Streptomyces bulbus and multifunctional microbial agent and application thereof

Abstract

The invention discloses streptomyces bulbus as well as a multifunctional fungicide and application thereof. According to the invention, firstly, a strain of Streptomyces tauricus zhanshen-LZ-12 is separated and screened from straw returning soil, and the preservation number of the strain is CGMCC (China General Microbiological Culture Collection Center) No.34456. The invention also discloses a preparation method of the Streptomyces tauricus zhanshen-LZ-12. The strain has the functions of degrading cellulose, decomposing protein, fixing nitrogen, resisting salt, degrading phenolic acid autotoxic substances (benzoic acid, p-hydroxybenzoic acid and cinnamic acid) and the like. Bacterial powder obtained after fermentation of the bacterial strain is uniformly mixed with bacillus bacterial powder to obtain the multifunctional bacterial agent, and when straw returning or composting is carried out, the multifunctional bacterial agent is adopted, straw decomposition can be accelerated, soil ecology can be improved, crop growth can be promoted, and the stress resistance of crops can be enhanced.

Description

Technical Field

[0001] The invention relates to a bull Streptomyces strain and a multifunctional bacterial agent and application thereof, belonging to the field of agricultural biotechnology. Background Art

[0002] my country is a major agricultural producer, with an annual crop straw production of up to 900 million tons. If these straws are not rationally and comprehensively utilized, it will not only result in a waste of resources, but also cause air pollution due to open-air burning. Among the diversified comprehensive utilization methods of straw, such as energy, feed, and fertilizer, fertilizer utilization has the advantages of simple operation, large processing capacity, and low cost, and is the most important utilization method. Straw composting and straw return to the field are the two core methods of straw fertilizer utilization. However, due to the long composting cycle, serious nitrogen loss, impact on crop root growth, and aggravation of continuous cropping obstacles, their promotion and application face many obstacles and are in urgent need of technological breakthroughs and innovations.

[0003] Inoculation with microbial agents can accelerate straw decomposition, reduce nitrogen loss, and alleviate problems with continuous cropping. Developing multifunctional microbial agents is crucial for addressing the specific needs of straw return and composting. Actinomycetes are a key group within the soil microbiome. They not only efficiently secrete hydrolytic enzymes such as cellulases, xylanases, and proteases to rapidly degrade straw, but also possess the ability to synthesize antibiotics and degrade toxic and hazardous soil substances. Specific actinomycete strains have been screened for exceptional performance in straw degradation: their high cellulose degradation efficiency significantly shortens the straw decomposition cycle; their antibiotic production effectively inhibits soil-borne pathogens, mitigating soil-borne diseases; and their ability to degrade toxic and hazardous substances helps alleviate problems with continuous cropping. This multifunctional combination of efficient degradation and bio-pathogen inhibition makes actinomycetes a core resource for the development of high-performance microbial agents, demonstrating significant potential for application in the resource-based utilization of agricultural waste.

[0004] With the accelerated modernization of agriculture in my country and the widespread adoption of intensive cropping practices, soil salinization is becoming a significant problem, posing a serious threat to arable land quality and sustainable agricultural development. Against this backdrop, the development of microbial agents suitable for salinized soils is of great significance. Halotolerant actinomycetes not only maintain stable metabolic activity under high salt stress but also regulate soil pH and improve aggregate structure by secreting functional metabolites such as organic acids and exopolysaccharides, thus facilitating the ecological restoration of salinized soils. Summary of the Invention

[0005] Based on this, the present invention provides a strain of Streptomyces bullsii and its multifunctional bacterial agent and application. The present invention first isolates and screens a strain of Streptomyces bullsii from the soil of straw return to the field. Streptomyces tauricuszhanshen-LZ-12, a strain with the ability to degrade cellulose, decompose protein, fix nitrogen, tolerate salt, and degrade phenolic autotoxicants (benzoic acid, p-hydroxybenzoic acid, and cinnamic acid). The powder obtained from fermentation of this strain is mixed evenly with Bacillus powder to produce a multifunctional inoculant. When used in straw return or composting, this inoculant not only accelerates straw decomposition and improves soil ecology, but also promotes crop growth and enhances crop resistance. This inoculant has important applications in saline-alkali land improvement and stress-tolerant crop cultivation.

[0006] The present invention first isolates and screens a strain of Streptomyces bulls from the soil of straw return. Streptomyces tauricus zhanshen-LZ-12, which was deposited with the General Microbiology Center of the China General Culture Collection Administration (CGMCC) on May 8, 2025, at No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, under the accession number CGMCC No. 34456. This strain has the ability to degrade cellulose, decompose proteins, fix nitrogen, tolerate salt, and degrade phenolic autotoxicants (benzoic acid, p-hydroxybenzoic acid, and cinnamic acid).

