A composite microbial agent coupling straw decomposition and soil carbon sequestration and its preparation method

Abstract

The present invention discloses a composite microbial agent for coupling straw decomposition and soil carbon sequestration and a preparation method thereof. The composite microbial agent of the present invention can rapidly promote the degradation of lignocellulose of straw in soil by compounding Bacillus subtilis, Bacillus licheniformis, Pseudomonas aeruginosa, etc., providing a basic material energy source for the activities of soil microorganisms. At the same time, the corresponding microorganisms achieve long-term sequestration of organic carbon through humus stabilization and mineral-associated organic carbon (MAOC) stabilization, and significantly enhance the efficiency of organic carbon sequestration through nano-Fe3O4. Under the synergistic action of various strains in this composite microbial agent, it can effectively reduce the carbon loss during straw returning to the field, improve the soil carbon sequestration capacity, and increase the organic carbon content in the soil.

Description

Technical Field

[0001] The present invention relates to the technical field of microorganisms, and particularly relates to a composite microbial agent for coupling straw decomposition and soil carbon sequestration and a preparation method thereof. Background Art

[0002] In recent years, the problem of global climate change has attracted wide attention. The emission of greenhouse gases, especially carbon dioxide, is considered to be the main driving factor for global warming. In order to slow down climate change and control the concentration of carbon dioxide, carbon sequestration and absorption have become an important environmental protection technology.

[0003] In nature, soil is an important carbon pool. The organic carbon storage in soil is much higher than that in the atmosphere and plants. Therefore, optimizing soil management to increase soil carbon storage and promote soil carbon sequestration has become one of the important ways to slow down global climate change.

[0004] The organic carbon in soil comes from the decomposition process of plant residues, animal remains and other organic substances. Straw is one of the main plant residues produced in the agricultural production process, accounting for more than 70% of agricultural waste. Microorganisms play a key role in the straw decomposition process and can convert complex organic substances in straw into organic carbon that can be absorbed and utilized by soil. At present, there are already some microbial agents specifically for straw decomposition on the market, but most products can only promote straw degradation singly and fail to effectively improve soil carbon sequestration ability, which needs to be improved. Summary of the Invention

[0005] To solve the above at least one technical defect, the present invention provides the following technical solutions:

[0006] This application document discloses a composite microbial agent for coupling straw decomposition and soil carbon sequestration, including:

[0007] Functional bacteria A, which includes: Bacillus subtilis with the preservation number CGMCC.NO.26196 and Bacillus licheniformis with the preservation number CGMCC.NO.26194, and the liquid volume ratio of the two is 1 - 2:2 - 6;

[0008] Functional bacteria B, which is Pseudomonas aeruginosa with the preservation number CGMCC.NO.26195;

[0009] Functional bacteria C, which is Trichoderma longibrachiatum with the preservation number CGMCC.NO.40444;

[0010] A protective agent and nano - Fe3O4.

[0011] Among them, the liquid volume ratio of the functional bacteria A, functional bacteria B, and functional bacteria C is 1-2:4-8:2-7; the proportion of nano-Fe3O4 in the composite bacterium agent is 0.1wt%-0.5wt%, and the proportion of the protective agent in the composite bacterium agent is 2wt%-5wt%.

[0012] As Figure 1 shown, the working principle of the bacterium agent is as follows:

