Bacillus laterosporus, microbial inoculum, preparation method of bacillus laterosporus and application of bacillus laterosporus in tick biological control

Abstract

The invention relates to the technical field of microorganisms, and particularly discloses bacillus laterosporus, a fungicide, a preparation method and application of the bacillus laterosporus to biological prevention and control of ticks. The bacillus laterosporus is brevibacillus laterosporus HNYJTHS227, the preservation number is CGMCC (China General Microbiological Culture Collection Center) No.31258, the preservation date is July 10, 2024, the preservation unit is China General Microbiological Culture Collection Center, and the preservation address is No.3, Yard 1, Beichen West Road, Chaoyang District, Beijing. The invention further provides a bacillus laterosporus biological agent, the biological agent is simple in preparation method, can achieve a good tick killing effect by being sprayed on animal body surfaces, and is convenient to use, free of residues, efficient and safe.

Description

Technical Field

[0001] The invention belongs to the technical field of microorganisms, and specifically relates to a strain of Bacillus laterosporus, a bacterial agent, a preparation method and application thereof in biological control of ticks. Background Art

[0002] Ticks are the second largest infectious disease vector after mosquitoes. They are a type of parasite that feeds on terrestrial vertebrates and are specialized blood suckers. They are the vectors or reservoir hosts of many viruses, protozoa, bacteria, etc. The distribution of ticks is affected by a variety of ecological and environmental factors such as the host, humidity, altitude and temperature. They are widely distributed around the world. In my country, they are mainly prevalent in Xinjiang, Northeast China, Inner Mongolia, Qinghai, Fujian, Yunnan and Gansu. More than 800 species of ticks have been found worldwide, and it has been determined that they can transmit at least 217 pathogens. There are 119 species of ticks in 2 families and 10 genera distributed in China, of which 14 species are recorded as soft ticks, 13 of which are distributed in the mainland and 3 in Taiwan. The ticks that harm cattle and sheep are mainly Boophilus, Dermacentor, Haemaphysalis, Rhipicephalus, Hyalomma and Ixodes of the Ixodidae family. Among them, Rhipicephalus microplus can carry 160 viruses, of which about 25% are zoonotic pathogens, such as piroplasmosis, rickettsia and Ehrlichia. Ticks parasitize on the body surface of livestock, bite and suck animal blood, causing anemia, emaciation and skin inflammation in the host, which seriously endangers the healthy development of animal husbandry. It is reported that the U.S. cattle industry suffers more than $70 million in economic losses every year due to ticks parasitic on the body surface of cattle. In recent years, infectious diseases caused by tick bites often occur. For example, a certain area in Sichuan, my country has also suffered from the harm of Haemaphysalisphiloxeroides, infecting more than 500,000 people and livestock, and the affected area accounts for 97.4%, which seriously threatens human health, hinders the development of animal husbandry, and causes huge economic losses.

[0003] Piroplasmosis is a general term for Babesiasis and Theileriosis. It is a tick-borne blood protozoan disease that must be transmitted biologically by arthropod ticks. It mainly harms cattle, sheep and camels. The main symptoms of sick livestock are persistent high fever, anemia, hemoglobinuria, jaundice, loss of appetite, weight loss, alternating constipation and diarrhea, swollen lymph nodes on the surface of the body, conjunctivitis, varying degrees of swelling of the pre-shoulder lymph nodes (often more obvious on one side, about the size of a walnut), and accelerated heart rate. In acute attacks, calves or lambs die within 2 to 4 days. Chronic diseases significantly reduce livestock production performance and have a great impact on the development of the cattle and sheep industry. In recent years, the spread and prevalence of tick-borne diseases have been complex and changeable, and new tick-borne pathogens continue to appear around the world. Since 2010, infection with Severe fever with thrombocytopenia syndrome bunyavirus (SFTSV) and Heartland virus (HRTV) has caused more than 30 deaths; in 2022, there were reports of several elderly people dying from tick-borne "severe fever with thrombocytopenia syndrome bunyavirus". In view of the above situation, it is obvious that the harm of ticks and tick-borne diseases not only affects the healthy development of the breeding industry, but is also an urgent problem that public health needs to solve, and has become a major social public health problem. Therefore, to eliminate diseases transmitted by ticks, killing ticks is the key to source control.

