Earthworm compost upgrading method based on bacillus velezensis BV-1 aerobic compost product

Abstract

The invention discloses an earthworm compost upgrading method based on a bacillus velezensis BV-1 aerobic compost product. Comprising the following steps: by taking an aerobic compost rotten product pretreated by bacillus velezensis BV-1 as a substrate, adjusting the moisture content of the substrate to a proper value without additionally adding a conditioner, inoculating eisenia foetida, performing earthworm composting in a dark environment, slightly turning piles every 4-5 days during the period to prevent anaerobism, and maintaining the moisture content of the substrate to be stable. The quality of the earthworm cast is remarkably improved through'matrix advantage + microorganism continuation effect 'of a BV-1 aerobic composting product, and the total nitrogen content of the earthworm cast reaches 18.29 g / kg and is improved by 12.6% compared with that of a control group; the conductivity is reduced to 1.84 mS / cm and is reduced by 8.91% compared with that of a control group; meanwhile, a nitrogen cycle functional gene (the relative expression quantity of the nosZ gene is increased by 15 times compared with that of a control group) is activated, organic matter degrading bacteria Arenibacter (the relative abundance is 8.37%) are enriched, and unification of high nitrogen, low salt and high biological activity of earthworm compost products is achieved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of resource utilization of organic solid waste, and specifically relates to a method for improving the quality of earthworm compost by using the aerobic compost product of Bacillus velezensis BV-1 as a substrate, which focuses on solving the problems of low nitrogen content, high salt content and insufficient biological activity of the earthworm compost product, and is suitable for the large-scale production of high-quality vermicompost organic fertilizer. BACKGROUND

[0002] Earthworm composting is a key "secondary composting" process after aerobic composting. Through the synergistic action of earthworms and microorganisms, it further decomposes organic matter, enriches nutrients, and reduces pollutants. The product, earthworm manure, is widely used in agricultural production due to its high content of available nutrients and plant growth regulators. However, there are two major bottlenecks in existing earthworm composting technology:

[0003] (1) Insufficient basic nutrients in the substrate: Traditional earthworm composting often uses aerobic compost products that have not been pretreated with functional microbial agents as the substrate. This type of substrate has a low nitrogen retention rate (usually < 85%) and poor available nitrogen form, resulting in a final earthworm manure total nitrogen content generally lower than 16 g / kg, limiting its fertilizer effect; (2) Imbalance between product salt content and microbial activity: There are many residual soluble salt ions in traditional substrates (EC often > 2.0 mS / cm), which not only affect the metabolic activity of earthworms, but also cause high salt content in earthworm manure, which can easily lead to secondary salinization risk when applied to soil. At the same time, the amount of functional microorganisms carried by the substrate is small, making it difficult to activate the nitrogen cycle process in earthworm composting, and the risk of denitrification gas emission is high.

[0004] In existing technology, the means to improve the quality of earthworm composting are mostly focused on "external addition of conditioning agents" (such as desulfurized gypsum for salt reduction, biochar for nitrogen retention), but this method has the defects of high cost, easy introduction of impurities, and dependence on the characteristics of the substrate; there are also studies that attempt to directly inoculate bacteria during the earthworm composting stage, but the compatibility of exogenous bacteria with earthworm gut microorganisms is poor, and it is difficult to form a functional continuation with the previous aerobic composting process, resulting in unstable quality improvement effect. There are also schemes that use aerobic compost products pretreated with functional microbial agents as the substrate for earthworm breeding / composting (e.g., CN 119404813 A); however, the bacteria used in the pretreatment stage are aimed at improving treatment efficiency and worm yield, and the nitrogen retention rate of the aerobic compost product is limited, so the nitrogen content of the final earthworm manure may still be at a low level as in traditional technology. In addition, the salt content of livestock and poultry manure is relatively high, and since it is not specifically reduced during the pretreatment stage, the EC value of the earthworm manure is high, and the earthworm manure obtained by this method may still have an EC value higher than the crop safety threshold, posing a risk of causing secondary salinization of the soil when applied. At the same time, there are also the same defects of insufficient biological activity and difficulty in forming a functional continuation with the previous aerobic composting process, resulting in unstable quality improvement effect. SUMMARY