[0007] The present invention also provides a fermentation method for the bull Streptomyces strain zhanshen-LZ-12, which is characterized by sequentially subjecting the bull Streptomyces strain zhanshen-LZ-12 to activation, preparation of seed liquid in a triangular flask, preparation of strain in a seed tank, and solid-state fermentation culture, and drying the fermentation product to obtain bull Streptomyces zhanshen-LZ-12 bacterial powder, as follows: (1) Strain activation: Inoculate the bull Streptomyces strain zhanshen-LZ-12 into the slant of a test tube containing Gao's solid medium No. 1 and culture at 25-30°C for 4-6 days to obtain the activated strain; (2) Preparation of triangular flask seed solution: inoculate the activated strain into Gao's liquid medium No. 1 and culture at 25-30°C for 4-6 days to obtain the triangular flask seed solution of Streptomyces bullsii zhanshen-LZ-12; (3) Preparation of seed tank strains: Inoculate the bull Streptomyces zhanshen-LZ-12 triangular flask seed liquid at an inoculum rate of 4%-8% (v / m) into a seed tank containing Gao's No. 1 liquid medium and culture for 4-6 days to obtain seed tank strains; (4) Solid-state fermentation culture: The bull Streptomyces zhanshen-LZ-12 seed tank strain was inoculated into the solid-state fermentation medium at an inoculum rate of 4%-8% (v / m), and the fermentation culture was carried out for 4-6 days. During the fermentation process, the product temperature was controlled at 28-30°C, and the water content of the culture medium was maintained at 50±2% by atomization water replenishment to obtain the fermentation product; The solid-state fermentation medium has a formula of 38-42% bran, 8-12% soybean meal powder, 47-52% corn straw powder, and 0.8-1.2% CaCO3 by mass ratio, with an initial moisture content of 50-60%; preferably, the solid-state fermentation medium has a formula of 40% bran, 10% soybean meal powder, 49% corn straw powder, and 1% CaCO3 by mass ratio, with an initial moisture content of 50-60%. (5) After the fermentation is completed, the fermentation product is dried at 40-50°C and crushed to 80-100 mesh to obtain the bull Streptomyces zhanshen-LZ-12 bacterial powder, the content of which can reach 1.0×10 9 -1.0×10 10 CFU / g.

[0008] The present invention also provides a multifunctional bacterial agent, characterized in that 60-80 parts by weight of Streptomyces bullsii zhanshen-LZ-12 powder and 20-40 parts by weight of Bacillus powder are evenly mixed to obtain a multifunctional bacterial agent. The Bacillus powder has an effective viable cell count of ≥1.0×10 10 CFU / g.

[0009] The present invention also provides the use of the bull Streptomyces strain zhanshen-LZ-12 or its multifunctional bacterial agent in straw fertilizer utilization, wherein the straw fertilizer utilization includes straw composting and straw returning to the field.

[0010] Preferably, the method for applying the multifunctional bacterial agent in straw composting is: mixing the multifunctional bacterial agent with water in a weight ratio of 1: (50-100), and then evenly sprinkling the mixture on 500-2000 parts by weight of straw.

[0011] Preferably, the application method of the multifunctional bacterial agent in returning straw to the field is: the dosage of the multifunctional bacterial agent is 1-10 kg / mu, or calculated based on the amount of straw returned to the field, it is 0.5-10 kg / ton of straw; after the crops are harvested, the multifunctional bacterial agent is evenly spread in the field and the cultivated land is deep plowed.

[0012] Beneficial effects of the present invention: 1. The bull Streptomyces zhanshen-LZ-12 strain provided by the present invention has the functions of degrading cellulose, decomposing proteins, fixing nitrogen, being salt-tolerant, and degrading phenolic acid autotoxic substances (benzoic acid, p-hydroxybenzoic acid, and cinnamic acid). Therefore, it can play a role in multiple aspects such as accelerating straw degradation, improving soil, increasing nutrient supply, and degrading phenolic acid autotoxic substances. It has good application effects in straw returning to the field, straw composting, agricultural planting, etc.

[0013] 2. The powder obtained after fermentation of the above strains is evenly mixed with Bacillus powder to obtain a multifunctional bacterial agent. When this multifunctional bacterial agent is used when returning straw to the field or composting, it can not only accelerate the decomposition of straw and improve soil ecology, but also promote crop growth and enhance the crop's resistance to stress.

