Plant-derived bacillus velezensis YNSCB-1 for promoting growth of bombyx mori and application of plant-derived bacillus velezensis YNSCB-1 in prevention and treatment of silkworm white muscardine silkworm

Abstract

According to the invention, a strain of bacillus velezensis is separated from a mulberry leaf fermentation product, is named as YNSCB-1, has a preservation number of CGMCC (China General Microbiological Culture Collection Center) NO.36475, and is preserved in the China General Microbiological Culture Collection Center. After the bacterial strain is added into mulberry leaves to feed silkworms, the bacterial strain has a very good growth promoting effect on the silkworms; meanwhile, the strain shows high antagonistic activity on silkworm white muscardine disease pathogens in an indoor confrontation test, and the morbidity of the silkworm white muscardine disease pathogens inoculated after silkworm feeding is remarkably reduced compared with other test strains and a pathogenic bacteria control group. The adopted YNSCB-1 strain has good safety to silkworms, active factors such as cellulase can be generated in intestinal tracts of the silkworms after the YNSCB-1 strain is added to the silkworms, the conversion efficiency of mulberry leaf feed can be remarkably improved, and the growth of the silkworms is promoted; meanwhile, after the bacterial strain is added, a certain prevention and treatment effect is achieved on the silkworm white muscardine silkworm.

Description

[0001] This invention relates to the field of probiotics for silkworms, and in particular to the growth-promoting effect of a plant-derived Bacillus belye var. salina YNSCB-1 on silkworms and its application in the prevention and control of white muscular dystrophy in silkworms. Background Technology

[0002] As the most successfully domesticated economic insect, the silkworm's high degree of domestication, while creating significant economic value, has also led to biological vulnerability. In intensive farming, high-density feeding, disease outbreaks, and heat stress have multiple adverse effects on silkworm growth, often causing severe economic losses. Research indicates that microbial imbalance within the silkworm's body or environment is a major cause of poor growth and disease occurrence. Adding probiotics can promote the synthesis of digestive enzymes and antibacterial substances in the silkworm, thereby improving nutritional metabolism efficiency, maintaining microbial balance, and effectively preventing and treating silkworm diseases.

[0003] Bacillus belesiensis ( Bacillus velezensis *Bacillus belyssus* is a Gram-positive bacterium widely distributed in nature. It was first isolated in 2005 by Spanish researchers from a river called *Velres*. This species was long considered a synonym of *Bacillus amyloliquefaciens* until 2016, when American researchers, through whole-genome analysis, demonstrated its taxonomic independence, confirming its existence as a separate species. *Bacillus belyssus* has an extremely wide distribution and can be isolated from various environments, including marine and river sediments, soil, plant rhizosphere, plant tissues, and animal intestines.

[0004] Silkworms lack a complete enzyme production system and do not contain endogenous enzyme genes. Their intestinal digestive fluids contain insufficient enzymes, requiring beneficial intestinal microorganisms to provide key enzymes such as cellulose digestive enzymes to complete functions such as mulberry leaf digestion, nutrient absorption, and metabolism. Existing research has also confirmed that Bacillus strains isolated from the silkworm's intestines can effectively reduce the abundance of intestinal pathogens and decrease the incidence of viral diseases. Simultaneously, they can activate the host's immune system and enhance the activity of chitinase in silkworms, thereby strengthening their defense against pathogens. Therefore, screening for probiotic Bacillus strains suitable for silkworms is of great significance for improving mulberry leaf conversion rate, increasing cocoon yield, and enhancing the silkworm's immune resistance. Currently, the application of probiotics in silkworm farming is still in the initial exploratory stage, and research on suitable exogenous probiotics for silkworms is particularly lacking. Summary of the Invention

[0005] The purpose of this invention is to provide a plant-derived Bacillus belye var. yanhusuo YNSCB-1 strain that promotes the growth of silkworms and its application in the prevention and control of white muscular dystrophy in silkworms, so as to solve the problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides the following solution: One of the technical solutions of this invention is a plant-derived Bacillus belye (Bacillus velezensis ) YNSCB-1, which is preserved in the China General Microbiological Culture Collection Center on November 03, 2025, and the address of the preservation center is No. 1, Beichen West Road, Chaoyang District, Beijing, and the preservation number is CGMCC No. 36475.

