Compound microbial agent as well as preparation method and application thereof

Abstract

The invention discloses a compound microbial agent as well as a preparation method and application thereof, and belongs to the technical field of agricultural waste rapid composting microbial agents. The prepared composite microbial agent comprises bacillus siamensis, bacillus megatherium, azotobacter chroococcum, bacillus subtilis, bacillus amyloliquefaciens, actinomycetes, saccharomycetes and lactobacillus plantarum, and is used in the composting process of compatibility of pig manure and sorghum straw. Substances such as protein, starch, cellulose and lignin in the raw material pig manure and crop straw can be decomposed, and the degradation speed and effect of compost are improved; the composting quality can be improved, harmful substances are reduced, and the composting is safer and more efficient. The compound microbial agent has excellent performance in actual use, and can provide high-quality organic fertilizer for agricultural production.

Description

Technical Field

[0001] The invention belongs to the technical field of agricultural waste rapid composting inoculants, and in particular relates to a composite microbial inoculant and a preparation method and application thereof. Background Art

[0002] With the rapid development of agriculture, animal husbandry and wine brewing industries, the output of pig manure and sorghum straw is huge. The ever-increasing output and low utilization rate have brought tremendous pressure to the human living environment. Resource processing under various modes cannot solve the problem of increasingly serious oversupply.

[0003] At present, aerobic composting of livestock and poultry manure and straw is one of the most effective ways to recycle resources. Traditional natural composting has the disadvantages of long cycle, low composting temperature, short duration of high temperature stage, poor composting effect and low compost quality; there are many types of composting microorganisms, but the strains have poor stability, low microbial activity, weak impact resistance and ability to adapt to the environment, and high-quality strains are expensive. Although there are many studies on composting microbial agents, based on the diversity and instability of composting microorganisms, different composite agents and ratios lead to different composting maturity effects, and microbial agents are still a key breakthrough point; for microbial agent products, the quality of similar products produced by different companies varies greatly, and there are large differences between different production batches. The homogeneity of strains and products is serious, the production strains (strains / bacteria lines) are homogeneous, the product combinations are mostly similar, and the replacement is slow; the screening, preservation, and rejuvenation of strains are not given enough attention. Therefore, the optimization of biological strains for preparing organic fertilizer from composting sorghum straw for wine and livestock and poultry manure, the construction of high-activity bacterial agents, and the guarantee of the stable activity of microbial agents are the long-term and unremitting efforts of researchers and related companies.

[0004] In summary, there is an urgent need to construct a composite bacterial agent with high activity, strong adaptability, complementary functions and mutual cooperation for environmentally friendly degradation of organic matter, and to compost and domesticate it with wine-making sorghum straw and pig manure. Summary of the invention

[0005] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a composite microbial agent and a preparation method and application thereof, so as to solve the problems of poor stability of strain performance, low microbial activity, weak impact resistance and environmental adaptability of existing composting microbial agents, and poor composting effect of poultry manure and straw.

[0006] The technical solution of the present invention to solve the above technical problems is as follows: a composite microbial agent is provided, including Bacillus siamese, Bacillus megaterium, round brown nitrogen-fixing bacteria, Bacillus subtilis, Bacillus amyloliquefaciens, actinomycetes, yeast and Lactobacillus plantarum.

