A strain of pristinamycetin and its bacterial agent and application

Abstract

The present application relates to the technical field of microbial separation and application, in particular to a strain of pristinamycetin and its bacterial agent and application. The pristinamycetin has been preserved in the China General Microbiological Culture Collection Center on May 12, 2026, the preservation number is CGMCC No. 38653, and the preservation unit address is: No. 3, Institute of Microbiology, Chinese Academy of Sciences, No. 1, Beichen West Road, Chaoyang District, Beijing. The 28-day degradation rate of the strain to PE is 15.88%, and the strain also has good degradation ability to PU and PP, and can be used as a microplastic biodegradation bacterium.

Description

Technical Field

[0001] This invention relates to the field of microbial isolation and application technology, specifically to a strain of Priestella megaterium, its inoculum, and its applications. Background Technology

[0002] Microplastics are plastic particles with a diameter of less than 5 mm, widely distributed in environmental media such as oceans, freshwater, soil, and the atmosphere, and have become a global environmental pollutant. Synthetic polymers such as polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), and polyurethane (PU) are extremely difficult to degrade naturally in the environment, posing a serious ecological threat due to their continuous accumulation. Furthermore, due to their large specific surface area and strong hydrophobicity, microplastics easily adsorb heavy metals, organic pollutants, and pathogenic microorganisms, forming complex pollution; they can also be ingested by plankton, shellfish, and fish, passing through the food chain and ultimately endangering human health. Therefore, developing efficient and environmentally friendly microplastic removal technologies is of significant environmental and social importance.

[0003] Currently, microplastic removal methods mainly fall into three categories: physical separation (such as filtration and sedimentation), chemical degradation (such as advanced oxidation and photocatalysis), and biodegradation. Physical methods only achieve phase transfer and cannot fundamentally eliminate the polymer structure; chemical methods are energy-intensive, prone to generating secondary pollutants (such as toxic intermediates and halogenated byproducts), and have limited applicability in complex water / soil environments. In contrast, biodegradation, especially microbial degradation, is considered the most sustainable approach to microplastic pollution control due to its mild operating conditions, good environmental compatibility, and ability to be remediated in situ.

[0004] The efficiency of microbial degradation of microplastics mainly depends on the strain's ability to adsorb and colonize plastic polymers, secrete extracellular enzymes (such as lipases, proteases, keratinases, and PETases), and metabolize polymer depolymerization products. Currently, strains with certain plastic degradation capabilities have been reported to be isolated and screened from habitats such as soil, oceans, and landfill sites. However, effective strain resources remain scarce, and degradation efficiency is low, limiting the industrial application of biodegradation technology.

[0005] Therefore, developing microorganisms that can efficiently isolate and screen microplastics and enrich the resources of plastic-degrading strains has important scientific value and application prospects. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a strain of Priestella megaterium, which is classified and named as follows: Priestia megateriumThis strain was isolated and screened from the intestines of black leaf monkeys and then cultured under directed conditions. The strain achieved a 15.88% degradation rate of PE after 28 days and also exhibited good degradation capabilities for PU and PP. Because of its excellent degradation ability for PE, PU, ​​and PP, this strain can be prepared into bacterial agents, bacterial solutions, and bacterial powders for microplastic degradation. This invention provides a new approach to the screening and domestication of bacterial strains, enriching the resources of plastic-degrading microorganisms.

[0007] To achieve the above-mentioned objectives, the specific technical solution of this invention is as follows: This invention protects a strain of *Priscilla megaterium*, whose taxonomic name is [missing information]. Priestia megaterium This strain was deposited on May 12, 2026, at the China General Microbiological Culture Collection Center (CGMCC), with accession number CGMCC No. 38653. The address of the depository is No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences.

[0008] Furthermore, the original source of the *Priestella megaterium* was fresh feces from black leaf monkeys.

[0009] Furthermore, the *Priestella megaterium* is a bacterium domesticated by PE microplastics and PU microplastics.

[0010] This invention also protects a Priestella megaterium inoculum agent, wherein the Priestella megaterium mentioned above is prepared by existing technology and will not be described in detail. For example, it can be prepared into inoculum powder, inoculum liquid, or other inoculum containing an effective number of viable bacteria.

