Fermentation substrate for bacillus, bacillus liquid fermentation inoculant and application

Abstract

The invention belongs to the technical field of microbial fermentation, and particularly relates to a fermentation substrate for bacillus, a bacillus liquid fermentation inoculant and application. The fermentation substrate is prepared by adding traditional Chinese medicine residues into a yeast culture medium so as to improve the concentration of bacillus after fermentation; the traditional Chinese medicine residues are prepared by compounding motherwort herb residues, astragalus membranaceus herb residues and ginseng herb residues according to the mass ratio of 1: (1-2): (1-1.5); the mass ratio of the yeast culture medium to the traditional Chinese medicine residues is (20-26): (6-8). The concentration of the bacillus can reach 3.3 * 10 < 9 > CFU / mL in a bacillus liquid fermentation inoculant obtained by adopting the fermentation substrate disclosed by the invention.

Description

Technical Field

[0001] The invention belongs to the technical field of microbial fermentation, and in particular relates to a fermentation substrate for bacillus, a liquid fermentation agent for bacillus and applications thereof. Background Art

[0002] Bacillus accounts for 7 of the top 10 strains of microbial fertilizers, which shows that Bacillus occupies a dominant position in microbial fertilizer products. The main reason is that Bacillus has good production performance and preservation performance. Usually, Bacillus reproduces quickly and has strong vitality. In an unfavorable growth environment, Bacillus can produce dormant spores. Since the spores have strong resistance to unfavorable environments, Bacillus is easily used to make stable microbial fertilizer products with a long shelf life and is widely used.

[0003] At present, the common Bacillus products on the market are liquid fermentation agents and solid powders, both of which have some shortcomings. Compared with the fermentation liquid of Bacillus, the solid powder lacks fermentation metabolites, so its effect of reducing the incidence is far lower than that of the liquid fermentation agent. At the same time, the solid powder is a dormant spore, and its germination time is uncertain, so the application of liquid fermentation agents is wider. Liquid fermentation agent refers to the fermentation liquid after the liquid fermentation of Bacillus is completed. It has high vitality and is best applied to crops. The culture medium used to prepare the liquid fermentation agent of Bacillus is the key to preparing the liquid fermentation agent of Bacillus. The commonly used culture media include yeast culture medium, broth agar culture medium, glucose culture medium, broth nutmeg culture medium, J-agar culture medium, etc., and the main nutrients are agar, peptone, yeast extract and sugars. However, the above culture medium has a poor fermentation effect on Bacillus, and the concentration of Bacillus is low after fermentation. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a fermentation substrate for Bacillus, a liquid fermentation agent for Bacillus and applications thereof, which can effectively improve the concentration of Bacillus and the fermentation effect.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows.

[0006] The first aspect of the present invention provides a fermentation substrate for Bacillus, wherein the fermentation substrate is a yeast culture medium in which Chinese medicinal residues are added to increase the concentration of Bacillus after fermentation;

[0007] The Chinese medicine residue is prepared by mixing motherwort residue, astragalus residue and ginseng residue in a mass ratio of 1:1 to 2:1 to 1.5;

[0008] The mass ratio of the yeast culture medium to the traditional Chinese medicine residue is 20-26:6-8.

[0009] The invention mixes Chinese medicinal residues prepared by compounding motherwort residues, astragalus residues and ginseng residues in a mass ratio of 1:1 to 2:1 to 1.5 into a traditional fermentation matrix yeast culture medium, and after inoculating Bacillus, the live bacterial count of Bacillus is increased by the Chinese medicinal residues.

[0010] In another preferred embodiment, the motherwort residue, the astragalus residue and the ginseng residue are all decocted residues.

[0011] In another preferred embodiment, the mesh size of the traditional Chinese medicine residue is 8-12 meshes.

[0012] In another preferred embodiment, the yeast culture medium is prepared from the following raw materials in parts by mass:

[0013] 8 to 10 parts of peptone, 6 to 8 parts of yeast extract, and 6 to 8 parts of brown sugar.

[0014] The second aspect of the present invention provides a Bacillus solid-state fermentation agent, which is prepared according to the following method:

[0015] After sterilizing the fermentation substrate, inoculating the Bacillus bacterial solution and performing aerobic fermentation to obtain the Bacillus solid-state fermentation agent;

[0016] The volume ratio of the Bacillus bacterial liquid to the Bacillus liquid fermentation agent is 1:50-100.