[0007] The invention has the following beneficial effects: Bacillus siamensis has strong antibacterial and organic matter decomposition capabilities, can improve the decomposition speed of compost and reduce pathogenic bacteria; Bacillus megaterium can decompose organic substances that are difficult to degrade, such as cellulose and lignin, and can be combined with organic matter in pig manure and straw to promote the decomposition of organic matter and the release of nutrients, thereby improving the quality and efficiency of compost; at the same time, it can also produce phytase to decompose phytic acid and improve the utilization rate of phosphorus in compost; round brown nitrogen-fixing bacteria can fix nitrogen in the atmosphere, increase the nitrogen content in compost, and can be combined with organic matter in pig manure and straw to promote the decomposition of organic matter and the release of nutrients, thereby improving the nutrient content of compost; Bacillus subtilis has disease resistance , and can decompose a variety of organic matter, especially large molecular proteins and sugars; Bacillus amyloliquefaciens can decompose starch and other complex sugars, produce amylase, and improve the efficiency of compost fermentation; Bacillus amyloliquefaciens can also inhibit the release of H2S and NH3 in pig manure, and reduce the generation of odor in compost; Actinomycetes can decompose complex organic matter, such as cellulose and lignin, and produce antibiotics to inhibit the growth of harmful microorganisms; Yeast can decompose soluble carbohydrates, produce nutrients, such as vitamins and amino acids, and can also increase the organic matter content in compost; Lactobacillus plantarum can produce lactic acid, reduce the pH value of compost, inhibit the growth of pathogens, and improve the stability of compost fermentation.

[0008] The decomposition activities of different microorganisms can release different nutrients (such as nitrogen, phosphorus, enzymes and organic acids), which can be used by other microorganisms to promote their own growth and decomposition activities; the lactic acid produced by Lactobacillus plantarum can lower the pH value of the compost. This acidic environment can inhibit the growth of harmful microorganisms while promoting certain beneficial microorganisms; when multiple disease-resistant microorganisms (such as Bacillus subtilis, Bacillus siamensis and actinomycetes) coexist, they can form a complex ecosystem that effectively inhibits the growth of pathogenic microorganisms.

[0009] Pig manure and straw contain a large amount of organic matter, such as cellulose, hemicellulose, protein and fat. Different microorganisms can decompose these different organic components and improve the degradation rate and effect of composting. Pig manure contains pathogens and harmful substances that may cause environmental problems and health threats. The use of these beneficial microorganisms can reduce the number of pathogens, degrade harmful substances, and improve the safety of composting.

[0010] The synergistic effect of the microorganisms used in the composting process can effectively improve composting efficiency, improve composting quality, reduce harmful substances, and make composting safer and more efficient. This composite microbial agent performs well in actual use and can provide high-quality organic fertilizer for agricultural production.

[0011] The present invention also provides a method for preparing the composite microbial agent, comprising the following steps:

[0012] 1) Inoculating siam Bacillus, megaterium, round brown nitrogen-fixing bacteria, Bacillus subtilis, Bacillus amyloliquefaciens, actinomycetes, yeast and Lactobacillus plantarum into slant culture medium for activation culture at a temperature of 33 to 36° C. for 24 to 48 hours to obtain a strain activation solution;

[0013] 2) inoculating the activated bacterial strain liquid into the seed culture medium for fermentation culture at a temperature of 33 to 36° C. for 18 to 24 hours to obtain a seed liquid, and mixing the eight seed liquids to obtain a mixed seed liquid;

[0014] 3) The mixed seed liquid is inoculated into a fermentation medium for amplified culture at a temperature of 33 to 36° C. for 18 to 24 hours to obtain a composite bacterial agent liquid.

[0015] On the basis of the above technical solution, the present invention can also be improved as follows:

[0016] Further, in step 2), the 8 seed solutions are mixed in equal volume ratios.

[0017] Further, the slant culture medium is LB culture medium, the seed culture medium comprises the following components by weight: 4-8 parts of yeast extract, 8-12 parts of peptone, 18-20 parts of potato extract, 8-12 parts of sodium chloride, 15-20 parts of agar, 800-1100 parts of distilled water, and the fermentation culture medium comprises the following components by weight: 800-1000 parts of pig manure extract and 50-200 parts of potato extract;

[0018] The preparation method of potato extract is as follows: add fresh potatoes into water, boil, filter, and obtain;

[0019] The preparation method of the pig manure extract is as follows: adding dry pig manure into water, extracting, filtering, and obtaining the extract.

[0020] Furthermore, the LB medium, seed medium and fermentation medium were sterilized at 121° C. for 20 min before inoculation, and the pH of the seed medium and fermentation medium was 7.0-7.6.

[0021] The present invention also provides an application of the composite microbial agent in pig manure and straw composting.