[0011] Since the selected *Priestella megaterium* exhibits good degradation characteristics for microplastics, this invention also protects the application of *Priestella megaterium* or agents containing *Priestella megaterium* in the biodegradation of microplastics.

[0012] Furthermore, the microplastics include at least one of polyethylene, polypropylene, polystyrene, polyethylene terephthalate, polyurethane, and polybutylene adipate / terephthalate.

[0013] Preferably, in the application described, the microplastic is one or more of PE, PU, ​​and PP.

[0014] Preferably, in application, the degradation manifests as the appearance of numerous erosion pits, cracks, bacterial biofilm adhesion, yellowing, and at least one of the following degradation intermediates on the microplastic surface:

[0015] Furthermore, during application, the PE degradation process breaks down the CC backbone of PE through oxidation, generating small molecule compounds that can be metabolized and utilized by microorganisms.

[0016] Furthermore, the small molecule compounds are long-chain alkane oxidation products (including methyl dodecanoate, methyl hexadecanoate, methyl 9-octadecenoate, etc.) and medium-chain fatty acid esters.

[0017] Furthermore, in the aforementioned application, the degradation time is 9-28 days.

[0018] Furthermore, when applied to the biodegradation of microplastics, the degradation time is short; even further, this short period is more than 9 days, such as 9-28 days.

[0019] As a preferred embodiment of this application, a method for isolating and screening microplastic-degrading bacteria from black leaf monkey feces includes the following steps: Step S1: Collection and pretreatment of black leaf monkey fecal samples Fresh fecal samples from black leaf monkeys were collected, placed in sterile sampling tubes, and stored at low temperature before being transported to the laboratory. Under sterile conditions, the fecal samples were taken, diluted with sterile PBS buffer, vortexed, allowed to settle, and the supernatant was collected to obtain a fecal bacterial suspension.

[0020] Step S2: Directional Acclimation of Composite Microplastics The fecal microbial suspension obtained in step S1 was inoculated into an inorganic salt culture medium containing composite microplastics. Minimal Salt Medium In MSM, the composite microplastic is subjected to directional domestication culture; the composite microplastic is selected from at least two of polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), and polyurethane (PU); the domestication culture conditions are: 25-37℃, 150-200 rpm shaking culture, and every 5-7 days, it is transferred to fresh domestication culture medium at an inoculum rate of 5-10%, and the domestication is continuously passaged for 3-5 generations.

[0021] Step S3: Selective enrichment culture The culture medium acclimated in step S2 was spread onto MSM solid plates with a single type of microplastic as the sole carbon source, and incubated upside down in a constant temperature incubator at 25-37℃ for 3-7 days to observe the colony growth.

[0022] Step S4: Strain Isolation and Purification Select a single colony that has grown well in step S3 and inoculate it onto LB solid medium or MSM solid medium using the streak plate method. Repeat the streak purification 2 to 3 times until a pure culture strain is obtained.

[0023] Step S5: Initial screening of degradation capacity The pure culture strains obtained in step S4 were inoculated into MSM liquid medium containing microplastic films or microplastic particles, with uninoculated MSM medium as a negative control. The culture was carried out at 25–37°C and 150–200 rpm for 14–28 days. Candidate strains with degradation activity were screened by measuring the weight loss rate of microplastics.

[0024] Step S6: Rescreening and confirmation of degradation capacity For the candidate strains screened in step S5, the changes in the surface morphology of microplastics were observed by scanning electron microscopy (SEM), the changes in the functional groups on the surface of microplastics were analyzed by Fourier transform infrared spectroscopy (FTIR), and the degradation intermediates were detected by gas chromatography-mass spectrometry (GC-MS) to comprehensively confirm the microplastic degradation ability of the strains.

[0025] Step S7: Strain Identification and Preservation For the strains with microplastic degradation capabilities identified in step S6, gene analysis combined with physiological and biochemical characteristics was used for strain identification, and one representative strain was submitted to the preservation center for preservation.

[0026] Preferably, the black leaf monkey fecal samples in step S1 are collected from fresh feces of captive black leaf monkeys and transported to the laboratory for processing within 48 hours at 4°C.

[0027] Preferably, the composite microplastic in step S2 is a mixture of polyethylene (PE) microplastic particles and polyurethane (PU) microplastic particles in equal mass ratio.