[0013] I. Degradation of lignocellulose

[0014] Bacillus subtilis CGMCC NO.26196 and Bacillus licheniformis CGMCC NO.26194 drive the efficient degradation of lignocellulose through multi-enzyme synergistic action. Bacillus subtilis CGMCC NO.26196 secretes endoglucanase and manganese peroxidase, randomly cuts the β-1,4-glycosidic bond from the inside of the cellulose chain and oxidizes the lignin benzene ring structure. At the same time, its β-glucosidase relieves the product inhibition of cellobiose. Bacillus licheniformis CGMCC NO.26194, under the action of exoglucanase and xylanase, continuously releases monosaccharides from the end of the cellulose chain and efficiently depolymerizes hemicellulose. Its laccase indirectly promotes lignin depolymerization by assisting in the oxidation of phenolic monomers. The two strains significantly improve the lignocellulose degradation efficiency through metabolic complementarity. At the same time, through partial lignin depolymerization and the secretion of surface-active substances, the substrate accessibility is enhanced, and the release of degradation products is promoted. Cellulose is decomposed into glucose, providing an energy source and a carbon skeleton for microorganisms. Hemicellulose is decomposed into arabinose, mannose, etc.; lignin is degraded into polyphenols and other substances. II. Stabilization of mineral-associated organic carbon (MAOC) in soil Soil organic carbon (SOC) is the basis index for the effect of straw entering the soil to achieve carbon fixation. The stability and dynamic characteristics of soil organic carbon (SOC) are jointly determined by its solid-phase carbon pool (MAOC and POC) and mobile components. Microorganisms decompose straw, transform substances such as lignin to form humus. Thus, part of the humus binds to minerals to form stable MAOC, which serves as the core stable component of SOC; while the other part of the free humus belongs to active POC or participates in the carbon cycle as an intermediate product of dynamic transformation. In addition, from a biochemical perspective, dissolved organic carbon (DOC) and soil microbial biomass carbon (MBC) both belong to independent mobile carbon pools, with migration and transformation characteristics different from those of the solid-phase carbon pool, mainly characterizing the biochemical activity during the carbon transformation process. In the pathway of mineral-associated organic carbon (MAOC) stabilization, the decomposition products of hemicellulose, mannose and mannuronic acid, are transformed into extracellular polysaccharides (EPS) by microorganisms such as Pseudomonas aeruginosa CGMCC.NO.26195. Among them, alginate, as the main component of EPS, the carboxyl group (-COOH) on the mannuronic acid chain binds with Ca 2+ 、Fe 3+ or Al3+ Cations such as these bind to the surface of clay minerals to form a ternary complex of "EPS-cation-mineral". One of the functions of nano-Fe3O4 is that its high specific surface area (>200 m 2 / g) and surface positive charge (Zeta potential +25 mV at pH 5-7) significantly enhance the adsorption efficiency of alginate to montmorillonite or hematite; the second function is that the colloidal coating layer formed by nano-Fe3O4 and EPS can effectively block the contact between hydrolase and organic substrates, increasing the residual rate of cellulase hydrolysis and significantly delaying the mineralization release of carbon.

[0015] III. Stabilization of soil humusIn the pathway of humus stabilization, the degradation of lignin is a key step in initiating carbon transformation. Trichoderma longibrachiatum CGMCC.NO.40444 can secrete lignin peroxidase and manganese peroxidase on the one hand. In the presence of Mn 2+ cofactor and H2O2, the β-O-4 ether bond of lignin is cleaved through a free radical chain reaction to release phenolic monomers such as vanillic acid and coniferyl alcohol. These polyphenolic substances then become the precursors for humus synthesis; on the other hand, it also secretes laccase to catalyze the oxidative dehydrogenation reaction of phenolic monomers to generate quinone free radicals, which further form polyaromatic compounds, namely humic acid precursors, through C-O or C-C bond coupling. In this enzymatic process, one of the functions of nano-Fe3O4 is that through the redox activity of surface Fe 3+ , it accelerates the generation and stabilization of free radicals, increasing the polymerization reaction rate; Fe 3+ forms Fe-O-C coordination bonds with the carboxyl and phenolic hydroxyl groups in humic acid molecules, significantly enhancing the chemical stability of humus; the second function is that under alkaline or neutral conditions, nano-Fe3O4 can also catalyze the non-enzymatic condensation process (Maillard reaction) of polyphenols and amino sugars to generate melanoidins, precursors of humus, and its conjugated carbonyl structure further enhances the ability to resist microbial decomposition.

[0016] The dual-pathway stabilization of straw residue carbon is a multi-process coupling system driven by microorganisms and mediated by minerals. Nano-Fe3O4 realizes the efficient directional regulation of carbon flow through multiple mechanisms such as chemical catalysis, electron transfer, and physical protection to meet the carbon sequestration requirements under different soil types and climate conditions.