[0007] The second technical scheme of the present application is a microbial agent, which comprises the plant-derived Bacillus velezensis YNSCB-1.

[0008] The third technical scheme of the present application is the application of the plant-derived Bacillus velezensis YNSCB-1 or the microbial agent in the preparation of a medicine for preventing and treating the white muscardine of silkworms.

[0009] The fourth technical scheme of the present application is a medicine for preventing and treating the white muscardine of silkworms, which comprises the plant-derived Bacillus velezensis YNSCB-1 or the microbial agent.

[0010] The fifth technical scheme of the present application is a breeding method of silkworms, which uses the plant-derived Bacillus velezensis YNSCB-1, the microbial agent or the medicine to feed silkworms.

[0011] The sixth technical scheme of the present application is the application of the plant-derived Bacillus velezensis YNSCB-1 or the microbial agent in promoting the growth of silkworms.

[0012] Based on the above technical scheme, the present application has the following technical effects: The present application discloses a plant-derived Bacillus velezensis YNSCB-1, which is proved by experiments that after feeding silkworms, the strain can promote the growth of silkworms, and as a probiotic, it can reduce the incidence of white muscardine of silkworms and effectively protect silkworms. As a biological control agent, Bacillus velezensis has the advantages of environmental friendliness and no pollution. After feeding silkworms, it can regulate intestinal flora, maintain intestinal mucosal barrier, resist bacteria and regulate immunity, and is safe for silkworms after feeding. It provides a reference for the selection of probiotics in the process of silkworm breeding. BRIEF DESCRIPTION OF DRAWINGS

[0013] In order to more clearly illustrate the technical schemes in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0014] Figure 1 YNSCB-1, YMB-3 and YNDYB-2 strain phylogenetic tree constructed based on 16S rDNA sequence.

[0015] Figure 2 The colony growth of Bacillus belyssus YNSCB-1 (A), Bacillus sicca YMB-3 (B), and Bacillus licheniformis YNDYB-2 (C) on LB medium.

[0016] Figure 3 The results show the antibacterial effects of three bacterial strains on *Beauveria bassiana* BJJ-1 in the experiment. A, E, and I represent the colony counts of *Beauveria bassiana* BJJ-1 at 7, 14, and 21 days of blank control culture; B, F, and J represent the inhibitory effects of strain YNSCB-1 on *Beauveria bassiana* BJJ-1 at 7, 14, and 21 days; C, G, and K represent the inhibitory effects of strain YMB-3 on *Beauveria bassiana* BJJ-1 at 7, 14, and 21 days; and D, H, and L represent the inhibitory effects of strain YNDYB-2 on *Beauveria bassiana* BJJ-1 at 7, 14, and 21 days.

[0017] Figure 4 The experimental groups fed with three different strains of Beauveria bassiana were inoculated with 1×10⁶ Beauveria bassiana spores. 6 Survival rate graph after cells / ml.

[0018] Figure 5 The experimental groups fed with three different strains of Beauveria bassiana were inoculated with 1×10⁶ Beauveria bassiana spores. 7 Survival rate graph after cells / ml. Detailed Implementation

[0019] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0020] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0021] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0022] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0023] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0024] Unless otherwise specified, the technical solutions described in this invention are all conventional solutions in the field, and the reagents or raw materials used are all purchased from commercial channels or are publicly available unless otherwise specified.

[0025] This invention provides a plant-derived Bacillus belye strain ( Bacillus velezensis YNSCB-1, this strain was deposited on November 3, 2025 at the China General Microbiological Culture Collection Center, located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, with accession number CGMCC No. 36475.