[0022] Furthermore, the above application comprises the following steps:

[0023] 1) Raw material processing: crush the straw to obtain straw powder; separate the pig manure into solid and liquid to obtain dry pig manure;

[0024] 2) Weighing raw materials: 45-60 parts of straw powder, 25-40 parts of dry pig manure, 20 parts of water, and mixing well to obtain a mixed material;

[0025] 3) Adding bacterial agent: Calculated by volume, take 100 parts of the mixed material and 3-10 parts of the composite bacterial agent liquid, add the composite bacterial agent liquid to the mixed material, mix, and obtain a mixed bacterial liquid material;

[0026] 4) Fermentation: The mixed bacterial liquid material is piled into strips, the surface of the pile is covered with a film, and fermented naturally;

[0027] 5) Composting: When the temperature at the center of the pile rises to 50-65°C, turn the pile over. When the temperature drops to room temperature, the turning is stopped and fermentation continues. The composting takes 30-35 days before fermentation is completed.

[0028] On the basis of the above technical solution, the present invention can also be improved as follows:

[0029] Furthermore, the moisture content of the straw is 45-65%, and the moisture content of the dry pig manure is 40-60%.

[0030] Furthermore, the particle size of the straw powder is 3 to 6 cm.

[0031] Furthermore, in step 3), the process of adding the composite bacterial agent liquid to the mixed material is to spray the composite bacterial agent liquid evenly into the mixed material while stirring it.

[0032] The present invention has the following beneficial effects:

[0033] 1. The microbial strains selected in the present invention can be isolated from compost raw materials and brewing materials (daqu, xiaoqu and fermented grains), and have a strong ability to decompose components of pig manure raw materials and sorghum straw raw materials.

[0034] 2. The microbial strains used in the present invention have good tolerance and adaptability. For example, Bacillus, actinomycetes, and lactic acid bacteria are all resistant to high temperatures. Yeast and lactic acid bacteria are facultative bacteria and can grow and metabolize well under facultative conditions.

[0035] 3. The microbial strains selected in the present invention are all probiotics and are harmless to the soil and crops. On the contrary, the combination of strains used has a growth-promoting effect on crops and an improving effect on the soil.

[0036] 4. The composite bacterial agent prepared by the present invention has strains that do not inhibit each other and can coexist. The bacterial agent is easy to cultivate, resistant to high temperatures, has a high composting rate for pig manure and sorghum straw materials, can decompose substances such as protein, starch, cellulose and lignin in the raw pig manure and crop straw, has high composting efficiency, and has good compost product quality. It has good fertilizer efficiency and growth-promoting effects on crops, and is a high-quality fertilizer. DETAILED DESCRIPTION

[0037] The raw materials and reagents involved in the present invention can be purchased from the market. The present invention has no special restrictions on the sources of Bacillus siamensis, Bacillus megaterium, Azotobacter chroococcum, Bacillus subtilis, Bacillus amyloliquefaciens, Streptomyces bangladeshensis, Saccharomyces cerevisiae and Lactobacillus plantarum. Commercially available products can be used, and bacteria separated and purified from nature can also be used.

[0038] The principles and features of the present invention are described below in conjunction with the examples, which are only used to explain the present invention and are not intended to limit the scope of the present invention. If no specific conditions are specified in the examples, the conditions are carried out according to conventional conditions or the conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0039] Embodiment 1:

[0040] A composite microbial agent comprises Bacillus siamese, Bacillus megaterium, round brown nitrogen-fixing bacteria, Bacillus subtilis, Bacillus amyloliquefaciens, actinomycetes, yeast and Lactobacillus plantarum.

