulose in straw after microbial decomposition and transformation is BFA. As an important participant in the formation process of BFA, microorganisms have become a new means of efficiently utilizing crop straw resources by selecting excellent fulvic acid-producing strains, controlling fermentation parameters, and using the microbial fermentation method to directionally ferment organic wastes of animals and plants to produce fulvic acid.

[0004] Therefore, the development of microbial strains with high efficiency in promoting BFA production is of extremely important significance for improving the efficiency of straw fermentation to produce BFA and enhancing the resource utilization degree of organic solid wastes. Summary of the Invention

[0005] One of the purposes of the present invention is to provide a strain capable of promoting the synthesis of biochemical fulvic acid.

[0006] Another purpose of the present invention is to provide the application of the strain in efficiently degrading corn straw and promoting the synthesis of biochemical fulvic acid.

[0007] In order to achieve the above purposes, the present invention adopts the following technical means:

[0008] A strain of Streptomyces that promotes the synthesis of biochemical fulvic acid from straw was screened in the present invention. The Streptomyces is named Streptomycetales sp. X184FX and is deposited in the China Center for Type Culture Collection, with the deposit number CCTCC NO: M20242611.

[0009] Furthermore, the present invention also proposes the application of the Streptomyces in straw degradation and promoting the synthesis of biochemical fulvic acid from straw.

[0010] Among them, preferably, the straw is corn straw.

[0011] Among them, preferably, the Streptomyces can improve the degradation rates of cellulose, hemicellulose, and lignocellulose in straw, and promote the formation of reducing sugars, amino acids, soluble proteins, and tannins, further promoting the synthesis of biochemical fulvic acid.

[0012] More preferably, the Streptomyces can increase the cellulose degradation rate by 11.57%, the hemicellulose degradation rate by 4.64%, and the lignin degradation efficiency by 3.76%.

[0013] Still further, the present invention also proposes a method for promoting the fermentation of corn straw to produce chemical fulvic acid, including the following steps:

[0014] (1) Dry the corn straw and crush it into corn straw powder with a size of 1 cm. Weigh 10 g of the corn straw powder into a 250 mL conical flask, add 100 mL of sterile water after high-temperature sterilization, add urea to adjust the C / N ratio to 20:1, and then add the above-mentioned Streptomyces.

[0015] (2) Then, place it in a shaker for fermentation.

[0016] Among them, preferably, the concentration of the Streptomyces is 2 g (wet weight) / mL, the inoculation amount of the Streptomyces is 1% v / v, the rotation speed of the shaker is 130 r / min, the fermentation temperature is 35.6 °C, and the fermentation time is 33.7 d.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] The present invention provides a Streptomyces strain that can promote straw degradation and simultaneously promote the synthesis of biochemical fulvic acid (BFA) from straw. The provided strain is of great significance for the production of BFA using straw and provides a new bacterial source for the further development of engineering strains. In addition, the optimal fermentation conditions proposed by the present invention have good reference value for the process of fermenting corn straw to prepare BFA and also lay a certain foundation for subsequent efficient production processes. Compared with the chemical industrial extraction method, the production of BFA using microbial fermentation technology has higher safety and significantly reduces environmental pollution. On the basis of following the principle of sustainable development, the present invention provides a theoretical basis and technical means for the resource utilization of straw and the production of BFA. Description of the Drawings

[0019] Figure 1 Shows the results of screening bacteria at different fermentation days;

[0020] In the figure, the letters a - j represent significant differences;

[0021] Figure 2 Shows the results of screening bacteria at different fermentation temperatures;

[0022] In the figure, the letters a - j represent significant differences;

[0023] Figure 3 Shows the basic information of strain X184FX;

[0024] Among them, (a) and (b) are scanning electron microscope images of the strain, (c) is the plate morphology of the strain, (d) is the microscopic examination image of the strain, and (e) is the phylogenetic tree of the strain;

[0025] Figure 4 Shows the results of single - factor experiments on fermentation process conditions;

