Method and kit for detecting pseudomonas aeruginosa

Abstract

The application provides a kind of pseudomonas aeruginosa detection method and kit.The method comprises the following steps: S1, the sample to be measured is mixed with galactose modified magnetic nanoparticles in dispersion system, to obtain mixed dispersion system;S2, the mixed dispersion system of step S1 is placed in magnetic field, and magnetic material is obtained by magnetic separation;S3, the magnetic material of step S2 is placed in sterile liquid medium with fluorescent molecule loaded gelatinase sensitive particles and cultured, to obtain culture solution;S4, the culture solution of step S3 is centrifuged, to obtain supernatant;S5, the fluorescence intensity of the supernatant of step S4 is determined, and whether the sample to be measured contains pseudomonas aeruginosa is judged according to fluorescence intensity.The detection method provided by the application is based on the specific interaction between galactose and the surface of pseudomonas aeruginosa and the characteristics of pseudomonas aeruginosa metabolizing gelatinase, realizing the rapid detection of pseudomonas aeruginosa.

Description

Technical Field

[0001] This invention relates to the field of microbial detection technology, and in particular to a method and kit for detecting Pseudomonas aeruginosa. Background Technology

[0002] Pseudomonas aeruginosa is a common opportunistic pathogen in the natural environment and one of the main pathogens in hospitals, causing infections of wounds, the respiratory tract, and the urinary system. Current quality testing standards for food and cosmetics explicitly require that Pseudomonas aeruginosa must not be detected in samples.

[0003] Existing methods for detecting Pseudomonas aeruginosa are relatively complex. Taking GB 8538-2022, "National Food Safety Standard - Test Methods for Drinking Natural Mineral Water," as an example, the current national standard for detecting Pseudomonas aeruginosa involves: filtering a 250 mL water sample using a bacterial filter membrane; attaching the filter membrane to the surface of a solid culture medium and incubating it in a professional laboratory at a constant temperature for 20-48 hours; selecting suspected colonies, counting them, and further identifying the presence of Pseudomonas aeruginosa through tests such as pyocyanin, ammonia production, 42℃ growth, oxidase, and fluorescence.

[0004] The current national standard method for detecting Pseudomonas aeruginosa has high accuracy and specificity. However, it also has the problem of long testing time, which increases the storage costs of the food industry and is difficult to meet the timeliness requirements for food safety assurance during major social events. Summary of the Invention

[0005] In view of the technical problems existing in the background art, the present invention provides a method for detecting Pseudomonas aeruginosa. The method is based on the specific interaction between galactose and the surface of Pseudomonas aeruginosa and the characteristics of Pseudomonas aeruginosa's gelatinase metabolism, achieving rapid detection of Pseudomonas aeruginosa.

[0006] This invention provides a method for detecting Pseudomonas aeruginosa for non-diagnostic purposes, comprising the following steps:

[0007] S1. The sample to be tested is mixed with galactose-modified magnetic nanoparticles in a dispersion system to obtain a mixed dispersion system;

[0008] S2. Place the mixed dispersion system described in step S1 in a magnetic field and obtain a magnetic material through magnetic separation;

[0009] S3. Place the magnetic material described in step S2 and the gelatinase-sensitive particles carrying fluorescent molecules in a sterile liquid culture medium and culture them to obtain a culture solution.

[0010] S4. Centrifuge the culture medium obtained in step S3 to obtain the supernatant;

[0011] S5. Measure the fluorescence intensity of the supernatant described in step S4, and determine whether the sample to be tested contains Pseudomonas aeruginosa based on the fluorescence intensity.

[0012] Preferably, the concentration of the galactose-modified magnetic nanoparticles in step S1 in the mixed dispersion system is 0.08-0.15 mg / mL.

[0013] Preferably, the strength of the magnetic field in step S2 is 0.4-0.8 Tesla.

[0014] Preferably, after obtaining the magnetic material in step S2, the magnetic material is washed with sterile water.