[0041] The composite microbial agent in this embodiment is prepared by the following steps:

[0042] 1) Inoculating and activating the bacterial strains of Bacillus siame, Bacillus megaterium, Azotobacter foetida, Bacillus subtilis, Bacillus amyloliquefaciens, Actinomycetes, yeast and Lactobacillus plantarum on a slant culture medium respectively, the culture temperature is 35° C., the culture time is 48 h, and a bacterial strain activation solution is obtained;

[0043] The slant medium used in this step is LB medium, which is sterilized at 121°C for 20 min before inoculation;

[0044] 2) Inoculate the activated strain into the seed culture medium for fermentation. Take 5 loops of activated strains with an inoculation loop and inoculate them into 100 portions of seed culture medium. The culture temperature is 35°C and the constant temperature shaking culture is 150r / min for 24 hours until the bacterial cell density (OD 600 ) is about 1, stop shaking culture, take the culture solutions of 8 strains, mix them in equal volume ratio, and obtain mixed seed solution;

[0045] The components of the seed culture medium used in this step by weight are: 8 parts of yeast extract, 12 parts of peptone, 20 parts of potato extract, 12 parts of sodium chloride, 20 parts of agar, 1100 parts of distilled water, pH 7.5, and the culture medium is sterilized at 121°C for 20 minutes before inoculation;

[0046] 3) The mixed seed liquid was inoculated into the fermentation medium for amplification culture, 2000 parts of the fermentation medium were placed in a 3L fermenter, and after sterilization, 120 parts of the seed liquid were inoculated, the temperature was 36°C, the ventilation flow rate was 4.5L / min, the stirrer speed was 150r / min, and the fermentation was carried out for 24h to obtain the composite bacterial agent bacterial liquid;

[0047] The fermentation medium used in this step has the following components by weight: 900 parts of pig manure extract, 100 parts of potato extract, pH 7.6, and is sterilized at 121° C. for 20 minutes before inoculation.

[0048] The preparation methods of the potato extract and the pig manure extract in the present embodiment are as follows:

[0049] Preparation of potato extract: Take fresh peeled potatoes, cut into small pieces, weigh 500 parts, add to 1000 parts of water, boil and simmer for 40 minutes, filter through 2 layers of gauze, and dilute the filtrate to 1000 parts by weight;

[0050] Preparation of pig manure extract: weigh 200 parts of dry pig manure ground into fine powder, add 800 parts of distilled water, stir evenly and extract for 60 minutes, filter through 2 layers of gauze to obtain the pig manure extract.

[0051] Embodiment 2:

[0052] A composite microbial agent comprises Bacillus siamese, Bacillus megaterium, round brown nitrogen-fixing bacteria, Bacillus subtilis, Bacillus amyloliquefaciens, actinomycetes, yeast and Lactobacillus plantarum.

[0053] The composite microbial agent in this embodiment is prepared by the following steps:

[0054] 1) Inoculating and activating the bacterial strains of Bacillus siame, Bacillus megaterium, Azotobacter sphaeroides, Bacillus subtilis, Bacillus amyloliquefaciens, Actinomycetes, yeast and Lactobacillus plantarum on a slant culture medium respectively, the culture temperature is 33° C., the culture time is 48 h, and a bacterial strain activation solution is obtained;

[0055] The slant medium used in this step is LB medium, which is sterilized at 121°C for 20 min before inoculation;

[0056] 2) Inoculate the activated strain into the seed culture medium for fermentation. Take 3 loops of activated strains with an inoculation loop and inoculate them into 100 portions of seed culture medium. The culture temperature is 33°C and the constant temperature shaking culture is 150r / min for 18h until the bacterial cell density (OD 600 ) is about 1, stop shaking culture, take the culture solutions of 8 strains, mix them in equal volume ratio, and obtain mixed seed solution;

[0057] The components of the seed culture medium used in this step by weight are: 4 parts of yeast extract, 8 parts of peptone, 18 parts of potato extract, 8 parts of sodium chloride, 15 parts of agar, 800 parts of distilled water, pH 7.0, and the culture medium is sterilized at 121°C for 20 minutes before inoculation;

[0058] 3) The mixed seed liquid was inoculated into the fermentation medium for amplification culture, 1800 parts of the fermentation medium were placed in a 3L fermenter, 60 parts of the seed liquid were inoculated after sterilization, the temperature was 33°C, the ventilation flow rate was 2.0L / min, the stirrer speed was 150r / min, and the fermentation was carried out for 18h to obtain the composite bacterial agent bacterial liquid;

[0059] The fermentation medium used in this step has the following components by weight: 900 parts of pig manure extract, 100 parts of potato extract, pH 7.0, and is sterilized at 121° C. for 20 minutes before inoculation.