[0026] Among them, (a) shows the effect of fermentation temperature on the extraction rate of BFA, (b) shows the effect of the solid - to - liquid ratio of the fermentation broth on the extraction rate of BFA, (c) shows the effect of the inoculum addition amount on the extraction rate of BFA, (d) shows the effect of the fermentation carbon - to - nitrogen ratio on the extraction rate of BFA, and (e) shows the effect of the fermentation days on the extraction rate of BFA; the letters a - d represent significant differences;

[0027] Figure 5 Shows the results of response surface experiments on fermentation process conditions;

[0028] Figure 6 Shows the enzyme activity of strain X184FX;

[0029] Figure 7 Shows the degradation efficiency of straw;

[0030] Among them, (a) is the straw weight loss rate, (b) is the cellulose degradation rate, (c) is the hemicellulose degradation rate, and (d) is the lignin degradation rate;

[0031] Figure 8 It is a graph of the change in the content of BFA precursor substances in the straw fermentation broth;

[0032] Among them, (a) is the content of soluble sugar, (b) is the content of reducing sugar, (c) is the content of amino acid, and (d) is the content of soluble protein.

[0033] Strain preservation information:

[0034] Strain name: Streptomycetales sp. X184FX

[0035] Taxonomic naming: Streptomycetales sp. X184FX

[0036] Preservation number: CCTCC NO: M 20242611

[0037] Preservation unit: China Center for Type Culture Collection (CCTCC)

[0038] Preservation address: Wuhan University, Wuhan, China

[0039] Preservation date: November 21, 2024. Detailed implementation manners

[0040] The present invention will be further described by the following embodiments. The embodiments only represent the preferred implementation manners of the present invention, and the description is relatively specific and detailed, but it should not be construed as a limitation to the scope of the patent of the present invention. It should be noted that these embodiments are only for illustrative purposes and in no way limit the protection scope of the present invention.

[0041] Example 1 Screening of BFA-producing strains

[0042] 1. Materials and methods

[0043] 1.1 Test materials

[0044] 1.1.1 Test strains

[0045] The strains used are from the highly efficient lignocellulose-degrading bacteria preserved in the Microbial Ecology Laboratory of Qiqihar University. The strains were initially screened from the samples of decomposed straw compost, and after isolation and purification, molecular biological identification was carried out. According to the enzyme activities of the strains such as laccase, xylanase, and glucosidase, 12 strains with the strongest enzyme activities were selected for the experiment.

[0046] 1.1.2 Culture medium

[0047] Beef extract peptone liquid medium: 3 g of beef extract, 10 g of peptone, 5 g of sodium chloride, add water to make 1000 mL of solution.

[0048] Corn straw liquid fermentation medium: Dry and crush corn straw into corn straw powder with a particle size of 1 cm. Weigh 10 g of corn straw powder into a 250 mL conical flask, add 100 mL of sterile water and 0.2 g of urea after high-temperature sterilization.

[0049] 1.2 Screening of strains

[0050] Activate highly efficient lignocellulose-degrading bacteria using beef extract peptone liquid medium, culture in a shaker at 30 °C and 110 r / min for 36 h. Centrifuge the bacterial suspension at 8000 r / min for 5 min to remove the medium, and resuspend with sterile water. Adjust the concentration of the bacterial suspension to OD 600nm = 0.8. Transfer 1 mL of the bacterial suspension to the corn straw liquid fermentation medium, culture at 40 °C and 130 r / min, measure the content of BFA in the fermentation broth at 10 d, 20 d, 30 d and 40 d of fermentation, and screen the strains with the extraction rate of BFA as the index. To avoid the inhibitory effect of temperature on the activity of lignocellulose-degrading enzymes and affect the efficiency of BFA production by the strains, this invention further conducts a 10-day fermentation test at 30 °C, 35 °C, 40 °C and 45 °C, and also screens the strains with the extraction rate of BFA as the index.

[0051] 1.3 Data analysis

[0052] The original data was preliminarily sorted using Microsoft Excel Office 2016 software, one-way ANOVA (ANOVA) was performed between different treatment groups using SPSS Statistics 26, and graphs were plotted using Origin 2021 software.

