Compound antibacterial liquid as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of microbial control, and particularly discloses a compound antibacterial liquid, a preparation method and application, and the compound antibacterial liquid is obtained by compounding a cinnamomum camphora essential oil nano-emulsion and a chitosan solution; the cinnamomum camphora essential oil nano-emulsion is an oil-in-water type nano-emulsion; the concentration of the chitosan solution is 0.5 to 1.5 percent. The method comprises the following steps: by taking a nano-emulsion as a carrier of the cinnamomum camphora essential oil and the cinnamomum camphora essential oil as an oil-phase medicine, adding a limited emulsifier to improve the emulsifying capacity of a system, and carrying out high-speed and high-pressure homogenization treatment to obtain the cinnamomum camphora essential oil nano-emulsion; the chitosan solution is added to be compounded with the cinnamomum camphora essential oil nano-emulsion, so that the activity of the cinnamomum camphora essential oil can be effectively improved, and the addition amount of the cinnamomum camphora essential oil is further reduced. The compounded antibacterial liquid has a good synergistic antibacterial effect, and the antibacterial effect is superior to the sum of the two independent effects, so that the compounded antibacterial liquid is used as a natural antibacterial agent to be applied to the prevention and treatment of the soft rot of the amorphophallus bulbifer and the amorphophallus konjac, and is particularly suitable for the prevention and treatment of the soft rot of the amorphophallus bulbifer and the amorphophallus konjac.

Description

Technical Field

[0001] The invention belongs to the technical field of microbial control, and specifically relates to a compound antibacterial liquid, a preparation method and an application thereof. Background Art

[0002] Konjac is a perennial herbaceous plant of the Araceae family. Its corm has great economic value and has become an economic crop in some mountainous and hilly areas. Konjac is currently the only plant that can synthesize konjac glucomannan in large quantities, and has great economic value and development and application potential. The huge market demand has caused the konjac planting model to shift from scattered planting to large-scale and intensive planting, which has effectively increased konjac yield and land utilization, but also aggravated the occurrence of konjac diseases, especially konjac soft rot. Konjac soft rot can cause konjac to reduce production by about 15%, and in severe cases, it can reach 30%-50%, or even a total crop failure, causing huge economic losses to growers and seriously affecting the sustainable development of the konjac industry.

[0003] Konjac soft rot is a soil-borne disease caused by some bacteria of the genera Pectobacterium, Erwinia, Enterobacter and Dickie's of the Enterobacteriaceae family. At present, the prevention and control measures for konjac soft rot include chemical pesticide control, agricultural control, disease-resistant breeding, and biological control. Chemical control can quickly and efficiently inhibit the occurrence of pests and diseases, but the duration of chemical control is short. Long-term use can easily make soft rot bacteria resistant to drugs, causing environmental pollution, threatening the ecological environment and human safety; agricultural control includes improving the climate of crop growth, adjusting cultivation methods, and building facilities and devices. It is widely used, but its control effect is limited and easily affected by environmental conditions, which is not conducive to large-scale and long-term use; the selection of excellent disease-resistant varieties is an important measure to reduce the occurrence of konjac soft rot, but genetic engineering research takes a long time; biological control has the advantages of being environmentally friendly and having a long-lasting control effect, but the effect is slow, the control effect is greatly affected by environmental conditions, and the cost is relatively high.

[0004] Based on this, the present invention is proposed. Summary of the invention

[0005] Based on the above reasons, one of the purposes of the present invention is to provide a composite antibacterial liquid, which has a good antibacterial effect and can be used to prevent and treat konjac soft rot caused by microbial infection; the second purpose is to provide the application of the composite antibacterial liquid in the prevention and treatment of konjac soft rot, so as to improve the antibacterial ability of konjac plants.

[0006] The present invention is achieved through the following technical solutions: A compound antibacterial liquid is obtained by compounding a camphor essential oil nanoemulsion and a chitosan solution; the camphor essential oil nanoemulsion is an oil-in-water nanoemulsion; and the concentration of the chitosan solution is 0.5-1.5%.

[0007] Furthermore, the mass fraction of the camphor nano essential oil in the compound antibacterial liquid is 5-10%.

[0008] Furthermore, the average particle size of the camphor essential oil nanoemulsion is 200-600 nm.

[0009] Furthermore, the preparation method of the camphor essential oil nanoemulsion is: The camphor essential oil and the emulsifier are stirred and dissolved and mixed evenly, and then mixed with sterile water to obtain a crude liquid; The crude liquid is homogenized at high speed and high pressure to obtain the camphor essential oil nanoemulsion.