[0060] The preparation methods of the potato extract and the pig manure extract in the present embodiment are as follows:

[0061] Preparation of potato extract: Take fresh peeled potatoes, cut into small pieces, weigh 500 parts, add to 1000 parts of water, boil and simmer for 30 minutes, filter through 2 layers of gauze, and dilute the filtrate to 1000 parts by weight;

[0062] Preparation of pig manure extract: weigh 200 parts of dry pig manure ground into fine powder, add 800 parts of distilled water, stir evenly and extract for 40 minutes, filter through 2 layers of gauze to obtain the pig manure extract.

[0063] Embodiment 3:

[0064] A composite microbial agent comprises Bacillus siamese, Bacillus megaterium, round brown nitrogen-fixing bacteria, Bacillus subtilis, Bacillus amyloliquefaciens, actinomycetes, yeast and Lactobacillus plantarum.

[0065] The composite microbial agent in this embodiment is prepared by the following steps:

[0066] 1) Inoculating and activating the bacterial strains of Bacillus siame, Bacillus megaterium, Azotobacter foetida, Bacillus subtilis, Bacillus amyloliquefaciens, Actinomycetes, yeast and Lactobacillus plantarum on a slant culture medium respectively, the culture temperature is 35° C., the culture time is 48 h, and a bacterial strain activation solution is obtained;

[0067] The slant medium used in this step is LB medium, which is sterilized at 121°C for 20 min before inoculation;

[0068] 2) Inoculate the activated strain into the seed culture medium for fermentation. Take 4 loops of activated strains with an inoculation loop and inoculate them into 100 portions of seed culture medium. The culture temperature is 35°C and the temperature is shaken at 150 rpm for 20 hours until the bacterial cell density (OD 600 ) is about 1, stop shaking culture, take the culture solutions of 8 strains, mix them in equal volume ratio, and obtain mixed seed solution;

[0069] The components of the seed culture medium used in this step by weight are: 5 parts of yeast extract, 10 parts of peptone, 19 parts of potato extract, 10 parts of sodium chloride, 18 parts of agar, 1000 parts of distilled water, pH 7.5, and the culture medium is sterilized at 121°C for 20 minutes before inoculation;

[0070] 3) The mixed seed liquid was inoculated into the fermentation medium for amplification culture, 1900 parts of the fermentation medium were placed in a 3L fermenter, 100 parts of the seed liquid were inoculated after sterilization, the temperature was 35°C, the ventilation flow rate was 3L / min, the stirrer speed was 150r / min, and the fermentation was carried out for 20h to obtain the composite bacterial agent bacterial liquid;

[0071] The fermentation medium used in this step has the following components by weight: 900 parts of pig manure extract, 200 parts of potato extract, pH 7.5, and is sterilized at 121° C. for 20 minutes before inoculation.

[0072] The preparation methods of the potato extract and the pig manure extract in the present embodiment are as follows:

[0073] Preparation of potato extract: Take fresh peeled potatoes, cut into small pieces, weigh 500 parts and add 1000 parts of water, boil and simmer for 35 minutes, filter through 2 layers of gauze, and adjust the filtrate to 1000 parts by weight;

[0074] Preparation of pig manure extract: weigh 200 parts of dry pig manure ground into fine powder, add 800 parts of distilled water, stir evenly and extract for 50 minutes, filter through 2 layers of gauze to obtain the pig manure extract.

[0075] The composite bacterial agent liquid prepared in Examples 1-3 of the present invention has similar effects. The composite bacterial agent liquid prepared in Example 1 was selected and applied to the composting process of brewing sorghum straw and pig manure to verify its effect.