[0053] 2. Results and analysis

[0054] Inoculate highly efficient lignocellulose-degrading strains into the corn straw liquid fermentation medium, measure the extraction rate of BFA in the fermentation broth at 10 d, 20 d, 30 d and 40 d of fermentation under the condition of a fermentation temperature of 40 °C. The obtained results are as Figure 1 shown. It can be seen from the figure that the strain with a significant effect on the BFA production rate is X184FX. Considering the influence of high temperature on the enzyme activity of the strain, a fermentation test under different temperature conditions was then carried out to further breed the strain. Under the condition of a fermentation day of 10 d, the extraction rate of BFA in the fermentation broth was measured at fermentation temperatures of 30 °C, 35 °C, 40 °C and 45 °C. The obtained results are as Figure 2As shown. It can be seen from the figure that when the fermentation temperature is 30 °C, 35 °C and 40 °C, the strain that has a significant effect on the BFA yield is X184FX. Considering the influence of the strain on the BFA extraction rate under different fermentation days and different fermentation temperature conditions, X184FX, which is relatively stable and has a more significant effect, is selected as the target strain, and its fermentation conditions are further optimized to maximize the amount of BFA produced by straw fermentation.

[0055] Figure 3 (a) and (b) are scanning electron micrographs of strain X184FX, Figure 3 (c) is the plate morphology of strain X184FX, Figure 3 (d) is the microscopic examination image of strain X184FX, Figure 3 (e) is the phylogenetic tree of strain X184FX. The obtained strain X184FX was named Streptomycetales sp. X184FX and deposited in the China Center for Type Culture Collection with the deposit number CCTCC NO: M 20242611.

[0056] Example 2 Optimization of Fermentation Conditions for Straw Fermentation to Produce BFA

[0057] 1. Test method

[0058] 1.1 Single-factor optimization test

[0059] The fermentation test for optimizing the fermentation process parameters was carried out with reference to Example 1. Taking the extraction rate of BFA as the index, the fermentation temperature (25 °C, 30 °C, 35 °C, 40 °C, 45 °C); liquid-solid ratio (volume of sterile water to weight of corn straw (v / w) = 8:1, 9:1, 10:1, 11:1, 12:1); addition amount of X184FX bacterial agent with a concentration of 2 g (wet weight) / mL (1% v / v, 2% v / v, 3% v / v, 4% v / v, 5% v / v), the concentration of X184FX bacterial agent is 2 mg / L (wet weight); adjusting the carbon-nitrogen ratio by adding urea (C / N = 20:1, 23:1, 25:1, 27:1, 30:1); fermentation days (0 d, 10 d, 20 d, 30 d, 40 d), etc. were used for single-factor tests, and the best reference values of each factor were found in the test results to provide a basis for the orthogonal test.

[0060] 1.2 Orthogonal optimization test

[0061] Based on the results of the single-factor test, three factors that have the most significant influence on the yield of fulvic acid were selected. Taking the extraction rate of BFA as the response value, using Design-Expert 13 software, an orthogonal test design with 3 factors and 3 levels was carried out to fit the optimal condition parameters and further optimize the fermentation conditions.

[0062] 1.3 Data processing

[0063] The original data was preliminarily sorted using Microsoft Excel Office 2016 software, one-way (ANOVA) analysis of variance between different treatment groups was performed using SPSS Statistics 26, and graphs were plotted using Origin 2021 software. The orthogonal optimization experimental data was processed using Design-Expert 13 software, and response surface analysis was carried out.

[0064] 2. Results and Analysis

[0065] 2.1 Single-Factor Optimization Experiment

[0066] As can be seen from Figure 4 a, as the temperature increases, the extraction rate of BFA also gradually increases. When the temperature is 35 °C, its extraction rate reaches the maximum value of 4.11%. When the temperature exceeds 35 °C, the BFA extraction rate decreases with the increase in temperature. Therefore, the optimal fermentation temperature appears around 35 °C. Similarly, it can be seen from Figure 4 b that the optimal liquid-solid ratio for fermentation is 10:1, and at this time, the extraction rate of BFA is 3.86%. Figure 4 It can be seen from Figure 4 c that the optimal fermentation C / N = 23:1, and at this time, the extraction rate of BFA is 4.19%. It can be seen from Figure 4 d that the influence of the inoculant addition amount on the BFA extraction rate is not significant. From the perspective of cost reduction and efficiency improvement, 1% v / v is selected as the optimal inoculant addition amount. The influence of the fermentation days on the BFA extraction rate is as shown in