[0005] In view of the defects of insufficient nutrients, high salt content and low biological activity of existing vermicompost substrates, the present application provides a method for improving the quality of vermicompost based on Bacillus velezensis BV-1 aerobic compost products. Bacillus velezensis BV-1 (CGMCC No. 29418) was deposited at the China General Microbiological Culture Collection Center (CGMCC) on December 27, 2023. The strain has shown excellent nitrogen preservation ability during the aerobic composting stage, but specific research on its aerobic compost products as vermicompost substrates has not been reported. The present application provides a precise substrate solution for improving the quality of vermicompost through systematic exploration of the "nutrient release pattern", "microbial persistence effect" and "earthworm-microbe synergistic mechanism" of the substrate in vermicomposting. The core innovation of the present application lies in the "high nitrogen substrate advantage" and "functional microbial persistence" of BV-1 aerobic compost products, which can achieve "high nitrogen, low salt and high activity" of vermicompost without additional conditioning agents, with the advantages of simple process, controllable cost and stable quality improvement effect.

[0006] The technical solutions adopted to achieve the above-mentioned purposes of the present application are as follows: <First aspect> The present application provides a method for improving the quality of vermicompost based on Bacillus velezensis BV-1 aerobic compost products, characterized in that the method comprises the following steps: S1, preparation of vermicompost substrate: take the aerobic composting mature product pretreated by Bacillus velezensis BV-1 as the vermicompost substrate, without adding additional conditioning agents; the Bacillus velezensis BV-1 is Bacillus velezensis (BV-1 CGMCC No. 29418); Bacillus velezensis S2, inoculation and culture of earthworms: spray sterile water to the substrate to adjust the moisture content to 65%-70%; select healthy pre-treated earthworms and inoculate them into the substrate at a density of 0.08-0.12 kg / kg substrate for vermicomposting; S3, management and product collection of vermicomposting: gently turn the substrate during composting; supplement sterile water regularly to maintain the moisture content of the substrate at 65%-70% by weighing method; collect the loose vermicompost at the bottom after the culture is completed, and obtain the high-quality vermicompost product.

[0007] As an embodiment, in step S1, the total nitrogen content of the aerobic composting mature product (BV-1 aerobic composting product) is ≥2.99%, EC is ≤3.35 mS / cm, and moisture content is ≤65%.​

[0008] As an implementation plan, the nitrogen retention rate of BV-1 aerobic compost products is ≥90.25%, and the organic matter retention rate is ≥71.50%, providing sufficient nitrogen and carbon sources for vermicomposting and avoiding growth stagnation of earthworms due to insufficient nutrients.

[0009] As one implementation scheme, in step S1, the aerobic composting product is prepared by the following steps: mixing livestock and poultry manure with corn stalks at a C / N ratio of 20-30:1, inoculating with BV-1 bacterial suspension and a compound microbial agent, and then aerobically composting. The compound microbial agent is a commercially available compound microbial agent, such as a chicken manure / pigeon manure fermentation agent.

[0010] As one implementation, the effective viable count of the BV-1 bacterial suspension is 0.8–1.2 × 10⁻⁶. 8 CFU / mL, inoculation volume is 10-20 mL: 20 kg; compound bacterial agent inoculation volume is 25-35 mL: 20 kg.

[0011] As one implementation scheme, in step S2, the conditions for vermicomposting are: temperature 20±1℃, relative humidity 65%-70%, and avoidance of light (i.e., light intensity <50 μmol·m⁻²). - ²·s - Cultivate in an environment of ¹ for 20-30 days; As one implementation scheme, in step S2, the pretreatment method for Eisenia fetida is as follows: starve the earthworms for 20-30 hours in a sterile, moist filter paper environment to remove residual substrate in the intestines, ensuring that the earthworms quickly adapt to the new substrate and start digestion and metabolism after inoculation.

[0012] As an implementation plan, in step S3, the substrate is lightly turned over every 4-5 days during composting, with a turning depth of ≤5cm, to prevent local anaerobic conditions and avoid damaging the earthworms.