[0076] Application Example 1:

[0077] Example 1 The application of the composite bacterial agent solution in pig manure and sorghum straw composting is prepared, and the specific steps are as follows:

[0078] 1) Raw material processing: the brewing sorghum straw can be fresh straw (high water content) or dry sorghum straw (low water content). The moisture content of the brewing sorghum straw is controlled to about 65% by drying or adding additional water, and then crushed into powder with a particle size of 3 cm to obtain sorghum straw powder; the pig manure is subjected to solid-liquid separation to obtain dry pig manure, and the moisture content of the dry pig manure is about 60%;

[0079] 2) Weighing the raw materials: Calculate by volume, mix 60 parts of sorghum straw powder and 40 parts of dry pig manure, add 20 parts of water, mix well and let stand, when adjusting the moisture, pinch the mixture with your hands, and observe that there is water but the water does not drip out of the fingers, and the mixture is obtained;

[0080] 3) Adding bacterial agent: Calculated by volume, 100 parts of the mixed material and 10 parts of the composite bacterial agent liquid, spray the composite bacterial agent liquid evenly into the mixed material, stir while spraying, and fully mix the sprayed bacterial liquid and the mixed material to obtain a mixed bacterial liquid material;

[0081] 4) Fermentation: The mixed bacterial liquid material is piled into strips with the size of: length * width * height = 1.5m * 1.5m * 1.0m, and the surface of the pile is covered with plastic film and then fermented naturally;

[0082] 5) Composting: Monitor the temperature change of the pile during the fermentation process. When the temperature in the center of the pile rises to 65°C, start turning the pile after about 2 days of fermentation. Keep the original spatial properties and continue fermenting after turning. Turn the pile every 1 day until the temperature shows a downward trend. Turn the pile back when it drops to room temperature and continue fermentation. Fermentation is completed after 30 days of composting.

[0083] Application Example 2:

[0084] Example 1 The application of the composite bacterial agent solution in pig manure and sorghum straw composting is prepared, and the specific steps are as follows:

[0085] 1) Raw material processing: the brewing sorghum straw can be fresh straw (high water content) or dry sorghum straw (low water content). The moisture content of the brewing sorghum straw is controlled to about 45% by drying or adding additional water, and the sorghum straw is crushed into powder with a particle size of 6 cm to obtain sorghum straw powder; the pig manure is subjected to solid-liquid separation to obtain dry pig manure, and the moisture content of the dry pig manure is about 40%;

[0086] 2) Weighing the raw materials: Calculate by volume, mix 45 parts of sorghum straw powder and 25 parts of dry pig manure, add 15 parts of water, mix well and let stand, when adjusting the moisture, pinch the mixture with your hands, and observe that there is water but the water does not drip out of the fingers, and the mixture is obtained;

[0087] 3) Adding bacterial agent: Calculated by volume, 100 parts of the mixed material and 3 parts of the composite bacterial agent liquid, spray the composite bacterial agent liquid evenly into the mixed material, stir while spraying, and fully mix the sprayed bacterial liquid and the mixed material to obtain a mixed bacterial liquid material;

[0088] 4) Fermentation: The mixed bacterial liquid material is piled into strips with the size of: length * width * height = 2m * 2m * 1.2m, and the surface of the pile is covered with plastic film and then fermented naturally;

[0089] 5) Composting: Monitor the temperature change of the pile during the fermentation process. When the temperature in the center of the pile rises to 50°C, start turning the pile after about 4 days of fermentation. Keep the original spatial properties and continue fermenting after turning. Turn the pile every 1 day until the temperature shows a downward trend. Turn the pile over until it drops to room temperature and continue fermentation. Fermentation is completed after 35 days of composting.

[0090] Comparative Example 1:

[0091] The composite bacterial agent solution prepared in Example 1 was not applied, step 3) was omitted, and the other processing steps were the same as those in Application Example 1.

[0092] Take the pile samples of Application Examples 1 to 2 and Comparative Example 1, refer to the detection methods in the national standard and industry standard (NY / T525-2021) for organic fertilizer, and measure the values ​​of various technical indicators in the pile. The specific data are shown in Table 1:

[0093] Table 1 Technical indicators of compost samples

[0094]

[0095] It can be seen from the table that the composite bacterial agent of the present invention can effectively promote the composting process of pig manure and straw, shorten the composting cycle, improve the composting maturity, accelerate the biodegradation of raw organic matter, and reduce the loss of nutrients such as nitrogen. The composite bacterial agent of the present invention can act on all indicators of pig manure + sorghum straw compost, and is significantly better than the compost sample without the composite bacteria of the present invention, and is an organic fertilizer of good quality.