[0067] 2.2 Orthogonal Optimization Experiment

[0068] Taking the extraction rate of BFA as the response value, the response surface optimization experiment was designed using Design-Expert 13 software. The experiment was carried out according to the combined design in the software. There were a total of 17 groups of experiments, and the extraction rate of BFA in each group was measured. The results are shown in Table 1. Using Design-Expert 13 software to analyze the results of the response surface optimization experiment, the optimal fermentation conditions were obtained as follows: fermentation temperature = 35.6 °C, fermentation days = 33.7 d, fermentation C / N = 20:1. Under these conditions, the extraction rate of BFA can reach 7.53% ( Figure 5 ).

[0069] Table 1 Response Surface Experimental Design and Results

[0070]

[0071] Example 3 Analysis of the Characteristics of Strain X184FX

[0072] 1. Materials and Methods

[0073] 1.1 Test Materials

[0074] 1.1.1 Kits

[0075] Cellulose content kit (Suzhou Grees Biotechnology Co., Ltd.); hemicellulose content kit (Suzhou Grees Biotechnology Co., Ltd.); lignin content kit (Suzhou Grees Biotechnology Co., Ltd.); reducing sugar content kit (Suzhou Grees Biotechnology Co., Ltd.); soluble protein content kit (Nanjing Jiancheng Bioengineering Institute); amino acid content kit (Nanjing Jiancheng Bioengineering Institute); tannin content kit (Suzhou Grees Biotechnology Co., Ltd.); cellulase kit (Suzhou Grees Biotechnology Co., Ltd.); peroxidase kit (Suzhou Grees Biotechnology Co., Ltd.); xylanase kit (Suzhou Grees Biotechnology Co., Ltd.); α-galactosidase kit (Suzhou Grees Biotechnology Co., Ltd.); β-glucosidase kit (Suzhou Grees Biotechnology Co., Ltd.).

[0076] 1.1.2 Reagents

[0077] 80% ethanol: Take 400 mL of absolute ethanol, add 100 mL of ultrapure water, mix well and seal for later use;

[0078] Glucose standard solution: Accurately weigh 10 mg of analytical pure anhydrous glucose, dissolve it in ultrapure water and make up the volume to 100 mL;

[0079] Anthrone reagent: Weigh 0.5 g of anthrone reagent, dissolve it in 500 mL of 80% concentrated sulfuric acid, cool to room temperature, and store it in a stoppered brown bottle for later use.

[0080] 1.1.3 Media

[0081] Corn straw liquid fermentation medium: Dry and crush corn straw into corn straw powder with a particle size of 1 cm. Weigh 10 g of corn straw powder into a 250 mL conical flask, sterilize it at high temperature, add 100 mL of sterile water, and add urea to adjust the C / N ratio to 20:1.

[0082] Straw liquid enzyme-producing fermentation medium: Ammonium dihydrogen phosphate 2 g, potassium dihydrogen phosphate 0.6 g, MgSO 4 ·7H 20.5 g of O, 0.4 g of dipotassium hydrogen phosphate, 10 mL of trace element solution, with straw powder added as the sole carbon source, pH 7.0. (The 10 mL of trace element solution contains: CaC l2 ·2H 2 O 7.40 g, FeSO 4 ·7H 2 0 1.20 g, ZnSO 4 ·7H 2 O 0.66 g, MnSO 4 ·4H 2 O 0.50 g, CoC l2 ·6H 2 O 0.10 g, thiamine 1 mg).

[0083] 1.2 Test methods

[0084] 1.2.1 Determination of the activities of enzymes related to lignocellulose degradation

[0085] The X184FX strain screened in Example 1 was inoculated into the straw liquid enzyme-producing fermentation medium, cultured in a shaking incubator at 30 °C and 120 r / min for 7 d, and three independent replicate tests were set up. The supernatant was taken to measure the enzyme activities of cellulase, lignin peroxidase (LiP), xylanase kit, α-galactosidase (α-gal), and β-glucosidase (β-D-Glu).