[0010] Furthermore, the camphor essential oil nanoemulsion comprises 10-20 parts of camphor essential oil, 65-80 parts of sterile water and 10-15 parts of emulsifier.

[0011] Furthermore, the emulsifier is an oil-in-water emulsifier, specifically one of polyoxyethylene fatty acid ester and polysorbate.

[0012] Furthermore, the high-speed and high-pressure homogenization treatment is as follows: first, the mixed solution is homogenized by a high-speed homogenizer at 8000-10000 rpm for 5-8 minutes, and then homogenized by a high-pressure homogenizer at a pressure of 50-120 MPa for 5-10 minutes, with an interval of 10 seconds, and the high-pressure homogenization is repeated 3-5 times.

[0013] The present invention also provides a method for preparing the above-mentioned compound antibacterial liquid, comprising the following compounding steps: Diluting the camphor essential oil nanoemulsion by 2-4 times to obtain solution 1; Dissolve chitosan in 1% acetic acid solution to obtain solution 2; The solution one and the solution two are mixed evenly to obtain a compound antibacterial solution.

[0014] The invention also provides the use of the compound antibacterial liquid in the prevention and treatment of konjac soft rot, wherein the compound antibacterial liquid is sprayed on the petioles, tubers and leaves of konjac plants at intervals of 3-5 days during the growth period of konjac corms.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention uses nanoemulsion as a carrier of camphor essential oil, camphor essential oil is an oil phase drug, a limited emulsifier is added to improve the emulsification ability of the system, and the camphor essential oil nanoemulsion is obtained after high-speed high-pressure homogenization treatment; by adding chitosan solution and compounding with the camphor essential oil nanoemulsion, the activity of the camphor essential oil can be effectively improved, thereby reducing the addition amount of the camphor essential oil. The compounded antibacterial liquid has a good synergistic antibacterial effect, the camphor essential oil nanoemulsion can quickly enter the bacterial cell membrane, increase the membrane permeability, destroy the structure of the membrane, and effectively inhibit the growth and reproduction of bacteria, while the rapid film formation of chitosan makes the camphor essential oil evenly distributed on the contact surface, on the other hand, the microorganisms are agglomerated together, and interact with the negative charge on the surface of the bacteria, causing the bacterial cell membrane to demagnesize and decalcify, so that the bacteria lose activity, and the antibacterial effect is better than the sum of the two acting alone, so that the compounded antibacterial liquid is used as a natural antibacterial agent in the prevention and treatment of konjac soft rot, and is particularly suitable for the prevention and treatment of soft rot of pearl bud konjac and flower konjac. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments.It should be understood that these descriptions are exemplary only, and are not intended to limit the scope of the present invention.In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.Unspecified conditions in the embodiments are carried out according to the conditions of normal conditions or manufacturer recommendations.Reagents used or instruments that do not specify manufacturers are conventional products that can be purchased and obtained commercially.

[0017] The first embodiment of the present invention provides a composite antibacterial liquid, which is obtained by compounding a camphor essential oil nanoemulsion and a chitosan solution; the camphor essential oil nanoemulsion is an oil-in-water nanoemulsion; the concentration of the chitosan solution is 0.5-1.5%; the mass fraction of the camphor essential oil nanoemulsion in the composite antibacterial liquid is 5-10%; and the average particle size of the camphor essential oil nanoemulsion is 200-600nm.

[0018] It should be noted that, in the present invention, camphor essential oil is prepared into a nanoemulsion, the emulsion has a sustained release effect, and the droplet size is reduced, which is more conducive to the penetration of camphor essential oil and the transmission of effective components. The water-in-oil emulsion has better water permeability and can better play the role of the effective components in the camphor essential oil; and the chitosan solution has certain gelation and antibacterial effect, further improves the activity of the camphor essential oil, thereby reducing the amount of the camphor essential oil and improving the utilization rate. When the concentration of the chitosan solution is 0.5-1.5%, the compatibility with the nanoemulsion is better, and a film is quickly formed during application, so that the camphor essential oil is locked on the surface of the plant, and the retention time of the camphor essential oil is prolonged. After the two are compounded, the water-in-oil camphor essential oil nanoemulsion quickly enters the bacterial cell membrane, increases the membrane permeability, destroys the membrane structure, and effectively inhibits the growth and reproduction of bacteria. The gelation of chitosan, on the one hand, makes the camphor essential oil evenly distributed on the contact surface, and on the other hand, aggregates the microorganisms together and interacts with the negative charge on the bacterial surface, causing the bacterial cell membrane to demagnesize and decalcify, making the bacteria inactive. The synergistic effect of the two makes the antibacterial effect significant.