[0013] As an implementation plan, the key indicators of the resulting vermicompost products (vermicompost products) meet the following requirements: total nitrogen content ≥18g / kg, ammonium nitrogen content ≥50 mg / kg, EC ≤1.84 mS / cm, and nitrite nitrogen content ≤0.80 mg / kg.

[0014] As one implementation scheme, the relative expression levels of nitrogen cycle functional genes in the obtained earthworm compost products met the following requirements: nifH ≥ 11.65, nirS ≥ 19.19, and nosZ ≥ 20.86. The relative expression levels of nitrogen cycle functional genes (nifH, nirS, and nosZ) were more than 10-fold higher than those in the control group.

[0015] As one implementation scheme, the relative abundance of the organic matter degrading bacteria Arenibacter in the resulting vermicompost products is ≥8.37%.

[0016] <Second aspect> This invention provides an application of aerobic composting products of Bacillus belyssus BV-1 in the improvement of vermicompost quality. The aerobic composting products serve as a vermicompost substrate, used to increase the total nitrogen content of vermicompost, reduce salinity, and activate nitrogen cycle functional genes. The Bacillus belyssus BV-1 is a type of Bacillus belyssus (… Bacillus velezensis BV-1CGMCCNo. 29418. This aerobic compost not only provides earthworms with a high-nitrogen, easily degradable substrate, but also carries the BV-1 strain and its induced functional microbial community, which can continuously regulate nitrogen cycling and reduce salinity during the earthworm composting stage, thereby achieving a targeted improvement in the quality of vermicompost.

[0017] In some implementation examples, the vermicomposting quality improvement method based on Bacillus belye BV-1 aerobic compost products includes the following steps: (1) Preparation of earthworm compost substrate: The aerobic composting product pretreated with Bacillus belysin BV-1 was selected as the substrate. The product was prepared by the following method: Livestock and poultry manure (moisture content 65.2%, total nitrogen 4.03%) and corn straw (moisture content 12.1%, total nitrogen 0.43%) were mixed at C / N=25:1, and inoculated with 15 mL of BV-1 bacterial suspension (1×10 8 The substrate is prepared by adding 30 mL of commercial compound microbial agent (CFU / mL) and undergoing 60 days of aerobic composting (3 days at a high temperature of >60℃, with a cumulative heat integral of 85.34). Its total nitrogen content is 2.99%, EC 3.35 mS / cm, and moisture content is 60%. Sterile water is sprayed into the substrate to adjust the moisture content to 65%-70%, and no other conditioning agents are required.

[0018] (2) Earthworm inoculation and culture: Select healthy adult Eisenia fetidae (body weight 200-300 mg / worm, activity ≥95%) and inoculate them into the above-mentioned substrate at a density of 0.1 kg / kg substrate; put the inoculated substrate into a plastic basin with a diameter of 30 cm and a height of 25 cm (drill 8-10 ventilation holes in the basin wall / bottom, and cover the holes with gauze to prevent leakage), and place it at 20±1℃ in the dark (light intensity <50μmol·m - ²·s - ¹) In a constant temperature environment with a relative humidity of 65%-70%, earthworm composting is carried out for 25 days.

[0019] (3) Earthworm composting management and product collection: During the composting period, the substrate is turned over slightly with a bamboo rake every 4-5 days (turning depth ≤ 5 cm) to avoid damaging the earthworms; sterile water is added regularly by weighing to maintain the substrate moisture content at 65%-70%; after 25 days, earthworms are separated by sieving (healthy adult earthworms are retained for subsequent batches), and the loose vermicompost at the bottom layer is collected to obtain high-quality earthworm compost products.