[0026] This invention also provides a microbial inoculant, including the plant-derived Bacillus belye YNSCB-1.

[0027] This invention also provides the application of the plant-derived Bacillus belyceae YNSCB-1 or the microbial agent in the preparation of drugs for the prevention and treatment of white muscardine disease in silkworms.

[0028] In some specific implementations, the plant-derived Bacillus belye YNSCB-1 is fed to silkworms together with mulberry leaves to reduce the incidence of white muscular dystrophy in silkworms.

[0029] This invention also provides a drug for preventing and treating white muscular dystrophy in silkworms, comprising the plant-derived Bacillus belye YNSCB-1 or the microbial agent.

[0030] This invention also provides a method for raising silkworms, which involves feeding silkworms with the plant-derived Bacillus belye YNSCB-1, the microbial agent, or the drug.

[0031] This invention also provides the application of the plant-derived Bacillus belye YNSCB-1 or the microbial agent in promoting the growth of silkworms.

[0032] In some specific implementations, the plant-derived Bacillus belye YNSCB-1 is fed to silkworms together with mulberry leaves to promote silkworm growth.

[0033] To investigate the effects of exogenous probiotics on the intestinal health and immunity of silkworms, this invention uses silkworms as the experimental subject and adds plant-derived Bacillus belye, Bacillus sicca, and Bacillus licheniformis. The weight changes, developmental period, cocooning rate, and cocoon layer rate of silkworms in the feeding experiment were systematically compared. Indoor experiments were conducted to further evaluate the antagonistic effects of different strains on the pathogen of white muscardine disease in silkworms and to further analyze the effect of adding exogenous probiotic strains on the incidence of white muscardine disease in silkworms.

[0034] The strain used in this invention was isolated from fermented mulberry leaves in Mengzi City, Yunnan Province. *Bacillus belycera*, as a multifunctional probiotic, can grow and reproduce even under highly acidic or alkaline external conditions. It has numerous successful applications as a probiotic supplement in livestock, poultry, and aquatic animals. After entering the intestines of livestock and poultry, *Bacillus belycera* maintains an anaerobic intestinal environment by occupying attachment sites and consuming oxygen. Simultaneously, it secretes digestive enzymes such as proteases, lipases, cellulases, and amylases, significantly improving the weight gain rate, feed conversion rate, and nutrient metabolism efficiency of livestock, poultry, and aquatic animals. After colonizing the intestines, it directly inhibits the growth of 60%-85% of pathogenic bacteria through competitive exclusion mechanisms and the secretion of lipopeptide antimicrobial substances such as surfactants and iturobrinein, thus maintaining intestinal flora homeostasis.

[0035] The plant-derived Bacillus belyssus YNSCB-1 provided by this invention produces metabolites and enzymes that help silkworms better absorb nutrients and improve feed conversion rate. After feeding with this bacterium, silkworms experience significant weight gain, a shorter development period, and a simultaneous increase in cocooning rate and cocoon layer rate. This effect of promoting healthy growth in silkworms helps improve their resistance to diseases, thereby reducing the probability of white muscardine disease.

[0036] The plant-derived Bacillus belycetamol YNSCB-1 provided in this invention serves as a probiotic, improving the intestinal microenvironment of silkworms, regulating the intestinal flora structure, increasing the number of beneficial bacteria, and reducing the abundance of harmful bacteria. This barrier function, which improves the intestinal microenvironment, helps enhance the immunity of silkworms, enabling them to better resist Beauveria bassiana infection.

[0037] Beauveria bassiana produces a variety of antibacterial substances that can inhibit the growth of pathogens. It produces enzymes such as chitinase, protease, lipase, amylase, cellulase, oxidase, and catalase. These enzymes can disrupt the cell wall or cell membrane of Beauveria bassiana, thereby inhibiting its growth and reproduction. In addition, Beauveria bassiana also produces secondary metabolites such as antibacterial proteins, lipopeptide antibiotics, and antibiotics synthesized from polyketide compounds. These substances have broad-spectrum antibacterial activity and can effectively inhibit the growth of Beauveria bassiana.

