Strain XY-144 and its fermentation supernatant and applications

Abstract

The present application relates to the field of microbial technology, and discloses a strain XY-144, fermentation supernatant and application thereof.The Latin classification of the strain XY-144 is Fangia hongkongensis, the preservation unit is China General Microbiological Culture Collection Center, the preservation address is No. 1, Xibenchengli, Chaoyang District, Beijing, the preservation number is CGMCC No: 31090, and the preservation date is June 26, 2024.The fermentation supernatant prepared from the strain XY-144 can obviously inhibit the formation of methicillin-resistant Staphylococcus aureus biofilm and remove the methicillin-resistant Staphylococcus aureus biofilm, the fermentation supernatant has good thermal stability, no antibacterial activity and toxicity are found, so that the strain XY-144 and the fermentation supernatant thereof are safe and reliable in application in the food industry, which has great advantages in food application.

Description

Technical Field

[0001] This invention relates to the field of microbial technology, and in particular to strain XY-144 and its fermentation supernatant and applications. Background Technology

[0002] Food safety has long been a major factor affecting public health, and the incidence of foodborne illnesses caused by microbial pathogens is on the rise worldwide. Methicillin-resistant Staphylococcus aureus (MRSA) is a common foodborne pathogen, and foodborne illnesses caused by it have become a global public health problem.

[0003] Currently, the main strategies for preventing and controlling foodborne diseases are the use of microbial disinfectants or exposure to low doses of ultraviolet A (UVA). However, direct killing methods may lead to problems such as the development of antibiotic resistance. In addition, these foodborne pathogens often have the ability to form biofilms, which can protect the pathogens from the cleaning process and allow them to continue to survive in the environment.

[0004] While some strategies used in the food industry to control biofilms, such as cleaning and disinfection, plasma treatment, and ultrasonic treatment, are effective, they are still difficult to completely control biofilms. Therefore, there is an urgent need for more effective and sustainable strategies to combat foodborne pathogens. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the present invention provides a strain XY-144 capable of removing biofilms or inhibiting biofilm formation and its fermentation supernatant, aiming to solve the problem of the lack of more effective and sustainable strategies to combat foodborne pathogens in the prior art.

[0006] The technical solution of the present invention is as follows:

[0007] Firstly, strain XY-144 is provided. The Latin classification name of strain XY-144 is Fangiahongkongensis. The depositary institution is the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing. The deposit number is CGMCC No. 31090, and the deposit date is June 26, 2024.

[0008] In a second aspect, a fermentation supernatant of strain XY-144 is provided, said fermentation supernatant being prepared by fermentation of strain XY-144 as described in the first aspect.

[0009] The preferred technical solution, the method for preparing the fermentation supernatant, includes the following steps:

[0010] A single colony of strain XY-144 was placed in SGTYP liquid medium and cultured by shaking to obtain a fermentation broth; the fermentation broth was then centrifuged to obtain the fermentation supernatant.

[0011] A further preferred technical solution is that the shaking culture conditions are: temperature 20-37℃, rotation speed 100-300rpm, and time 2-4 days.

[0012] A further preferred technical solution is that the centrifugation conditions are: temperature 0-10℃, rotation speed 8000-12000rpm, and time 10-30 minutes.

[0013] Thirdly, the use of strain XY-144 as described in the first aspect or fermentation supernatant as described in the second aspect in the preparation of products for removing biofilms is provided.

[0014] In a preferred embodiment, the biofilm removal product is specifically a product for removing methicillin-resistant Staphylococcus aureus (MRSA) biofilm.

[0015] Fourthly, the use of strain XY-144 as described in the first aspect or fermentation supernatant as described in the second aspect in the preparation of products that inhibit biofilm formation is provided.

[0016] In a preferred embodiment, the product that inhibits biofilm formation is specifically a product that inhibits the formation of methicillin-resistant Staphylococcus aureus biofilm.