[0028] Preferably, the temperature for directional domestication culture in step S2 is 30±1℃, the rotation speed is 180 rpm, and the domestication cycle is 5 generations.

[0029] Preferably, the single type of microplastic in step S3 is a PE microplastic film, a PP microplastic film, a PS microplastic particle, a PET microplastic particle, or a PU foam sheet.

[0030] Preferably, the weight loss rate of the microplastics in step S5 is calculated according to the following formula: weight loss rate (%) = (initial mass - post-treatment mass) / initial mass × 100%.

[0031] Preferably, the MSM culture medium has the following formulation: NH4NO3 1.0 g / L, KH2PO4 0.5 g / L, K2HPO4 1.5 g / L, MgSO4·7H2O 0.2 g / L, NaCl 0.5 g / L, CaCl2·2H2O 0.02 g / L, FeSO4·7H2O 0.01 g / L, pH 7.0–7.2.

[0032] Compared with existing technologies, the present invention has the following advantages: (1) This invention is the first to isolate and screen bacteria that degrade microplastics from black leaf monkey feces, enriching the resources of plastic-degrading bacteria.

[0033] (2) This invention uses a combination of SEM, FTIR, and GC-MS to systematically evaluate the degradation ability of the strains, ensuring the reliability of the screening results and the clarity of the degradation mechanism. SEM showed erosion pores and cracks on the surface of the PE film, FTIR confirmed the formation of carbonyl and hydroxyl groups, and GC-MS detected intermediate products such as methyl dodecanoate.

[0034] (3) The giant Priestella preserved in this invention has a good degradation ability for microplastics. The degradation rate of PE in 28 days is 15.88%, and it also has a good degradation ability for PU, PP and other materials (11.23% degradation rate for PU and 8.64% degradation rate for PP), providing a new strain resource for the biodegradation of microplastics. Attached Figure Description

[0035] Figure 1 This is a flowchart of the method for isolating and screening *Priscilla megaterium* strains that degrade microplastics from the intestines of black leaf monkeys according to the present invention.

[0036] Figure 2 This is a photograph of the colony growth of the *Priestella giantiformis* strain screened in Example 1 on an MSM solid plate with PE microplastics as the sole carbon source (after 5 days of incubation).

[0037] Figure 3 The images show scanning electron microscope (SEM) images of the *Priestella giantiformis* strain obtained in Example 1 before and after culturing in MSM liquid medium containing PE microplastic membranes for 28 days. Among them, A: before degradation (×5000 times), the surface is smooth and flat; B: after degradation (×5000 times), the surface has a large number of erosion pits, cracks and bacterial biofilms.

[0038] Figure 4 This is a comparison of the Fourier transform infrared (FTIR) spectra of the PE microplastic film before and after degradation by *Priscilla megaterium* strain HT-PE01 in Example 1; the black spectral line represents the untreated PE control, and the red spectral line represents the PE film treated with strain HT-PE01 for 28 days. The arrow indicates the newly added characteristic absorption peak (1715 cm⁻¹). -1 carbonyl peak, 3400 cm⁻¹ -1 (hydroxyl peak).

[0039] Figure 5Macroscopic photographs of the PU foam sheets before and after 28 days of culture in MSM liquid medium containing PU foam sheets by the *Priestella giantiformis* strain obtained in Example 3; A: Before degradation (intact, white, dense structure); B: After degradation (crushed, yellowed, loose structure).

[0040] Figure 6 The growth curve (OD) of the Priestella megaterium strain in Example 2 is shown. 600 The graph shows the dynamic changes in the weight loss rate of PE microplastics (left vertical axis) and the culture time (days) on the horizontal axis.

[0041] Figure 7 This is the mass spectrum of methyl dodecanoate, an intermediate product of the degradation of PE microplastics by the *Priestella gianti* strain detected by GC-MS analysis in Example 2. Wherein, A: Total Ion Chromatography (TIC), with the arrow indicating the target peak; B: Mass spectrum of the target peak, with a match degree of >95% with the standard spectrum of methyl dodecanoate in the NIST library.

[0042] Figure 8 Phylogenetic tree of the Priestella megaterium strain in Example 1 (neighbor-joining method, bootstrap=1000 replicates).