[0014] 3. Experiments on straw compost maturity showed that compared with the control group, the treatment group heated up faster and had a longer high-temperature period, which was beneficial to accelerating straw maturity and shortening the maturity cycle. The organic matter, organic nitrogen and fulvic acid contents in the finished compost using the multifunctional bacterial agent of the present invention were increased, and the seed germination index was improved, which shows that the use of the multifunctional bacterial agent of the present invention can improve the quality and safety of compost products.

[0015] 4. The effect test on wheat growth and development in saline-alkali soil showed that compared with the control group, the plant height and stem diameter of wheat samples taken at the heading stage were significantly increased when straw and saline-alkali soil were treated with the multifunctional bacterial agent of the present invention, indicating that the multifunctional bacterial agent provided by the present invention can effectively promote wheat growth; its proline, soluble sugar, SOD, POD and CAT activities were significantly increased, indicating that the multifunctional bacterial agent provided by the present invention can enhance the adaptability of wheat to saline-alkali stress by regulating proline synthesis, sugar metabolism and antioxidant defense system, and has important application value in saline-alkali land improvement and crop stress resistance cultivation. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 :Colony morphology of Streptomyces bull strain zhanshen-LZ-12; Figure 2 :Mycelial and spore morphology of Streptomyces bull strain zhanshen-LZ-12; Figure 3 : Phylogenetic tree of Streptomyces bullosa strain zhanshen-LZ-12; Figure 4 : Cellulose degradation ability of Streptomyces bull strain zhanshen-LZ-12; Figure 5 : Nitrogen fixation ability of Streptomyces bulli strain zhanshen-LZ-12; Figure 6 :Protease production capacity of Streptomyces bull strain zhanshen-LZ-12; Figure 7 :Streptomyces bulli strain zhanshen-LZ-12 grows normally on 6% salt concentration medium; Figure 8 : Application Example 2 Temperature changes during composting process. DETAILED DESCRIPTION

[0017] The following is a description of the specific embodiments and drawings: Example 1: Screening of Streptomyces bullosa LZ-12 Straw-returned soil from Ancheng Town, Pingyin County, Jinan City, Shandong Province was isolated and screened using the following method: 10.0 g of soil sample was weighed, 90 mL of sterile water was added, and the sample was shaken and extracted on a constant temperature shaker at 28°C and 180 rpm for 30 min to obtain the extract. The strains were then isolated and screened as follows: (1) Screening of cellulose-degrading strains: Take 1 mL of the above extract and perform -1 -10 -7 Serial concentration gradient dilution, then take 10 -3 , 10 -4 and 10 -5 Three dilutions were plated onto CMC-Na medium plates and incubated upside down at 28°C for 5 days. After colonies grew, they were stained with Congo red and decolorized with sodium chloride solution. Strains with clear zones were selected, and the clear zone diameter (D) and colony diameter (d) were recorded. Strains with large D / d ratios were preferred.

[0018] The selected strains were inoculated into a filter paper disintegration culture medium and cultured at 28°C and 180 rpm for 5 days to screen out strains with strong filter paper disintegration ability. The selected strains were further screened using the straw weight loss method. Specific method: Cut corn straw into small segments of 3-5 cm, dry at 85°C, weigh 50.00 g and put into a nylon mesh bag; take 1 mL of the culture medium of the strain to be screened, dilute it 50 times with water, add 0.1 g of urea, stir to dissolve, and then sprinkle it on the corn straw; bury the straw in the field to a depth of 15-20 cm, remove it after 15 days, wash it with clean water, dry it and weigh it, and select strains with higher straw weight loss rates for subsequent screening.

[0019] Among them, the formula of CMC-Na culture medium is: dissolve 5 g CMC-Na, 1 g potassium nitrate, 0.5 g potassium dihydrogen phosphate, 0.5 g magnesium sulfate, 0.5 g sodium chloride, and 0.01 g ferrous sulfate in distilled water, add 15-20 g agar, dilute to 1000 mL, and adjust the pH to 7.4-7.6.

[0020] The components of the filter paper disintegration medium are: (NH4)2SO4 1g, KH2PO4 1g, MgSO4·7H2O 0.7g, NaCl 0.5g, distilled water 1000mL, and 3 filter paper strips of 6cm×1cm.