[0017] The third aspect of the present invention provides a Bacillus liquid fermentation agent, wherein the Bacillus liquid fermentation agent is prepared according to the following method:

[0018] After sterilizing the fermentation substrate, inoculating the Bacillus liquid, adding sterile water to make the fermentation substrate liquid, and performing aerobic fermentation to obtain the Bacillus liquid fermentation agent;

[0019] The volume ratio of the Bacillus bacterial liquid to the Bacillus liquid fermentation agent is 1:50-100.

[0020] In another preferred embodiment, the concentration of the Bacillus bacterial solution is 1.5×10 9 CFU / mL~1.8×10 9 CFU / mL.

[0021] In another preferred embodiment, the Bacillus bacterial solution is any one of Bacillus subtilis bacterial solution, Bacillus licheniformis bacterial solution, Bacillus amyloliquefaciens bacterial solution, and Bacillus megaterium bacterial solution.

[0022] In another preferred embodiment, during the aerobic fermentation process, the flow rate of oxygen is 8 m / s to 10 m / s.

[0023] The fourth aspect of the present invention provides the use of the Bacillus liquid fermentation agent in preventing and controlling taro root rot.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The present invention mixes the Chinese medicinal residue obtained by compounding Leonurus herb residue, Astragalus herb residue and Ginseng herb residue in a mass ratio of 1:1 to 2:1 to 1.5 with a traditional Bacillus fermentation matrix yeast culture medium, so that the obtained fermentation matrix can effectively increase the concentration of Bacillus after fermentation.

[0026] (2) After fermenting Bacillus using the Bacillus solid fermentation agent and the Bacillus liquid fermentation agent of the present invention, the concentration of Bacillus can be effectively increased. Among them, after fermenting Bacillus using the Bacillus liquid fermentation agent for 72 hours, the concentration of Bacillus can reach 3.3×10 9 CFU / mL, compared with the traditional fermentation matrix yeast medium after 72 hours, the concentration of Bacillus was 1.78×10 9 CFU / mL, the concentration of Bacillus increased by nearly 1 times. In addition, Chinese medicine residues can provide carbon and nitrogen sources for Bacillus, further improving the fermentation effect of Bacillus.

[0027] (3) The liquid fermentation agent of the Bacillus sp. of the present invention uses the Chinese medicine residue as the fermentation substrate during the fermentation process, which not only effectively increases the number of live bacteria, but also improves the recycling of the Chinese medicine residue waste. At the same time, it can also effectively prevent and control taro root rot, reducing the incidence of taro root rot by 85%, thereby reducing the amount of chemical fertilizers used.

[0028] The liquid fermentation agent of Bacillus obtained by fermentation of the fermentation substrate in the method of the present invention has an OD 600 The values ​​and Bacillus concentrations are comparable to those of the prior art fermentation tanks, and the fermentation cost is reduced by 50% compared to the fermentation tanks.

[0029] (4) The method of the present invention is simple to operate, and farmers can realize independent fermentation, on-site fermentation and on-site application, which is convenient for promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 These are photos of fermentation conditions in the fermentation tank; A and B are both in the early stages of fermentation, and C is in the late stages of fermentation.

[0031] Figure 2 Schematic diagram of fermentation in a fermentation barrel used in the fermentation process of the present invention.

[0032] Figure 3 It is a schematic diagram of fermentation in a fermenter using the prior art.

[0033] Figure 4 This is a graph showing the effects of different fermentation methods on Bacillus concentration.

[0034] Figure 5 Effect of different fermentation methods on OD 600 The effect of value on the result graph.

[0035] Figure 6 The figures are demonstration test pictures of the effect of Bacillus liquid fermentation agent on taro cultivation soil; among them, A and B are comparison pictures of taro disease and health, and the arrows point to the diseased plants; C shows that the root of the diseased plants is seriously rotten; D is taro applied with fermentation liquid; E is taro not applied with Bacillus liquid fermentation agent, and F is taro applied with Bacillus liquid fermentation agent. 1 is a cut picture of taro not applied with Bacillus liquid fermentation agent, and the arrow points to the rotten root part; 2 is a cut picture of taro applied with Bacillus liquid fermentation agent. DETAILED DESCRIPTION

[0036] The present invention is described in detail below in conjunction with specific examples, but it should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the following examples are conventional means well known to those skilled in the art, and the materials, reagents, etc. used in the following examples, unless otherwise specified, can be obtained from commercial sources.