[0019] In some specific embodiments, the preparation method of the camphor essential oil nanoemulsion is: stirring and dissolving the camphor essential oil and the emulsifier to mix evenly, and then mixing with sterile water to obtain a crude liquid; the crude liquid is subjected to high-speed and high-pressure homogenization to obtain the camphor essential oil nanoemulsion; the emulsifier is an oil-in-water emulsifier, specifically one of polyoxyethylene fatty acid esters and polysorbate.

[0020] It should be noted that in the present invention, nanoemulsion is used as a carrier of camphor essential oil, camphor essential oil is an oil phase drug, and a limited emulsifier is added to improve the emulsification ability of the system. The camphor essential oil and the emulsifier are first mixed by a two-step method, and then mixed with water to greatly improve the solubility of the emulsifier. After two steps of high-speed homogenization and high-pressure homogenization, the crude liquid is prepared to obtain a transparent or translucent microemulsion nanoemulsion, the average particle size of which is between 200-600nm, which can improve the transfer and absorption efficiency of macromolecular essential oils in plants, thereby improving the bioavailability of essential oils in plants, while improving the stability of essential oils and reducing volatility.

[0021] The present invention also provides a method for preparing the above-mentioned compound antibacterial liquid, comprising the following compounding steps: Diluting the camphor essential oil nanoemulsion by 2-4 times to obtain solution 1; Dissolve chitosan in 1% acetic acid solution to obtain solution 2; The solution one and the solution two are mixed evenly to obtain a compound antibacterial solution.

[0022] It should be noted that, in the present invention, a camphor essential oil nanoemulsion with high stability and easy preservation is first obtained, which needs to be diluted in actual application and then mixed with a chitosan solution; chitosan has a low solubility in water and has good solubility in acetic acid solution.

[0023] The invention also provides the use of the compound antibacterial liquid in the prevention and treatment of konjac soft rot. The compound antibacterial liquid is sprayed on the petioles, tubers and leaves of konjac plants at intervals of 3-5 days during the growth period of konjac corms.

[0024] It should be noted that konjak soft rot is a bacterial disease, and the site of disease is mostly petiole, leaf or top branch. After the plant is infected, the disease extends downward to the tuber along the petiole, so that the tuber rots, and along with the aggravation of the degree of tuber and root rot, the absorption function of water and nutrients weakens, causing the blade to wither, half or all of the plant turns yellow, and the blade wilts slightly, and after the tuber and petiole junction are broken, it can be found that the broken part has some petiole tissue browning, and then the whole plant dies. The composite antibacterial liquid obtained by the present invention has significant inhibitory activity to the pathogen causing konjak soft rot, and can be applied to the prevention and treatment of konjak soft rot by the form of spraying, compared to using camphor essential oil nanoemulsion or chitosan solution alone, the antibacterial effect of the composite solution is significantly improved, greatly reducing the consumption of camphor essential oil and chitosan, reducing the use cost, and less impact on plant and soil.

[0025] It can be understood that, except for the above special instructions, other parameters of the embodiments of the present application are obtained by experiments by those skilled in the art according to general experience or actual needs. The present application is not particularly limited, and only provides some preferred embodiments. For example, in some preferred embodiments, the camphor essential oil nanoemulsion comprises 10-20 parts of camphor essential oil, 65-80 parts of sterile water and 10-15 emulsifiers; in some preferred embodiments, the high-speed high-pressure homogenization treatment is: first, the mixed solution is homogenized at 8000-10000rpm for 5-8min by a high-speed homogenizer, and then homogenized at a pressure of 50-120Mpa by a high-pressure homogenizer for 5-10min, intermittently for 10s, and cyclic high-pressure homogenization for 3-5 times.

[0026] The following will disclose specific embodiments for implementing the present application, as well as corresponding comparative examples to demonstrate the relevant technical effects of the present application.