[0015] Preferably, the concentration of the gelatinase-sensitive particles carrying fluorescent molecules in the culture medium in step S3 is 0.35-0.5 mg / mL.

[0016] Preferably, the sterile liquid culture medium in step S3 includes tryptone, yeast extract, NaCl, and water.

[0017] Preferably, the culture temperature in step S3 is 35-37℃, and the culture time is 5-10h.

[0018] Preferably, the centrifugation parameters in step S4 are 4000-6000 rpm for 2-4 minutes.

[0019] Preferably, the criteria for judgment in step S5 include:

[0020] When the fluorescence intensity of the test sample group is ≥ twice that of the fluorescence intensity of the negative control group, it is determined that the test sample contains Pseudomonas aeruginosa.

[0021] If the fluorescence intensity of the test sample group is less than twice that of the negative control group, it is determined that the test sample does not contain Pseudomonas aeruginosa.

[0022] Preferably, the detection method includes any of the following applications:

[0023] (1) The sample to be tested in step S1 is a food product; used to detect whether the food product contains Pseudomonas aeruginosa;

[0024] (2) The sample to be tested in step S1 is a cosmetic product; used to detect whether the cosmetic product contains Pseudomonas aeruginosa.

[0025] (3) The sample to be tested in step S1 is an in vitro environmental sample; used to detect whether Pseudomonas aeruginosa is present in the in vitro environment.

[0026] The present invention also provides a kit for detecting Pseudomonas aeruginosa, comprising the galactose-modified magnetic nanoparticles, the gelatinase-sensitive particles carrying fluorescent molecules, and the sterile liquid culture medium.

[0027] Beneficial effects:

[0028] This invention provides a method and kit for detecting *Pseudomonas aeruginosa*. The detection method includes the following steps: S1, mixing the sample to be tested with galactose-modified magnetic nanoparticles in a dispersion system to obtain a mixed dispersion system; S2, placing the mixed dispersion system obtained in step S1 in a magnetic field to obtain magnetic material through magnetic separation; S3, culturing the magnetic material obtained in step S2 with gelatinase-sensitive particles carrying fluorescent molecules in a sterile liquid culture medium to obtain a culture solution; S4, centrifuging the culture solution obtained in step S3 to obtain a supernatant; S5, measuring the fluorescence intensity of the supernatant obtained in step S4, and determining whether *Pseudomonas aeruginosa* is present in the sample to be tested based on the fluorescence intensity. The detection method provided by this invention is based on the specific interaction between galactose and the surface of *Pseudomonas aeruginosa*, enabling accurate identification and efficient magnetic separation of *Pseudomonas aeruginosa* in the sample to be tested; furthermore, based on the characteristics of *Pseudomonas aeruginosa*'s gelatinase metabolism, by adding gelatinase-sensitive particles carrying fluorescent molecules to a sterile liquid culture medium, rapid detection of *Pseudomonas aeruginosa* is achieved. The detection method provided by this invention can shorten the detection time of traditional Pseudomonas aeruginosa from several days to 5-10 hours, with high sensitivity and low false detection rate. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in this invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be described below.

[0030] Figure 1 This is a schematic diagram of the reaction principle for the preparation of PLAMA as described in Example 1 of this invention;

[0031] Figure 2 This is a schematic diagram illustrating the detection principle of Pseudomonas aeruginosa as described in Example 2 of the present invention;

[0032] Figure 3 This is a diagram showing the results of the Pseudomonas aeruginosa detection experiment in Example 2 of the present invention. Detailed Implementation

[0033] This invention provides a non-diagnostic method for detecting Pseudomonas aeruginosa, the method comprising step S1: mixing the sample to be tested with galactose-modified magnetic nanoparticles in a dispersion system to obtain a mixed dispersion system.

