Listeria chromogenic medium formula and preparation method thereof
By using powdered phospholipids to replace traditional phosphatidylinositol in Listeria chromogenic culture medium, the problem of high production costs is solved, and the cost is significantly reduced, while ensuring the effectiveness of the detection.
Patent Information
- Application Number
- CN202510108152.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-23
- Publication Date
- 2025-04-11
AI Technical Summary
Phosphatidylinositol used in traditional Listeria chromogenic culture medium is expensive, resulting in high production costs.
Powdered phospholipids are used as a substitute, and the formula ratio is adjusted (7% to 7.3% for Listeria basal culture medium, 0.2% to 0.8%, antibacterial agent 2.5%, and the rest is purified water) and the corresponding preparation methods are formulated, including weighing and dissolving, autoclaving, solution mixing and aliquoting of plates.
It significantly reduces the production cost of Listeria chromogenic culture medium, and at the same time has little impact on the selective characteristics of Listeria, ensuring the effectiveness of the detection.
Smart Images
Figure CN119799839A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of Listeria chromogenic culture medium, in particular to a Listeria chromogenic culture medium formula and a preparation method thereof. Background Art
[0002] Listeria chromogenic medium is a culture medium used to detect and isolate Listeria, mainly used for the detection of food, medicine and environmental samples.
[0003] Relevant studies at home and abroad have shown that phosphatidylinositol can act on the specific phospholipase PI-PLC in Listeria monocytogenes, and can be used as a specific detection substrate in Listeria chromogenic culture medium. Compared with the prior art, the phosphatidylinositol (PI) in the traditional preparation method is expensive, while soybean lecithin and powdered lecithin are cheap and contain the effective ingredient phosphatidylinositol. Soybean lecithin is a product obtained by purifying and refining powdered lecithin. Powdered lecithin is a powdered soybean lecithin or sunflower seed lecithin product without oil. Its raw material comes from the concentrated phospholipids in the soybean or sunflower seed oil pressing process. It is a powdered lecithin product made by deoiling, deodorization and other purification processes. The price of powdered lecithin is one hundred times lower than that of soybean lecithin and one hundred thousand times lower than that of phosphatidylinositol. Studies have found that the use of powdered lecithin as a substrate has no significant effect on the selectivity characteristics of Listeria chromogenic culture medium. The purpose of the present invention is to overcome the deficiencies in the above-mentioned prior art and provide a Listeria chromogenic culture medium formula and a preparation method thereof. Summary of the invention
[0004] The object of the present invention is to provide a Listeria chromogenic culture medium formula and a preparation method thereof, so as to solve the problems raised in the above-mentioned background technology.
[0005] To achieve the above object, the present invention provides the following technical solution: a Listeria chromogenic culture medium, wherein the formula of the Listeria chromogenic culture medium is calculated in proportion to 7% to 7.3% of Listeria basal culture medium, 0.2% to 0.8% of powdered lecithin, 2.5% of antibacterial agent, and the rest is purified water.
[0006] Preferably, the formula of Listeria chromogenic culture medium includes 7.21% Listeria basal culture medium, 0.6% powdered lecithin, 2.5% antibacterial agent, and the rest is purified water.
[0007] Preferably, the formula of Listeria chromogenic culture medium includes 7.21% Listeria basal culture medium, 0.8% powdered lecithin, 2.5% antibacterial agent, and the rest is purified water.
[0008] Preferably, the formula of Listeria chromogenic culture medium includes 7.21% Listeria basal culture medium, 0.4% powdered lecithin, 2.5% antibacterial agent, and the rest is purified water.
[0009] Preferably, the formula of Listeria chromogenic culture medium includes 7.21% Listeria basal culture medium, 0.2% powdered lecithin, 2.5% antibacterial agent, and the rest is purified water.
[0010] A method for preparing a Listeria chromogenic culture medium comprises the following steps:
[0011] Step 1, weighing and dissolving: Place the weighed powdered lecithin in a clean and dry container, add 5-10 parts of 45°C purified water to the container, stir to dissolve, add a magnetic stirring bar, place on a magnetic stirrer and heat and stir for 1 hour; Place the weighed Listeria monocytogenes base in another clean and dry container, add purified water to the container, heat and stir to dissolve;
[0012] Step 2, high pressure sterilization: sterilize the above solution with high pressure steam at 121°C for 15 minutes, and cool to 45-50°C after sterilization;
[0013] Step 3, solution mixing: under sterile conditions, add powdered lecithin solution and antibacterial agent to the Listeria base and mix thoroughly;
[0014] Step 4, filling plates: under sterile conditions, pour sterile plates. The poured plates should not be stacked and need to be cooled and solidified as quickly as possible to obtain the culture medium.