[0004] At present, ticks are mainly killed by chemical disinfection and biological control. Chemical disinfection often uses chemical drugs such as trichlorfon, acaricide, ivermectin, etc. However, chemical drugs are highly toxic. Although they have a certain killing effect on ticks, the killing effect on different ticks in different regions is different, and there are negative effects on animals, especially calves, lambs and camels. Biological control currently generally uses natural enemies of ticks, such as some parasitic wasps of the Hymenoptera family, which can lay eggs in ticks and cause the death of ticks; however, this biological control method may cause some unpredictable damage to the local ecology because it requires the introduction of new species. Therefore, it is still urgent to develop new green biological tick control methods and control agents. Summary of the invention

[0005] In view of the defects and problems of current tick control, such as being difficult to prevent and control, having strong drug resistance and having no specific drugs, the present invention provides a medicinal plant endophyte, Bacillus laterosporus, which has a good effect on ticks, and provides a biological bacterial agent containing the Bacillus laterosporus and its metabolites, a preparation method and its application in tick control.

[0006] The present invention provides a strain of Bacillus laterosporus, wherein the Bacillus laterosporus is Brevibacillus laterosporus HNYJTHS227, with a deposit number of CGMCC No.31258, a deposit date of July 10, 2024, a deposit unit of the General Microbiological Center of China National Committee for the Preservation of Microorganisms, and a deposit address of No. 3, Yard No. 1, Beichen West Road, Chaoyang District, Beijing.

[0007] The above-mentioned Bacillus laterosporus, the Brevibacillus laterosporus HNYJTHS227 is separated and screened from chrysanthemum and its plant tissues.

[0008] The present invention also provides a Bacillus laterosporus biological bacterial agent, comprising the above-mentioned Brevibacillus laterosporus HNYJTHS227 and / or a metabolite of the Brevibacillus laterosporus HNYJTHS227.

[0009] The above-mentioned Bacillus laterosporus biological agent has a live bacterial concentration of 10-13×10 11 cfu / mL.

[0010] The present invention also provides a method for preparing a Bacillus laterosporus biological agent, which is prepared by using Brevibacillus laterosporus HNYJTHS227, comprising the following steps:

[0011] S1. Inoculate Brevibacillus laterosporus HNYJTHS227 onto a tryptic soy agar solid medium and culture at 30-32° C. for 24-48 hours;

[0012] S2, take the strain cultured in S1 and inoculate it into tryptic soy liquid culture medium, culture it at 30-32°C for 24-48h to obtain seed liquid;

[0013] S3. Inoculate the seed liquid into the fermentation medium at an inoculation rate of 2-3%, ferment and culture for 24-48 hours at 30-32° C., a rotation speed of 100-120 rpm, and a pH of 7.0-7.2, and collect the fermentation liquid to obtain a microbial agent.

[0014] In the preparation method of the above-mentioned Bacillus laterosporus biological agent, the concentration of live bacteria of Bacillus laterosporus in the microbial agent in step S3 is 10-13×10 11 CFU / mL.

[0015] The preparation method of the above-mentioned Bacillus laterosporus biological agent also includes adding 5% skimmed milk powder to the fermentation liquid obtained in step S3, and spraying it into dry powder using a powder spraying device to obtain biological bacterial powder, wherein the live bacteria content in the bacterial powder is 1-2×10 10 CFU / mL.

[0016] The present invention also provides the use of the Bacillus laterosporus biological agent in the prevention and treatment of tick diseases in animals, wherein the tick diseases in animals include goat ticks, cattle ticks, camel ticks and sheep ticks.

