Method and application of straw degradation synthetic microbial inoculum in acidic red soil

Abstract

The invention discloses a method and application of a synthetic microbial inoculum for straw degradation in acidic red soil. The synthetic microbial inoculum comprises bacteria B and actinomycetes C, the bacterium B is Rhodococcus erythropolis, the strain Straw-P2F9 is preserved in the China General Microbiological Culture Collection Center on January 20, 2025, and the preservation number is CGMCC (China General Microbiological Culture Collection Center) No.33465; the actinomycete C is Paenarthrobacter nitroguajalicus, the strain of the actinomycete C is Straw-B50, the strain of the actinomycete C is preserved in the China General Microbiological Culture Collection Center on January 20, 2025, and the preservation number of the actinomycete C is CGMCC No. 33463. The synthetic bacterial agent improves the degradation rate of straw in acidic red soil, and improves the yield and quality of crops.

Description

Technical Field

[0001] The present invention relates to the technical field of lignin and cellulose degrading synthetic bacterial agents, and particularly relates to a method and application of a synthetic bacterial agent for straw degradation in acidic red soil. Background Art

[0002] Straw returning to the field is an important measure to achieve green development of agriculture and efficient utilization of resources. However, in the acidic red soil areas of southern China, due to the low soil pH value, insufficient organic matter content, and limited microbial activity, the natural degradation efficiency of complex organic matters such as lignin and cellulose in straw is relatively low, often resulting in straw accumulation, breeding of pests and diseases, and decline in nutrient cycling efficiency, which restricts the further improvement of agricultural production efficiency. Therefore, developing efficient and adaptable straw degradation technologies is the key to solving this problem. Summary of the Invention

[0003] Aiming at the technical problems and practical needs of developing targeted and efficient straw degradation synthetic bacterial agents in the prior art, the present invention provides a method and application of a synthetic bacterial agent for straw degradation in acidic red soil. In view of the particularity of southern acidic red soil, the present invention has significant innovation and application value. Traditional single bacterial agents often have limited effects in specific environments, while this synthetic bacterial agent optimizes and combines the functional characteristics of three types of microorganisms to construct a microbial community with diverse degradation capabilities and environmental adaptability. Multiple bacteria have advantages in decomposing cellulose and rapidly releasing primary nutrients, which can significantly accelerate the initial decomposition process of straw. Moreover, actinomycetes have strong adaptability in acidic environments and can promote the synergistic effect of other microorganisms by releasing secondary metabolites, while improving soil microbial diversity. In addition, fungi, especially Sordariomycetes fungi, are widely distributed in farmland ecosystems and have strong lignin degradation and organic carbon conversion capabilities, thus significantly improving the straw degradation efficiency and promoting the conversion of straw carbon into soil organic carbon. This combination of bacteria, fungi, and actinomycetes, through complementary functions and synergistic effects, can not only achieve efficient straw degradation in acidic red soil, but also release a large amount of organic matter and mineralized nutrients, improving the soil microbial community structure and ecological functions. The innovation of the synthetic bacterial agent is also reflected in its environmental adaptability and wide application. It is particularly suitable for complex soil environments such as acidic red soil, promoting straw resource utilization while enhancing soil health and crop yield.

[0004] Promoting this technology can not only provide a green solution for agricultural production in southern acidic red soil areas, but also offer new ideas for jointly promoting straw returning to the field and soil improvement. The synthetic bacterial agent combining bacteria, fungi, and actinomycetes has significant technical advantages and will play an important role in the sustainable development of modern agriculture, showing broad promotion prospects.

[0005] To achieve the above object, the present invention adopts the following technical solution: A synthetic microbial agent for straw degradation in acidic red soil, characterized in that it comprises bacterium B and actinomycete C;

[0006] The bacterium B is Rhodococcus erythropolis, strain Straw-P2F9, which was deposited at the General Microbiological Center of the China Committee for Culture Collection of Microorganisms on January 20, 2025, with the deposit number: CGMCC No. 33465;

[0007] The actinomycete C is Paenarthrobacter nitroguajacolicus, strain Straw-B50, which was deposited at the General Microbiological Center of the China Committee for Culture Collection of Microorganisms on January 20, 2025, with the deposit number: CGMCC No. 33463.

[0008] Preferably, the abundance ratio of bacterium B to actinomycete C in the synthetic microbial agent is (2 - 5):(1 - 5).