[0034] In this invention, the sample to be tested in step S1 includes a solid sample or a liquid sample; this invention does not particularly limit the amount of sample to be tested added; when the sample to be tested is a solid sample, this invention preferably uses a 400-800 mesh filter to filter solid residue; this invention does not particularly limit the source of the sample to be tested, and any Pseudomonas aeruginosa sample not for diagnostic purposes is acceptable. In a more specific embodiment of this invention, the sample to be tested can be selected from any one or more of food products, cosmetics, and in vitro environmental samples.

[0035] In this invention, the mass content of the galactose-modified magnetic nanoparticles in the mixed dispersion system in step S1 is preferably 0.08-0.15 mg / mL, more preferably 0.1 mg / mL. This invention does not particularly limit the specific source of the galactose-modified magnetic nanoparticles; any magnetic nanoparticles grafted with galactose on their surface are acceptable. In a more specific embodiment of this invention, the galactose-modified magnetic nanoparticles are preferably prepared by reacting gold-coated magnetic nanoparticles, poly(2-lactoamide methyl methacrylate) (PLAMA), and sodium borohydride. The principle of the reaction is as follows: sodium borohydride reduces the thioester bonds at the ends of PLAMA to thiol groups, and then the thiol groups coordinate with the gold on the surface of the nanoparticles, achieving the grafting of the galactose polymer onto the surface of the nanoparticles.

[0036] In this invention, the dispersion system is preferably water. Preferably, the sample to be tested is mixed with galactose-modified magnetic nanoparticles in water to obtain a mixture. In this invention, the mixing temperature is preferably 25-37°C; the mixing method is preferably shaking mixing; the shaking mixing speed is preferably 100-150 rpm; and the shaking mixing time is preferably 1-5 min, more preferably 2-3 min.

[0037] The non-diagnostic Pseudomonas aeruginosa detection method of the present invention includes step S2: placing the mixed dispersion system described in step S1 in a magnetic field and obtaining magnetic substances through magnetic separation.

[0038] In this invention, the strength of the magnetic field in step S2 is preferably 0.4-0.8 Tesla, more preferably 0.5-0.7 Tesla. This invention does not impose any particular limitation on the source of the magnetic field; any magnetic field environment that meets the strength requirements is acceptable.

[0039] After obtaining the magnetic material in step S2, the magnetic material is preferably washed with sterile water; the number of sterile water washes is preferably 3 times.

[0040] The non-diagnostic Pseudomonas aeruginosa detection method of the present invention includes step S3: placing the magnetic material described in step S2 and gelatinase-sensitive particles carrying fluorescent molecules in a sterile liquid culture medium for culture to obtain a culture solution.

[0041] This invention does not particularly limit the source of the gelatinase-sensitive particles carrying fluorescent molecules described in step S3; any gelatinase-sensitive particles coated with fluorescent molecules are acceptable. In a more specific embodiment of this invention, the gelatinase-sensitive particles carrying fluorescent molecules are gelatin particles, and the particle size of the gelatin particles is preferably 300-500 nm. In this invention, the excitation wavelength of the fluorescent molecules coated on the gelatinase-sensitive particles is preferably 480-500 nm, and the detection wavelength is preferably 510-530 nm.

[0042] This invention does not impose particular limitations on the composition, concentration, or source of the sterile liquid culture medium described in step S3; any sterile liquid culture medium suitable for culturing Pseudomonas aeruginosa in the art is acceptable. In a more specific embodiment of this invention, the sterile liquid culture medium is preferably LB medium, with the following formula: 10g tryptone, 5g yeast extract, 10g NaCl, and 950ml sterile purified water.

[0043] In this invention, the concentration of the gelatinase-sensitive particles carrying fluorescent molecules in the culture medium in step S3 is preferably 0.35-0.5 mg / mL, more preferably 0.4 mg / mL. In this invention, the culture temperature in step S3 is preferably 35-37°C, more preferably 37°C; the culture time in step S3 is preferably 5-10 h, more preferably 6-8 h.