[0017] In the above application, the ticks include Ixodes, Soft Ticks, Dermacentor, Ixodes caprifolia, Haemaphysalis, Ixodes persulcatus, Ornithodoros, Ornithodoros persianus, Ornithodoros lahore, Hyalomma pitta, Hyalomma shieldii and Dermacentor silvophyllum.

[0018] In the above application, the genus Ixodes includes Hyalomma microplus, Hyalomma asiaticum, Rhipicephalus turanica, Rhipicephalus sanguineus and Dermacentor marginale.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The diameter of the inhibition zone of Brevibacillus laterosporus HNYJTHS227 isolated and screened from chrysanthemum and its tissues in the present invention against "super-resistant" Escherichia coli carrying both New Delhi metallo-β-lactamases NDM1 / NDM5 and NDM4 / NDM5 is greater than 30 mm, indicating that Brevibacillus laterosporus HNYJTHS227 has a strong antibacterial effect on "super-resistant" Escherichia coli carrying New Delhi metallo-β-lactamases.

[0021] 2. The Brevibacillus laterosporus HNYJTHS227 bacterial agent of the present invention can achieve 100% control effect on goat ticks, cattle ticks, camel ticks and sheep ticks, and the effect is significant, and can be used for biological control of ticks.

[0022] 3. The biological agent of the present invention has good safety and is easy to use. It can achieve a good tick-killing effect by spraying it on the body surface of animals without the risk of chemical drug residues. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The figure shows the antibacterial activity of Bacillus laterosporus HNYJTHS227 against "super-resistant" Escherichia coli carrying New Delhi metallo-β-lactamase (NDM1 / NDM4 / NDM5). In the figure, A shows the effect of Bacillus laterosporus HNYJTHS227 against "super-resistant" Escherichia coli carrying NDM1 / NDM5; and B shows the effect of Bacillus laterosporus against "super-resistant" Escherichia coli carrying NDM4 / NDM5.

[0024] Figure 2The antibacterial activity of Brevibacillus laterosporus HNYJTHS227 against "super-resistant" Escherichia coli carrying New Delhi metallo-β-lactamase (NDM1 / NDM4 / NDM5) was measured by the inhibition zone method; A in the figure shows the antagonistic effect of Brevibacillus laterosporus against "super-resistant" Escherichia coli carrying NDM1 / NDM5; B in the figure shows the antagonistic effect of Brevibacillus laterosporus against "super-resistant" Escherichia coli carrying NDM4 / NDM5.

[0025] Figure 3 The colony morphology characteristics of Bacillus laterus HNYJTHS227 and the bacterial morphology under a microscope after Gram staining, including the colony morphology (a) and Gram staining (b) photos of strain HNYJTHS227.

[0026] Figure 4 This is the phylogenetic tree of Brevibacillus laterosporus HNYJTHS227.

[0027] Figure 5 This is the effect of the fermentation supernatant of Brevibacillus laterosporus HNYJTHS227 on the "super-resistant" Escherichia coli carrying New Delhi metallo-β-lactamase (NDM1 / NDM4 / NDM5). Figure A shows the antibacterial effect of the fermentation broth of HNYJTHS227 strain on the "super-resistant" Escherichia coli carrying NDM1 / NDM5; Figure B shows the antibacterial effect of the fermentation broth of HNYJTHS227 strain on the "super-resistant" Escherichia coli carrying NDM4 / NDM5. DETAILED DESCRIPTION

[0028] In view of the defects and problems existing in the current tick control, the present invention provides a medicinal plant endophyte - Bacillus laterosporus with good effect on ticks, and provides a biological bacterial agent containing the Bacillus laterosporus and its metabolites, a preparation method and its application in tick control.