[0038] Bacillus velezensis can grow rapidly in the environment and form a dominant flora, thereby competing with Beauveria bassiana for ecological niches. By occupying the growth space and nutrient resources of Beauveria bassiana, Bacillus velezensis can reduce the growth opportunities of Beauveria bassiana, thereby reducing the risk of infection of silkworms.

[0039] Compared with chemical drugs, Bacillus velezensis as a biological probiotic has the advantages of environmental friendliness and no pollution. It will not cause secondary pollution to the environment, nor will it leave harmful residues in the silkworm body, meeting the requirements of modern ecological agriculture and sustainable development.

[0040] The silkworm variety used in the experiment of the present application is: Jin Song x Hao Yue, from the Silkworm and Bee Research Institute of Yunnan Academy of Agricultural Sciences.

[0041] Example 1 I. Bacillus velezensis (source, activity preservation, and phylogenetic tree) 1. The Bacillus velezensis YNSCB-1 used in the experiment of the present application is isolated from the fermentation of mulberry leaves in Caoba Town, Mengzi City, Yunnan Province. The molecular biology identification result is that YNSCB-1 is clustered with Bacillus velezensis (CP023075.1), indicating that YNSCB-1 is a strain of Bacillus velezensis . Combined with the morphological characteristics and the molecular biology identification result, it is determined that the strain is Bacillus velezensis, named YNSCB-1. 2. The Bacillus siamensis YMB-3 used in the experiment is isolated from corn in Caoba Town, Mengzi City, Yunnan Province. The molecular biology identification result is that YMB-3 is clustered with Bacillus siamensis (MZ1488821.1), indicating that YNSCB-1 is a strain of Bacillus siamensis . Combined with the morphological characteristics and the molecular biology identification result, it is determined that the strain is Bacillus siamensis, named YMB-3.

[0042] 3. The Bacillus licheniformis YNDYB-2 used in the experiment is isolated from the fermentation of mulberry leaves in Caoba Town, Mengzi City, Yunnan Province. The molecular biology identification result is that YNDYB-2 is clustered with Bacillus licheniformis (LC768853.1), indicating that YNDYB-2 is a strain of Bacillus licheniformis . Combined with the morphological characteristics and the molecular biology identification result, it is determined that the strain is Bacillus licheniformis, named YNDYB-2.

[0043] The above three strains are all from the Silkworm and Bee Research Institute of Yunnan Academy of Agricultural Sciences. The phylogenetic tree of Bacillus velezensis is shown in Figure 1 .

[0044] II. Promoting effect of the three test strains on the growth of silkworms (I) Cultivation and determination of the strain: 1. Preparation of LB solid medium for inoculation: In the experiment, 150 mL of LB solid medium was prepared in a 250 mL conical flask, and the preparation ratio was as follows (taking 300 mL as an example): tryptone 3 g, yeast extract 1.5 g, agar powder 6 g, sodium chloride (NaCl) 3 g, and pure water (ddH2O) 300 mL.

[0045] 2. Preparation of LB liquid medium for shaking culture: In the experiment, 150 mL of LB liquid medium was prepared in a 250 mL conical flask, and the preparation ratio was as follows (taking 150 mL as an example): tryptone 3 g, yeast extract 1.5 g, sodium chloride (NaCl) 3 g, and pure water (ddH2O) 150 mL.