[0009] Preferably, it further comprises fungus A, and the fungus A is Chaetomium sp., strain WCF15, purchased from the General Microbiological Center of the China Committee for Culture Collection of Microorganisms, with the deposit number CGMCC No. 41259.

[0010] Preferably, the abundance ratio of fungus A, bacterium B to actinomycete C in the synthetic microbial agent is 5:(2 - 5):(1 - 5).

[0011] Preferably, the abundance ratio of fungus A, bacterium B to actinomycete C in the synthetic microbial agent is 5:5:5.

[0012] Preferably, for the synthetic microbial agent, the inoculation amount is 10 4 -10 8 order of magnitude cells / g of soil.

[0013] Preferably, for the synthetic microbial agent, the inoculation amount is 10 8 order of magnitude cells / g of soil.

[0014] Preferably, the fungus A, bacterium B and actinomycete C can all degrade lignin and cellulose.

[0015] Preferably, the niche overlap index ρ of bacterium B and actinomycete C is 0.35, and f 细菌B / f 放线菌C is 0.6, and bacterium B and actinomycete C stably coexist between ρ and 1 / ρ.

[0016] Preferably, the niche overlap index ρ of the fungal A and bacterial system (bacterial B and actinomycete C) and the fitness difference f is 0.2 真菌A / f 细菌体系 is 0.7, between ρ and 1 / ρ, and the fungal and bacterial systems coexist stably.

[0017] Preferably, the abundances of fungal A, bacterial B, and actinomycete C in the synthetic inoculant are set to 5:4:1, 5:5:5, and 5:2.5:2.5.

[0018] Preferably, after sterilization 13 the C-labeled corn straw is uniformly mixed with red soil according to the dry weight ratio of 1% (straw / red soil), and the synthetic inoculant is inoculated, and the inoculation amount is 10 4 、10 6 and 10 8 order of magnitude cells / gram of soil.

[0019] Beneficial effects:

[0020] The synthetic inoculant constructed by integrating bacteria, fungi, and actinomycetes in the present invention realizes efficient decomposition of straw, is simple to operate and environmentally friendly, and significantly improves the resource utilization efficiency of straw returning to the field and agricultural production benefits. Applying the synthetic inoculant of the present invention to acidic red soil in the south can accelerate the degradation of lignin and cellulose, improve soil structure, and enhance soil fertility and crop yield. Compared with the prior art, the present invention has the following remarkable advantages:

[0021] (1) Multifunctional microbial communities cooperate to degrade and improve the straw decomposition efficiency. By screening and optimizing bacterial, fungal, and actinomycete strains, the present invention constructs a cooperative degradation inoculant. Bacteria decompose cellulose, fungi efficiently degrade lignin, and actinomycetes adapt to acidic environments and promote the synergistic effect of microbial communities, effectively enhancing the degradation rate of lignin and cellulose in straw and shortening the straw decomposition cycle. The technical solution simplifies the straw treatment process, has the characteristics of low operating cost and wide adaptability, and is convenient for large-scale promotion.

[0022] (2) Improve the soil environment and enhance nutrient utilization efficiency. After applying the synthetic inoculant, the contents of available phosphorus and available potassium in acidic red soil are increased. At the same time, a large amount of organic matter generated by straw decomposition improves the physical and chemical properties of red soil, enhances the soil nutrient cycling efficiency, and provides a high-quality nutrient environment for crop growth.

[0023] (3) Promote crop growth and improve yield and quality. The synthetic inoculant of the present invention not only accelerates straw decomposition, promotes crop absorption and utilization of soil nutrients, but also significantly improves the yield and quality of field crops such as corn. After application, the above-ground and root biomasses of crops increase, and the contents of soluble sugar, soluble protein, and indole acetic acid in leaves are significantly increased, the growth potential of crops is enhanced, and the stress resistance is improved.

[0024] The present invention has remarkable effects in accelerating the resource utilization of straw, improving the quality of acidic red soil, and enhancing the yield and quality of crops, and has broad prospects for popularization and application, which can provide important technical support for the green and sustainable development of modern agriculture. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a process diagram for screening straw-degrading bacteria;

[0026] Figure 2 It is the influence of synthetic bacterial agents with different abundance ratios and different inoculation amounts on straw degradation;

[0027] Figure 3 It is the influence of inoculation with the optimized synthetic bacterial agent on the properties of red soil and crops. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The following further explains the present invention in conjunction with embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention, and should not and cannot be used to limit the protection scope of the present invention.