[0021] (2) Screening of protease-producing strains: The strains with strong straw degradation ability obtained by the above screening were inoculated onto skim milk powder medium plates. After culturing at 28°C for 5 days, strains that could produce a transparent zone were screened. The skim milk powder medium formula was: 3.0 g skim milk powder, 1.6% agar, 200 mL deionized water, pH = 7.0-7.2, and sterilized at 108°C for 15 min.

[0022] (3) Screening of nitrogen-fixing strains: The strains with strong straw degradation ability and strong protease production ability obtained from the above screening were inoculated onto Ashby nitrogen-free medium plates and cultured at 28°C for 5 days to screen strains that can grow in Ashby nitrogen-free medium. The formula of the Ashby medium is as follows: mannitol 10 g, KH2PO4 0.2 g, MgSO4·7H2O 0.2 g, NaCl 0.2 g, CaSO4·2H2O 0.1 g, CaCO3 5 g, distilled water 1000 mL, pH 7.0, sterilized at 115°C for 30 min.

[0023] (4) Screening of salt-tolerant strains: The strains obtained above with beneficial functions such as straw degradation, protease production, and nitrogen fixation were further transferred to high-salt culture plates and incubated inverted at 28°C for 5-7 days to screen strains that can grow normally under the corresponding salt concentration. The formula of the high-salt culture medium is: 10g peptone, 5g yeast extract, 60g NaCl, 20g agar, 1000mL distilled water, pH 7.0, and sterilized at 121°C for 20min.

[0024] (5) The strains obtained from the above screening, which have beneficial functions such as straw degradation, protease production, nitrogen fixation, and salt tolerance, were inoculated on inorganic salt solid culture plates with benzoic acid, p-hydroxybenzoic acid, and cinnamic acid as the sole carbon source (all at a concentration of 80 mg / L). The composition of the inorganic salt culture medium is: 2.0 g ammonium sulfate, 0.50 g sodium dihydrogen phosphate, 0.50 g dipotassium hydrogen phosphate, 0.20 g magnesium sulfate heptahydrate, 0.10 g calcium chloride dihydrate, distilled water was added to make the volume 1000 mL, the pH value was adjusted to 7.0, and high-pressure steam sterilization was performed at 115°C for 30 min. The inoculated plates were placed in a constant temperature incubator at 28°C and cultured for 5-7 days. The strains that can grow on the three inorganic salt solid culture media as the sole carbon source were selected, purified, and preserved, and the strains with the ability to degrade benzoic acid, p-hydroxybenzoic acid, and cinnamic acid were obtained.

[0025] Through the above isolation and screening work, a strain with strong straw degradation, protease production, nitrogen fixation, salt tolerance and degradation of phenolic acid autotoxic substances (benzoic acid, p-hydroxybenzoic acid and cinnamic acid, etc.) was finally screened out and named zhanshen-LZ-12.

[0026] Example 2: Identification of Streptomyces bullosa LZ-12 The colony morphology of the strain zhanshen-LZ-12 screened in Example 1 on Gao's solid medium No. 1 is as follows: Figure 1 As shown in the figure, the colony has a compact texture, a velvety surface, and the aerial hyphae and the soluble pigment produced are red. Figure 2 As shown, the mycelium is well developed, the spores are oval or oblong, and the surface is smooth.

[0027] Physiological and biochemical characteristics of strain zhanshen-LZ-12: Indole test +, VP test +, starch hydrolysis test +, nitrite reduction test +, ammonia production test +, nitrate reduction test -, methyl red test -, denitrification test -. Note: +, positive; -, negative.

[0028] The genomic DNA of strain zhanshen-LZ-12 was extracted and PCR amplified using 16S rDNA universal primers. The amplification conditions were: pre-denaturation at 95°C for 3 minutes; denaturation at 94°C for 1 minute, annealing at 55°C for 1 minute, extension at 72°C for 1.5 minutes, for a total of 30 cycles; extension at 72°C for 10 minutes. The amplified 16S rDNA gene sequence was sequenced, and the sequencing results are shown in SEQ ID No. 1. The obtained 16S rDNA sequence was subjected to BLAST analysis with the sequences already in the NCBI database, and strains with similar homology were selected. The phylogenetic tree was constructed using MEGA11.0 software, as shown in the following figure: Figure 3 shown.

[0029] Combined with the morphological, physiological and biochemical characteristics of the strain, it was identified as Streptomyces bulls ( Streptomyces tauricus The strain was deposited in the General Microbiology Center of China Culture Collection Administration (CGMCC) on May 8, 2025, at No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, with the deposit number CGMCC No. 34456.