[0017] Beneficial Effects: This invention provides a novel bacterial strain, XY-144, classified as Fangiahongkongensis. The fermentation supernatant prepared from this strain significantly inhibits and eliminates methicillin-resistant Staphylococcus aureus (MRSA) biofilms, exhibiting good thermal stability and better maintaining activity and efficacy in practical applications. Furthermore, experimental results show that the fermentation supernatant of XY-144 does not exhibit antibacterial activity and is unlikely to induce drug resistance in pathogens; it is also non-toxic, having no effect on the germination rate or sprout length of alfalfa seeds. Therefore, the application of strain XY-144 and its fermentation supernatant in the food industry is safe and reliable, offering significant advantages for food applications. Attached Figure Description

[0018] Figure 1 This is a phylogenetic tree of strain XY-144 from Example 1 and the reference strain.

[0019] Figure 2 This is a graph showing the antibacterial activity test results of the fermentation supernatant of XY-144 against MRSA in Example 2.

[0020] Figure 3This is a graph showing the results of verifying the scavenging and inhibitory activity of the fermentation supernatant of XY-144 on MRSA biofilm in Example 3.

[0021] Figure 4 This is a graph showing the results of the activity verification of each component of the fermentation supernatant of XY-144 in Example 4 in scavenging MRSA biofilm.

[0022] Figure 5 This is a graph showing the thermal stability test results of the fermentation supernatant of XY-144 in Example 5.

[0023] Figure 6 This is a graph showing the toxicity test results of the XY-144 salting-out component in Example 6. Detailed Implementation

[0024] This invention provides strain XY-144, its fermentation supernatant, and its applications. To make the purpose, technical solution, and effects of this invention clearer and more explicit, the invention is further described in detail below.

[0025] Biofilms are aggregates of microorganisms. They enhance bacterial resistance or tolerance to harsh environmental conditions, and the extracellular polymeric substance (EPS) matrix restricts the diffusion of antimicrobial drugs. Biofilm formation significantly enhances bacterial survival. However, removing mature biofilms is far more challenging than inhibiting their formation. Studies have found a positive correlation between biofilm formation and increased EPS production; disrupting EPS can achieve an anti-biofilm effect. Therefore, developing anti-biofilm methods using quorum sensing quenching as a breakthrough point holds promise. Currently, methods for removing biofilms mainly include plant-derived active products, novel antimicrobial peptides, surfactants, quorum sensing inhibitors, or quorum sensing quenching enzymes. There are few reports of biofilm-removing active substances derived from marine microorganisms, and even fewer active substances targeting foodborne pathogens.

[0026] Based on this, the present invention provides strain XY-144, which is named Fangia hongkongensis in Latin classification. The depositary institution is the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing. The deposit number is CGMCC No. 31090, and the deposit date is June 26, 2024.

[0027] Specifically, the inventors initially collected a sample of a manatee from the shallow waters of the Dapeng Nature Reserve in Shenzhen and isolated approximately 200 strains. Activity screening of these strains revealed that strain XY-144 produces substances that scavenge biofilms and inhibit biofilm formation. 16S rRNA sequence and whole genome sequence alignment analysis showed that strain XY-144 is evolutionarily closest to strain Fangia hongkongensis FSC776. T The 16S rRNA sequence similarity was 99.37%, and the number of homologous core genes was 78%, therefore it is speculated that XY-144 is a new strain.

[0028] This invention provides a fermentation supernatant of strain XY-144, which is prepared by fermenting strain XY-144 as described above.

[0029] In one embodiment, the method for preparing the fermentation supernatant includes the following steps:

[0030] A single colony of strain XY-144 was placed in SGTYP liquid medium and cultured by shaking to obtain a fermentation broth; the fermentation broth was then centrifuged to obtain the fermentation supernatant.

[0031] In a more specific embodiment, the shaking culture conditions are: temperature 20–37°C, rotation speed 100–300 rpm, and time 2–4 days.