[0029] Example 1

[0030] Liquid medium - bacteria: Nutrient broth medium (cultured at 27°C for 24 hours).

[0031] Liquid medium - actinomycetes: Gao's No. 1 agar medium. Method for preparing 3% potassium dichromate solution: Put 100 mL of deionized water into a 200 mL reagent bottle, weigh 3 g of potassium dichromate and add it to the bottle, shake well to dissolve, and place it in a 4°C refrigerator for later use. For every 500 mL, add 1.7 mL of 3% potassium dichromate solution to inhibit the growth of bacteria and fungi, and continuously culture at 27°C for 3 days.

[0032] Liquid medium - fungi: Potato dextrose agar medium (PDA). Continuously culture at 28°C for 3 days.

[0033] Screen key lignin- and cellulose-degrading fungi, bacteria, and actinomycetes. The specific steps are as follows:

[0034] Prepare the culture medium plates including: Carboxymethyl cellulose sodium medium (CMC): 10 g of CMC-Na, 1 g of yeast extract, 15 - 20 g of agar, 1000 mL of distilled water, pH 7.0 - 7.5, autoclave at 121°C. After sterilization, make plates. Lignin selection medium (LIG): 1 g of peptone, 3 g of lignin, 5 g of NaCl, 15 - 20 g of agar powder, 1 L of distilled water, natural pH value, autoclave at 121°C. After sterilization, make plates.

[0035] The CMC and LIG media were each divided into three types: CMC-B, for isolating cellulose-decomposing bacteria on plates, containing 25 mg / L cycloheximide; CMC-F, for isolating cellulose-decomposing fungi on plates, containing 100 μL of 50 mg / mL kanamycin; CMC-A, for isolating cellulose-decomposing actinomycetes on plates, containing 1.7 mL of 3% potassium dichromate; LIG-B, for isolating lignin-decomposing bacteria on plates, containing 25 mg / L cycloheximide; LIG-F, for isolating lignin-decomposing fungi on plates, containing 100 μL of 50 mg / mL kanamycin; LIG-A, for isolating lignin-decomposing actinomycetes on plates, containing 1.7 mL of 3% potassium dichromate. After all the plates were prepared, they were inverted.

[0036] Quaternary red clay red soil (Ultisols) was collected at the Red Soil Ecological Experiment Station of the Chinese Academy of Sciences in Yingtan City, Jiangxi Province (116°55’E, 28°13’N). According to the Chinese soil classification, the soil type is Udic Ferralosols; according to the United States Department of Agriculture soil classification system, the soil type is Ultisols. This area belongs to the mid-subtropical monsoon climate, with an average annual temperature of 17.6 °C and an average annual precipitation of 1795 mm. Soil samples were collected from the surface layer (0 - 40 cm), sieved to 4 mm, and visible roots and gravel were removed with forceps. Weighed 10 g of red soil samples, placed them in 90 mL of sterile water, and oscillated and mixed them evenly at 160 r / min for 30 min to evenly disperse the soil particles in the sterilized water. The standing suspension was then diluted with sterile water to 10 -3 , 10 -4 , 10 -5 , etc. dilution degrees (performed in a laminar flow hood). 50 - 100 μl of the sample solutions with different dilution degrees were inoculated onto various culture medium plates. After spreading evenly, the plates were placed in an incubator at 28 °C for 3 - 5 days. Observe the colonies formed on the plates. Through morphological observation, different single colonies in each plate were picked out, streaked and purified on the corresponding plates, and the plates were placed in an incubator at 28 °C. After monoclonal colonies grew out on the plates, purification and culturing were repeated once. The monoclonal colonies in each culture medium were picked out and placed in 5 ml of liquid culture medium (using a 50 mL centrifuge tube) and enriched cultured in a shaker (28 °C, 180 rpm). After culturing to the logarithmic growth phase (visible turbidity in the culture system with the naked eye), a part of the bacterial liquid was taken out and the bacterial liquid was mixed with 50% glycerol in equal volume of 1:1 under sterile conditions into a preservation tube and numbered. Finally, the final concentration of glycerol was 25%. In addition, 1 mL of the bacterial liquid was aliquoted to extract DNA for strain identification.