[0043] Figure 9 The Priestella megaterium in Example 3 Priestia megaterium Bar graph showing the degradation rate of different types of microplastics (PE, PP, PS, PET, PU, ​​PBAT) by the strain (28 days). Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and examples. It should be understood that the specific embodiments listed in this invention are merely examples, and this invention is not limited to the specific embodiments described below. For those skilled in the art, any equivalent modifications and substitutions to the embodiments described below are also within the scope of this invention. Therefore, all equivalent transformations and modifications made without departing from the spirit and scope of this invention should be covered within the protection scope of this invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. All reagents or instruments without specified manufacturers are commercially available conventional products. To better illustrate this invention, numerous specific details are given in the following specific embodiments. Those skilled in the art should understand that this invention can also be implemented without certain specific details. In some other embodiments, methods, means, equipment, and steps well known to those skilled in the art are not described in detail in order to highlight the main points of this invention.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. Unless otherwise specified, all units used in this specification are International Standard Units (SI), and all numerical values ​​and ranges appearing in this invention should be understood to include unavoidable systematic errors in industrial production.

[0046] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0047] Unless otherwise specified, "%" in the following examples refers to percentage content by mass.

[0048] Example 1: The flowchart for the isolation, screening, and preservation of Priestella megaterium is shown below. Figure 1 : 1.1 Fecal Sample Collection and Pretreatment In September 2024, fresh fecal samples were collected from three healthy adult black leaf monkeys in a nature reserve in Guizhou Province. Approximately 5 g of fecal sample was collected using a sterile sampling shovel, placed in a 50 mL sterile centrifuge tube, and transported to the laboratory within 48 hours at 4°C with an ice pack inserted.

[0049] In a sterile operating table, take 5 g of fecal sample and add 45 mL of sterile PBS buffer (pH 7.4). Vortex for 5 min to fully disperse the sample. After standing for 5 min to settle, take the supernatant to obtain a fecal bacterial suspension.

[0050] 1.2 Directional Acclimation of Composite Microplastics MSM medium (formulation: NH4NO3 1.0 g / L, KH2PO4 0.5 g / L, K2HPO4 1.5 g / L, MgSO4·7H2O 0.2 g / L, NaCl 0.5 g / L, CaCl2·2H2O 0.02 g / L, FeSO4·7H2O 0.01 g / L, pH = 7.0) was prepared, and 0.1% (w / v) of composite microplastics (PE microplastic particles and PU microplastic particles in a 1:1 mass ratio, wherein the particle size of PE microplastic particles is 200-300 μm and the particle size of PU microplastic particles is 100-200 μm) was added as the sole carbon source.

[0051] Take 5 mL of fecal bacterial suspension and inoculate it into 100 mL of the above-mentioned acclimatization medium. Incubate at 30℃ and 180 rpm on a shaker. Every 7 days, transfer the inoculum to fresh acclimatization medium at a rate of 5% (v / v) and continue acclimatization and subculturing for 5 generations.

[0052] 1.3 Selective enrichment culture The fifth-generation domestication culture medium was serially diluted to 10 with sterile PBS. -3 10 -4 10 -5 100 μL of each sample was spread onto an MSM solid plate with PE microplastic membrane (0.1%, w / v) as the sole carbon source (the PE membrane was pre-sterilized with 75% ethanol and irradiated with UV for 30 min). The plates were then incubated upside down in a 30℃ incubator for 5–7 days.

[0053] Result: As Figure 2 As shown, after 5 days of incubation, circular colonies with a diameter of about 1 to 3 mm appeared on PE-MS plates. The colonies were milky white or pale yellow, with a moist and smooth surface and neat edges. A total of 12 single colonies with different morphologies were isolated.

[0054] 1.4 Strain isolation and purification Select healthy single colonies from PE-MS plates and inoculate them onto LB agar using the streak plate method. Incubate at 30°C for 24–48 h. Repeat the streak purification process three times until a pure culture strain is obtained. Number the purified strains as HT-PE01 to HT-PE12 and store them in 4°C slant agar or -80°C glycerol tubes.

[0055] 1.5 Initial screening of degradation ability – determination of weight loss rate Twelve candidate bacterial strains were inoculated into MSM liquid medium containing PE microplastic sheets (circular sheets with a diameter of 1 cm, a thickness of approximately 0.1 mm, and an initial mass of approximately 8–10 mg), with uninoculated MSM medium serving as a negative control. Each strain was incubated in triplicate. The cultures were incubated at 30°C and 180 rpm for 28 days.