[0037] Northeast China has a significant share of the Chinese herbal medicine market due to its unique climatic conditions. The climate and soil conditions in the northern temperate zone are very suitable for the growth of ginseng, astragalus and motherwort. The annual output of high-quality ginseng and astragalus can reach thousands of tons, and the annual output of motherwort can reach hundreds of tons. However, the residues after the decoction of Chinese herbal medicines are often abandoned and become a neglected biomass resource. In fact, these residues are rich in nutrients and can provide a good basis for the fermentation of Bacillus. The rich polysaccharides, proteins and cellulose in the residues of Chinese medicine provide the necessary carbon and nitrogen sources for Bacillus, promote its growth and synthesize high-value products such as organic acids, antimicrobial peptides and enzymes. Therefore, recycling and utilizing the residues of Chinese medicine can effectively reduce resource waste.

[0038] Based on the rapid growth characteristics of Bacillus, the present invention provides a Bacillus liquid fermentation agent and its preparation method and application. The fermentation process in the present invention adopts open fermentation, that is, the fermentation conditions are low and the operation is simple. Unlike the traditional closed fermentation tank, the present invention can achieve rapid reproduction in a short time and form a dominant group after the fermentation raw materials are prepared, thereby reducing the risk of contamination by miscellaneous bacteria. At the same time, Chinese medicine residues are added to the fermentation raw materials, and the fermentation effect is optimized through pretreatment, which not only realizes the resource utilization of waste, but also reduces the fermentation cost and promotes its green application in agriculture. The present invention uses Chinese medicine residues as a fermentation matrix, and the required fermentation equipment is low in cost and simple to operate. Farmers can achieve autonomous fermentation, achieve on-site fermentation and on-site application, and are convenient for promotion.

[0039] Bacillus amyloliquefaciens (China Culture Collection Center Accession Number: CGMCC23330) and Bacillus megaterium (China Culture Collection Center Accession Number: CGMCC24262) in the following examples. Bacillus subtilis and Bacillus licheniformis are disclosed in the literature: Yang Yongfeng. Study on the ability of Bacillus to prevent and control bark rot and promote growth of Hanfu apple trees [M]. Shenyang Agricultural University, 2023.

[0040] The yeast extracts in the following examples were purchased from World Trade Food Ingredients City, specification: Angel Yeast Food Grade FD00-A. The Chinese medicine residues were all obtained after decoction.

[0041] The fermentation process in the following examples was carried out in a plastic barrel with a volume of 160 L. During the fermentation process, the plastic barrel, the gas pipe and the gas stone were cleaned three times to avoid bacteriophage contamination. The specific cleaning process is as follows:

[0042] The initial cleaning is to clean the fermentation barrel, gas pipe and gas stone before fermentation, wash away the dust and attached bacteria on the surface, reduce the contamination rate, and require that there is no debris visible to the naked eye; the secondary cleaning is to clean the fermentation barrel, gas stone and gas pipe The residual Bacillus is cleaned after fermentation; the tertiary cleaning is to inject boiling hot water into the fermentation barrel on the basis of the secondary cleaning, use water vapor to sterilize the surface of the fermentation barrel, and soak the gas stone and gas pipe in hot water.

[0043] The following is a detailed description of a fermentation substrate for Bacillus, a liquid fermentation agent for Bacillus and its application.

[0044] Example 1

[0045] A fermentation substrate for Bacillus, prepared from the following raw materials:

[0046] According to the mass ratio of 1:1:1, 2g of Leonurus herb residue, 2g of Astragalus herb residue and 2g of ginseng herb residue were weighed respectively, and the Leonurus herb residue, Astragalus herb residue and ginseng herb residue were ground respectively, and then filtered through 8-mesh, 10-mesh and 12-mesh sieve gradients in turn to obtain fine powders of the three kinds of residues, and the fine powders of the three kinds of residues were mixed to obtain fine powder of Chinese medicine residues.

[0047] 8 g of peptone, 6 g of yeast extract, 6 g of brown sugar and 6 g of fine powder of traditional Chinese medicine residue were mixed to obtain a fermentation matrix for Bacillus.

[0048] A Bacillus solid-state fermentation agent is prepared using the above fermentation matrix, and the specific process is as follows:

[0049] S1. Place the fermentation substrate in a fermentation pot filled with boiling water and boil for 15 minutes. Take it out and put it into 4 fermentation barrels. At the same time, distribute the air stone of the oxygen pump into the fermentation barrels and introduce oxygen at a flow rate of 8m / s.