[0037] The cellulose and lignin-degrading bacterium B is Rhodococcus erythropolis, strain Straw-P2F9 (Figure 1 Left), it was deposited in the General Microbiology Center of the China Committee for Culture Collection of Microorganisms on January 20, 2025, with the deposit number: CGMCC No. 33465;

[0038] The cellulolytic and lignin-degrading actinomycete C is Paenarthrobacter nitroguajacolicus, strain Straw-B50 ( Figure 1 Right), it was deposited in the General Microbiology Center of the China Committee for Culture Collection of Microorganisms on January 20, 2025, with the deposit number: CGMCC No. 33463. The abundance ratio of bacteria B and actinomycete C in the in-situ red soil by high-throughput sequencing is 4:1.

[0039] The purchased strains were cultured individually (fungus A) and co-cultured pairwise with the previously obtained strains (bacteria B and actinomycete C, with an abundance ratio of 4:1). Fluorescent quantitative PCR was used to determine the copy numbers of different strains in the culture system; at the same time, guided by the contemporary coexistence theory, an invasion experiment was designed. The fungal and bacterial systems (bacteria B and actinomycete C) were mixed into 500 μL of 1× M9 medium at different ratios of 10:1, 1:1, 1:10, and 1:100, with a straw extract of 0.07 C-mol / L as the sole carbon source. After culturing at 30 °C for 48 h, 8 μL of the culture solution was transferred to a new culture solution and the above operation was repeated 7 times. The microbial composition was obtained by high-throughput sequencing. According to the method of Ke and Letten (2018), the niche overlap index ρ of bacteria B and actinomycete C was calculated to be 0.35 (mean value), and the fitness difference f 细菌B / f 放线菌C value was 0.6 (mean value), between the niche overlap index ρ and 1 / ρ, indicating the occurrence of stable coexistence of bacteria B and actinomycete C. The niche overlap index ρ between fungus A and the bacterial system was 0.2 (mean value), and the fitness difference f 真菌A / f 细菌体系 value was 0.7 (mean value), between the niche overlap index ρ and 1 / ρ, indicating the occurrence of stable coexistence of fungus A, bacteria B, and actinomycete C.

[0040] Example 2

[0041] Treatment group A: Add fungus A at a concentration of 10 7 order of magnitude cells / gram of soil;

[0042] Treatment group B: Add bacteria B at a concentration of 10 7 order of magnitude cells / gram of soil;

[0043] Treatment group C: Add actinomycete C at a concentration of 10 7 order of magnitude cells / gram of soil;

[0044] Treatment group AB: Add fungus A and bacterium B, with concentrations of 1 / 2×10 7 order of magnitude cells / gram of soil;

[0045] Treatment group AC: Add fungus A and actinomycete C, with concentrations of 1 / 2×10 7 order of magnitude cells / gram of soil;

[0046] Treatment group BC: Add bacterium B and actinomycete C, with concentrations of 1 / 2×10 7 order of magnitude cells / gram of soil;

[0047] Treatment group ABC: Add fungus A, bacterium B and actinomycete C, with concentrations of 1 / 3×10 7 order of magnitude cells / gram;

[0048] Quaternary red clay red soil (Ultisols) was collected at the Red Soil Ecological Experiment Station of the Chinese Academy of Sciences in Yingtan City, Jiangxi Province (116°55’E, 28°13’N). All red soil samples were collected from the surface layer (0 - 40 cm), air-dried naturally at room temperature, sieved to 4 mm, and visible roots and gravel were removed with tweezers. The 13 13C-labelled corn straw (C = 39.1%, C / N = 38.5, 13C = 41.6 atom%) was crushed to 2 mm for the following incubation experiment. 13 After sterilization, the 13C-labelled corn straw was uniformly mixed with the red soil according to the dry weight ratio of 1% (straw / red soil). The inoculants in treatment groups A, B, C, AB, AC and BC were inoculated. After inoculation, all samples were incubated at 25°C for 90 days. The 13 13C straw residue, the residues of cellulose and lignin were measured to evaluate the effect of the synthetic microbial community on straw decomposition; meanwhile, the 13 13C amino sugar content in the red soil was measured to evaluate the effect of the synthetic microbial community on converting straw carbon into red soil organic carbon (microbial residue carbon).