[0032] In a more specific embodiment, the centrifugation conditions are: temperature 0–10°C, rotation speed 8000–12000 rpm, and time 10–30 minutes.

[0033] This invention provides the application of strain XY-144 as described above or the fermentation supernatant as described above in the preparation of products for removing biofilms.

[0034] In one embodiment, the biofilm removal product is specifically a product for removing methicillin-resistant Staphylococcus aureus (MRSA) biofilms.

[0035] This invention provides the application of strain XY-144 as described above or fermentation supernatant as described above in the preparation of products that inhibit biofilm formation.

[0036] In one embodiment, the product that inhibits biofilm formation is specifically a product that inhibits the formation of methicillin-resistant Staphylococcus aureus biofilm.

[0037] The present invention will be further described below through specific embodiments.

[0038] In this embodiment of the invention, the culture medium is prepared with deionized water, and the formula is as follows:

[0039] LB liquid medium: 10 g / L tryptone, 1 g / L yeast extract, 5 g / L sodium chloride.

[0040] LB solid medium: tryptone 10g / L, yeast extract 1g / L, sodium chloride 5g / L, agar 15g / L.

[0041] MA solid medium: peptone 5 g / L, yeast extract 1 g / L, ferric citrate 0.1 g / L, sodium chloride 19.45 g / L, magnesium chloride 5.98 g / L, sodium sulfate 3.24 g / L, calcium chloride 1.8 g / L, potassium chloride 0.55 g / L, sodium carbonate 0.16 g / L, potassium bromide 0.08 g / L, strontium chloride 0.034 g / L, boric acid 0.022 g / L, sodium silicate 0.004 g / L, sodium fluoride 0.0024 g / L, sodium nitrate 0.0016 g / L, disodium hydrogen phosphate 0.008 g / L, agar 15 g / L.

[0042] SGTYP liquid medium: glucose 5g / L, soluble starch 5g / L, tryptone 1g / L, yeast extract 1g / L, peptone 1g / L.

[0043] SGTYP solid medium: glucose 5g / L, soluble starch 5g / L, tryptone 1g / L, yeast extract 1g / L, peptone 1g / L, agar 15g / L.

[0044] In this embodiment of the invention, the preparation process of the fermentation supernatant of XY-144 and the overnight seed culture of MRSA is as follows:

[0045] Fermentation supernatant of XY-144: A small amount of frozen XY-144 cells were scraped onto MA solid medium and streaked, and cultured at 28°C for 3 days. A single colony was then placed in 3 mL of SGTYP liquid medium and incubated at 28°C and 200 rpm for 3 days. After centrifugation at 10,000 rpm for 20 minutes at 4°C, the fermentation supernatant of XY-144 was obtained.

[0046] Overnight seed culture of MRSA: Scrape a small amount of frozen MRSA cells onto LB solid medium and streak. Incubate at 37°C for 1 day. Take a single colony and place it in 3 mL of LB liquid medium. Incubate overnight at 37°C and 200 rpm to obtain the overnight seed culture of MRSA.

[0047] Example 1: Isolation and Identification of Strain XY-144

[0048] Strain XY-144 was collected in March 2017 from Dapeng Nature Reserve in Shenzhen. It is a symbiotic bacterium of the marine invertebrate manatee.

[0049] DNA was extracted from XY-144 using the TIANamp Bacteria DNA Kit (TIANGEN). The 16S rDNA region of XY-144 was amplified by PCR using standard forward primer 27F and reverse primer 1492R. Sequencing was then performed to obtain the 16S rRNA sequence data of XY-144. Comparative analysis showed that the 16S rRNA sequence of XY-144 is similar to that of Fangia hongkongensis FSC776. T The 16S rRNA sequence of XY-144 showed a similarity of 99.37%, thus identifying XY-144 as belonging to Fangia hongkongensis. The 16S rRNA sequence of XY-144 has been submitted to the GenBank database, accession number OR262794.1.