[0027] Example 1 This embodiment 1 provides a composite antibacterial liquid, which is obtained by compounding a camphor essential oil nanoemulsion and a chitosan solution; the camphor essential oil nanoemulsion is an oil-in-water nanoemulsion with an average particle size of 400 nm; the concentration of the chitosan solution is 1%; and the mass fraction of the camphor essential oil nanoemulsion in the composite antibacterial liquid is 8%. The preparation method of the composite antibacterial liquid is as follows: Preparation of camphor essential oil nanoemulsion: by weight, 16 parts of camphor essential oil and 12 parts of polysorbate were stirred and dissolved and mixed evenly, then 72 parts of sterile water were added, and mixed evenly to obtain a crude liquid, the crude liquid was placed in a high-speed homogenizer for homogenization at 90000 rpm for 6 min, and then placed in a high-pressure homogenizer for homogenization at 100 MPa for 8 min, rested for 10 s, and circulated high-pressure homogenization for 4 times to obtain a camphor essential oil nanoemulsion; Preparation of chitosan solution: Prepare a 2% acetic acid solution, and stir 1 part of chitosan with 99 parts of 2% acetic acid solution by weight until the chitosan is completely dissolved, and mix well to obtain a 1% chitosan solution; Preparation of compound antibacterial solution: dilute the camphor essential oil nano solution by 2 times and add it into 1% chitosan solution, mix well to obtain the compound antibacterial solution.

[0028] Example 2 This embodiment 1 provides a composite antibacterial liquid, which is obtained by compounding a camphor essential oil nanoemulsion and a chitosan solution; the camphor essential oil nanoemulsion is an oil-in-water nanoemulsion with an average particle size of 550nm; the concentration of the chitosan solution is 1.5%; and the mass fraction of the camphor essential oil nanoemulsion in the composite antibacterial liquid is 5%. The preparation method of the composite antibacterial liquid is as follows: Preparation of camphor essential oil nanoemulsion: by weight, 20 parts of camphor essential oil and 10 parts of polyoxyethylene fatty acid ester were stirred and dissolved and mixed evenly, and then 70 parts of sterile water were added and mixed evenly to obtain a crude liquid, and the crude liquid was placed in a high-speed homogenizer for homogenization at 10000 rpm for 5 min, and then placed in a high-pressure homogenizer for homogenization at 120 MPa for 6 min, with an interval of 10 s, and the high-pressure homogenization was circulated for 3 times to obtain the camphor essential oil nanoemulsion; Preparation of chitosan solution: Prepare a 2% acetic acid solution, and stir 1.5 parts of chitosan with 98.5 parts of 2% acetic acid solution by weight until the chitosan is completely dissolved, and mix well to obtain a 1.5% chitosan solution; Preparation of compound antibacterial solution: dilute the camphor essential oil nano solution by 4 times and add it into 1.5% chitosan solution, mix well to obtain the compound antibacterial solution.

[0029] Example 3 This embodiment 1 provides a composite antibacterial liquid, which is obtained by compounding a camphor essential oil nanoemulsion and a chitosan solution; the camphor essential oil nanoemulsion is an oil-in-water nanoemulsion with an average particle size of 230 nm; the concentration of the chitosan solution is 0.5%; and the mass fraction of the camphor essential oil nanoemulsion in the composite antibacterial liquid is 10%. The preparation method of the composite antibacterial liquid is as follows: Preparation of camphor essential oil nanoemulsion: by weight, 20 parts of camphor essential oil and 15 parts of polysorbate were stirred and dissolved and mixed evenly, 65 parts of sterile water were added, and mixed evenly to obtain a crude liquid, the crude liquid was placed in a high-speed homogenizer for homogenization at 80000 rpm for 8 min, and then placed in a high-pressure homogenizer for homogenization at 60 MPa for 10 min, rested for 10 s, and circulated high-pressure homogenization for 5 times to obtain the camphor essential oil nanoemulsion; Preparation of chitosan solution: Prepare a 2% acetic acid solution, and stir 0.5 parts of chitosan with 99.5 parts of 2% acetic acid solution by weight until the chitosan is completely dissolved, and mix well to obtain a 0.5% chitosan solution; Preparation of compound antibacterial solution: dilute the camphor essential oil nano solution by 2 times and add it into 0.5% chitosan solution, mix well to obtain the compound antibacterial solution.

[0030] Comparative Example 1 The preparation method is the same as that of Example 1, except that the camphor essential oil nanoemulsion is prepared as a water-in-oil nanoemulsion.

[0031] Comparative Example 2 The preparation method is the same as that of Example 1, except that the concentration of the chitosan solution is 0.4%.