[0029] The present invention separates, identifies and selects endophytes from different tissues of chrysanthemum, such as roots, stems, leaves and flowers, and studies the antibacterial effects and antibacterial active substances, laying a foundation for the screening of new antibacterial active substances, providing a reference for the research of new anti-resistant microbial drugs and the prevention and control of parasitic diseases, and providing ideas for the improvement and research of antibiotic substitutes in livestock and poultry production. The present invention is described in detail below in conjunction with the accompanying drawings and examples. Note: The instruments and equipment involved in the following embodiments are all conventional instruments and equipment unless otherwise specified; the reagents and culture media involved are all conventionally available on the market unless otherwise specified; the test methods involved are all conventional methods unless otherwise specified. The "super-resistant" E. coli carrying New Delhi metallo-β-lactamase (NDM1 / NDM4 / NDM5) used in the experiment are the super-resistant E. coli used in "Identification and drug resistance study of E. coli producing carbapenemase NDM5 and NDM" in "Biotechnology Bulletin", 2022, 28(9): 106-115; and the E. coli used in "Whole genome sequencing analysis of porcine E. coli carrying New Delhi metallo-β-lactamase and drug screening of sensitive plant extracts", Chinese Journal of Veterinary Drugs, 2023, 57(6): 23-33.

[0030] Example 1: Isolation and screening of Brevibacillus laterosporus HNYJTHS227

[0031] (1) Isolation and purification of strains

[0032] The roots, stems, leaves and other tissues of chrysanthemum (collected from the chrysanthemum planting base in Yucheng County, Shangqiu, Henan Province) were disinfected on the surface, and then inoculated on PDA and LB culture media, cultured at 30-32°C for 48-72h, and colonies of different morphologies were picked and purified on TSA culture media, and then the same strains were eliminated by morphological characteristics under a microscope. The purified strain was named HNYJTHS227 and stored at -80°C with 10% skim milk powder.

[0033] (2) Screening of antibacterial endophytes

[0034] Endophytes stored at -80℃ were selected and inoculated into TSA culture plates. The antibacterial activity was tested by streak method. A line was drawn in the center of the TSA culture plate and inoculated with endophytes. Then, "super-resistant" Escherichia coli carrying New Delhi metallo-β-lactamase (NDM1 / NDM4 / NDM5) were inoculated on both sides of the streaked endophytes. The plates were then placed in a 30-32℃ incubator for 24 hours to observe the antibacterial activity of endophytes against multi-drug resistant bacteria. The results are shown in Table 1. Figure 1 .

[0035] Depend on Figure 1It can be seen that the endophyte HNYJTHS227 has a good antibacterial and bactericidal effect on "super-resistant" Escherichia coli carrying New Delhi metallo-β-lactamase (NDM1 / NDM4 / NDM5).

[0036] In order to further identify the antibacterial strength of the endophyte HNYJTHS227, the size of the inhibition zone was measured by the inhibition zone method. The endophyte stored at -80°C was selected and inoculated into the center of the TSA plate, and then 1×10 9 Escherichia coli was spread around the endophytes and placed in a 37°C incubator for 24 hours to observe the antibacterial effects of the endophytes on the pathogens. If there is a transparent antibacterial circle around the endophytes, it means that this strain of endophytes has antibacterial and bactericidal effects on the pathogens. Specifically, the strength of the antibacterial effect is represented by the size of the antibacterial circle. An antibacterial circle diameter of >20mm indicates a strong antibacterial and bactericidal effect, 10mm < antibacterial circle <20mm indicates a medium antibacterial and bactericidal effect, and an antibacterial circle <10mm indicates a weak antibacterial and bactericidal effect. See the results. Figure 2 In the figure, A shows the inhibition zone size of 39mm for endophytes against "super-resistant" Escherichia coli carrying NDM1 / NDM5; in the figure, B shows the inhibition zone size of 42mm for endophytes against "super-resistant" Escherichia coli carrying NDM4 / NDM5.