[0050] DNA was extracted from XY-144 using the TIANamp Bacteria DNA Kit (TIANGEN), and sequenced to obtain the whole genome data of XY-144. A phylogenetic tree was then constructed based on the sequencing results, as detailed below. Figure 1 As shown. By Figure 1 It can be seen that XY-144 belongs to the genus Fangia, and the most closely related strain is Fangia hongkongensis FSC776. T The core gene homology is 78%, therefore it is speculated that XY-144 is a new strain.

[0051] XY-144 was deposited on June 26, 2024, at the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, with accession number CGMCCNo: 31090.

[0052] Example 2: Antibacterial activity of strain XY-144

[0053] The overnight seed culture of MRSA was diluted 1000 times with LB liquid medium, and 40 μL was spread onto LB solid medium, with circular paper discs placed on top. 5 μL each of the fermentation supernatant of XY-144, SGTYP liquid medium (negative control), and SGTYP liquid medium containing 5 μg / mL vancomycin (positive control) were spotted onto circular paper discs, and then incubated at 37°C for 1 day. The experimental results are as follows: Figure 2 As shown. Figure 2 In this context, 1 refers to the addition of XY-144 fermentation supernatant; 2 refers to the addition of SGTYP liquid medium; and 3 refers to the addition of SGTYP liquid medium containing 5 μg / mL vancomycin. Figure 2 It can be seen that the fermentation supernatant of XY-144 has no antibacterial activity against MRSA.

[0054] Example 3: Verification of biofilm scavenging and inhibitory activities of strain XY-144

[0055] Overnight MRSA seed culture was diluted 100-fold by volume in LB liquid medium containing 0.5% (w / v) glucose, and 1 mL / well was added to each well of a 24-well plate. After incubation at 37°C for 1 day, the bacterial culture was slowly aspirated using a pipette to obtain 24-well plates containing MRSA biofilm. XY-144 fermentation supernatant was diluted with LB liquid medium containing 0.5% (w / v) glucose to obtain different concentrations (75%, 50%, 25%, 12.5%, and 6.25% of the XY-144 fermentation supernatant volume). 1 mL / well of these dilutions was slowly added to each well of the 24-well plate containing MRSA biofilm. SGTYP liquid medium was also diluted in the same proportion and added as a negative control. After incubation at 37°C for 1 day, the bacterial culture was slowly aspirated using a pipette, washed once with physiological saline, dried at 37°C for 30 minutes, fixed at 65°C for 30 minutes, and then cooled to room temperature. Add 1 mL of 0.1% (w / v) crystal violet solution to each well for staining. Wash off the stain after 5 minutes, dry, and observe the biofilm removal effect. (Specific details are as follows...) Figure 3 As shown in (a). Figure 3 In (a), 144 75% refers to a dilution containing 75% (v / v) XY-144 fermentation supernatant; 144 50% refers to a dilution containing 50% (v / v) XY-144 fermentation supernatant; 144 12.5% ​​refers to a dilution containing 12.5% ​​(v / v) XY-144 fermentation supernatant; 144 6.25% refers to a dilution containing 6.25% (v / v) XY-144 fermentation supernatant; SG 75% refers to a dilution containing 75% (v / v) SGTYP liquid medium; SG 50% refers to a dilution containing 50% (v / v) SGTYP liquid medium; SG 12.5% ​​refers to a dilution containing 12.5% ​​(v / v) SGTYP liquid medium; SG 6.25% refers to the addition of a dilution containing 6.25% (v / v) SGTYP liquid medium. Figure 3 As shown in (a), the fermentation supernatant of XY-144 has a scavenging effect on MRSA biofilm, and the scavenging effect increases with the increase of the proportion of fermentation supernatant.