[0017] The protectant can improve the resistance of microorganisms, reduce the external influence on them, enhance the stability of microbial cells, and then play a better role subsequently.

[0018] Furthermore, the concentrations of Bacillus subtilis with the preservation number CGMCC.NO.26196 and Bacillus licheniformis with the preservation number CGMCC.NO.26194 in functional bacterium A are 4-6×10 10 CFU / ml and 5-8×1010 CFU / ml. The concentrations of functional bacterium B and functional bacterium C are respectively 5 - 7×10 9 CFU / ml and 2 - 6×10 10 CFU / ml.

[0019] Furthermore, the protective agent includes 10 - 20wt% glycerol, 10 - 15wt% sucrose, 1 - 2wt% sodium alginate, 1 - 3wt% sodium chloride, and the balance is deionized water. Glycerol can be used as a protective agent to help maintain the structure of microbial cells, prevent dehydration and damage. Especially during cryopreservation, glycerol can effectively improve the survival rate of microorganisms. Sucrose can prevent the osmotic pressure imbalance of microbial cells, maintain the moisture inside the cells, and enhance the frost resistance of microorganisms. Sodium alginate, as a natural polymer, can form a film to protect microorganisms from the external environment, especially helping to preserve the integrity of cells. Sodium chloride is used to adjust the osmotic pressure and help maintain the stability of microbial cells.

[0020] This application document also discloses a preparation method of the above composite bacterium agent, including the following steps:

[0021] S1. Mix the Bacillus subtilis bacterial liquid with a preservation number of CGMCC.NO.26196 and a concentration of 4 - 6×10 10 CFU / ml and the Bacillus licheniformis bacterial liquid with a preservation number of CGMCC.NO.26194 and a concentration of 5 - 8×10 10 CFU / ml according to a volume ratio of 1 - 2:2 - 6 to form functional bacterium A;

[0022] Mix the above functional bacterium A bacterial liquid, the functional bacterium B bacterial liquid with a concentration of 5 - 7×10 9 CFU / ml, and the functional bacterium C bacterial liquid with a concentration of 2 - 6×10 10 CFU / ml according to a volume ratio of 1 - 2:4 - 8:2 - 7;

[0023] S2. Add nano - Fe3O4 and the protective agent to the mixed bacterial liquid of functional bacterium A, functional bacterium B, and functional bacterium C and mix evenly to form a bacterium agent, where the mass ratio of nano - Fe3O4 in the composite bacterium agent is 0.1wt% - 0.5wt%, and the mass ratio of the protective agent in the composite bacterium agent is 2wt% - 5wt%.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] The composite microbial bacterium agent of the present invention can rapidly promote the degradation of lignocellulose in straw in the soil, provide a basic material and energy source for the activities of soil microorganisms. At the same time, the corresponding microorganisms achieve the long - term sequestration of organic carbon through humus stabilization and mineral - associated organic carbon (MAOC) stabilization, and significantly enhance the efficiency of organic carbon sequestration through nano - Fe3O4.

[0026] Under the synergistic action of each strain in this microbial agent, it can effectively reduce the carbon loss during straw returning to the field, improve the soil's carbon sequestration capacity, and increase the content of organic carbon in the soil. Description of the Drawings

[0027] Figure 1 It is a schematic diagram of the action process of this microbial agent;

[0028] Among them: Bacterium A: Functional bacterium A, Bacterium B: Functional bacterium B, Bacterium C: Functional bacterium C, where Fe 3+ is ionized from nano-Fe3O4. Detailed Embodiments

[0029] The present invention will be further described below in conjunction with specific embodiments.

[0030] The principle of this microbial agent in straw treatment is as Figure 1 shown.

[0031] Bacillus subtilis ( Bacillus subtilis ) was deposited on December 14, 2022, at the China General Microbiological Culture Collection Center (CGMCC), deposit number: CGMCC.NO.26196, and the deposit address is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing.

[0032] Bacillus licheniformis ( Bacillus licheniformis ) was deposited on December 14, 2022, at the China General Microbiological Culture Collection Center (CGMCC), deposit number: CGMCC.NO.26194, and the deposit address is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing.