[0037] Depend on Figure 2 It can be seen that the diameter of the inhibition zone of the endophyte HNYJTHS227 against Escherichia coli is greater than 20 mm, indicating that the strain HNYJTHS227 has a strong antibacterial effect on "super-resistant" Escherichia coli carrying New Delhi metallo-β-lactamase (NDM1 / NDM4 / NDM5).

[0038] (3) Morphological identification of endophytes

[0039] The strain HNYJTHS227 was inoculated on a TSA culture plate and placed in a 30°C incubator for 24 h. The colonies and bacterial morphology of the endophytic bacteria were observed. Figure 3 a and Figure 3 b.

[0040] Depend on Figure 3 a It can be seen that strain HNYJTHS227 forms round light yellow colonies on the solid culture medium, and the surface of the colonies is smooth and moist. Figure 3 b It can be seen that the endophyte is rod-shaped, the spores are fusiform or oval, located in the center of the body, 1.0-1.2μm×3-5μm, the end of the bacteria is blunt or truncated, and it is a Gram-negative bacterium. Combining the morphological observation results of the colony and the body, it is preliminarily determined that the endophyte is Bacillus laterosporus.

[0041] (4) Molecular identification of endophytes

[0042] 16S rRNA was used for PCR amplification and sequencing identification. The primers used are shown in Table 1 below.

[0043] Table 1 16S rRNA primer sequences

[0044]

[0045] The DNA of endophytes was used as a template and amplified in 50 μL amplification system. The amplified product was first electrophoresed using 1% agarose gel to determine the size and position of the band. The PCR product was then sent to Shanghai Shenggong Biotechnology Co., Ltd. for sequencing. The sequence is shown in SEQ ID NO.3.

[0046] (SEQ ID NO.3).

[0047] The sequencing results were analyzed and compared in the NCBI database, and the phylogenetic tree was constructed using the Neighbor Joining method in MEGA5.0 software. Figure 4 .

[0048] from Figure 4It can be seen that there are 19 strains with high homology to HNYJTHS227, with a homology of more than 99%, of which the homology to Bacillus laterosporus is 100%. According to the sequencing results, the strain HNYJTHS227 was determined to be Bacillus laterosporus.

[0049] On July 10, 2024, the Bacillus laterosporus HNYJTHS227 was deposited in the General Microbiology Center of the China Culture Collection Administration, with the deposit address at No. 3, Yard No. 1, Beichen West Road, Chaoyang District, Beijing; the deposit number is CGMCC No. 31258.

[0050] (5) Antibacterial activity test of Bacillus laterosporus HNYJTHS227 fermentation broth

[0051] In order to further verify the antibacterial and bactericidal effect of the endophytic fermentation broth, the HNYJTHS227 strain was fermented and the antibacterial activity of the fermentation broth was detected. 100 μL of endophytic fermentation broth was added to each plate, and 4 replicates were added. After 24 hours of culture, the size of the inhibition zone was measured. The results are shown in Figure 5 , Figure 5 A is the inhibition zone of Bacillus laterosporus against Escherichia coli carrying NDM1 / NDM5 "super-resistant" is 33±0.20mm; Figure 5 B is the inhibition zone of Bacillus laterosporus against "super-resistant" Escherichia coli carrying NDM4 / NDM5, which is 37±0.22mm.

[0052] Example 2: Preparation of Bacillus laterosporus HNYJTHS227 bacterial agent

[0053] (1) Strain culture and preparation

[0054] Brevibacillus laterosporus HNYJTHS227 was inoculated onto tryptone soy agar plates and cultured at 30°C for 24 h;

[0055] (2) Preparation of seed solution

[0056] The bacteria cultured in step (1) were inoculated into a tryptone soy broth medium and cultured at 30° C. for 24 h to obtain a seed solution;

[0057] (3) Liquid fermentation production

[0058] The seed liquid was inoculated into the fermentation medium at a rate of 3%. After fermentation at 30°C, 120 rpm, and pH 7.0 for 48 hours, the fermentation liquid was collected to obtain the microbial agent. The viable bacterial concentration of the agent was measured to be 10-13×10 11 CFU / mL.