[0046] The experimental strains obtained by screening and identification were taken out from the -80°C refrigerator; a small amount of strain was taken with an inoculation needle and quickly inoculated on a plate, and then sealed and labeled after inoculation by streaking method; placed in a fresh-keeping bag, inverted and placed in an artificial climate incubator for culture (37°C). Shaking culture: take LB liquid medium, take disposable inoculation ring and inoculated plate, take a small amount of strain from the plate with disposable inoculation ring, quickly inoculate into LB liquid medium (conical flask); set the shaking bed temperature to 37°C, the rotation speed to 220 r / min, and shake culture for about 36 h; after the culture is completed, take it out and store it in a 4°C refrigerator. Centrifugation and washing of bacteria: centrifuge at 4000 r / min for 10 min, take the precipitate, and wash it twice with 25 mL of sterile inorganic salt liquid medium; vortex to prepare a suspension with 10 mL of sterile inorganic salt liquid medium.

[0047] 3. Bacterial liquid value setting: Adjust the concentration of the bacterial suspension, and adjust the OD value of the bacterial liquid to 10 7 cfu / ml and 10 8 cfu / ml. The bacterial liquid concentration of Bacillus velezensis YNSCB-1 was 10 7 cfu / ml for the S1 experimental group, and the bacterial liquid concentration of Bacillus velezensis YNSCB-1 was 10 8 cfu / ml for the S2 experimental group; the bacterial liquid concentration of Bacillus siamensis YMB-3 was 10 7 cfu / ml for the Y1 experimental group, and the bacterial liquid concentration of Bacillus siamensis YMB-3 was 10 8 cfu / ml for the Y2 experimental group; the bacterial liquid concentration of Bacillus licheniformis YNDYB-2 was 10 7 cfu / ml for the D1 experimental group, and the bacterial liquid concentration of Bacillus licheniformis YNDYB-2 was 10 7cfu / ml is the D2 experimental group.

[0048] (B) Bacterial liquid feeding and sterile water treatment: Bacterial liquid feeding method: The experimental set of sterile water control group (CK) and probiotic treatment group. The conventional method of silkworm eggs after hatching, in the temperature of 25℃±1℃, humidity of 80%±2% conditions normal feeding to 3 age, start feeding probiotics treatment mulberry leaves, feeding mulberry leaves as control group. Mulberry leaves soaked in sterile water or bacteria suspension for 5 min after drying feeding. Each group of silkworms are divided into 3 areas, 50 heads in each area, feeding to the upper cocoon.

[0049] (Three) after feeding bacillus velezensis experimental silkworm growth and development Chron and the influence of economic traits of cocoon Feeding 3 strains of experimental silkworm growth and development and economic traits of cocoon index survey as shown in Table 1.

[0050] Table 1: Silkworm growth and development and economic traits of cocoon index survey after feeding 3 strains of silkworm

[0051] From Table 1, according to the data in Table 1, the influence of different strains of feeding treatment on silkworm growth and development and cocoon quality traits is different. The four age development period of all treatment groups is shorter than that of the control group (CK) by 3.6-4.0 hours, and the body weight of four age dormant silkworm is generally higher than that of CK, indicating that the tested strains have a certain growth promoting effect. The five age development period of S1 and S2 is the shortest, about 2.5 hours shorter than CK, and the rest of the treatment is close to or slightly longer than CK. In terms of cocoon quality, the cocoon rate of S1 treatment is the highest (98.63%), followed by S2 (95.73%) and Y2 (93.58%), all higher than CK (93.56%); while D1, D2 and Y1 treatment is significantly reduced. The cocoon layer rate varies slightly among the treatments, with S1 being the highest (22.54%), D1 being the lowest (20.30%), and the rest of the treatments being basically the same as CK (21.10%).

[0052] In summary, S1 and S2 treatment is better in shortening the whole age development time, maintaining higher cocoon rate and cocoon layer rate; Y2 is particularly outstanding in improving the cocoon rate, but the development time is slightly longer; D group and Y1 promote the growth in the early stage, but the cocoon rate decreases significantly, which may limit its application potential.