[0033] Pseudomonas aeruginosa ( Pseudomonas aeruginosa ) was deposited on December 14, 2022, at the China General Microbiological Culture Collection Center (CGMCC), deposit number: CGMCC.NO.26195, and the deposit address is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing.

[0034] Trichoderma longibrachiatum ( Trichoderma longiflorum ) was deposited on December 14, 2022, at the China General Microbiological Culture Collection Center (CGMCC), deposit number: CGMCC.NO.40444, and the deposit address is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing.

[0035] Case Group 1

[0036] Example 1: The functional bacteria A includes Bacillus subtilis (deposit number CGMCC.NO.26196) and Bacillus licheniformis (deposit number CGMCC.NO.26194). The composition of the special fermentation medium A for the functional bacteria A is as follows: sodium carboxymethyl cellulose 20 g / L, ammonium sulfate 2 g / L, dipotassium hydrogen phosphate 1 g / L, magnesium sulfate 0.5 g / L, calcium chloride 1 g / L, manganese sulfate 0.05 g / L, ferrous sulfate 0.05 g / L, pH 6 - 7.0. Bacillus subtilis with deposit number CGMCC.NO.26196 and Bacillus licheniformis with deposit number CGMCC.NO.26194 were respectively cultured in medium A to a concentration of 5.2×10 10 CFU / ml and 6.8×10 10 CFU / ml.

[0037] The functional bacteria B is Pseudomonas aeruginosa (deposit number CGMCC.NO.26195). The composition of the special fermentation medium B for the functional bacteria B is as follows: sodium carboxymethyl cellulose 20 g / L, dipotassium hydrogen phosphate 2 g / L, ammonium sulfate 1.4 g / L, magnesium sulfate heptahydrate 0.6 g / L, calcium chloride 0.3 g / L; pH is 6.5. Pseudomonas aeruginosa with deposit number CGMCC.NO.26195 was cultured in medium B to a concentration of 5.9×10 9 CFU / ml.

[0038] The functional bacteria C is Trichoderma longibrachiatum (deposit number CGMCC.NO.40444). The composition of the special fermentation medium C (spore amplification medium) for the functional bacteria C is as follows: potato leachate 200 g / L, dipotassium hydrogen phosphate 2 g / L, sodium carboxymethyl cellulose 20 g / L, guaiacol 0.1 g / L, pH 6. Trichoderma longibrachiatum with deposit number CGMCC.NO.40444 was cultured in medium C to a concentration of 2.2×10 10 CFU / ml.

[0039] The preparation of the compound microbial agent is as follows:

[0040] S1. The bacterial liquid of Bacillus subtilis (deposit number CGMCC.NO.26196) with a concentration of 5.2×10 10 CFU / ml and the bacterial liquid of Bacillus licheniformis (deposit number CGMCC.NO.26194) with a concentration of 6.8×10 10 CFU / ml were mixed in a volume ratio of 1:2 to form the functional bacteria A.

[0041] The above-mentioned functional bacteria A bacterial liquid, the functional bacteria B bacterial liquid with a concentration of 5.9×10 9 CFU / ml, and the functional bacteria C bacterial liquid with a concentration of 2.2×10 10 CFU / ml were mixed in a volume ratio of 1:4:6.

[0042] By mass, 20% glycerol, 10% sucrose, 2% sodium alginate, 1% sodium chloride, and 67% deionized water are uniformly mixed to form a protective agent.

[0043] S2. Add nano-Fe3O4 (average particle size 100 nm) and the protective agent to the mixed bacterial solution of functional bacteria A, functional bacteria B, and functional bacteria C and mix evenly to form a composite bacterial agent, where the mass ratio of nano-Fe3O4 in the composite bacterial agent is 0.3%, and the mass ratio of the protective agent in the composite bacterial agent is 5%.