[0059] (4) Preparation of powder

[0060] The fermentation liquid obtained in step (3) was added with 5% skimmed milk powder and sprayed into dry powder using a powder spraying device to obtain biological bacterial powder. The live bacteria content in the bacterial powder was 1-2×10 10 CFU / mL.

[0061] Test Example 1: In order to evaluate and verify the insecticidal effect of HNYJTHS227 fermentation liquid on ticks, 50 ticks were collected from the body surfaces of cattle and sheep infected with ticks, respectively, and placed in conical bottles. 10-13×10 11 CFU / mL fermentation liquid, and observe the tick condition every 1 hour.

[0062] One hour after spraying the fermentation liquid, some ticks began to die, and all died after 4 hours, indicating that the HNYJTHS227 fermentation liquid has a good tick-killing effect on ticks.

[0063] Test Example 2: Experimental verification of the Bacillus laterosporus HNYJTHS227 bacterial agent (bacterial powder prepared in Example 2) in biological control of goat ticks

[0064] This experimental verification was conducted in July 2024 at a large-scale breeding farm in Hami, Xinjiang, using ivermectin and saline as controls, and goats were sprayed with ivermectin at 0.02 ml per kilogram of body weight.

[0065] The specific steps are as follows:

[0066] (1) A total of 500 sheep with tick infestations were selected and randomly divided into different bacterial agent experimental groups, ivermectin control group and blank control group.

[0067] (2) The goats were treated with Bacillus laterosporus HNYJTHS227 and ivermectin to observe whether there were still ticks on the goat's body surface and to calculate the treatment effect. The results of the treatment experiment are shown in Table 2.

[0068] Table 2 Biological control effect of Bacillus laterosporus HNYJTHS227 powder on goat ticks

[0069]

[0070] As can be seen from Table 2, both the 5× microbial agent experimental group and the 10× microbial agent experimental group had 100% control effect on goat ticks.

[0071] Test Example 3: Experimental verification of the Bacillus laterosporus HNYJTHS227 bacterial agent (bacterial powder prepared in Example 2) in biological control of beef cattle ticks

[0072] The test verification was carried out in a beef cattle farm in Hami, Xinjiang in June 2024. The beef cattle farm was infected with ticks, and a large number of ticks occurred in the udders, vulva, and inner thighs of beef cattle.

[0073] The infected area was sprayed with 5× bacterial agent twice a day for 2 consecutive days. After 2 days of external spraying, all the ticks died and fell off the cattle's body surface, and new tissues grew at the bite sites, and all were cured.

[0074] In summary, the experimental results show that the biological bacterial agent prepared by Bacillus laterosporus HNYJTHS227 of the present invention has a good control effect on the beef tick, and can effectively solve the problem of biological control of the beef tick.

[0075] Test Example 4: Experimental verification of the Bacillus laterosporus HNYJTHS227 bacterial agent (bacterial powder prepared in Example 2) in biological control of camel ticks

[0076] This experimental verification was carried out in a dairy camel farm in Yiwu County, Hami in July 2024, using 1% trichlorfon and saline as controls.

[0077] The specific steps are as follows:

[0078] (1) A total of 100 dairy camels infested with ticks were selected and divided into five groups, each with 20 camels, including a different bacterial agent experimental group, a trichlorfon control group, and a saline blank control group.

[0079] (2) Bacillus laterosporus HNYJTHS227 and trichlorfon were used for treatment, and the treatment effects were observed and statistically analyzed. The results of the treatment experiment are shown in Table 3:

[0080] Table 3 Effect of Bacillus laterosporus HNYJTHS227 on biological control of camel ticks

[0081]

[0082] It can be seen from Table 3 that both the 5× microbial agent experimental group and the 10× microbial agent experimental group had 100% control effect on camel tick biological control.