[0044] The non-diagnostic Pseudomonas aeruginosa detection method of the present invention includes step S4: centrifuging the culture medium obtained in step S3 to obtain a supernatant. In the present invention, the centrifugation parameters in step S4 are preferably 4000-6000 rpm for 2-4 min; more preferably 5000 rpm for 3 min.

[0045] The non-diagnostic Pseudomonas aeruginosa detection method of the present invention includes step S5: measuring the fluorescence intensity of the supernatant obtained in step S4, and determining whether the sample to be tested contains Pseudomonas aeruginosa based on the fluorescence intensity.

[0046] In this invention, the criteria for judgment in step S5 preferably include:

[0047] When the fluorescence intensity of the test sample group is ≥ twice that of the fluorescence intensity of the negative control group, it is determined that the test sample contains Pseudomonas aeruginosa.

[0048] If the fluorescence intensity of the test sample group is less than twice that of the negative control group, it is determined that the test sample does not contain Pseudomonas aeruginosa.

[0049] The present invention also provides a kit for detecting Pseudomonas aeruginosa, comprising the galactose-modified magnetic nanoparticles, the gelatinase-sensitive particles carrying fluorescent molecules, and the sterile liquid culture medium.

[0050] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention. Unless otherwise specified, the experimental methods used in the embodiments are all conventional methods; the materials and reagents used are all commercially available.

[0051] Materials involved in this invention:

[0052] Lactobionic acid: Aladdin, L109639-500g; Anhydrous methanol: Sinopharm Shanghai Test, 500mL; Trifluoroacetic acid: Maclean, T818782-100ml; Hydroxyethyl methacrylate: Adamas, 40449H-25g; Hydroquinone: Maclean, HB11114-100g; Triethylamine: Shanghai Test 500mL; Dichloromethane: Shanghai Test 500mL; 4-Cyanobionic acid (phenylthiocarbamoylthio)valerate: Aladdin, C132316-1g; 2,2'-Azobisisobutyronitrile: Maclean, A800354-100g;

[0053] The instrument involved in this invention:

[0054] Vacuum drying oven: DZ-2BCIV, Tianjin Tester Instrument Co., Ltd.; Circulating water vacuum pump: SHZ-S(III) (ABS type with top water reversal), Shanghai Lichen Bangxi Instrument Technology Co., Ltd.; Rotary evaporator: Hei-VAP Core ML / G3, Heidolph, Germany; Heat-collecting constant temperature magnetic stirrer: DF-101S, Wuhan Keer Instrument Equipment Co., Ltd.; Magnetic stirrer: MS-H280-Pro, SCILOGEX, USA.

[0055] Example 1

[0056] 1. Preparation of poly(2-lactosamidomethyl methacrylate) (PLAMA)

[0057] The reaction principle for the preparation of poly(2-lactosamide-methyl methacrylate) (PLAMA) is described in [reference needed]. Figure 1 The steps include:

[0058] (1) Preparation of 2-lactosamide methyl methacrylate (LAMA)

[0059] Lactobionic acid lactone (10.0 g, 29.4 mmol) was dissolved in methanol at 40 °C, then cooled to room temperature. 2-Aminoethyl methacrylate hydrochloride (10.0 g, 60.4 mmol), triethylamine (10.0 mL), and hydroquinone (0.25 g) were then added. The mixture was stirred for 5 hours, concentrated under vacuum, and precipitated in isopropanol. The resulting white solid was filtered, washed with isopropanol, and dried under vacuum to obtain the LAMA monomer.