[0086] 1.2.2 Corn straw liquid fermentation test

[0087] 1 mL of the X184FX strain screened in Example 1 was inoculated into the corn straw liquid fermentation medium, and fermentation was carried out according to the optimal conditions optimized in Example 2 (fermentation temperature = 35.6 °C, fermentation days = 33.7 d, fermentation C / N = 20:1). At the same time, the corn straw liquid fermentation medium with 1 mL more distilled water added was used as the control group.

[0088] 1.2.3 Determination of the straw weight loss rate

[0089] The remaining straw in the corn straw liquid fermentation medium after fermentation for 5 d, 10 d, 20 d, and 40 d was collected, washed with distilled water, and then dried in an oven to a constant weight to calculate the straw weight loss rate.

[0090] 1.2.4 Determination of the lignocellulose degradation rate

[0091] The dried corn straw powder in 1.2.4 of Example 3 was taken, and the contents of lignin, cellulose, and hemicellulose were measured according to the requirements of the kit, and the degradation efficiency was calculated.

[0092] 1.2.5 Determination of the content of BFA precursor substances

[0093] Take the liquid fermentation medium of corn straw fermented for 5 days, 10 days, 20 days, and 40 days, and determine the contents of reducing sugar, soluble protein, amino acid, and tannin in the fermentation broth according to the requirements of the kit, and determine the soluble sugar content in the fermentation broth by the anthrone method.

[0094] Determination of soluble sugar content: Dilute the 100 μg / mL glucose standard solution to 80 μg / mL, 60 μg / mL, 40 μg / mL, and 20 μg / mL with distilled water. Take 1 mL of glucose solution and add 5 mL of anthrone reagent. After mixing, place it in a boiling water bath for 10 min, take it out and cool it. At a wavelength of 620 nm, zero with the blank and measure the absorbance value. Plot a standard curve with the absorbance as the ordinate and the glucose content as the abscissa. Take 1 mL of the fermentation broth diluted 40 times, add 5 mL of anthrone reagent, mix well, place it in a boiling water bath for 10 min, take it out and cool it. At a wavelength of 620 nm, zero with the blank and measure its absorbance value, and calculate the soluble sugar content in the fermentation broth according to the measured standard curve.

[0095] 1.3 Data analysis

[0096] The original data was preliminarily sorted using Microsoft Excel Office 2016 software, independent sample t-test analysis was performed between different treatment groups using SPSS Statistics 26, and graphing was performed using Origin 2021 software.

[0097] 2. Results and analysis

[0098] 2.1 Enzyme activity of X184FX strain

[0099] The enzyme activity of X184FX strain is as Figure 6As shown in the figure. All five enzyme activities measured in the present invention are closely related to the degradation of lignocellulose. After detection, the X184FX strain has the activities of these five key enzymes. Among them, the α-gal activity in the X184FX strain is the highest, reaching 0.6481 μmoL / min / mL. α-gal can catalyze the hydrolysis of α-galactoside bonds and promote the synthesis of oligosaccharides. The LiP activity in the X184FX strain is 0.0051 μmoL / min / mL. LiP is the main degrading enzyme in the biodegradation process of lignin and can degrade lignin in straw. The cellulase activity in the X184FX strain is 0.2781 μmoL / min / mL, and cellulase is a protein that can decompose cellulose into oligosaccharides or monosaccharides. The xylanase activity in the X184FX strain is 0.0425 μmoL / min / mL. Xylanase is an enzyme system that degrades xylan and can hydrolyze xylan into xylooligosaccharides such as small oligosaccharides and xylobiose, as well as a small amount of xylose and arabinose. The β-D-Glu activity is 0.0190 μmoL / min / mL. β-D-Glu belongs to one of the enzymes in the cellulase system and can hydrolyze the β-D-glucose bond bound to the terminal non-reducing end, releasing β-D-glucose and the corresponding ligand at the same time. The ability of X184FX to accelerate the degradation of lignocellulose in straw depends largely on its high activity of lignocellulose-degrading enzymes.