[0049] The method for measuring the 13 13C straw residue is as follows:

[0050] 13 13C-SOC = SOC × (atom% 13 13C labelled-atom% 13 13C unlabelled)

[0051] where, atom% 13 13C labelled represents the 13 13C atomic percentage of organic carbon in the soil added with corn straw, atom% 13C unlabelled represents the percentage of C atoms of organic carbon in soil without added corn straw, and SOC represents the SOC content in soil with added corn straw. 13 The percentage of C atoms, and SOC represents the SOC content in soil with added corn straw.

[0052] The calculation method of lignin residue is as follows: The alkaline CuO oxidation-hydrolysis method is widely used to measure lignin phenols in soil. This procedure involves weighing air-dried soil, CuO powder, and [Fe(NH 4 ) 2 (SO 4 ) 2 -6H 2 O] in a polytetrafluoroethylene container. Subsequently, 15 mL of 2 M NaOH solution (previously purged with nitrogen) and 400 μL of ethyl vanillin are added. Then the container is sealed and heated with vigorous shaking at 170 °C for 2 hours. After cooling, the resulting mixture is transferred to a centrifuge tube, leaving any remaining precipitate, which is further washed and combined. The sample is centrifuged to separate the liquid phase, then acidified with 6 M HCl and left to stand in the dark. After further centrifugation, the clear supernatant is collected, diluted, and subjected to solid-phase extraction using a C18 column and ethyl acetate as the extraction solvent. The organic phase is collected, concentrated by rotary evaporation, and mixed with a benzoic acid solution. After dissolution, the solution is transferred to another bottle for derivatization. Subsequently, phenolic oxidation products are separated and measured using an HP 6890A gas chromatograph and a flame ionization detector. Lignin phenols are calculated by summing Vanillyl (V), Syringyl (S), and Cinnamyl (C) monomers.

[0053] The calculation method of cellulose residue is as follows: Take a certain amount of plant material or soil sample. Wash the sample with distilled water to remove soluble sugars. Treat the sample with concentrated sulfuric acid (72% H 2 SO 4 ) to remove lignin and other non-cellulose substances by acid hydrolysis. Then treat the sample with sodium hydroxide (NaOH) to further remove residual lignin and other non-cellulose components. Wash the sample thoroughly with water to remove all acid and base solutions. Dry the treated sample in an oven and weigh it after it reaches a constant weight. Weigh the remaining substance, which is the cellulose residue. The final remaining solid substance is the content of cellulose (containing a small amount of other structural sugars). Its residue is calculated by comparing the initial weight and the dried weight of the sample.

[0054] The results showed that the straw degradation rates of the inoculated treatment groups A, B, C, AB, AC, BC, and ABC were 42.1%, 36.5%, 41.3%, 45.6%, 52.3%, 46.9%, and 62.3% in sequence, the cellulose degradation rates were 16.2%, 13.8%, 14.6%, 17.3%, 17.8%, 15.7%, and 21.6% in sequence, and the lignin degradation rates were 11.3%, 9.1%, 10.3%, 12.3%, 13.1%, 11.6%, and 17.8% in sequence. 13 The C-SOC contents were 0.45, 0.46, 0.51, 0.52, 0.53, 0.53, and 0.72 g / kg in sequence, and the amino sugar contents were 321.3, 410.2, 412.3, 423.6, 419.7, 442.3, and 484.6 mg / kg in sequence. 13 The C amino sugar contents were 114.6, 121.4, 120.5, 136.2, 139.6, 136.9, and 141.3 mg / kg in sequence.

[0055] Example 3

[0056] Quaternary red clay Ultisols were collected from the Red Soil Ecological Experimental Station of the Chinese Academy of Sciences in Yingtan City, Jiangxi Province (116°55’E, 28°13’N). All red soil samples were collected from the surface layer (0 - 40 cm), air-dried naturally at room temperature, sieved to 4 mm, and visible roots and gravel were removed with tweezers. The pulse labeling method was used to obtain 13 13C-labeled corn straw (C = 39.1%, C / N = 38.5, 13 13C = 41.6 atom%) was crushed to 2 mm for the following incubation experiment. The 13 13C-labeled corn straw was sterilized and uniformly mixed with the red soil at a dry weight ratio of 1% (straw / red soil). The addition amounts of fungus A, bacterium B, and actinomycete C in the synthetic inoculant were 5:4:1 (C1), 5:5:5 (C2), and 5:2.5:2.5 (C3). The inoculation concentration of the synthetic inoculant was 10 4 、10 6 、10 8 order of magnitude cells / gram of soil. After inoculation, all samples were incubated at 25°C for 90 days. The 13 13C straw residue amount, the residue amounts of cellulose and lignin were measured to evaluate the effect of the synthetic microbial community on straw decomposition; meanwhile, the newly formed 13 13C amino sugar content in the red soil was measured to evaluate the effect of the synthetic microbial community on converting straw carbon into red soil organic carbon (microbial residue carbon).