[0020] This invention discovers that Bacillus belye BV-1, through aerobic composting pretreatment, can form an optimized substrate with both high nitrogen content and a specific functional microbial community. This substrate's microbial community exhibits significant "continuity," and can synergistically activate nitrogen cycling functional genes with earthworms in subsequent vermicomposting, simultaneously reducing salinity and enriching functional bacteria, thereby synergistically achieving a quality improvement in vermicompost that is "high nitrogen, low salinity, and high bioactivity." Compared with existing technologies, this invention has the following beneficial effects: (1) No additional conditioner required, process simplified: Relying on the excellent characteristics of BV-1 aerobic compost products, the addition of conditioners such as desulfurized gypsum and biochar is eliminated, reducing costs and avoiding the introduction of impurities; (2) Significantly increased total nitrogen in vermicompost: The total nitrogen content of vermicompost reached 18.29 g / kg, which is 12.6% higher than that of traditional vermicompost products (around 16 g / kg), solving the core problem of low fertilizer efficiency; (3) Synergistic optimization of salt content and bioactivity: the EC of earthworm castings is reduced to 1.84 mS / cm, while activating nitrogen cycle functional genes and enriching beneficial bacteria, taking into account both agricultural safety and bioactivity. Attached Figure Description

[0021] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 The graph shows the dynamic changes in pH during the earthworm composting process in the embodiments and comparative examples of the present invention. The horizontal axis represents the composting time (day 10 and day 25), the vertical axis represents the pH value, CK represents the control group, and BV represents the experimental group. Figure 2 The graph shows the dynamic changes of EC during the earthworm composting process in the embodiments and comparative examples of the present invention; the horizontal axis represents the composting time (day 10 and day 25), the vertical axis represents the EC value (mS / cm), CK is the control group, and BV is the experimental group; Figure 3 This is a comparison chart of the total nitrogen content of vermicompost at the end of vermicomposting in the embodiments and comparative examples of the present invention; the horizontal axis represents the treatment group (CK is the control group, BV is the experimental group), and the vertical axis represents the total nitrogen content (g / kg). Figure 4This is a comparison of the relative expression levels of nitrogen cycle functional genes (nifH, nirS, nosZ) at the end of earthworm composting in the embodiments and comparative examples of the present invention; the horizontal axis represents the treatment groups (CK is the control group, BV is the experimental group), and the vertical axis represents the relative expression level. Detailed Implementation

[0022] The present invention will be described in detail below with reference to embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several adjustments and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0023] Example 1. Preparation of aerobic compost products from Bacillus belyssus BV-1 Mix livestock and poultry manure (moisture content 65.2%, total nitrogen 4.03%) and corn stalks (moisture content 12.1%, total nitrogen 0.43%) (C / N=25:1), and inoculate with 15 mL of BV-1 bacterial suspension (1×10⁻⁶). 8 The product was prepared by aerobic composting for 60 days (3 days at a high temperature of >60℃, cumulative calorific value 85.34) with a total nitrogen content of 2.99%, EC 3.35 mS / cm, and a moisture content of 60%, using a substrate of "30 mL of commercial compound microbial agent" as the substrate (preparation conditions were the same as the experimental group, except that BV-1 bacterial suspension was not added), with a total nitrogen content of 2.71%, EC 2.90 mS / cm, and a moisture content of 60%. The commercial compound microbial agent used was Nongfukang chicken and pigeon manure fermentation agent.

[0024] Among them, total nitrogen: the Kjeldahl method was used to determine the total nitrogen of the composted product, referring to Appendix D of the industry standard "Organic Fertilizer NY / T525-2021"; electrical conductivity (EC): 5.0 g of composted sample that passed through a 2 mm sieve was weighed, added to a centrifuge tube at a ratio of sample:pure water = 5:1, shaken at 180 rpm and 25 ℃ for 3 min, and then allowed to stand for 30 min. The EC was then measured using an electrical conductivity meter; moisture content: dried.

[0025] 2. Earthworm composting experiment design (1) Experimental group (BV-vermicular castings group): Using BV-1 aerobic compost as substrate, the moisture content was adjusted to 65%, and 0.2 kg of Eisenia fetida (pretreated, body weight 200-300 mg / worm, activity ≥95%) was inoculated into every 2 kg of substrate; the inoculated substrate was placed in a plastic basin with a diameter of 30 cm and a height of 25 cm (8-10 ventilation holes were drilled in the basin wall / bottom, and the holes were covered with gauze to prevent leakage), and placed at 20±1℃ in the dark (light intensity <50 μmol·m- ²·s - ¹) Earthworms were cultured for 25 days in a constant temperature environment with a relative humidity of 65% for composting. During composting, the substrate was gently turned over with a bamboo rake every 4 days (turning depth ≤ 5 cm) to avoid damaging the earthworms' body surface and intestinal microorganisms, repeated 3 times. Sterile water was added regularly by weighing to maintain the substrate moisture content at a stable 65%. After 25 days, earthworms were separated by sieving (healthy adult earthworms were retained for subsequent batches), and the loose vermicompost at the bottom was collected to obtain high-quality earthworm compost.