[0056] Overnight MRSA seed culture was diluted 100-fold by volume with LB liquid medium containing 0.5% (w / v) glucose, and 1 mL / well was added to each well of a 24-well plate to obtain MRSA-containing 24-well plates. XY-144 fermentation supernatant was diluted with LB liquid medium containing 0.5% (w / v) glucose to obtain different concentrations (75%, 50%, 25%, 12.5%, and 6.25% of the XY-144 fermentation supernatant volume). 1 mL / well of each dilution was slowly added to each well of the MRSA-containing 24-well plates. SGTYP liquid medium was also diluted in the same proportion and added as a negative control. After incubation at 37°C for 1 day, the bacterial culture was slowly aspirated with a pipette, washed once with physiological saline, dried at 37°C for 30 minutes, fixed at 65°C for 30 minutes, and then cooled to room temperature. Add 1 mL of 0.1% (w / v) crystal violet solution to each well for staining. Wash off the stain after 5 minutes, dry, and observe the inhibitory effect on the biofilm. (Specific details are as follows...) Figure 3 As shown in (b). Figure 3 In (b), 144 75% refers to a dilution containing 75% (v / v) XY-144 fermentation supernatant; 144 50% refers to a dilution containing 50% (v / v) XY-144 fermentation supernatant; 144 12.5% ​​refers to a dilution containing 12.5% ​​(v / v) XY-144 fermentation supernatant; 144 6.25% refers to a dilution containing 6.25% (v / v) XY-144 fermentation supernatant; SG 75% refers to a dilution containing 75% (v / v) SGTYP liquid medium; SG 50% refers to a dilution containing 50% (v / v) SGTYP liquid medium; SG 12.5% ​​refers to a dilution containing 12.5% ​​(v / v) SGTYP liquid medium; SG 6.25% refers to the addition of a dilution containing 6.25% (v / v) SGTYP liquid medium. Figure 3 As shown in Figure (b), the fermentation supernatant of XY-144 has an inhibitory effect on the formation of MRSA biofilm, and the inhibitory effect increases with the increase of the proportion of fermentation supernatant.

[0057] Example 4: Isolation and purification of active ingredients from strain XY-144

[0058] Tris-HCl buffer (1M, pH 8) was added to the fermentation supernatant of XY-144 until the volume percentage of Tris-HCl buffer was 10%. Ammonium sulfate powder was then slowly added until the mass concentration was 50%. The mixture was then incubated overnight at 4°C to precipitate the protein, resulting in a precipitated protein solution. The precipitated protein solution was centrifuged at 10,000 rpm for 20 minutes at 4°C, the supernatant was discarded, and the precipitate was resuspended in ddH2O to obtain the precipitated sample. Salting out the precipitated sample was then performed. Before salting out, the dialysis bag (Beyotime, 44mm, 14kDa) was sequentially boiled for 10 minutes with dialysis bag treatment solution (2% (w / v) NaHCO3, 1M EDTA, pH 8), ddH2O, 1M EDTA, and ddH2O, followed by cooling. After leak testing, the above-mentioned precipitated sample was added to a dialysis bag and dialyzed for 20 hours at 4°C using ddH2O as the dialysate on a horizontal shaker at 80 rpm. The dialysate was replaced 3 times during the process. After the last replacement, the sample was dialyzed for another 2 hours to obtain the XY-144 salting-out fraction.

[0059] The XY-144 salting-out fraction was concentrated using an ultrafiltration tube (Millipore, 3 kDa). The resulting filtrate and concentrate were designated as XY-144 filtrate and XY-144 ultrafiltration fraction, respectively. The XY-144 ultrafiltration fraction was then further purified using an anion exchange column. A 3 mL column of DEAE homogenate resin was packed into the column, washed sequentially with 3 column volumes of 2M NaCl solution and ddH2O, and then equilibrated with 3 column volumes of 20 mM Tris-HCl buffer (pH = 8). Finally, 6 mL of the XY-144 ultrafiltration fraction was loaded onto the column. The sample was washed with three column volumes of 20 mM Tris-HCl (pH 8) solution containing 0.1 M NaCl to obtain the XY-144 sample pass-through, denoted as FT. Then, it was eluted sequentially with three column volumes of 20 mM Tris-HCl (pH 8) solutions containing 0.1 M, 0.25 M, 0.5 M, and 1 M NaCl to obtain the XY-144 eluent, denoted as E. 0.1 E 0.25 E 0.5 And E1; finally, the column was regenerated with 4 column volumes of 20 mM Tris-HCl (pH 8) solution containing 2 M NaCl.