[0050] S2. Inoculate 1L of Bacillus subtilis solution, Bacillus licheniformis solution, Bacillus amyloliquefaciens solution, and Bacillus megaterium solution into four fermentation barrels, respectively, wherein the volume ratio of the inoculation amount of the above four bacterial solutions to the total volume of the Bacillus liquid fermentation agent is 1:100. Fermentation is carried out at 28°C for 3 days, and the fermentation status is observed every 6 hours during the fermentation process. After the fermentation is completed, the Bacillus solid fermentation agent is obtained.

[0051] Example 2

[0052] A fermentation substrate for Bacillus, prepared from the following raw materials:

[0053] According to the mass ratio of 1:1:1, 2g of Leonurus herb residue, 2g of Astragalus herb residue and 2g of ginseng herb residue were weighed respectively, and the Leonurus herb residue, Astragalus herb residue and ginseng herb residue were ground respectively, and then filtered through 8-mesh, 10-mesh and 12-mesh sieve gradients in turn to obtain fine powders of the three kinds of residues, and the fine powders of the three kinds of residues were mixed to obtain fine powder of Chinese medicine residues.

[0054] 8 g of peptone, 6 g of yeast extract, 6 g of brown sugar and 6 g of fine powder of traditional Chinese medicine residue were mixed to obtain a fermentation matrix for Bacillus.

[0055] A liquid Bacillus fermentation agent is prepared by using the above fermentation matrix, and the specific process is as follows:

[0056] S1. Place the fermentation substrate in a fermentation pot filled with boiling water and boil for 15 minutes. Take it out and put it into 4 fermentation barrels filled with 100L of tap water of equal volume. At the same time, distribute the air stone of the oxygen pump into the fermentation barrel and introduce oxygen at a flow rate of 8m / s.

[0057] S2. Inoculate 1L of Bacillus subtilis solution, Bacillus licheniformis solution, Bacillus amyloliquefaciens solution, and Bacillus megaterium solution into 4 fermentation barrels respectively, wherein the volume ratio of the inoculation amount of the above 4 bacterial solutions to the total volume of the Bacillus liquid fermentation agent is 1:100, and ferment at 28°C for 3 days. During the fermentation process, observe the fermentation situation every 6 hours to judge the fermentation degree, as follows: Figure 1 As shown; after the fermentation is completed, the Bacillus liquid fermentation agent is obtained.

[0058] Example 3

[0059] A fermentation substrate for Bacillus, prepared from the following raw materials:

[0060] According to the mass ratio of 1:1:1.5, 2g of Leonurus herb residue, 2g of Astragalus herb residue and 3g of ginseng herb residue were weighed respectively, and the Leonurus herb residue, Astragalus herb residue and ginseng herb residue were ground respectively, and then filtered through 8-mesh, 10-mesh and 12-mesh sieve gradients in turn to obtain fine powders of the three kinds of residues, and the fine powders of the three kinds of residues were mixed to obtain fine powder of Chinese medicine residues.

[0061] 9 g of peptone, 7 g of yeast extract, 7 g of brown sugar and 7 g of fine powder of traditional Chinese medicine residue were mixed to obtain a fermentation matrix for Bacillus.

[0062] A method for preparing a liquid fermentation agent of Bacillus sp. is prepared by using the above-mentioned fermentation matrix, and the specific process is as follows:

[0063] S1. Place the fermentation substrate in a fermentation pot filled with boiling water and boil for 20 minutes. Take it out and put it into 4 fermentation barrels filled with 75L of tap water of equal volume. At the same time, distribute the air stone of the oxygen pump into the fermentation barrel and introduce oxygen at a flow rate of 9m / s.

[0064] S2. Inoculate 1 L of Bacillus subtilis solution, Bacillus licheniformis solution, Bacillus amyloliquefaciens solution, and Bacillus megaterium solution into four fermentation barrels, respectively, wherein the volume ratio of the inoculation amount of the above four bacterial solutions to the total volume of the Bacillus liquid fermentation agent is 1:75. Fermentation is carried out at 28°C for 4 days. During the fermentation process, the fermentation situation is observed every 6 hours to determine the fermentation degree. After the fermentation is completed, a Bacillus liquid fermentation agent is obtained.