[0030] Example 3: Beneficial properties and functions of Streptomyces zhanshen-LZ-12 (1) Cellulose degradation ability The bull Streptomyces zhanshen-LZ-12 strain was inoculated onto a CMC-Na medium plate using a sterilized toothpick. After culturing at 28°C for 5 days, the clear zone and colony diameter were measured, and the clear zone to colony diameter ratio (HC) was calculated. The experimental results showed that the clear zone diameter produced on the CMC-Na medium was 13.2 mm, the colony diameter was 5 mm, and the HC value was 2.64 ( Figure 4), indicating that this strain has strong cellulose degradation ability. The CMC-Na medium recipe is as follows: Dissolve 5 g CMC-Na, 1 g potassium nitrate, 0.5 g dipotassium hydrogen phosphate, 0.5 g magnesium sulfate, 0.5 g sodium chloride, and 0.01 g ferrous sulfate in distilled water. Add 15-20 g agar, dilute to 1000 mL, and adjust the pH to 7.4-7.6.

[0031] (2) Nitrogen fixation capacity The bull Streptomyces zhanshen-LZ-12 strain was inoculated onto an Ashby nitrogen-free medium plate using a sterile inoculation loop. After incubation at 28°C for 5 days, the growth of the strain on the plate was observed. If colonies grew, it was considered to have the ability to fix nitrogen. The experimental results showed that the strain could grow on Ashby nitrogen-free medium, indicating that it has the ability to fix nitrogen ( Figure 5 The formula of Ashby medium is as follows: mannitol 10 g, KH2PO4 0.2 g, MgSO4·7H2O 0.2 g, NaCl 0.2 g, CaSO4·2H2O 0.1 g, CaCO3 5 g, distilled water 1000 mL, pH 7.0, sterilized at 115°C for 30 min.

[0032] (3) Protease production capacity The strain of Streptomyces zhanshen-LZ-12 was inoculated onto skim milk powder plates using a sterilized toothpick. After culturing at 28°C for 5 days, the clear zone and colony diameters were measured, and the clear zone to colony diameter ratio (HC) was calculated. The experimental results showed that the clear zone diameter of Streptomyces zhanshen-LZ-12 on skim milk powder was 17.25 mm, the colony diameter was 8.5 mm, and the HC value was 2.03, indicating that this strain has a strong ability to produce proteases ( Figure 6 ).

[0033] (4) Salt tolerance While maintaining the pH of Gao's medium No. 1 constant, a salt concentration gradient was established, with NaCl contents at 4.0%, 6.0%, and 8.0% (w / w). The Streptomyces zhanshen-LZ-12 strain was inoculated onto plates with different salt concentration gradients and incubated in an inverted manner at 28°C for 5-7 days. Growth was observed and recorded. If colonies could grow at the corresponding salt concentration, it indicated that the strain could tolerate that salt concentration. The experimental results showed that the strain could grow colonies at a salt concentration of 6.0%, indicating that it has strong salt tolerance ( Figure 7 ).

[0034] (5) Degradation test of benzoic acid, p-hydroxybenzoic acid and cinnamic acid Prepare a benzoic acid-containing culture medium with the following formula: 80 mg of benzoic acid, 5 g of peptone, 0.5 g of ammonium sulfate, 20 g of complex inorganic salt (NaCl: KCl: MgCl2 = 10:1:1), 1000 ml of water, pH 7.0.

[0035] Prepare a culture medium containing p-hydroxybenzoic acid with the following formula: 80 mg of p-hydroxybenzoic acid, 5 g of peptone, 0.5 g of ammonium sulfate, 20 g of complex inorganic salt (NaCl: KCl: MgCl2 = 10:1:1), 1000 ml of water, pH 7.0.

[0036] Prepare a cinnamic acid-containing culture medium with the following formula: 80 mg of cinnamic acid, 5 g of peptone, 0.5 g of ammonium sulfate, 20 g of complex inorganic salt (NaCl: KCl: MgCl2 = 10:1:1), 1000 ml of water, pH 7.0.