[0032] Comparative Example 3 The preparation method is the same as that of Example 1, except that the concentration of the chitosan solution is 1.6%.

[0033] Test Example 1 Antibacterial Test Prepare LB solid medium: Dissolve 5.0 g of yeast extract powder, 5.0 g of NaCl, 10.0 g of tryptone, 1000 mL of distilled water, and 15.0 g of agar powder, adjust the pH to 7.0, sterilize in an autoclave at 121°C for 20 min, wait for the medium to cool to 50-55°C, pour the medium onto a plate, and cool it for later use; Test 1 for determination of inhibition zone: The bacterial suspensions of three strains of konjac soft rot pathogens isolated and purified from konjac plants and determined by pathogenicity were inoculated on LB solid culture medium and evenly spread on a bacterial stick; filter papers with a diameter of 6 mm, respectively soaked with the camphor essential oil nanoemulsion in Example 1, the camphor essential oil nanoemulsion diluted 2 times, 1% chitosan solution, and the composite antibacterial liquids of Examples 1-3 and Comparative Examples 1-3, were placed in the middle of the inoculated LB culture medium, placed in a constant temperature incubator at 28° C. and cultured for 24 h, the inhibition diameter was observed, and the average value was calculated. The filter paper soaked in sterile water was used as the blank experimental group.

[0034] The results of the inhibition zone diameter measurement are shown in Table 1: Table 1 Measurement results of the diameter of the inhibition zone of the pathogenic bacteria of konjac soft rot .

[0035] Result analysis: It can be seen from Table 1 that when the four sample solutions of Example 1 (samples 1-4) were used to inhibit three kinds of konjac soft rot pathogens, due to the synergistic antibacterial effect of the camphor essential oil nanoemulsion and the chitosan solution, the inhibitory effect of the composite inhibition solution on the three kinds of konjac soft rot pathogens was stronger than that of the two when used alone, and the difference in antibacterial effect with the undiluted camphor essential oil solution was small, indicating that the antibacterial effect of the two solutions was improved after compounding, and the use of camphor essential oil could be greatly reduced. Compared with Sample 4, Sample 7 (oil-in-water camphor essential oil nanoemulsion) changed the type of camphor essential oil nanoemulsion, and its antibacterial zone was reduced and the antibacterial effect was weakened. This may be because the permeability of oil is less than that of water, and the diffusion rate of the effective ingredients is slow, resulting in a reduction in the antibacterial zone; the antibacterial zone of Sample 8 (reducing the chitosan concentration) was reduced, indicating that the chitosan content was low and the gel effect was small, resulting in a radial antibacterial zone, a reduction in the central antibacterial zone, and a weakened antibacterial effect; the antibacterial zone of Sample 9 (increasing the chitosan concentration) was also reduced, indicating that the high chitosan content enhanced the gel effect and the antibacterial effect, but the high gel property also limited the penetration of camphor essential oil, resulting in a reduction in the antibacterial zone; in summary, according to the technical solution of the present invention, the antibacterial effect of the compound antibacterial liquid can be effectively improved, while reducing the amount of camphor essential oil added.

[0036] Test Example 2 Field Observation Test The growth cycle of konjac includes several key stages. June to August is the rapid growth period of leaves and bulbs. It is also the peak period of soft rot, especially in July. Therefore, the field prevention and control observation experiment of konjac soft rot was carried out in June to August.