[0057] The results are as Figure 2As shown, the addition amounts of fungus A, bacterium B, and actinomycete C in the synthetic microbial agent are 5:5:5, and the inoculation concentration of the synthetic microbial agent in the red soil is 10 8 order of magnitude cells / g of soil, the straw degradation rate is 77.2%, the cellulose degradation rate is 26.8%, and the lignin degradation rate is 21.3%. 13 The C-SOC content is 0.95 g / kg, and the amino sugar content is 564.8 mg / kg. 13 The C amino sugar content is 153.2 mg / kg.

[0058] Example 4

[0059] Maize field planting experiment

[0060] In this experiment, three treatments were set up: CK, without addition; T1, inoculated with red soil bacterial suspension (the red soil bacterial suspension was obtained from the red soil where maize had been planted for a long time, and the inoculation amount was 10 8 order of magnitude cells / g of soil); T2, inoculated with the synthetic microbial agent (the abundance ratio of fungus A, bacterium B, and actinomycete C is 5:5:5, and the inoculation amount is 10 8 order of magnitude cells / g of soil). The test plot area is 20 m 2 (5 m × 4 m), and each treatment has 3 replicates.

[0061] The maize seeds are Suyu No. 24, which have excellent characteristics such as high disease resistance, drought resistance, and high temperature resistance. The seeding rate is generally 20 kg / hm 2 , the row spacing is 20 cm × 40 cm, the sowing depth is 10 - 15 cm, and the planting density is 68000 plants / hm 2 . The rapeseed seeds are Qingyou No. 8. The seeding rate is 4 kg / hm 2 , the row spacing is 15 cm × 30 cm, the sowing depth is 3 - 4 cm, and the planting density is about 90000 plants / hm 2 . In maize planting, the application amounts of urea, calcium magnesium phosphate fertilizer, and potassium fertilizer are 152.72 kg N / hm 2 , 116.20 kg P 2 O 5 / hm 2 and 166.32 kg K 2 O / hm 2 . The pig manure was completely composted through the high-temperature composting technology. After composting, the water content of the pig manure was less than 50%. The application amount of pig manure was 5 tons / hm 2 (dry basis) to replace 60% of the chemical fertilizers. All phosphorus and potassium were used as basal fertilizers, 70% of the nitrogen fertilizer was used as basal fertilizer, and 30% was used as top dressing at the small trumpet stage. The straw addition amount was 2556.5 kg / hm 2 , and it was evenly spread on the surface of the test field before sowing and incorporated into the surface cultivated soil by plowing.

[0062] During the maize planting period, adjust the water content of the red soil to 60%-70% of the field water holding capacity. During the critical growth periods of the crops such as the seedling stage and the flowering stage, irrigate in a timely manner according to the water requirement law of the crops to ensure the normal growth of the crops. In case of drought during the growth period of maize, irrigate in a timely manner. In case of heavy rainfall, drain water in a timely manner. Except for not spraying pesticides, field management such as manual weeding and topdressing shall be carried out according to the local routine. The field experiment was carried out until the maize matured. The rhizosphere red soil of the plants was collected, and the contents of organic carbon, available phosphorus and available potassium in the red soil of each treatment were measured respectively. The results are as Figure 3 shown: Compared with the CK and T1 treatment groups, the contents of organic carbon, available phosphorus and available potassium in the red soil with the addition of the synthetic bacterium agent increased by 15.02% and 10.86%, 2.65% and 1.14%, 5.37% and 4.85% respectively.