[0100] 2.2 Straw weight loss rate

[0101] The change in the straw weight loss rate during the fermentation process is as Figure 7 (a) shown. It can be seen from the figure that as the fermentation progresses, the straw is gradually hydrolyzed. After adding the X184FX strain, the degradation of corn straw is significantly promoted, and its straw weight loss rate is 5.06% higher than that of the CK group.

[0102] 2.3 Degradation rate of straw

[0103] From Figure 7 (b)-(d), it can be seen that after adding the X184FX strain, the degradation of cellulose, hemicellulose, and lignocellulose in corn straw is significantly promoted. Among them, Figure 7 (b) is the change diagram of the cellulose degradation rate. Compared with the CK group, its cellulose degradation rate has increased by 11.57%. Figure 7 (c) is the change diagram of the hemicellulose degradation rate, and the hemicellulose degradation rate has increased by 4.64%. Figure 7 (d) is the change diagram of the lignin degradation rate, and the lignin degradation efficiency has increased by 3.76%.

[0104] 2.4 Content of BFA precursor substances

[0105] Some studies have shown that sugars, amino acids, proteins, polyphenols, etc. are the main small-molecule compounds that form BFA. Detecting their change processes helps to monitor the formation of BFA. The changes in the content of BFA precursor substances during the fermentation process are as follows Figure 8 shown. It can be seen from the figure that the addition of strain X184FX did promote the formation of BFA precursor substances. Among them Figure 8 (a) shows the change in the content of soluble sugars. It can be seen from the figure that after adding strain X184FX, the content of soluble sugars is lower than that of the CK group. This is mainly because the growth and reproduction of the strain preferentially utilize easily degradable soluble sugars as nutrients. Figure 8 (b)-(d) show the contents of reducing sugars, amino acids, soluble proteins, and tannins. Compared with the CK group, the addition of strain X184FX promoted the formation of small-molecule compounds such as reducing sugars, amino acids, proteins, and polyphenols.

[0106] Conclusion:

[0107] Strain X184FX can accelerate the degradation of cellulose, hemicellulose, and lignocellulose in straw, and at the same time promote the formation of small-molecule compounds such as reducing sugars, amino acids, proteins, and polyphenols, thereby promoting the synthesis of biochemical fulvic acid. When strain X184FX is inoculated into a liquid fermentation medium of corn straw and fermented under the conditions of fermentation temperature = 35.6 °C, fermentation days = 33.7 d, fermentation C / N = 20:1, X184FX inoculum dosage = 1% v / v, and liquid-solid ratio = 10:1, the BFA extraction rate can reach 7.53%.

Claims

1. A Streptomycetales sp. that promotes the fermentation of straw to synthesize biochemical fulvic acid, characterized in that: The streptomyces is named as Streptomycetales sp. X184FX and is deposited in China Center for Type Culture Collection with a deposit number of CCTCC NO: M 20242611.

2. Use of the Streptomyces described in claim 1 in straw degradation and promotion of straw synthesis of biochemical fulvic acid.

3. The use according to claim 2, characterized in that The straw is corn straw.

4. The use according to claim 2 or 3, characterized in that The streptomyces can increase the degradation rate of cellulose, hemicellulose and lignocellulose in the straw, and promote the formation of reducing sugars, amino acids, soluble proteins and tannins, and further promote the synthesis of biochemical fulvic acid.

5. The use according to claim 4, characterized in that The streptomyces can increase the cellulose degradation rate by 11.57%, the hemicellulose degradation rate by 4.64%, and the lignin degradation efficiency by 3.76%.

6. A method for promoting the fermentation of corn stalks to synthesize biochemical fulvic acid, characterized in that: The following steps are involved: (1) Dry corn stalks and crush them into 1 cm corn stalk powder, weigh 10 g of corn stalk powder into a 250 mL conical flask, sterilize at high temperature, add 100 mL of sterile water, add urea to adjust the C / N ratio to 20:1, and then add the Streptomyces described in claim 1; (2) Then, place it in a shaking incubator for fermentation.

7. The method according to claim 4, characterized in that The concentration of Streptomyces is 2 g (wet weight) / mL, the inoculation amount of Streptomyces is 1% v / v, the rotation speed of the shaking table is 130 r / min, the fermentation temperature is 35.6° C., and the fermentation time is 33.7 days.

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