[0037] The field observation test was conducted in Chengdu, Sichuan Province from April to November 2023. The flower konjac sown in spring, the growth period of konjac corms is from June to August. The test site is a flat test field. Konjac has been planted in the early stage, and the konjac is of good quality, without soft rot and other diseases. The soil environment was inspected before the test. It was suitable for the growth of konjac. Two large sample plots A and B (50m×50m) were selected for prevention and treatment tests. Each experimental sample plot was 50m apart. Sample A was sprayed with the compound antibacterial liquid of Example 1 before spraying the pathogenic bacteria, and whether the plant was infected after spraying the pathogenic bacteria was observed. Sample B was sprayed with the compound antibacterial liquid of Example 1 after spraying the pathogenic bacteria, and the changes in plant lesions were observed. Different treatment groups (2m×2m) were set up in the large sample plots, with a spacing of 2m between the treatment groups, and the space was blocked by a film. Healthy konjac seed blocks were evenly sown in the test site in early April. On July 1, the konjac leaves were sprayed with the pathogenic bacteria of soft rot, and the treatment groups were treated with the following methods: Test plot A1: 30 days before spraying the pathogenic bacteria, spray the plot with antibacterial liquid; Test plot A2: 20 days before spraying the pathogenic bacteria, spray the plot with antibacterial liquid; Test plot A3: 10 days before spraying the pathogenic bacteria, spray the plot with antibacterial liquid; Test plot A4: 5 days before spraying the pathogenic bacteria, spray the plot with antibacterial liquid; Test plot B1: After spraying the pathogens, when obvious lesions appear, start spraying the compound antibacterial solution of Example 1, once every 2 days; Test plot B2: After spraying the pathogens, when obvious lesions appear, spray the compound antibacterial solution of Example 1 once every 3 days; Test sample B3: After spraying the pathogenic bacteria, when obvious lesions appear, start spraying the compound antibacterial solution of Example 1, once every 4 days; Test plot B4: After spraying the pathogenic bacteria, when obvious lesions appear, spray the compound antibacterial solution of Example 1, once every 5 days; Control group: No compound antibacterial liquid was sprayed after spraying the pathogenic bacteria; Blank group: No treatment was done on the konjac plants.

[0038] The results of the sample plot observations are shown in Table 2: Table 2 Field observation experiment results .

[0039] As can be seen from Table 2, it can be seen from the observation results of sample A that spraying the antibacterial liquid 5 days before spraying the pathogenic bacteria can effectively prevent konjac from being infected with soft rot. The composite antibacterial liquid of the present invention has the effect of preventing konjac soft rot, which may be due to the chitosan solution forming an antibacterial film on the surface of the konjac plant, which effectively resists the pathogenic bacteria; it can be seen from the observation results of sample B that after being infected with pathogenic bacteria, spraying the antibacterial liquid can effectively control the growth of lesions and can achieve the therapeutic effect by supplementing the spraying at an interval of 3 days; in summary, it can be seen that during the growth period of konjac corms, konjac soft rot can be effectively prevented at an interval of 3-5 days.

[0040] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A compound antibacterial solution, characterized in that: The compound antibacterial liquid is obtained by compounding camphor essential oil nanoemulsion and chitosan solution; the camphor essential oil nanoemulsion is an oil-in-water nanoemulsion; and the concentration of the chitosan solution is 0.5-1.5%.

2. The compound antibacterial liquid according to claim 1, characterized in that: The mass fraction of the camphor nano essential oil in the compound antibacterial liquid is 5-10%.

3. The compound antibacterial liquid according to claim 1, characterized in that: The average particle size of the camphor essential oil nanoemulsion is 200-600nm.

4. The compound antibacterial liquid according to claim 1, characterized in that: The preparation method of the camphor essential oil nanoemulsion is: The camphor essential oil and the emulsifier are stirred and dissolved and mixed evenly, and then mixed with sterile water to obtain a crude liquid; The crude liquid is homogenized at high speed and high pressure to obtain the camphor essential oil nanoemulsion.

5. The compound antibacterial liquid according to claim 4, characterized in that: The camphor essential oil nanoemulsion comprises 10-20 parts of camphor essential oil, 65-80 parts of sterile water and 10-15 parts of emulsifier.

6. The compound antibacterial liquid according to claim 4, characterized in that: The emulsifier is an oil-in-water emulsifier, specifically one of polyoxyethylene fatty acid ester and polysorbate.

7. The compound antibacterial liquid according to claim 4, characterized in that: The high-speed high-pressure homogenization treatment is as follows: firstly, the crude liquid is homogenized by a high-speed homogenizer at 8000-10000 rpm for 5-8 minutes, and then by a high-pressure homogenizer at a pressure of 50-120 MPa for 5-10 minutes, with an interval of 10 seconds, and the high-pressure homogenization is repeated 3-5 times.

8. The method for preparing the composite antibacterial solution according to any one of claims 1 to 7, characterized in that: The compounding steps include: Diluting the camphor essential oil nanoemulsion by 2-4 times to obtain solution 1; Dissolve chitosan in 1% acetic acid solution to obtain solution 2; The solution one and the solution two are mixed evenly to obtain a compound antibacterial solution.

9. Use of the composite antibacterial liquid in the prevention and treatment of konjac soft rot according to any one of claims 1 to 7.

10. The use according to claim 9, characterized in that: The compound antibacterial liquid is sprayed on the petioles, tubers and leaves of the konjac plants at intervals of 3-5 days during the growth period of the konjac corms.