[0056] After incubation, the PE membrane was removed and washed with 2% SDS solution at 50℃ for 2 h to remove bacteria adhering to the surface. It was then repeatedly rinsed with distilled water, dried at 60℃ to constant weight, and weighed to calculate the weight loss rate. The results are shown in Table 1.

[0057] Table 1. Degradation rate of PE microplastic film by each candidate strain (28 days)

[0058] As shown in Table 1, during the 28-day culture period, strain HT-PE01 exhibited the highest weight loss rate in PE microplastics, reaching 15.88%, significantly higher than the negative control (0.33%). P The value <0.01 indicates that the strain has a strong ability to degrade PE, and it can be further developed into a strain that degrades PE.

[0059] 1.6 Confirmation of Degradation Capability – SEM Morphology Observation PE membranes before and after degradation treatment with strain HT-PE01 (treatment conditions as above) were observed using scanning electron microscopy. Sample processing steps: PE membranes were fixed with 2.5% glutaraldehyde for 24 h, dehydrated with graded ethanol, critical point dried, sputter-coated with gold, and observed under a SU8010 scanning electron microscope.

[0060] The results are as follows Figure 3 As shown. Figure 3 A in the figure shows that the PE film surface was smooth and flat before degradation, with no obvious defects; Figure 3 Figure B shows that after 28 days of treatment with strain HT-PE01, obvious bacterial biofilms appeared on the surface of the PE membrane, and the membrane surface showed a large number of irregular depressions, cracks and erosion holes, indicating that strain HT-PE01 had a significant degradation effect on the PE membrane through the surface erosion mechanism.

[0061] 1.7 Confirmation of Degradation Capacity – FTIR Functional Group Analysis FTIR analysis was performed on the PE films before and after degradation treatment. A Nicolet iS10 Fourier transform infrared spectrometer in ATR mode was used, with a scanning range of 4000–400 cm⁻¹. -1 4 cm resolution -1 .

[0062] The results are as follows Figure 4 As shown. Compared with the untreated PE control, the PE film treated with strain HT-PE01 for 28 days showed a new characteristic absorption peak in the FTIR spectrum: at 1715 cm⁻¹. -1 A carbonyl (C=O) stretching vibration peak appeared at 3400 cm⁻¹. -1 A broad peak of the hydroxyl (-OH) stretching vibration appeared nearby, in the range of 1100–1250 cm⁻¹. -1 Multiple absorption peaks of ester groups (CO) appeared within the range. The presence of carbonyl and hydroxyl groups indicates that the PE molecular chain underwent oxidative breakage, generating oxygen-containing functional groups, which is a typical characteristic of PE microbial oxidative degradation.

[0063] 1.8 Strain Identification and Preservation Genomic DNA was extracted from strain HT-PE01, and the 16S rRNA gene fragment was amplified using universal bacterial primers. The PCR product was purified, sequenced, and subjected to BLAST alignment analysis in the NCBI GenBank database.

[0064] Phylogenetic analysis of strain HT-PE01 was performed using MEGA 11 software, and a phylogenetic tree was constructed using the Neighbor-Joining (NJ) method (bootstrap value 1000 replicates). The phylogenetic tree is shown below. Figure 8 As shown, strain HT-PE01 and Priestia megaterium The model strains clustered in the same evolutionary branch, and the bootstrap support rate reached 98%.

[0065] The results showed that the 16S rRNA of strain HT-PE01 was related to... Priestia megaterium (Priestella megaterium) showed the highest similarity, reaching 99.86%. This was further supported by colony morphology and Gram staining characteristics (G...). + Based on the characteristics of the rod-shaped bacteria and their physiological and biochemical properties (positive for catalase, oxidase, gelatin liquefaction, and starch hydrolysis), strain HT-PE01 was identified as *Priscilla megaterium*. Priestia megaterium ), named Priestia megaterium HT-PE01 was deposited on May 12, 2026, at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 38653. The address of the depository is: Institute of Microbiology, Chinese Academy of Sciences, No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing.