[0060] (2) Preparation of poly(2-lactamide methyl methacrylate) (PLAMA)

[0061] PLAMA was synthesized via RAFT using monomers, chain transfer agents, and initiators in varying molar ratios. The concentrations of PLAMA were 0.4-0.7 M, chain transfer agents 3-8 mM, and free radical initiators 1.5-4 mM. CPADB was used as the chain transfer agent, and AIBN as the initiator. CPADB, AIBN, and the monomer PLAMA were added to water, and the mixture was further degassed by bubbling nitrogen for 30 min. The reaction vessel was sealed, and the reaction was carried out at 70°C for 12 h. The polymerization process was quenched in an ice bath. The resulting solution was then poured into an excess of methanol (more than 10 times the volume of the solvent used in the polymerization process) to precipitate the polymer. The sample was then dried under vacuum to obtain the final product.

[0062] 2. Preparation of galactose-modified magnetic nanoparticles

[0063] Gold-coated magnetic nanoparticles (70-100 nm) and PLAMA were mixed and uniformly dispersed in an aqueous system. Sodium borohydride was added to the dispersion under ice-water bath conditions, and the mixture was stirred at 600 rpm for 1-2 hours to obtain galactose-modified magnetic nanoparticles with a diameter of 82-115 nm. The particle diameter was determined by dynamic light scattering.

[0064] The reaction principle is as follows: sodium borohydride can reduce the thioester bond at the end of PLAMA to a thiol group, and then the thiol group coordinates with the gold on the surface of the nanoparticles to achieve the grafting of galactose polymer on the surface of the nanoparticles.

[0065] 3. Preparation of gelatinase-sensitive particles carrying fluorescent molecules

[0066] Prepare a 1.25 g (0.05 g / mL) gelatin solution using 25 mL of deionized water. After complete dissolution (at 40℃), add 25 mL of acetone to precipitate purified gelatin. Dissolve the precipitated purified gelatin in deionized water, controlling the gelatin concentration to be 5.0-12.0 g / L, and then add FITC-labeled BSA. Adjust the pH to 12 using 1 mol / L NaOH, and then add acetone dropwise while stirring. Once the mixture turns milky white again, add a certain amount of glutaraldehyde (5%) for cross-linking. After filtration, centrifugation (10000 g for 6 min, repeated three times), nitrogen purging to remove acetone, and freeze-drying, the fluorescent gelatinase-sensitive particles with a particle size range of 300-500 nm are obtained and stored at 4℃.

[0067] Example 2

[0068] 1. Detection test for Pseudomonas aeruginosa

[0069] For the detection principle of Pseudomonas aeruginosa, please refer to [link / reference needed]. Figure 2 The main principles include: galactose can specifically recognize proteins on the surface of *Pseudomonas aeruginosa*. Therefore, after galactose-modified magnetic nanoparticles are mixed with the sample to be tested, they can specifically adhere to the surface of *P. aeruginosa* based on the interaction between galactose and the surface proteins of *P. aeruginosa*. Then, under the action of a magnetic field, if the sample contains *P. aeruginosa*, it can be separated from the mixture. *P. aeruginosa* is a gelatinase-positive bacterium, and it can metabolize a large amount of gelatinase during its growth and metabolism. In this invention, after magnetic separation, the magnetic material is co-cultured with sterile liquid culture medium and gelatinase-sensitive nanoparticles carrying fluorescent molecules. The gelatinase-sensitive nanoparticles decompose under the action of *P. aeruginosa* metabolites, releasing pre-loaded fluorescent molecules. By detecting the fluorescence intensity of the supernatant, it is possible to distinguish whether the sample contains *P. aeruginosa*.

[0070] 2. Response of different concentrations of Pseudomonas aeruginosa

[0071] Frozen samples of *Pseudomonas aeruginosa* were inoculated into LB medium (10g tryptone, 5g yeast extract, 10g NaCl, 950mL sterile water) and cultured at 37°C with shaking at 120 rpm for 12 hours to activate the bacteria. Then, 1 mL of the activated bacterial culture was added to 50 mL of sterile LB medium and cultured at 37°C with shaking at 120 rpm for 5 hours. The *Pseudomonas aeruginosa* concentration was then diluted to 10000 CFU / mL, 1000 CFU / mL, 100 CFU / mL, 10 CFU / mL, 1 CFU / mL, and 0.1 CFU / mL; no *Pseudomonas aeruginosa* was added as a negative control.