[0026] (2) Control group (CK-vermectin group): The aerobic compost products of the control group were used as the substrate, and the other conditions were completely the same as those of the experimental group, with 3 replicates.

[0027] The pretreatment method for Eisenia fetida is as follows: the earthworms are placed in a sterile, moist filter paper environment and starved for 24 hours to remove residual substrate in the intestines, ensuring that the earthworms can quickly adapt to the new substrate and start digestion and metabolism after inoculation.

[0028] 3. Monitoring and Efficacy Verification of Vermicomposting Process 3.1 Dynamic monitoring of the physical and chemical environment (1) pH changes: such as Figure 1 As shown, the initial pH of the experimental group was 7.53, while that of the control group was 8.11. The initial pH of the experimental group was closer to neutral, indicating a higher degree of composting. At the end of composting, the pH of both groups dropped to 7.3-7.4. The pH drop of the experimental group was only 2.26%, which was significantly lower than the 9.86% drop of the control group. This indicates that the BV-1 substrate can buffer pH fluctuations in earthworm composting and provide a stable acid-base environment for earthworms.

[0029] (2) EC changes: such as Figure 2 As shown, at the end of composting, the EC value of the experimental group was 1.84 mS / cm, a decrease of 8.91% compared to the control group (2.02 mS / cm). The final EC value of the experimental group was significantly lower, indicating that the BV-1 substrate can reduce soluble salt residues. It should be noted that the reduction of nitrates in soil mainly relies on the direct metabolic activities of the strain in the soil niche, such as denitrification and assimilation. However, the mechanism for forming a low-salt substrate in aerobic composting may be completely different. This is not because the BV-1 strain directly reduces salt in composting, but more likely because it regulates the entire fermentation process, such as promoting the humification of organic matter to fix base ions, altering the microbial community structure to optimize metabolites, or producing a synergistic effect with conditioners such as straw, thereby optimizing the salt composition of the substrate from the source. This is an indirect, systematic regulatory result.

[0030] 3.2 Nutrient Content Analysis of Vermicompost (1) Total nitrogen content: such as Figure 3As shown, the total nitrogen content of vermicompost in the experimental group was 18.29 g / kg, which was 12.6% higher than that in the control group (16.24 g / kg). (2) Ammonium nitrogen content: Ammonium nitrogen (NH4) was determined by back titration after distillation. + -N), referring to the industry standard "Determination of Nitrate Nitrogen, Ammonium Nitrogen and Amide Nitrogen Content in Fertilizers NY / T1116-2014"; the experimental group had 50.1 mg / kg, which was 39.6% higher than the control group (35.2 mg / kg), indicating a significant enhancement in the supply capacity of available nitrogen; (3) Nitrite nitrogen content: Nitrite nitrogen (NO2) was determined by N-(1-naphthyl)-ethylenediamine spectrophotometry. - -N); the experimental group was 0.80 mg / kg, which was 70.4% lower than the control group (2.70 mg / kg), thus avoiding the accumulation of harmful intermediate products.

[0031] 3.3 Expression of nitrogen cycle functional genes Functional gene and microbial characteristic analysis (1) Extraction of total DNA from samples Total DNA was extracted from the samples using the Ezup column-based genomic DNA extraction kit (Shanghai Sangon Biotech Co., Ltd.).

[0032] (2) Determination of the relative abundance of nitrogen cycle-related functional genes The relative abundance of nitrogen cycle functional genes was determined using real-time quantitative PCR. Sample DNA was used as a template, and nitrogen cycle functional gene primers were used to amplify the target genes. The Ct values ​​were corrected using bacterial 16S rDNA Ct values. Primer sequences are shown in Table 1 below.