[0066] Example 2 Degradation kinetics and degradation product analysis 2.1 Degradation kinetics determination The degradation kinetics of the *Priscilla gigantea* strain HT-PE01, screened and preserved in Example 1, were determined by culturing it in MSM medium containing PE microplastic films (0.1%, w / v) at 30°C. The growth curve and dynamic changes in the weight loss rate of the PE films were measured. Odulescence (OD) was measured every 3 days. 600 The absorbance was measured, and the PE film was removed, cleaned, dried, and weighed to calculate the cumulative weight loss rate.

[0067] Table 2. Growth curves and dynamic changes in PE weight loss rate of strain HT-PE01

[0068] The results are as follows Figure 6 As shown in Table 2, strain HT-PE01 entered the logarithmic growth phase on day 9 and reached its maximum growth (OD) around day 15. 600 =1.124), and then entered the stationary and decline phases. The weight loss rate of the PE film showed a continuous increasing trend with the culture time, increasing from 2.45% on day 9 to 15.88% on day 28. The weight loss rate showed a good positive correlation with the growth curve of the strain, indicating that the growth of the strain is directly related to the degradation and metabolism of PE.

[0069] 2.2 Analysis of Degradation Intermediate Products The culture broth of *Priscilla megaterium* strain HT-PE01, after PE degradation for 28 days, was centrifuged (12000 rpm, 10 min), and the supernatant was collected. This supernatant was extracted with ethyl acetate, dehydrated with anhydrous sodium sulfate, dried under nitrogen, and then derivatized using BSTFA. Analysis was performed using an Agilent 7890B-5977B GC-MS. Chromatographic conditions: HP-5MS capillary column (30 m × 0.25 mm × 0.25 μm), high-purity helium (1.0 mL / min) as carrier gas, temperature program: 50℃ for 2 min, increased to 300℃ at 10℃ / min, and held for 10 min.

[0070] GC-MS analysis results show that ( Figure 7 The degradation products contained a variety of long-chain alkane oxidation products, including methyl dodecanoate (retention time 12.34 min), methyl hexadecanoate (retention time 16.78 min), methyl 9-octadecenoate (retention time 19.22 min), and a variety of medium-chain fatty acid esters. Figure 7 In the chromatogram, A represents the total ion current chromatogram, and the arrow indicates the methyl dodecanoate peak; Figure 7 The B peak in the spectrum has a mass spectrum that matches the standard spectrum of methyl dodecanoate in the NIST library with a match rate of >95%. The detection of these products further confirms that strain HT-PE01 breaks down the CC skeleton of PE through an oxidation pathway, generating small molecule compounds that can be metabolized and utilized by microorganisms.

[0071] Example 3 Degradation profile analysis of different microplastic substrates To evaluate the degradation ability of the strains screened and preserved in this invention for different types of microplastics, the preserved *Priscilla gigantea* strain HT-PE01 was selected. Using PE, PP, PS, PET, PU, ​​and PBAT microplastics as the sole carbon source, the strains were cultured for 28 days according to the method in Example 1, and the weight loss rate of each substrate was measured. Specific results are shown in Table 3. Figure 5 and Figure 9 .

[0072] Table 3. Degradation rate of different types of microplastics by *Priscilla megaterium* strain HT-PE01 (28 days)

[0073] Figure 9 A bar chart (28 days) showing the degradation rates of different types of microplastics (PE, PP, PS, PET, PU, ​​PBAT) by the preserved strain of *Priestella giantiflora* HT-PE01. Figure 5 Macroscopic photographs of PU foam sheets before and after 28 days of treatment with *Priscilla megaterium* strain HT-PE01. (From Table 3 and...) Figure 9It can be seen that the *Priscilla megaterium* strain HT-PE01 exhibits the strongest degradation ability for PE (15.88%), and also shows good degradation ability for PU and PP (11.23% and 8.64%, respectively). Its degradation ability for PET and PS is relatively weaker, but it still possesses some degradation ability. Figure 5 It can be seen that the treated PU foam sheet has a loose structure, broken edges, and its color changes from white to light yellow. There are obvious signs of erosion on the surface, while the control group (undegraded) PU foam sheet maintains an intact structure.