[0037] Streptomyces zhanshen-LZ-12 was inoculated into each of the three aforementioned culture media and cultured at 28°C with shaking at 180 rpm for 7 days. Ten mL of the culture medium was centrifuged at 3500 rpm for 15 minutes, the precipitate discarded, and the supernatant extracted with 10 mL of dichloromethane. The extract was evaporated to dryness using a vacuum rotary evaporator, and the residue was dissolved in 1 mL of methanol and set aside. High-performance liquid chromatography (HPLC) was used to determine the residual amounts of benzoic acid, p-hydroxybenzoic acid, and cinnamic acid in the samples, and the degradation rates were calculated. The following conditions were used: a C18 reversed-phase column with a mobile phase of acetonitrile and water (adjusted to pH 2.8 with acetic acid), a flow rate of 1.0 mL / min, a column temperature of 30°C, and a detection wavelength of 280 nm. Gradient elution was used: acetonitrile was increased from 5% to 40% over 0-30 minutes, maintained at 40% acetonitrile over 30-40 minutes, and then decreased from 40% to 5% acetonitrile over 40-45 minutes. The results of HPLC showed that the degradation rates of benzoic acid, p-hydroxybenzoic acid and cinnamic acid by Streptomyces zhanshen-LZ-12 were 54.2%, 69.3% and 58.7% respectively.

[0038] Example 4: Preparation method of multifunctional bacterial agent (1) Preparation of Streptomyces bullosa LZ-12 powder: Activation of the strain: Inoculate the bull Streptomyces zhanshen-LZ-12 into the slant of a test tube containing Gao's solid medium No. 1 and culture at 28°C for 5 days to obtain the activated strain; Preparation of triangular flask seed solution: The activated strain was inoculated into Gao's liquid medium No. 1 and cultured at 180 rpm and 28°C for 5 days to obtain the triangular flask seed solution of Streptomyces bulls zhanshen-LZ-12; Seed tank culture preparation: Inoculate a 5% (v / m) inoculum of Streptomyces bullsii zhanshen-LZ-12 seed solution from a triangular flask into a seed tank containing Gao's No. 1 liquid medium. Incubate at 28°C for 5 days to obtain the seed tank culture. The volume of the seed tank should be 10 L, the liquid volume should be 7-8 L, the agitator speed should be 150-180 rpm, and the ventilation rate should be 7-8 L / min.

[0039] Solid-state fermentation: Inoculate the solid-state fermentation medium with a 5% (v / m) inoculum of Streptomyces zhanshen-LZ-12 seed solution. Ferment for 5 days. During the fermentation process, maintain the product temperature at 28-30°C and add water through atomization to maintain the water content of the medium at 50±2% to obtain the fermentation product. After fermentation, the fermentation product is dried at 40-50°C and crushed to 80-100 mesh to obtain the Streptomyces zhanshen-LZ-12 powder, which has a viable cell content of up to 1.0×10 9 -1.0×10 10 CFU / g.

[0040] The solid-state fermentation medium is formulated, by weight, as follows: 40% bran, 10% soybean meal, 49% corn straw meal, and 1% CaCO₃. The initial moisture content is 50-60%. Culture is performed in a 55 cm x 100 cm stainless steel shallow tray. The solid-state fermentation medium is sterilized at 121°C for 20 minutes, cooled, and spread evenly in the tray to a thickness of 3-5 cm.

[0041] (2) Preparation of multifunctional bacterial agents: 70 parts by weight of Streptomyces bullsii zhanshen-LZ-12 powder and 30 parts by weight of Bacillus powder are mixed evenly to obtain a multifunctional microbial agent. The Bacillus powder can be purchased from the agricultural supply market. Its effective microorganisms include but are not limited to one or more of Bacillus subtilis and Bacillus licheniformis, and the effective viable cell count is ≥1.0×10 10 CFU / g.

[0042] Application Example 1: Effect of Multifunctional Microbial Agent on Field Composting of Straw A field composting experiment was conducted in Ancheng Town, Pingyin County, Shandong Province, in 2024. Randomly selected intact corn stalks of similar thickness were removed, leaves removed, and cut into 3-5 cm segments. The stalks were then dried in an 85°C forced air drying oven for 12 hours. The stalks were weighed to the nearest 0.01 g and placed into nylon mesh bags, with each bag containing 50 g of straw. Forty-five bags of straw were weighed according to this method, with the maximum difference in straw mass between bags not exceeding 0.5 g.

[0043] The straw samples were subjected to the following three treatments. T1 treatment group: urea and the multifunctional bacterial agent prepared in Example 4 of the present invention were weighed separately, wherein the amount of urea was 0.5% of the weight of the straw, and the amount of the multifunctional bacterial agent was 0.2% of the weight of the straw; urea and the multifunctional bacterial agent were mixed, and then mixed with water in a weight ratio of 1:50 to obtain a suspension; the suspension was used to infiltrate the straw, and after the straw was fully infiltrated, the remaining suspension was evenly spread on the surface of the test area. T2 treatment group: an equal amount of commercially available composting agent was used to replace the multifunctional composite bacterial agent of the present invention, and the rest of the treatment methods were the same as those of the T1 treatment group. The commercially available composting agent was purchased from a local agricultural supply market, and its effective bacterial community was Bacillus subtilis and Aspergillus niger, and the number of effective live bacteria was ≥2.0×10 9 cfu / g. T3 treatment group: no bacterial agent was added.