[0072] Magnetic nanoparticles were added to several serially diluted bacterial suspensions, and after shaking and co-incubation for 20 min, the suspensions were magnetically separated. The magnetically separated material was then co-cultured with sterile liquid culture medium and gelatinase-sensitive nanoparticles carrying fluorescent molecules. Samples were taken at different time intervals, centrifuged, and the fluorescence intensity changes of the supernatant were measured. The longest sampling time was 45 h. The fluorescence of the supernatant after centrifugation was measured at 520 nm using a fluorescence spectrophotometer (model F97pro), with an excitation wavelength of 490 nm.

[0073] Experimental results are as follows Figure 3 As shown, in all samples containing *Pseudomonas aeruginosa*, the fluorescence concentration in the supernatant increased rapidly; in samples without *Pseudomonas aeruginosa*, the fluorescence intensity increased extremely slowly. The presence of *Pseudomonas aeruginosa* in a sample can be determined based on the intensity of the released fluorescent molecules.

[0074] Further analysis revealed that setting the standard intensity value for detection to twice the difference after 5-10 hours of co-cultivation balances detection efficiency and accuracy. Longer detection times result in a larger difference in fluorescence intensity, leading to higher accuracy but lower efficiency. According to this standard, the false detection rate is below 5%. The detection threshold for this method is 10. -1 cfu / ml. The correlation between the cutoff value and detection efficiency and accuracy is shown in Table 1.

[0075] Table 1. Correlation between judgment values ​​and detection efficiency and test accuracy

[0076] Strength ratio 3 2 1.5 1.01 Detection time (h) Greater than 10 5-10 3-4 1-2 Accuracy (%) 100 Greater than 95 Approximately 90 Approximately 40%

[0077] Example 3

[0078] For the detection of Pseudomonas aeruginosa in liquid foods

[0079] A suspension of *Pseudomonas aeruginosa* was prepared and dispersed in milk, milk tea, and fruit juice. The final concentrations of *P. aeruginosa* were 10 CFU / ml, 1 CFU / ml, and 0.1 CFU / ml. Three replicates were set up for each concentration in the three liquid foods, resulting in a total of 27 experimental samples. Three sterile food control samples were also set up for each food, totaling 9 samples. A total of 36 samples were tested. All samples were tested using both the method of this invention and the gold standard solid culture medium method as controls. The consistency with the traditional gold standard detection results reached 97.2%.

[0080] Example 4

[0081] For the detection of Pseudomonas aeruginosa in solid foods

[0082] Pseudomonas aeruginosa was prepared at final concentrations of 10 CFU / ml, 1 CFU / ml, and 0.1 CFU / ml. 10 ml of the bacterial suspension was applied to 10 square centimeters of bread, beef patties, steak, and basa fish. Three replicates were set up for each of the four solid food products, resulting in a total of 36 experimental samples. Three sterile food control samples were set up for each food product, totaling 12 samples. A total of 48 samples were tested. All samples were tested using both the method of this invention and the gold standard solid culture medium method as controls, achieving a 95.8% consistency with the traditional gold standard detection results.

[0083] Example 5

[0084] For the detection of Pseudomonas aeruginosa in environmental water bodies

[0085] Water was collected from natural water bodies and sterilized under high temperature and high pressure. Using the sterilized water, *Pseudomonas aeruginosa* suspensions were prepared at final concentrations of 10 CFU / ml, 1 CFU / ml, and 0.1 CFU / ml, with 10 samples prepared for each concentration. Ten sterilized water samples from natural water bodies served as negative controls. All samples were tested using both the method of this invention and the gold standard solid culture medium method as controls, achieving 100% consistency with the traditional gold standard detection results.