[0015] Preferably, in step 1, the weighed powdered lecithin is placed in a clean and dry container, 8 parts of 45° C. purified water are added to the container, stirred to dissolve without large particles, a magnetic stirring bar is added, and the mixture is placed in a magnetic stirrer and heated and stirred for 1 hour.
[0016] Preferably, the cooling temperature after sterilization in step 3 is preferably 45° C. If the solution temperature is higher than 50° C., in step 4, the plate cannot solidify as quickly as possible, resulting in unevenness of the plate.
[0017] Compared with the prior art, the present invention has the following beneficial effects:
[0018] Through the Listeria chromogenic culture medium formula and preparation method recorded in the present invention, powdered lecithin is used to replace traditional phosphatidylinositol. The price of powdered lecithin is much lower than that of phosphatidylinositol, thereby significantly reducing the production cost of the Listeria chromogenic culture medium and achieving the purpose of cost saving. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 is a flow chart of the preparation method of the present invention;
[0020] Figure 2 It is the bacterial colony growth diagram of the present invention:
[0021] Specifically, Figures 2a to 2b are graphs showing the colony growth after the quality control strain was inoculated into a Listeria chromogenic culture medium and cultured at 36±1°C for 18 to 24 hours. DETAILED DESCRIPTION
[0023] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.
[0024] See attached Figure 1-2 The present invention provides a Listeria chromogenic culture medium. The formula of the Listeria chromogenic culture medium comprises 7% to 7.3% of Listeria basal culture medium, 0.2% to 0.8% of powdered lecithin, 2.5% of antibacterial agent, and the rest of purified water.
[0025] A method for preparing a Listeria chromogenic culture medium comprises the following steps:
[0026] Step 1, weighing and dissolving: place the weighed powdered lecithin in a clean and dry container, add 5 to 10 parts of 45°C purified water to the container, stir to dissolve, add a magnetic stirring bar, place it on a magnetic stirrer and heat and stir for 1 hour; place the weighed Listeria monocytogenes base in another clean and dry container, add purified water to the container, heat and stir to dissolve; preferably, place the weighed powdered lecithin in a clean and dry container, add 8 parts of 45°C purified water to the container, stir to dissolve, add a magnetic stirring bar, place it on a magnetic stirrer and heat and stir for 1 hour;
[0027] Step 2, high pressure sterilization: sterilize the above solution with high pressure steam at 121°C for 15 minutes, and cool to 45-50°C after sterilization;
[0028] Step 3, solution mixing: under sterile conditions, add powdered phospholipid solution and antibacterial agent to Listeria base and mix thoroughly; the cooling temperature after sterilization is preferably 45°C;
[0029] Step 4, filling plates: under sterile conditions, pour sterile plates. The poured plates should not be stacked and need to be cooled and solidified as quickly as possible to obtain the culture medium.
[0030] Embodiment 1:
[0031] Each 1L of culture medium includes the following components: 72.05g of Listeria basal culture medium, 8g of soybean lecithin, 25ml of antibacterial agent, and 975ml of purified water.
[0032] Press Figure 1 The method shown is to prepare the Listeria chromogenic medium.
[0033] Step 1: Weighing and dissolving: Place the weighed powdered lecithin in a clean and dry container, add 5 parts of 45°C purified water to the container, stir to dissolve, add a magnetic stirring bar, place on a magnetic stirrer and heat and stir for 1 hour; Place the weighed Listeria basal culture medium in another clean and dry container, add purified water to the container, heat and stir to dissolve;
[0034] Step 2, high pressure sterilization: sterilize the above solution with high pressure steam at 121°C for 15 minutes, and cool to 50°C after sterilization;
[0035] Step 3, solution mixing: under sterile conditions, add the powdered phospholipid solution and the antibacterial agent to the Listeria basal medium and mix thoroughly;
[0036] Step 4, filling plates: under sterile conditions, pour sterile plates. The poured plates should not be stacked and need to be cooled and solidified as quickly as possible to obtain the culture medium.