[0044] A test site with flat terrain, uniform soil fertility, and good watering and drainage conditions was selected, and 15 bags of straw samples with the same treatment were divided into 5 groups, with 3 bags in each group tied together with a string. The 5 groups of samples were evenly buried in the test area in a five-point plum blossom shape, and the straw in the bags was evenly spread out. The burial depth was 10-15cm, so that the soil moisture was maintained at 60%-80% of the field water holding capacity. Samples were taken on the 15th and 30th days of the experiment. Each time a sample was taken, 1 bag of straw sample was randomly taken from each group of the same treatment, with a total of 5 bags per treatment; the obtained samples were rinsed with tap water, dried at 85°C in a forced air drying oven, and weighed. The mass was recorded as N x The straw weight loss rate of each bag sample (ω x ).

[0045] ω x =(N0-N x ) / N0×100% Where, N0 is the dry weight of straw before decomposition (g); N x is the dry weight of straw at a certain decomposition time (g).

[0046] The calculated results of corn straw weight loss rates under different treatment conditions are shown in Table 1. As can be seen from the data in Table 1, compared with the commercially available composting agent treatment group (T2) and the control group (T3) without the addition of a microbial agent, the multifunctional microbial agent treatment group (T1) provided by the present invention significantly increased the straw weight loss rate, which has important practical value for accelerating the composting rate of straw after returning it to the field.

[0047] Table 1 Weight loss rate of corn straw under different treatment conditions

[0048] Application Example 2: Impact on the maturity of straw compost A composting experiment was conducted in Ancheng Town, Pingyin County, Shandong Province, using corn straw and rice husk powder as raw materials. The composting reactor was an EPP foam box with an inner length of 60 cm, an inner width of 45 cm, an inner height of 40 cm, and a wall thickness of 3 cm. The experiment included one treatment group T and two control groups CK1 and CK2, with three composting bins set up in each group. Treatment group T: corn straw and rice husk powder were mixed at a weight ratio of 4:1, and the multifunctional bacterial agent prepared in Example 4 was inoculated with an inoculation amount of 0.12% (w / w), and the initial moisture content was adjusted to 55%. Control group CK1: Same as treatment group T, but the multifunctional bacterial agent prepared in Example 4 was replaced by a commercially available composting agent; the commercially available composting agent was purchased from a local agricultural supply market, and its effective microorganisms were Bacillus subtilis and Aspergillus niger, with an effective viable bacterial count of ≥2.0×10 9 cfu / g. Control group CK2: the same as treatment group T, but without adding any straw composting agent.

[0049] During the composting process, the compost was turned once every day between 14:00 and 16:00 to supply oxygen and mix the materials. The temperature of the compost was measured between 9:00 and 10:00 every day, and the average value was taken as the temperature of the compost for that day. Figure 8 As shown in Table 2, compared with controls CK1 and CK2, treatment group T experienced a faster temperature rise and a longer high-temperature period, which facilitated faster straw maturation and shortened the composting cycle. After composting, samples were taken, dried in a 60°C drying oven, and crushed to 60-80 mesh for nutrient content analysis. The results are shown in Table 2. Compared with CK1 and CK2, the finished compost of treatment group T showed increased organic matter, organic nitrogen, and fulvic acid content, as well as an improved seed germination index. This demonstrates that the use of the multifunctional bacterial agent described herein can improve the quality and safety of compost products, and has important application value in agricultural production.

[0050] Table 2 Composition and seed germination index of mature compost in different treatment groups

[0051] Application Example 3: Effects on Wheat Growth and Development in Saline-Alkali Soil The experiment used flower pots with an inner diameter of 22 cm at the top, 15 cm at the bottom, and 18 cm in height. Each pot was filled with 4.0 kg of simulated saline-alkali soil. The simulated saline-alkali soil was prepared by weighing 1.7532 g of NaCl, 4.2612 g of Na2SO4, 2.5203 ​​g of NaHCO3, and 3.1797 g of Na2CO3, respectively, in a molar ratio of 1:1:1:1:1. These were dissolved in 1 L of water. One L of saline-alkali water was then poured into each pot to create the simulated saline-alkali soil, resulting in a soil salt content of approximately 0.4% and a pH of approximately 8.4.