[0060] The collected components and SGTYP liquid medium (negative control) were diluted with LB liquid medium containing 0.5% (w / v) glucose to verify their activity in scavenging MRSA biofilms. For specific procedures, please refer to Example 3. The experimental results are as follows: Figure 4 As shown. Figure 4In (a), 20% salting out refers to the addition of a diluent containing 20% ​​(v / v) XY-144 salting out component; 10% salting out refers to the addition of a diluent containing 10% (v / v) XY-144 salting out component; 20% ultrafiltration refers to the addition of a diluent containing 20% ​​(v / v) XY-144 ultrafiltration component; 10% ultrafiltration refers to the addition of a diluent containing 10% (v / v) XY-144 ultrafiltration component; 20% negative control refers to the addition of a diluent containing 20% ​​(v / v) SGTYP liquid medium; 10% negative control refers to the addition of a diluent containing 10% (v / v) SGTYP liquid medium; 10% filtrate refers to the addition of a diluent containing 10% (v / v) XY-144 filtrate; and the blank control did not contain any component. Figure 4 In (b), FT 10% refers to the addition of a diluent containing 10% (v / v) of the XY-144 sample pass solution; E 0.1 5% refers to the addition of 5% (v / v) XY-144 elution component E. 0.1 diluent; E 0.25 5% refers to the addition of 5% (v / v) XY-144 elution component E. 0.25 diluent; E 0.5 5% refers to the addition of 5% (v / v) XY-144 elution component E. 0.5 The diluent; E1 5% refers to the addition of a diluent containing 5% (v / v) XY-144 elution fraction E1; the blank control did not contain any components. Figure 4 It can be seen that the XY-144 salt-precipitated fraction after salting out and the XY-144 ultrafiltration fraction after salting out and ultrafiltration concentration still have a scavenging effect on MRSA biofilm. However, the XY-144 filtrate after ultrafiltration did not show a scavenging effect on MRSA biofilm. The results of anion exchange purification of the ultrafiltration fraction showed that among the XY-144 eluents after DEAE column elution, only the XY-144 eluent E eluted with 20mM Tris-HCl (pH 8) solution containing 0.25M NaCl was effective. 0.25 It has the activity of scavenging MRSA biofilm.

[0061] Example 5: Thermal stability test of active ingredients in strain XY-144

[0062] The fermentation supernatant of XY-144 was incubated at 28℃, 40℃, 60℃, 80℃, and 100℃ for 30 minutes, then cooled to room temperature for activity verification in scavenging MRSA biofilm. Overnight MRSA seed culture was diluted 100-fold by volume with LB liquid medium containing 0.5% (w / v) glucose, and 1 mL / well was added to a 24-well plate. After incubation at 37℃ for 1 day, the bacterial culture was slowly aspirated using a pipette to obtain 24-well plates containing MRSA biofilm. Fermentation supernatants of XY-144 treated at different temperatures were diluted with LB liquid medium containing 0.5% (w / v) glucose to a volume ratio of 50% of the treated XY-144 fermentation supernatant. 1 mL / well was then slowly added to each well of a 24-well plate containing MRSA biofilm. SGTYP liquid medium was also diluted and added as a negative control. After incubation at 37°C for 1 day, the bacterial culture was slowly aspirated with a pipette, washed once with physiological saline, dried at 37°C for 30 minutes, fixed at 65°C for 30 minutes, and then cooled to room temperature. 1 mL of 0.1% (w / v) crystal violet solution was added to each well for staining, and the stain was washed off after 5 minutes. The plate was then dried. The biofilm removal effect was as follows: Figure 5 As shown in (a). Then, the pigment was dissolved in 5 mL of 30% (v / v) acetic acid solution, mixed well, and 100 μL was taken for OD measurement using a microplate reader. 550 The test results are as follows Figure 5 As shown in (b). From Figure 5 It can be seen that the fermentation supernatant of XY-144 has good thermal stability, and its activity in scavenging MRSA… biofilm removal remains very good after incubation at 60℃ for 30 minutes.