[0037] When 5 parts of purified water are used to dissolve the phospholipids in Example 1, the dissolved phospholipids are uniform and viscous liquids, which are difficult to absorb.
[0038] When the temperature of 50° C. is set to a flat plate in Example 1, the flat plate cannot solidify quickly and the flat plate becomes uneven.
[0039] Embodiment 2:
[0040] Each 1L of culture medium includes the following components: 72.05g of Listeria basal culture medium, 8g of soybean powder lecithin, 25ml of antibacterial agent, and 975ml of purified water.
[0041] Press Figure 1 The method shown is to prepare the Listeria chromogenic medium.
[0042] Step 1, weighing and dissolving: place the weighed powdered lecithin in a clean and dry container, add 10 parts of 45°C purified water to the container, stir to dissolve, add a magnetic stirring bar, place in a magnetic stirrer and heat and stir for 1 hour; place the weighed Listeria basal culture medium in another clean and dry container, add purified water to the container, heat and stir to dissolve;
[0043] Step 2, high pressure sterilization: sterilize the above solution with high pressure steam at 121°C for 15 minutes, and cool to 45°C after sterilization;
[0044] Step 3, solution mixing: under sterile conditions, add the powdered phospholipid solution and the antibacterial agent to the Listeria basal medium and mix thoroughly;
[0045] Step 4, filling plates: under sterile conditions, pour sterile plates. The poured plates should not be stacked and need to be cooled and solidified as quickly as possible to obtain the culture medium.
[0046] The method of dissolving lecithin with 10 parts of purified water in Example 2 was adopted. The dissolved lecithin was a uniform liquid and was easy to absorb. However, there were many bubbles after mixing with the Listeria basal culture medium.
[0047] By forming the flat plate at 45°C as in Example 2, the flat plate solidifies faster and the obtained flat plate is more uniform.
[0048] Embodiment 3:
[0049] Each 1L of culture medium includes the following components: 72.05g of Listeria basal culture medium, 8g of soybean powder lecithin, 25ml of antibacterial agent, and 975ml of purified water.
[0050] Press Figure 1 The method shown is to prepare the Listeria chromogenic medium.
[0051] Step 1, weighing and dissolving: Place the weighed powdered lecithin in a clean and dry container, add 8 parts of 45°C purified water to the container, stir to dissolve, add a magnetic stirring bar, place on a magnetic stirrer and heat and stir for 1 hour; Place the weighed Listeria basal culture medium in another clean and dry container, add purified water to the container, heat and stir to dissolve;
[0052] Step 2, high pressure sterilization: sterilize the above solution with high pressure steam at 121°C for 15 minutes, and cool to 45°C after sterilization;
[0053] Step 3, solution mixing: under sterile conditions, add the powdered phospholipid solution and the antibacterial agent to the Listeria basal medium and mix thoroughly;
[0054] Step 4, filling plates: under sterile conditions, pour sterile plates. The poured plates should not be stacked and need to be cooled and solidified as quickly as possible to obtain the culture medium.
[0055] In this example, 8 parts of purified water are used to dissolve the phospholipids. The dissolved phospholipids are uniform liquids, which are easy to absorb and have few bubbles after being mixed with the Listeria basal culture medium.
[0056] Embodiment 4:
[0057] Each 1L of culture medium includes the following components: 72.05g of Listeria basal culture medium, 8g of soybean lecithin (PC-35), 25ml of antibacterial agent, and 975ml of purified water.
[0058] The Listeria chromogenic medium was prepared using the same steps as in Example 3.
[0059] Embodiment 5:
[0060] Each 1L of culture medium includes the following components: 72.05g of Listeria basal culture medium, 6g of soybean powder lecithin, 25ml of antibacterial agent, and 975ml of purified water.
[0061] The Listeria chromogenic medium was prepared using the same steps as in Example 3.
[0062] Embodiment 6:
[0063] Each 1L of culture medium includes the following components: 72.05g of Listeria basal culture medium, 4g of soybean powder lecithin, 25ml of antibacterial agent, and 975ml of purified water.
[0064] The Listeria chromogenic medium was prepared using the same steps as in Example 3.