[0074] Example 4: Comparison of degradation performance between strain HT-PE01 and existing PE-degrading bacteria The degradation efficiency of the *Priestella giantiflora* strain HT-PE01, which was screened, domesticated, and preserved in Example 1 of this invention, was compared with that of existing PE-degrading bacteria. The degradation experimental steps and conditions were the same as in Example 1, except that the 12 candidate strains in 1.5 were replaced with preserved strains and existing strains (known PE-degrading bacteria). The specific results are shown in Table 4.

[0075] Table 4. Comparison of degradation performance between strain HT-PE01 and known PE-degrading bacteria.

[0076] As shown in Table 4, the HT-PE01 strain of this invention achieved a degradation rate of 15.88% for PE films during a 28-day culture period, demonstrating a high degradation rate but a shorter degradation cycle. Compared to most soil-derived degrading bacteria (with a degradation rate of only 2.86% after 60 days), the strain of this invention exhibits a significant advantage in degradation efficiency.

[0077] Example 5: Determination of the crude enzyme degradation activity of strain HT-PE01 To further confirm that the degradation activity originates from extracellular enzymes secreted by bacteria, the preserved *Priscilla gigantea* strain HT-PE01 was inoculated into MSM liquid medium containing a PE microplastic membrane (0.1%, w / v). After culturing at 30°C and 180 rpm for 15 days, the culture was centrifuged at 4°C and 12000 rpm for 10 min, and the supernatant was collected and filtered through a 0.22 μm filter to obtain the crude enzyme solution. 10 mL of the crude enzyme solution was reacted with one PE membrane (1 cm in diameter, initial mass approximately 8–10 mg) at 30°C for 14 days, with the crude enzyme solution inactivated (boiling at 100°C for 10 min) serving as a control. The weight loss rate and changes in surface functional groups of the PE membrane were measured.

[0078] Results: The PE membrane in the crude enzyme solution treatment group showed a weight loss of 6.7% after 14 days, while the inactivated control group showed only 0.4%. FTIR also showed a carbonyl peak (1715 cm⁻¹) in the crude enzyme solution treatment group. -1 ) and hydroxyl peak (3400 cm⁻¹)-1 This result indicates that strain HT-PE01 achieves PE degradation through the secretion of an extracellular oxidase system, laying the foundation for subsequent enzyme preparation development.

[0079] The embodiments described above merely illustrate specific implementation methods of this application, and while the descriptions are detailed, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the technical solution of this application, and these modifications and improvements all fall within the scope of protection of this application.

[0080] This background section is provided to generally present the context of the invention. The work of the currently named inventors, the work to the extent described in this background section, and aspects of this section that did not constitute prior art at the time of application are neither expressly nor impliedly acknowledged as prior art to the invention.

Claims

1. A strain of Priestella megaterium, its classification name is Priestia megaterium Its features are: This strain was deposited on May 12, 2026, at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 38653. The address of the depository is: Institute of Microbiology, Chinese Academy of Sciences, No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing.

2. The *Priestella megaterium* strain as described in claim 1, characterized in that: The original source of the *Priestella megaterium* was fresh feces from black leaf monkeys, and it was selectively acclimated using PE and PU microplastics.

3. A Priestella megaterium inoculum, characterized in that: The bacterial agent contains *Priestella gianti* as described in claim 1 or 2.

4. The application of *Priscilla megaterium* as described in claim 1 or 2, or the *Priscilla megaterium* inoculant as described in claim 3, in the biodegradation of microplastics, characterized in that: The microplastics include one or more of polyethylene, polypropylene, polystyrene, polyethylene terephthalate, polyurethane, and polybutylene adipate / terephthalate.

5. The application as described in claim 4, characterized in that, The degradation is manifested by at least one of the following on the surface of the microplastic: erosion pits, cracks, bacterial biofilm adhesion, and degradation intermediate products.

6. The application as described in claim 4, characterized in that: The microplastics are one or more of PE, PU and PP.

7. The application as described in claim 4, characterized in that: During application, in the process of degrading PE, the CC skeleton of PE is broken through the oxidation pathway, generating small molecule compounds that can be metabolized and utilized by microorganisms.

8. The application as described in claim 7, characterized in that: The small molecule compounds are long-chain alkane oxidation products and medium-chain fatty acid esters.

9. The application as described in any one of claims 5-8, characterized in that: The degradation time is 9-28 days.

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