[0044] Select the "rice-oil crop rotation" double-cropping planting area in Zhejiang for a long time, divide the experimental plots, the size of the experimental plots is 6 m × 6 m, and leave a 1 m-wide isolation belt between each treatment in the experimental plots to prevent the spread and pollution of the bacterial agent. The field environment is 5 - 15 °C. When the harvester harvests the crops, the straw is synchronously crushed and evenly covered on the flat open space at the field edge. The composite bacterial agent and water are uniformly mixed according to a mass ratio of 3:100. The application rate of the composite bacterial agent is 3 kg / mu. The mixture of the composite bacterial agent and water is evenly sprayed on the surface of the field straw. The straw enters the plough layer about 15 cm deep with the operation of the rotary tiller. Soil samples are randomly taken from each plot on the 30th day to measure the parameters as shown in Table 1, and soil samples are randomly taken on the 90th day to measure the parameters as shown in Table 2. The initial soil background value of the experimental plot is shown in Table 3.

[0045] At the same time, add a control group. For the convenience of viewing, the control group, Example 1 above, etc. are correspondingly named Treatment 1, Treatment 2, etc., as follows:

[0046] Among them, Treatment 1: The difference from the straw returning treatment in Example 1 is that in this example, no bacterial agent or auxiliary material is added. Treatment 2: That is, the straw returning scheme in Example 1. Treatment 3: The difference from the straw returning treatment in Example 1 is that the composite bacterial agent does not contain Bacillus subtilis (deposit number CGMCC.NO.26196). Treatment 4: The difference from the straw returning treatment in Example 1 is that the composite bacterial agent does not contain Bacillus licheniformis (deposit number CGMCC.NO.26194). Treatment 5: The difference from the straw returning treatment in Example 1 is that Pseudomonas aeruginosa in the composite bacterial agent is directly purchased from the market. Treatment 6: The difference from the straw returning treatment in Example 1 is that the composite bacterial agent does not contain Trichoderma longibrachiatum (deposit number CGMCC.NO.40444). Treatment 7: The difference from the straw returning treatment in Example 1 is that the composite bacterial agent does not contain nano-Fe3O4. Treatment 8: The difference from the straw returning treatment in Example 1 is that Trichoderma longibrachiatum in the composite bacterial agent is directly purchased from the market. Treatment 9: The difference from the straw returning treatment in Example 1 is that a straw treatment bacterial agent produced by Guangdong Weiliwang Company is used.

[0047] Table 1

[0048]

[0049] As can be seen from Table 1, when cultured in the field environment at 5 - 15°C for 30 days, the degradation rates of various celluloses, hemicelluloses and lignins and the enzyme activities of Treatment 1 were significantly lower than those of other treatments, proving that the addition of each microbial agent could promote the degradation of field lignocellulose and the improvement of microbial enzyme activity to varying degrees. The degradation rates of various lignocelluloses and microbial enzyme activities of Treatment 2 were significantly higher than those of other treatments or there were no significant differences. Except for peroxidase, all indicators of Treatment 3 and Treatment 4 were significantly lower than those of Treatment 2, proving that the components in Functional Bacteria A (composed of Bacillus subtilis preservation number CGMCC.NO.26196 and Bacillus licheniformis preservation number CGMCC.NO.26194) played an indispensable and important role in the degradation of lignocellulose and the improvement of related enzyme activities. The cellulose degradation rate of Treatment 5 had no significant difference from that of Treatment 2, but the degradation rates of hemicellulose and lignin and the xylanase activity were significantly lower than those of Treatment 2, proving that Functional Bacteria B (i.e., Pseudomonas aeruginosa preservation number CGMCC.NO.26195) had an irreplaceable role in the degradation and transformation of hemicellulose. Except for the cellulose degradation rate and polyphenol oxidase, all other indicators of Treatment 6 and Treatment 8 were significantly lower than those of Treatment 2, proving that Functional Bacteria C (i.e., Trichoderma longibrachiatum preservation number CGMCC.NO.40444) constituted the functional integrity of the composite microbial agent. The cellulose degradation rate and cellulase activity of Treatment 7 had no significant difference from those of Treatment 2, and the degradation rates of hemicellulose, lignin, xylanase activity and peroxidase activity were significantly lower than those of Treatment 2, proving that the role of nano - Fe3O4 was not related to cellulose degradation and was more focused on the degradation of hemicellulose and lignin; at the same time, nano - Fe3O4 had a significant promoting effect on the function of the composite microbial agent. The polyphenol oxidase activity of Treatment 9 was significantly lower than that of Treatment 2, and the cellulase, xylanase and peroxidase had no significant difference from those of Treatment 2, which proved that in practical applications, Treatment 2 and the commercially available microbial agent had a similar effect on the improvement of enzyme activity in the soil; however, the degradation rates of various lignocelluloses of Treatment 9 were significantly lower than those of Treatment 2. In summary, each component in Treatment 2 played an irreplaceable and important role in the high efficiency and integrity of the function; at the same time, the composite microbial agent of the present invention was applicable to the composting treatment of cold - region straw, and the composting application effect was better than that of Treatment 9 (i.e., the commercially available microbial agent).