[0096] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A composite microbial agent, characterized in that: Including Bacillus siamese, Bacillus megaterium, Bacillus thunbergii, Bacillus subtilis, Bacillus amyloliquefaciens, actinomycetes, yeast and Lactobacillus plantarum.

2. The method for preparing the composite microbial agent according to claim 1, characterized in that: The following steps are involved: 1) Inoculating siam Bacillus, megaterium, round brown nitrogen-fixing bacteria, Bacillus subtilis, Bacillus amyloliquefaciens, actinomycetes, yeast and Lactobacillus plantarum into slant culture medium for activation culture at a temperature of 33 to 36° C. for 24 to 48 hours to obtain a strain activation solution; 2) inoculating the activated bacterial strain liquid into the seed culture medium for fermentation culture at a temperature of 33 to 36° C. for 18 to 24 hours to obtain a seed liquid, and mixing the eight seed liquids to obtain a mixed seed liquid; 3) The mixed seed liquid is inoculated into a fermentation medium for amplified culture at a temperature of 33 to 36° C. for 18 to 24 hours to obtain a composite bacterial agent liquid.

3. The method for preparing the composite microbial agent according to claim 2, characterized in that: In step 2), the 8 seed solutions are mixed in equal volume ratios.

4. The method for preparing the composite microbial agent according to claim 2, characterized in that: The slant culture medium is LB culture medium, the seed culture medium comprises the following components by weight: 4-8 parts of yeast extract, 8-12 parts of peptone, 18-20 parts of potato extract, 8-12 parts of sodium chloride, 15-20 parts of agar, 800-1100 parts of distilled water, and the fermentation culture medium comprises the following components by weight: 800-1000 parts of pig manure extract and 50-200 parts of potato extract; The preparation method of the potato extract is as follows: adding fresh potatoes into water, boiling, filtering, and obtaining the extract; The preparation method of the pig manure extract is as follows: adding dry pig manure into water, extracting, filtering, and obtaining the extract.

5. The method for preparing the composite microbial agent according to claim 4, characterized in that: The LB medium, seed medium and fermentation medium were sterilized at 121° C. for 20 min before inoculation, and the pH of the seed medium and fermentation medium was 7.0-7.

6.

6. Use of the composite microbial agent according to claim 1 in pig manure and straw composting.

7. The use according to claim 6, characterized in that: The following steps are involved: 1) Raw material processing: crush the straw to obtain straw powder; separate the pig manure into solid and liquid to obtain dry pig manure; 2) Weighing raw materials: 45-60 parts of straw powder, 25-40 parts of dry pig manure, 20 parts of water, and mixing well to obtain a mixed material; 3) Adding bacterial agent: Calculated by volume, take 100 parts of the mixed material and 3-10 parts of the composite bacterial agent liquid, add the composite bacterial agent liquid to the mixed material, mix, and obtain a mixed bacterial liquid material; 4) Fermentation: The mixed bacterial liquid material is piled into strips, the surface of the pile is covered with a film, and fermented naturally; 5) Composting: When the temperature at the center of the pile rises to 50-65°C, turn the pile over. When the temperature drops to room temperature, the turning is stopped and fermentation continues. The composting takes 30-35 days before fermentation is complete.

8. The use according to claim 7, characterized in that: The moisture content of the straw is 45-65%, and the moisture content of the dry pig manure is 40-60%.

9. The use according to claim 7, characterized in that: The particle size of the straw powder segment is 3 to 6 cm.

10. The use according to claim 7, characterized in that: In step 3), the process of adding the composite bacterial agent liquid to the mixed material is to spray the composite bacterial agent liquid evenly into the mixed material while stirring it while spraying.

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