[0033] Table 1. Primers for nitrogen cycle functional genes

[0034] Real-time PCR program: 95 ℃, 30 s, 39 cycles; 95 ℃, 5 s; 60 ℃, 34 s; 65 ℃, 5 s; 95 ℃, 0 s. Real-time PCR system (total 25 μL): TBGreen 12.5 μL, DNA template 1 μL, forward primer 1 μL, reverse primer 1 μL, sterile water 9.5 μL. After constructing standard plasmids with the corresponding primers, a standard curve was constructed using real-time PCR. Based on the Ct values ​​of each DNA sample measured experimentally, the copy number of the target fragment can be obtained by combining the results with the standard curve.

[0035] like Figure 4As shown, the relative expression levels of nitrogen cycle functional genes in the experimental group were significantly higher than those in the control group: nifH (11.65 vs 1.00), nirS (19.19 vs 1.01), and nosZ (20.86 vs 1.00), upregulated by 11.6-fold, 19.0-fold, and 20.9-fold, respectively. This indicates that the microbial community carried by the BV-1 substrate can activate the nitrogen cycle process in earthworm composting and reduce the loss of gaseous nitrogen.

[0036] 3.4 Microbial community structure analysis The relative abundance of Arenibacter, an organic matter degrading bacterium, in the earthworm castings of the experimental group was 8.37%, which was 94.2% higher than that of the control group (4.31%). Arenibacter can efficiently decompose complex organic matter, providing earthworms with more easily digestible nutrients, while promoting the conversion of organic matter into humus and improving the stability of earthworm castings.

[0037] 4. Mechanism of Action The core mechanism of this invention lies in the "dual continuity effect" of BV-1 aerobic compost products: (1) Nutrient continuity effect: The high nitrogen content (2.99%) of BV-1 aerobic compost provides earthworms with sufficient nitrogen source. After ingestion, earthworms convert organic nitrogen into readily available ammonium nitrogen through intestinal digestion, while reducing nitrogen leaching loss. In addition, the stable organic matter in the product (71.50% retention rate) can adsorb some basic ions, reduce matrix EC, and improve the earthworm's living environment. (2) Microbial continuity effect: BV-1 aerobic compost products carry BV-1 strain and its induced functional microbial communities (such as Thermobifida and Saccharomonospora). After entering earthworm compost, these microbial communities work synergistically with earthworm gut microbes: on the one hand, BV-1 activates nitrogen cycle functional genes (such as nosZ), promotes the conversion of N2O to N2, and reduces nitrogen loss; on the other hand, the enriched Arenibacter decomposes organic matter, providing energy for earthworm metabolism, forming a virtuous cycle of "microbe-earthworm" synergistic quality improvement.

[0038] In summary, this invention uses aerobic composting products pretreated with Bacillus belye BV-1 CGMCC 29418 as the substrate, without the need for additional conditioners, and adjusts the substrate moisture content to 65%-70%; Eisenia fetida is introduced at a density of 0.1 kg / kg substrate; earthworm composting is carried out for 25 days in a light-protected environment at 20±1℃, during which the compost is slightly turned every 4-5 days to prevent anaerobic digestion and maintain stable substrate moisture content. This invention significantly improves the quality of vermicompost through the "matrix advantage + microbial continuity effect" of BV-1 aerobic compost products: the total nitrogen content of vermicompost reaches 18.29 g / kg, an increase of 12.6% compared with the control group; the electrical conductivity (EC) decreases to 1.84 mS / cm, a decrease of 8.91% compared with the control group; at the same time, it activates nitrogen cycle functional genes (the relative expression level of the nosZ gene is upregulated by 15 times compared with the control group), enriches the organic matter degrading bacteria Arenibacter (relative abundance 8.37%), and achieves the unity of high nitrogen, low salt and high biological activity of vermicompost products. It can be seen that the earthworm composting quality improvement method based on Bacillus belyssus BV-1 aerobic compost products provided by the present invention achieves three core technical effects through matrix characteristics and biological synergy: (1) the total nitrogen of vermicompost exceeds 18 g / kg, which is 12.6% higher than that of traditional earthworm compost, solving the bottleneck of low nitrogen content in the product; (2) the EC of vermicompost is reduced to 1.84 mS / cm, which is lower than the salt stress threshold of crop roots (2.0 mS / cm), improving agricultural safety; (3) the nitrogen cycle functional genes are upregulated by more than 10 times, enriching organic matter degrading bacteria, taking into account both nutrient preservation and biological activity, laying the foundation for subsequent secondary saline soil remediation.