[0086] Example 6

[0087] For the detection of Pseudomonas aeruginosa in cosmetics

[0088] Purchase five types of personal care products from the market: hand cream, facial cleanser, perfume, shower gel, and shampoo. (The text then abruptly shifts to a seemingly unrelated topic: "A concentration of 10...") 9 A suspension of *Pseudomonas aeruginosa* at CFU / ml was added to the five aforementioned personal care products, and the mixture was shaken to obtain samples with bacterial concentrations of 10 CFU / ml, 1 CFU / ml, and 0.1 CFU / ml. Three samples were prepared for each concentration gradient of each personal care product, resulting in a total of 45 experimental groups. Three sterile control samples were prepared for each personal care product, for a total of 60 samples. All samples were tested using both the method of this invention and the gold standard solid culture medium method as controls, and the consistency with the traditional gold standard detection results reached 96.7%.

[0089] The embodiments described above are merely illustrative of several implementations of the present invention, designed to facilitate a detailed understanding of the technical solutions of the present invention. However, they should not be construed as limiting the scope of patent protection. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for detecting Pseudomonas aeruginosa for non-diagnostic purposes, characterized in that, Includes the following steps: S1. The sample to be tested is mixed with galactose-modified magnetic nanoparticles in a dispersion system to obtain a mixed dispersion system; S2. Place the mixed dispersion system described in step S1 in a magnetic field and obtain a magnetic material through magnetic separation; S3. Place the magnetic material described in step S2 and the gelatinase-sensitive particles carrying fluorescent molecules in a sterile liquid culture medium and culture them to obtain a culture solution. The gelatinase-sensitive particles are gelatin particles. If Pseudomonas aeruginosa is present in the sample to be tested, the gelatinase produced by Pseudomonas aeruginosa metabolism will decompose the gelatinase-sensitive particles, thereby releasing the fluorescent molecules into the culture solution. S4. Centrifuge the culture medium obtained in step S3 to obtain the supernatant; S5. Measure the fluorescence intensity of the supernatant described in step S4, and determine whether the sample to be tested contains Pseudomonas aeruginosa based on the fluorescence intensity.

2. The detection method according to claim 1, characterized in that, The concentration of the galactose-modified magnetic nanoparticles in the mixed dispersion system in step S1 is 0.08-0.15 mg / mL.

3. The detection method according to claim 1, characterized in that, The strength of the magnetic field in step S2 is 0.4-0.8 Tesla.

4. The detection method according to claim 1, characterized in that, The concentration of the gelatinase-sensitive particles carrying fluorescent molecules in the culture medium in step S3 is 0.35-0.5 mg / mL.

5. The detection method according to claim 1, characterized in that, The sterile liquid culture medium in step S3 includes tryptone, yeast extract, NaCl, and water.

6. The detection method according to claim 1, characterized in that, The culture temperature in step S3 is 35-37℃, and the culture time is 5-10h.

7. The detection method according to claim 1, characterized in that, The centrifugation parameters in step S4 are 4000-6000 rpm for 2-4 minutes.

8. The detection method according to claim 1, characterized in that, The criteria for judgment in step S5 include: When the fluorescence intensity of the test sample group is ≥ twice that of the fluorescence intensity of the negative control group, it is determined that the test sample contains Pseudomonas aeruginosa. If the fluorescence intensity of the test sample group is less than twice that of the negative control group, it is determined that the test sample does not contain Pseudomonas aeruginosa.

9. The detection method according to any one of claims 1-8, characterized in that, The detection method includes any of the following applications: (1) The sample to be tested in step S1 is a food product; used to detect whether the food product contains Pseudomonas aeruginosa; (2) The sample to be tested in step S1 is a cosmetic product; used to detect whether the cosmetic product contains Pseudomonas aeruginosa. (3) The sample to be tested in step S1 is an in vitro environmental sample; used to detect whether Pseudomonas aeruginosa is present in the in vitro environment.

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