[0050] Table 2

[0051]

[0052] Table 3

[0053]

[0054] As can be seen from Table 2 and Table 3, there are basically no significant differences in soil organic carbon (SOC), mineral-associated organic carbon (MAOC), particulate organic carbon (POC), and total humus in Treatment 1 compared with those in Treatments 3, 4, 6, and 7. However, the dissolved organic carbon (DOC) and soil microbial biomass carbon (MBC) in Treatment 1 are significantly lower than those in other treatments, which proves that the addition of microbial agents can improve the biochemical metabolism degree of soil to varying degrees. However, due to the complexity of carbon turnover and the diversity of humus transformation, Treatments 3, 4, 6, and 7 have not achieved the fixation and geographical improvement of organic carbon in the soil. The indexes of Treatment 2 are higher than those of other treatments, which also proves the indispensability of each component in the compound microbial agent of the present invention. The SOC of the soil in Treatment 5 and Treatment 8 is significantly higher than that in Treatments 1, 3, 4, 6, and 7, but significantly lower than that in Treatment 2. At the same time, the DOC and MBC are significantly higher than those in Treatments 3, 4, 6, and 7 but significantly lower than those in Treatment 2. This shows that by replacing Pseudomonas aeruginosa and Trichoderma longibrachiatum, the biochemical metabolism degree of the soil can be improved to a certain extent, thereby enhancing the soil carbon sequestration ability, but the carbon sequestration effect is not as good as that of this compound microbial agent; each component in the compound microbial agent of the present invention is irreplaceable. The MAOC, DOC, and MBC in Treatment 9 are significantly higher than those in Treatment 1, but the SOC, POC, and total humus have no significant difference from those in Treatment 1 and are significantly lower than those in Treatment 2. This proves that although the commercially available microbial agent can improve the activity of microorganisms in the soil, it does not have the function of realizing soil carbon sequestration. Each component in the compound microbial agent of the present invention is indispensable and irreplaceable, and the integrity of the components is the fundamental guarantee for the compound microbial agent to exhibit excellent soil carbon sequestration ability.

[0055] Early rice was planted in the above experimental plots and harvested in July. Rice samples were taken for index detection, as shown in Table 4.

[0056] Table 4

[0057]

[0058] As can be seen from Table 4, there are no significant differences in the number of grains per panicle among the treatments. This index may depend on the rice variety, and at the same time, it also makes the seed setting rate, 1000-grain weight and yield of each treatment comparable. The effective panicle number, seed setting rate and 1000-grain weight of Treatment 2 are significantly higher than those of other treatments or there are no significant differences, which proves that Treatment 2 has varying degrees of promotion in all aspects of rice grain setting and development; the yield of Treatment 2 is significantly higher than that of other treatments, which also proves that Treatment 2 can improve soil fertility by optimizing the carbon sequestration process after straw enters the soil, thereby increasing rice yield. At the same time, the yields of Treatments 3, 4, 6 and 7 are significantly lower than that of Treatment 2, indicating that the lack of components in the composite bacterium agent of the present invention will affect all aspects of rice grain setting and development, resulting in a final yield lower than that of Treatment 2. The yield of Treatment 5 has no significant difference from that of Treatment 1, and the yields of Treatments 8 and 9 are significantly higher than that of Treatment 1 but significantly lower than that of Treatment 2, which proves that the replacement of Pseudomonas aeruginosa and Trichoderma longibrachiatum in the composite bacterium agent of the present invention does not ultimately achieve a better yield effect than Treatment 2. The yield of Treatment 9 is significantly higher than that of Treatment 1 but significantly lower than that of Treatment 2, which also proves that the commercially available bacterium agent can also increase the yield to a certain extent but is lower than the composite bacterium agent of the present invention. At the same time, Treatment 2 has the best yield improvement performance among all treatments.