[0039] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for improving the quality of vermicomposting based on aerobic compost products of Bacillus belye BV-1, characterized in that, The method includes the following steps: S1. Preparation of vermicompost substrate: Aerobic composting products pretreated with Bacillus vesiculus BV-1 are used as the vermicompost substrate; no additional conditioner is required. The Bacillus vesiculus BV-1 is a type of Bacillus vesiculus (…). Bacillus velezensis BV-1 CGMCC No. 29418; S2. Earthworm inoculation and cultivation: Spray sterile water onto the substrate and adjust the moisture content to 65%-70%; select pretreated healthy Eisenia fetida adult earthworms and inoculate them into the substrate at a density of 0.08-0.12 kg / kg substrate for earthworm composting; S3. Earthworm composting management and product collection: During composting, the substrate should be turned over slightly at regular intervals; sterile water should be added regularly by weighing to maintain the substrate moisture content at 65%-70%; after the cultivation is completed, the loose vermicompost at the bottom layer should be collected to obtain high-quality earthworm compost products.

2. The method for improving the quality of earthworm compost according to claim 1, characterized in that, In step S1, the total nitrogen content of the aerobic composting product is ≥2.99%, EC≤3.35 mS / cm, and moisture content≤65%.

3. The method for improving the quality of earthworm compost according to claim 1, characterized in that, In step S1, the aerobic composting product is prepared by the following steps: livestock and poultry manure and corn stalks are mixed at a C / N ratio of 20 to 30:1, inoculated with BV-1 bacterial suspension and compound bacterial agent, and then aerobically composted.

4. The method for improving the quality of earthworm compost according to claim 3, characterized in that, The effective viable count of the BV-1 bacterial suspension is 0.8–1.2 × 10⁻⁶. 8 CFU / mL, inoculation amount is 10-20 mL: 20 kg; compound bacterial agent inoculation amount is 25-35 mL: 20 kg.

5. The method for improving the quality of earthworm compost according to claim 1, characterized in that, In step S2, the conditions for vermicomposting are: temperature 20±1℃, relative humidity 65%-70%, and darkness (light intensity <50 μmol·m). - ²·s - Cultivate in an environment of ¹ for 20-30 days; And / or, the pretreatment method for Eisenia fetus is as follows: starvation for 20-30 hours in a sterile, moistened filter paper environment to remove residual matrix in the intestine.

6. The method for improving the quality of earthworm compost according to claim 1, characterized in that, In step S3, the substrate is lightly turned over every 4-5 days during composting, with a turning depth of ≤5 cm, to prevent local anaerobic conditions and avoid damaging the earthworms.

7. The method for improving the quality of earthworm compost according to claim 1, characterized in that, The resulting vermicompost products meet the following key indicators: total nitrogen content ≥18 g / kg, ammonium nitrogen content ≥50 mg / kg, EC ≤1.84 mS / cm, and nitrite nitrogen content ≤0.80 mg / kg.

8. The method for improving the quality of earthworm compost according to claim 1, characterized in that, The relative expression levels of nitrogen cycle functional genes in the obtained earthworm compost products met the following criteria: nifH≥11.65, nirS≥19.19, nosZ≥20.

86.

9. The method for improving the quality of earthworm compost according to claim 1, characterized in that, The relative abundance of the organic matter degrading bacteria Arenibacter in the obtained earthworm compost products was ≥8.37%.

10. The application of aerobic composting products of Bacillus belyeis BV-1 in the improvement of vermicompost, characterized in that, The aerobic composting products are used as a substrate for vermicomposting to increase the total nitrogen content of vermicompost, reduce salinity, and activate nitrogen cycle functional genes; the *Bacillus belyssus* BV-1 is *Bacillus belyssus* (… Bacillus velezensis BV-1CGMCCNo. 29418.

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