[0063] Example 6: Toxicity test of the active ingredient in strain XY-144

[0064] Tris-HCl buffer (1M, pH 8) was added to the fermentation supernatant of XY-144 until the volume percentage of Tris-HCl buffer was 10%. Ammonium sulfate powder was then slowly added until the mass concentration was 50%. The mixture was then incubated overnight at 4°C to precipitate the protein, resulting in a precipitated protein solution. The precipitated protein solution was centrifuged at 10,000 rpm for 20 minutes at 4°C, the supernatant was discarded, and the precipitate was resuspended in ddH2O to obtain the precipitated sample. Salting out the precipitated sample was then performed. Before salting out, the dialysis bag (Beyotime, 44mm, 14kDa) was sequentially boiled for 10 minutes with dialysis bag treatment solution (2% (w / v) NaHCO3, 1M EDTA, pH 8), ddH2O, 1M EDTA, and ddH2O, followed by cooling. After leak testing, the precipitated sample was added to a dialysis bag and dialyzed for 20 hours at 4°C using ddH2O as the dialysate on a horizontal shaker at 80 rpm, with the dialysate replaced three times. After the last dialysate replacement, dialyzing was performed for another 2 hours to obtain the XY-144 salting-out fraction. Alfalfa seeds were soaked in water, rinsed thoroughly with water on a filter screen, then soaked in sodium hypochlorite (10-fold diluted 84 disinfectant) for 10 minutes, washed 4-5 times with sterile water, air-dried, and stored in 50 mL EP tubes with desiccant. Fifty seeds were weighed into a petri dish, and 20 mL of sterile water containing 10% (v / v) XY-144 salting-out fraction was added. The mixture was incubated at 25°C. The negative control group consisted of 20 mL of sterile water. Observations and records were made at 24 and 48 hours. The results are as follows: Figure 6 As shown. By Figure 6 It is known that the XY-144 salting-out component has no effect on the germination of alfalfa, neither on the germination rate nor the length of the shoots, and is not toxic.

[0065] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. Strains XY-144, characterized in that, The Latin classification name of the strain XY-144 is... Fangia hongkongensis The depositary institution is the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing. The deposit number is CGMCC No. 31090, and the deposit date is June 26, 2024.

2. The fermentation supernatant of strain XY-144, characterized in that, The fermentation supernatant was prepared by fermentation of strain XY-144 as described in claim 1.

3. The fermentation supernatant according to claim 2, characterized in that, The method for preparing the fermentation supernatant includes the following steps: A single colony of strain XY-144 was placed in SGTYP liquid medium and cultured by shaking to obtain a fermentation broth; the fermentation broth was then centrifuged to obtain the fermentation supernatant.

4. The fermentation supernatant according to claim 3, characterized in that, The conditions for the shaking culture are: temperature 20~37℃, rotation speed 100~300rpm, and time 2~4 days.

5. The fermentation supernatant according to claim 3, characterized in that, The centrifugation conditions are: temperature 0~10℃, rotation speed 8000~12000rpm, and time 10~30 minutes.

6. The use of strain XY-144 as described in claim 1 or the fermentation supernatant as described in any one of claims 2 to 5 in the preparation of products for removing methicillin-resistant Staphylococcus aureus biofilms.

7. The use of strain XY-144 as described in claim 1 or the fermentation supernatant as described in any one of claims 2 to 5 in the preparation of a product that inhibits the formation of methicillin-resistant Staphylococcus aureus biofilm.

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