[0065] Embodiment 7:
[0066] Each 1L of culture medium includes the following components: 72.05 grams of Listeria basal culture medium, 2 grams of soybean powder lecithin, 25 milliliters of antibacterial agent, and 975 milliliters of purified water.
[0067] The Listeria chromogenic medium was prepared using the same steps as in Example 3.
[0068] Effect experiment of cultivating quality control strains.
[0069] Listeria monocytogenes ATCC 19115 and Listeria innocua ATCC 33090 were prepared into 1.0×108 cfu / mL bacterial suspensions, and 10 μL of the diluted bacterial suspensions (about 106 cfu / mL) were taken on the Listeria chromogenic medium prepared in Examples 3 to 7, inoculated using the four-zone streak method, and cultured in a constant temperature incubator at 36±1°C for 24 to 48 hours, as shown in Table 1.
[0070] Table 1: Colony growth of quality control strains inoculated into Listeria chromogenic medium
[0071]
[0072] Note: “+++” indicates good growth or obvious halo, 1 to 3 “+” indicate different halo effects, and “-” indicates no halo.
[0073] From the results in Table 1, it can be seen that in the color development medium of Examples 3 and 5, at the same addition concentration of phospholipids, the halo effect produced by powdered phospholipids as a substrate is better than that of soybean lecithin PC-35. In Examples 5 to 7, when the addition concentration of powdered phospholipids is too low, the halo effect is not obvious enough, so the addition concentration of powdered phospholipids is preferably 6 g / l.
[0074] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.
Claims
1. A Listeria chromogenic culture medium, characterized in that The formula of Listeria chromogenic culture medium is calculated in proportion: Listeria basic culture medium 7%-7.3%, powdered lecithin 0.2%-0.8%, antibacterial agent 2.5%, and the rest is purified water.
2. A Listeria chromogenic medium according to claim 1, characterized in that: The formula of Listeria chromogenic culture medium includes 7.21% Listeria basic culture medium, 0.6% powdered lecithin, 2.5% antibacterial agent, and the rest is purified water.
3. A Listeria chromogenic medium according to claim 1, characterized in that: The formula of Listeria chromogenic culture medium includes 7.21% Listeria basic culture medium, 0.8% powdered lecithin, 2.5% antibacterial agent, and the rest is purified water.
4. The Listeria chromogenic medium according to claim 1, characterized in that: The formula of Listeria chromogenic culture medium includes 7.21% Listeria basic culture medium, 0.4% powdered lecithin, 2.5% antibacterial agent, and the rest is purified water.
5. The Listeria chromogenic medium according to claim 1, characterized in that: The formula of Listeria chromogenic culture medium includes 7.21% Listeria basic culture medium, 0.2% powdered lecithin, 2.5% antibacterial agent, and the rest is purified water.
6. The method for preparing a Listeria chromogenic culture medium according to any one of claims 1 to 5, characterized in that: The steps include: Step 1, weighing and dissolving: Place the weighed powdered lecithin in a clean and dry container, add 5-10 parts of 45°C purified water to the container, stir to dissolve, add a magnetic stirring bar, place on a magnetic stirrer and heat and stir for 1 hour; Place the weighed Listeria monocytogenes base in another clean and dry container, add purified water to the container, heat and stir to dissolve; Step 2, high pressure sterilization: sterilize the above solution with high pressure steam at 121°C for 15 minutes, and cool to 45-50°C after sterilization; Step 3, solution mixing: under sterile conditions, add powdered lecithin solution and antibacterial agent to the Listeria base and mix thoroughly; Step 4, filling plates: under sterile conditions, pour sterile plates. The poured plates should not be stacked and need to be cooled and solidified as quickly as possible to obtain the culture medium.
7. The method for preparing a Listeria chromogenic culture medium according to claim 6, characterized in that: In the step 1, preferably, the weighed powdered lecithin is placed in a clean and dry container, 8 parts of purified water at 45° C. are added to the container, stirred to dissolve without large particles, a magnetic stirring bar is added, and the container is placed in a magnetic stirrer for heating and stirring for 1 hour.
8. The method for preparing a Listeria chromogenic culture medium according to claim 6, characterized in that: The cooling temperature after sterilization in step 3 is preferably 45°C.