[0083] Test Example 5: Experimental verification of the Bacillus laterosporus HNYJTHS227 bacterial agent (bacterial powder cultured in Example 2) in biological control of sheep ticks

[0084] The test verification was carried out in a sheep farm in Hami in August 2024. Some sheep on the farm were infected with ticks.

[0085] A therapeutic test was conducted on sick sheep using 10× bacterial agent, which was sprayed twice a day for 2 consecutive days. After 2 days, all the sick sheep were cured.

[0086] In summary, the experimental results show that the biological bacterial agent prepared by Bacillus laterosporus HNYJTHS227 of the present invention has a good control effect on ticks in goats, sheep, camels and beef cattle, and can effectively solve the problem of biological control of ticks.

[0087] The above description is only a preferred embodiment of the present invention and does not limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A strain of Bacillus laterosporus, characterized in that: The Bacillus laterosporus is Brevibacillus laterosporus HNYJTHS227, with a preservation number of CGMCC No.31258 and a preservation date of July 10, 2024. The preservation unit is the General Microbiology Center of the China Culture Collection Administration, and the preservation address is No. 3, Yard No. 1, Beichen West Road, Chaoyang District, Beijing.

2. The Bacillus laterosporus according to claim 1, wherein: The Brevibacillus laterosporus HNYJTHS227 is separated and screened from chrysanthemum and plant tissues thereof.

3. A Bacillus laterosporus biological agent, characterized in that: The method comprises the Brevibacillus laterosporus HNYJTHS227 according to claim 1 and / or a metabolite of the Brevibacillus laterosporus HNYJTHS227.

4. The Bacillus laterosporus biological agent according to claim 3, characterized in that: The concentration of live bacteria of Bacillus laterosporus in the biological agent is 10-13×10 11 cfu / mL.

5. A method for preparing a Bacillus laterosporus biological agent, characterized in that: The method is prepared by using Brevibacillus laterosporus HNYJTHS227 and comprises the following steps. S1. Inoculate Brevibacillus laterosporus HNYJTHS227 onto a tryptic soy agar solid medium and culture at 30-32° C. for 24-48 hours; S2, take the strain cultured in S1 and inoculate it into tryptic soy liquid culture medium, culture it at 30-32°C for 24-48h to obtain seed liquid; S3. Inoculate the seed liquid into the fermentation medium at an inoculation rate of 2-3%, ferment and culture for 24-48 hours at 30-32° C., a rotation speed of 100-120 rpm, and a pH of 7.0-7.2, and collect the fermentation liquid to obtain a microbial culture liquid.

6. The method for preparing the Bacillus laterosporus biological agent according to claim 5, characterized in that: The live bacterial concentration of Brevibacillus laterosporus in the microbial inoculant in step S3 is 10-13×10 11 cfu / m.

7. The method for preparing the Bacillus laterosporus biological agent according to claim 6, characterized in that: The method further comprises adding 5% skimmed milk powder to the fermentation liquid obtained in step S3, and spraying the powder into dry powder using a powder spraying device to obtain biological bacterial powder, wherein the live bacterial content in the bacterial powder is 1-2×10 10 CFU / mL.

8. The use of the Bacillus laterosporus biological agent in the prevention and treatment of tick diseases in animals as claimed in claim 3, characterized in that: The tick pests on animals include goat ticks, cattle ticks, camel ticks and sheep ticks.

9. The use according to claim 8, characterized in that: The ticks include Ixodes, Soft Ticks, Dermacentor, Ixodes caprifolia, Haemaphysalis, Ixodes persicae, Ornithodoros, Ornithodoros persicae, Ornithodoros lahore, Hyalomma pitta, Hyalomma shield and Dermacentor silvophila.

10. The use according to claim 9, characterized in that: The genus Ixodes includes the Hyalomma microplus, Hyalomma asiaticum, Rhipicephalus turanica, Rhipicephalus sanguineus and Dermacentor marginale.

Images