[0065] Example 4

[0066] A fermentation substrate for Bacillus, prepared from the following raw materials:

[0067] According to the mass ratio of 1:2:1.5, 2g of Leonurus herb residue, 4g of Astragalus herb residue and 3g of ginseng herb residue were weighed respectively, and the Leonurus herb residue, Astragalus herb residue and ginseng herb residue were ground respectively, and then filtered through 8-mesh, 10-mesh and 12-mesh sieve gradients in turn to obtain fine powders of the three kinds of residues, and the fine powders of the three kinds of residues were mixed to obtain fine powder of Chinese medicine residues.

[0068] 10 g of peptone, 8 g of yeast extract, 8 g of brown sugar and 8 g of fine powder of traditional Chinese medicine residue were mixed to obtain a fermentation matrix for Bacillus.

[0069] A method for preparing a liquid fermentation agent of Bacillus sp. is prepared by using the above-mentioned fermentation matrix, and the specific process is as follows:

[0070] S1. Boil the fermentation substrate in a fermentation pot filled with boiling water for 30 minutes, take it out and put it into 4 fermentation barrels filled with 50L of tap water of equal volume, and at the same time distribute the air stone of the oxygen pump into the fermentation barrel, and introduce oxygen at a flow rate of 10m / s.

[0071] S2. Inoculate 1L of Bacillus subtilis solution, Bacillus licheniformis solution, Bacillus amyloliquefaciens solution, and Bacillus megaterium solution into four fermentation barrels, respectively, wherein the volume ratio of the inoculation amount of the above four bacterial solutions to the total volume of the Bacillus liquid fermentation agent is 1:50. Ferment at 28°C for 4 days. During the fermentation process, observe the fermentation situation every 6 hours to determine the fermentation degree; after the fermentation is completed, obtain the Bacillus liquid fermentation agent.

[0072] In order to further illustrate the effect of the Bacillus liquid fermentation agent obtained by fermentation using the fermentation substrate of the present invention, the following experiment was conducted.

[0073] 1. Effect of Chinese medicine residue on Bacillus fermentation

[0074] The fermentation was carried out by the method of the Bacillus liquid fermentation agent in Example 2, and different combinations of Chinese medicine residue components were set, with no Chinese medicine residue added as the control group, and the fermentation concentrations of the four Bacillus under different Chinese medicine residue component ratios were measured. The results are shown in Tables 1 to 4.

[0075] Table 1 Bacillus subtilis fermentation concentration under different ratios of Chinese medicine residue components

[0076]

[0077] Table 2 Fermentation concentration of Bacillus licheniformis under different ratios of Chinese medicine residue components

[0078]

[0079]

[0080] Table 3 Fermentation concentration of Bacillus amyloliquefaciens under different ratios of Chinese medicine residue components

[0081]

[0082] Table 4 Bacillus megaterium fermentation concentration under different ratios of Chinese medicine residue components

[0083]

[0084] From the experiments in Tables 1 to 4 above, it can be seen that the Chinese medicine residues in the present invention can effectively increase the concentration of four types of Bacillus, including Bacillus subtilis, Bacillus licheniformis, Bacillus amyloliquefaciens, and Bacillus megaterium, and by controlling the ratio between the various components of the Chinese medicine residues, the concentration of the Bacillus liquid fermentation agent can be further increased, thereby making it more active and having better effects. From the results, the effects of combinations 4 to 6 are significantly better than those of combinations 1 to 3, but considering the cost factor, the Chinese medicine residue ratio in combination 4 is selected as the optimal ratio.

[0085] 2. Impact of different fermentation methods

[0086] The method in Example 2 was used for fermentation, and the same fermentation method was used, only the plastic barrel was replaced with a fermentation tank of the same volume for comparison, and a total of 4 barrels and 4 tanks were fermented. Figure 2 and Figure 3 As shown, the composition ratio of the Chinese medicine residue is the same as that of the raw materials in combination 4, the inoculated strain is uniformly Bacillus subtilis, the fermentation volume of each barrel and tank is 80L, the fermentation raw materials are uniformly peptone (640g / barrel and tank), yeast extract (480g / barrel and tank), brown sugar (480g / barrel and tank), and the initial inoculation OD 600 The value is 2.34, and the initial concentration of Bacillus subtilis is 0.2×10 9 CFU / mL. OD after fermentation 600 The values ​​and the concentration of Bacillus fermentation were determined, and the results were as follows Figure 4 and Figure 5 The cost of Example 1 and the fermentation tank was calculated, and the result is shown in Table 5.