[0053] Three, the application of three test strains in silkworm white muscardine (One) plate confrontation experiment: 1. Shake the bacteria: after inoculating 3 strains into LB liquid medium (conical flask), place it in a shaking bed for 24 hours at 37℃, with a shaking speed of 220r / s; 2. Isolation of Beauveria bassiana: The collected Dendrolimus punctatus from Mengzi area was immersed in 75% ethanol solution for surface disinfection for 30 s, rinsed with sterile water for 3 times and then dried with sterile filter paper. The tissue 2-4 mm below the cuticle of D. punctatus was cut with a scalpel and attached to PDA plate, which was placed in a 25℃ incubator for dark culture for 4 d. When white mycelium grew on the tissue or at the edge of the tissue, a small amount of mycelium was picked for culture, and then a single colony was transferred to a new PDA medium for preservation. 3. Confrontation experiment: (1) Preparation of PDA medium; (2) Preparation of Beauveria bassiana cake: A coating rod was used to dip the mycelium spores of the cultured Beauveria bassiana and evenly smear on the PDA medium, which was placed in a 37℃ incubator for 1 d. The cake maker was thoroughly sterilized with an alcohol lamp, and after cooling, the required cake was quickly punched on the Beauveria bassiana culture medium; (3) Placement of the cake: The punched cake was picked up with an inoculation needle and inverted on the center of the prepared PDA medium; (4) Placement of filter paper: The blank drug sensitive paper was placed with forceps at a distance of 1.5-2 cm from the cake, and one piece was placed on each side, so that the cake and the filter paper were on the same straight line; (5) Addition of bacterial liquid: 10 μL of the shaken bacterial liquid was dropped on the filter paper with a pipette; (6) Beauveria bassiana control only placed BJJ-1 cake; (7) Complete labeling and edge sealing work, wrap with plastic wrap and place in the incubator, observe and take pictures every 7 days.

[0054] The antagonistic effect of the three strains on the silkworm fungal pathogen was detected by plate confrontation test, and the influence on the growth of silkworm fungal mycelium was evaluated by co-culture test. Figure 3 As shown in Fig. 1, the growth of Bacillus velezensis YNSCB-1 itself and its antagonistic effect on the silkworm Beauveria bassiana BJJ-1 were better than those of Bacillus siamensis YMB-3 and Bacillus licheniformis YNDYB-2.

[0055] (II) Influence of survival of experimental silkworms fed with three strains and inoculated with Beauveria bassiana spores Experimental method: The experimental silkworms fed with bacterial liquid and inoculated with Beauveria bassiana spore suspension were the experimental group, the experimental silkworms treated with sterile water and inoculated with Beauveria bassiana spore suspension were the positive control group of Beauveria bassiana, and the experimental silkworms treated with sterile water and not inoculated with Beauveria bassiana spore suspension were the control group.

[0056] The sterile water control group (CK), the Beauveria bassiana control group (BJJ-1) and the three bacterial liquid treatment groups were set up. The concentration of Bacillus velezensis YNSCB-1 bacterial liquid was 10 7 cfu / ml for S1 experimental group, the concentration of Bacillus velezensis YNSCB-1 bacterial liquid was 108 cfu / ml was S2 experimental group; the concentration of Bacillus siamensis YMB-3 bacterial liquid was 10 7 cfu / ml was Y1 experimental group, the concentration of Bacillus siamensis YMB-3 bacterial liquid was 10 8 cfu / ml was Y2 experimental group; the concentration of Bacillus licheniformis YNDYB-2 bacterial liquid was 10 7 cfu / ml was D1 experimental group, the concentration of Bacillus licheniformis YNDYB-2 bacterial liquid was 10 7 cfu / ml was D2 experimental group. After the routine method of catalyzing green silkworm eggs, under the condition of temperature 25℃±1℃, humidity 80%±2%, normal feeding to 3rd instar silkworm, starting to feed probiotic treated mulberry leaves, the mulberry leaves treated with sterile water as control group. The mulberry leaves were soaked in sterile water or bacterial suspension for 5 min and dried for standby. Each group of silkworms was divided into 3 areas, 30 heads per area. Replace normal mulberry leaves after feeding for 24 hours each time, and repeat the above feeding method for each instar silkworm.