[0059] The above is only the preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions falling within the idea of the present invention belong to the protection scope of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and retouches should also be regarded as the protection scope of the present invention.

Claims

1. A composite microbial agent coupling straw decomposition and soil carbon sequestration, characterized in that, Comprising: The functional bacterium A is Bacillus subtilis with the preservation number of CGMCC.NO.26196 ( Bacillus subtilis ) and Bacillus licheniformis with the preservation number of CGMCC.NO.26194 ( Bacillus licheniformis ), and the volume ratio of their liquids is 1-2:2-6; Functional bacterium B, and the functional bacterium B is Pseudomonas aeruginosa with the preservation number CGMCC.NO.26195 ( Pseudomonas aeruginosa ) Functional bacterium C, and the functional bacterium C is Trichoderma longibrachiatum with the preservation number CGMCC.NO.40444 ( Trichoderma longiflorum ); a protective agent, and nano Fe3O4; Among them, the liquid volume ratio of the functional bacteria A, functional bacteria B and functional bacteria C is 1 - 2:4 - 8:2 - 7, the proportion of nano Fe3O4 in the composite bacterial agent is 0.1wt% - 0.5wt%, and the proportion of the protective agent in the composite bacterial agent is 2wt% - 5wt%.

2. The composite microbial inoculum coupling straw decomposition and soil carbon sequestration according to claim 1, characterized in that: In the functional bacterium A, the concentrations of Bacillus subtilis ( Bacillus subtilis ), Bacillus licheniformis ( Bacillus licheniformis ) are 4 - 6×10 10 CFU / ml and 5 - 8×10 10 CFU / ml respectively. The concentrations of the functional bacterium B and the functional bacterium C are 5 - 7×10 9 CFU / ml and 2 - 6×10 10 CFU / ml respectively.

3. A composite microbial agent coupling straw decomposition and soil carbon sequestration according to claim 1, characterized in that: By mass, the protective agent comprises 10 - 20wt% glycerol, 10 - 15wt% sucrose, 1 - 2wt% sodium alginate, 1 - 3wt% sodium chloride, and the balance is deionized water.

4. The preparation method of the composite bacterial agent according to any one of claims 1-3, characterized in that: Including the following steps: S1. Mix the Bacillus subtilis bacterial solution with a preservation number of CGMCC.NO.26196 and a concentration of 4 - 6×10 10 CFU / ml ( Bacillus subtilis ), and the Bacillus licheniformis bacterial solution with a preservation number of CGMCC.NO.26194 and a concentration of 5 - 8×10 10 CFU / ml ( Bacillus licheniformis ) in a volume ratio of 1 - 2:2 - 6 to form functional bacteria A; Mix the above-mentioned functional bacterium A bacterial liquid, the functional bacterium B bacterial liquid with a concentration of 5-7×10 9 CFU / ml, and the functional bacterium C bacterial liquid with a concentration of 2-6×10 10 CFU / ml in a volume ratio of 1-2:4-8:2-7; S2. Add nano Fe3O4 and the protective agent to the mixed bacterial liquid of the above-mentioned functional bacteria A, functional bacteria B and functional bacteria C and mix evenly to form a composite bacterial agent, wherein the proportion of nano Fe3O4 in the composite bacterial agent is 0.1wt% - 0.5wt%, and the proportion of the protective agent in the composite bacterial agent is 2wt% - 5wt%.

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