[0063] During the field experiment, maize grains were harvested until the maize matured, and the above-ground and root biomasses of the maize, the soluble sugar, soluble protein and indole acetic acid in the leaves were measured. The results showed that: compared with the CK and T1 treatment groups, the plant height, straw dry weight, the contents of soluble sugar, soluble protein and indole acetic acid in the leaves of the maize plants with the addition of the synthetic bacterium agent reached the highest. Under this condition, the straw dry weight of the maize was 15.9% and 10.3% higher than that of CK (209.8 g) and the T1 treatment group (220.5 g), and the root dry weight was 10.7% and 3.6% higher than that of CK (156.1 g) and the T1 treatment group (166.8 g); the contents of soluble sugar, soluble protein and indole acetic acid in the leaves of the maize plants were 13.3% and 6.3%, 12.5% and 5.6%, 13.6% and 6.7% higher than those of CK (0.45%, 17.8 mg / g, 17.9 ng / g) and the T1 treatment group (0.48%, 16.7 mg / g, 18.9 ng / g) respectively. The maize grain yield increased by 12.5% and 5.1% compared with the control CK (256.8 g) and the T1 treatment group (274.9 g).

[0064] In the present invention, a fungus and two bacteria are successively inoculated into a straw-red soil mixture under laboratory conditions to analyze the degradation effect of the synthetic microbial agent on refractory lignin and cellulose. (1) The screened lignin- and cellulose-degrading fungus A is Chaetomium sp., the bacterium B is Rhodococcus erythropolis, and the actinomycete C is Paenarthrobacter nitroguajacolicus. (2) Red soil is weighed from the experimental plot, and the synthetic microbial agent with different combinations and inoculation amounts is added. Through optimization experiments, the synthetic microbial agent under the optimal ratio conditions is selected as the field straw degradation microbial agent; (3) The synthetic microbial agent under the optimal ratio conditions is inoculated into the soil of the experimental plot. Field management is carried out on the soil of the experimental plot to maintain the stability of soil moisture, and the growth and yield changes of field corn under different inoculation conditions are detected. The present invention improves the degradation rate of field straw and the carbon conversion efficiency, and increases the degradation rates of lignin and cellulose and the amino sugar content in red soil. Through field experiments, it is found that inoculating the synthetic microbial agent increases the contents of organic carbon, available phosphorus, and available potassium in red soil, and improves the growth status and quality of corn.

[0065] Finally, the above are only several specific embodiments of the present invention, and do not limit the scope of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made to the technical solution of the present invention, which should all be regarded as the protection scope determined by the present invention.

Claims

1. A synthetic bacterial agent for straw degradation in acidic red soil, characterized in that: Includes bacteria B and actinomycetes C; The bacterium B is Rhodococcus erythropolis, strain Straw-P2F9, which was deposited in the General Microbiology Center of China Microbiological Culture Collection Administration on January 20, 2025, with the deposit number: CGMCC No.33465; The actinomycete C is Paenarthrobacter nitroguajacolicus, strain Straw-B50, which was deposited in the General Microbiology Center of China Microbiological Culture Collection Administration on January 20, 2025, with the deposit number: CGMCC No.33463.

2. The synthetic bacterial agent for straw degradation in acidic red soil according to claim 1, characterized in that: The abundance ratio of bacteria B and actinomycetes C in the synthetic bacterial agent is (2-5):(1-5).

3. The synthetic bacterial agent for straw degradation in acidic red soil according to claim 1, characterized in that: Also included is fungus A, which is Chaetomium sp., strain WCF15, purchased from the General Microbiological Center of China Microbiological Culture Collection Administration, with a collection number of CGMCC No.41259.

4. The synthetic bacterial agent for straw degradation in acidic red soil according to claim 3, characterized in that: The abundance ratio of fungus A, bacteria B and actinomycetes C in the synthetic bacterial agent is 5:(2-5):(1-5).

5. The method for applying the synthetic bacterial agent for straw degradation in acidic red soil according to claim 4, characterized in that: The abundance ratio of fungus A, bacteria B and actinomycetes C in the synthetic microbial agent is 5:5:

5.

6. The method for applying the synthetic bacterial agent for straw degradation in acidic red soil according to claim 1, characterized in that: The synthetic bacterial agent has an inoculation amount of 10 4 -10 8 Order of magnitude cells / gram soil.

7. The method for applying the synthetic bacterial agent for straw degradation in acidic red soil according to claim 6, characterized in that: The inoculum size is 10 8 Order of magnitude cells / gram soil.

Images