[0052] The experiment consisted of one treatment group (T) and one control group (CK), each with 18 pots. Ten wheat seeds (variety: Jimai 22) were sown in each pot, and five healthy seedlings were retained after emergence. In treatment group T, 20g of corn straw powder was mixed with 0.2g of the multifunctional inoculant prepared in Example 4, thoroughly mixed with soil, and then potted. In control group CK, 20g of corn straw powder was mixed with 0.2g of the pre-inactivated multifunctional inoculant prepared in Example 4, thoroughly mixed with soil, and then potted. Measurement Indicators and Methods: Wheat samples were collected at the heading stage to measure plant height, stem diameter, proline content, soluble sugar content, and the activities of antioxidant enzymes such as SOD, POD, and CAT. All measurements were repeated three times. The results are shown in Table 3.

[0053] Table 3. Wheat growth under different treatment conditions

[0054] As shown in Table 3, the multifunctional bacterial agent provided by the present invention showed good growth promotion and resistance to salt-alkali stress in wheat cultivation. Compared with the control group CK, the plant height and stem diameter of the treatment group T were significantly increased, which shows that the bacterial agent can effectively promote wheat growth. Compared with the control group CK, the proline, soluble sugar, SOD, POD and CAT activities of the treatment group T were significantly increased, which shows that the multifunctional bacterial agent provided by the present invention can enhance the adaptability of wheat to salt-alkali stress by regulating proline synthesis, sugar metabolism and antioxidant defense system, and has important application value in saline-alkali land improvement and crop stress resistance cultivation.

Claims

1. A strain of Streptomyces bulls ( Streptomyces tauricus )zhanshen-LZ-12, the deposit number of the strain is CGMCC No.34456.

2. Use of the bull Streptomyces strain zhanshen-LZ-12 according to claim 1 in cellulose degradation, protein decomposition, nitrogen fixation and salt tolerance.

3. Use of the bull Streptomyces strain zhanshen-LZ-12 according to claim 1 in degrading phenolic acid self-toxic substances, wherein the phenolic acid self-toxic substances are benzoic acid, p-hydroxybenzoic acid and cinnamic acid.

4. The fermentation method of the bull Streptomyces strain zhanshen-LZ-12 according to claim 1, characterized in that: The bull Streptomyces strain zhanshen-LZ-12 was activated, seed solution was prepared in a triangular flask, strain was prepared in a seed tank, and solid-state fermentation was carried out in sequence. The fermentation product was dried to obtain the bull Streptomyces zhanshen-LZ-12 bacterial powder. The solid-state fermentation culture comprises the following steps: inoculating a seed tank strain of Streptomyces bullsii zhanshen-LZ-12 into a solid-state fermentation medium at an inoculum rate of 4%-8%, and fermenting for 4-6 days, controlling the product temperature at 28-30° C. during the fermentation process, and maintaining the water content of the culture medium at 50±2% by atomization water replenishment to obtain a fermentation product; The solid-state fermentation medium comprises, by mass ratio, 38-42% bran, 8-12% soybean meal powder, 47-52% corn stalk powder, and 0.8-1.2% CaCO3, with an initial moisture content of 50-60%.

5. A multifunctional bacterial agent, characterized in that: 60-80 parts by weight of the Streptomyces bullsii zhanshen-LZ-12 powder prepared according to claim 4 and 20-40 parts by weight of Bacillus sp. powder are uniformly mixed to obtain a multifunctional bacterial agent.

6. The multifunctional bacterial agent according to claim 5, characterized in that: The effective viable bacteria count of the Bacillus powder is ≥1.0×10 10 CFU / g.

7. Use of the bull Streptomyces strain zhanshen-LZ-12 according to claim 1 or the multifunctional bacterial agent according to claim 5 in the utilization of straw fertilizer.

8. The use according to claim 7, characterized in that: The fertilizer utilization includes straw composting and returning straw to fields.

9. The use according to claim 8, characterized in that: The method for applying the multifunctional bacterial agent in straw composting is as follows: mixing the multifunctional bacterial agent with water in a weight ratio of 1: (50-100), and then evenly sprinkling the mixture on 500-2000 parts by weight of straw.

10. The use according to claim 8, characterized in that: The application method of the multifunctional microbial agent in returning straw to the field is as follows: the dosage of the multifunctional microbial agent is 1-10 kg / mu, or 0.5-10 kg / ton of straw calculated based on the amount of straw returned to the field; After the crops are harvested, the multifunctional fungal agent is evenly spread on the fields and the land is deep plowed.

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