[0057] On the 3rd day after the 5th instar silkworm, the control group (BJJ-1) and Bacillus perseus treatment group were inoculated with Beauveria bassiana spores, and the concentration of inoculated Beauveria bassiana spore suspension was adjusted to 1×10 6 and 1×10 7 per ml; Beauveria bassiana spore suspension: 50 ml for each concentration; each silkworm in the test group was soaked in Beauveria bassiana spore suspension for 10 seconds, then taken out and dried with filter paper to dry the surface moisture and dried, and then normally fed. Record the death of silkworms every 24 hours until the Beauveria bassiana control group is all dead to terminate the experiment.

[0058] The experimental results are shown in Figure 4 , 5 and Tables 2 and 3.

[0059] Table 2 Survival rate of each experimental group after inoculation with 1×10 6 per ml of Beauveria bassiana spores

[0060] Table 3 Survival rate of each experimental group after inoculation with 1×10 7 per ml of Beauveria bassiana spores

[0061] From Figures 4-5 and Tables 2-3, Table 2 and Figure 4 recorded the survival rate of each group after inoculation with 1×10 6 per ml of Beauveria bassiana spores, among which the S1 group had the best control effect and the survival curve decreased most gently; Table 3 and Figure 5 corresponded to 1×10 7The survival rate data of high concentration spore infection showed that the survival rate of all groups was lower than that in Table 2, and the S1 group still maintained the highest survival rate, but the difference between each group was more obvious at high concentration. The overall data analysis showed that Bacillus velezensis YNSCB-1 showed the best control effect at different concentrations, and the control effect was ranked as S1>S2>DYB>YMB>BJJ control group, there was a significant dose-effect relationship (the higher the spore concentration, the lower the survival rate), and the first 72 hours after infection was the rapid rising period of mortality. This result fully verified the effective protection ability of YNSCB-1 strain on the white muscardine of silkworm.

[0062] Obviously, the above embodiments of the present application are only examples for clearly illustrating the present application, and are not intended to limit the embodiments of the present application. For ordinary skilled users in the art, other different forms of changes or variations can be made on the basis of the above description. Here, it is not necessary and impossible to exhaust all the embodiments. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A plant-derived Bacillus belye ( Bacillus velezensis YNSCB-1, characterized in that, This strain was deposited on November 3, 2025, at the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, with accession number CGMCC No. 36475.

2. A microbial inoculant, characterized in that, Includes the plant-derived Bacillus belyssus YNSCB-1 as described in claim 1.

3. The use of the plant-derived Bacillus belyceae YNSCB-1 as described in claim 1 or the microbial agent as described in claim 2 in the preparation of a drug for preventing and treating white muscular dystrophy in silkworms.

4. The application according to claim 1, characterized in that, Feeding silkworms with the plant-derived Bacillus berberis YNSCB-1 and mulberry leaves reduced the incidence of white muscular dystrophy in silkworms.

5. A drug for preventing and treating white muscular dystrophy in silkworms, characterized in that, Includes the plant-derived Bacillus belyssus YNSCB-1 of claim 1 or the microbial agent of claim 2.

6. A method for raising silkworms, characterized in that, Silkworms were fed with the plant-derived Bacillus berreatus YNSCB-1 of claim 1, the microbial agent of claim 2, or the drug of claim 5.

7. The application of the plant-derived Bacillus belye var. YNSCB-1 as described in claim 1 or the microbial agent as described in claim 2 in promoting the growth of silkworms.

8. The application according to claim 7, characterized in that, The plant-derived Bacillus berreatus YNSCB-1 was fed to silkworms together with mulberry leaves to promote silkworm growth.

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