[0087] Table 5 Cost of different fermentation methods

[0088] Group Cost (yuan / can / 80L) Example 2 50 Fermentation tank fermentation 100

[0089] from Figure 4 and Figure 5 It can be seen from the results that the results obtained by the method in Example 1 of the present invention are equivalent to the fermentation effect in the fermenter. At 48h, the fermentation OD of Example 1 is 600 The value and concentration were higher than the fermentation tank OD 600The values ​​were 2.97 and 2.93 respectively; the concentrations of Bacillus were 2.5×10 9 CFU / mL, 2.6×10 9 CFU / mL, and reached the maximum OD at 72h. 600 The values ​​were 3.01 and 3.06 respectively; the concentrations were 3.3×10 9 CFU / mL, 3.1×10 9 It can be seen that at 72h of fermentation, the concentration of Bacillus in the Bacillus liquid fermentation agent obtained by fermentation in Example 1 is higher than that in the fermentation tank, and combined with the results in Table 5, it can be seen that the method of the present invention can not only increase the concentration of Bacillus, but also reduce the cost.

[0090] 3. Reduce the root rot rate of taro

[0091] On June 1, 2021, an experiment was conducted at a taro planting site in Beiduan Village, Changle County, Weifang City, Shandong Province. The Bacillus liquid fermentation agent prepared in Example 2 was used to solve the problem of local taro rot.

[0092] Three mu of taro fields with varying degrees of root rot were selected as experimental fields. Figure 6 The fermented Bacillus in combination 4 was applied to the field, and 400L of bacterial solution was irrigated per mu of land for 3 weeks, once a week. After 4 months, the root rot of taro was counted.

[0093] Statistics show that the incidence of taro root rot has been reduced by 85%, the taro heart has become plump and white, the yield of a single taro plant has increased significantly, and the total yield has increased by 10%.

[0094] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A fermentation substrate for Bacillus, characterized in that: The fermentation matrix is ​​to add Chinese medicine residues to the yeast culture medium to increase the concentration of Bacillus after fermentation; The Chinese medicine residue is prepared by mixing motherwort residue, astragalus residue and ginseng residue in a mass ratio of 1:1 to 2:1 to 1.5; The mass ratio of the yeast culture medium to the traditional Chinese medicine residue is 20-26:6-8.

2. The fermentation substrate for Bacillus according to claim 1, characterized in that The motherwort residue, the astragalus residue and the ginseng residue are all decocted residues.

3. The fermentation substrate for Bacillus according to claim 1, characterized in that: The particle size of the traditional Chinese medicine residue is 8-12 meshes.

4. The fermentation substrate for Bacillus according to claim 1, characterized in that The yeast culture medium is prepared from the following raw materials in parts by mass: 8 to 10 parts of peptone, 6 to 8 parts of yeast extract, and 6 to 8 parts of brown sugar.

5. A Bacillus solid-state fermentation agent, characterized in that: The Bacillus solid-state fermentation agent is prepared according to the following method: After sterilizing the fermentation substrate according to any one of claims 1 to 4, inoculating a Bacillus bacterial solution and performing aerobic fermentation to obtain the Bacillus solid fermentation agent; The volume ratio of the Bacillus bacterial liquid to the Bacillus solid fermentation agent is 1:50-100.

6. A Bacillus liquid fermentation agent, characterized in that: The bacillus liquid fermentation agent is prepared according to the following method: After sterilizing the fermentation substrate according to any one of claims 1 to 4, inoculating a Bacillus bacterial liquid, adding sterile water to make the fermentation substrate liquid, and performing aerobic fermentation to obtain the Bacillus liquid fermentation agent; The volume ratio of the Bacillus bacterial liquid to the Bacillus liquid fermentation agent is 1:50-100.

7. The Bacillus liquid fermentation agent according to claim 6, characterized in that: The concentration of the Bacillus liquid is 1.5×10 9 CFU / mL~1.8×10 9 CFU / mL.

8. The Bacillus liquid fermentation agent according to claim 6, characterized in that: The Bacillus bacterial solution is any one of Bacillus subtilis bacterial solution, Bacillus licheniformis bacterial solution, Bacillus amyloliquefaciens bacterial solution, and Bacillus megaterium bacterial solution.

9. The Bacillus liquid fermentation agent according to claim 6, characterized in that: During the aerobic fermentation process, the flow rate of oxygen is 8m / s to 10m / s.

10. Use of the Bacillus liquid fermentation agent according to any one of claims 6 to 9 in preventing and controlling taro root rot.

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