Stenotrophomonas maltophilia, bacterial agent, uses and methods

Abstract

Stenotrophomonas maltophilia, microbial agent, use and method. The stenotrophomonas maltophilia QY1 strain provided in the application can grow rapidly with nanometer polystyrene as the only carbon source, can significantly reduce the concentration and molecular weight of plastic, and can degrade polystyrene into styrene monomer. The widespread plastic pollution in the environment still has a wide demand for degrading bacteria, and the present technology enriches the plastic degrading bacteria resource library. The plastic degrading bacterial strain enrichment method provided in the application can aim at the difficulties in enriching plastic degrading bacteria, create an enrichment scene that is conducive to stimulating growth and gradual domestication, is simple to operate, low in cost, and can high-throughput enrich plastic degrading bacterial strains.

Description

TECHNICAL FIELD

[0001] The present disclosure generally relates to the field of microbiology, and in particular to a Stenotrophomonas maltophilia, a microbial inoculant comprising the same, uses thereof, a method for degrading polystyrene, and a method for enriching plastic-degrading bacteria. BACKGROUND

[0002] Plastic pollution is one of the most pressing ecological and health problems in the world today. Micro- and nano-plastics affect surface water, soil, air quality, and even the Earth's biochemical cycle, and even threaten the health of plants, animals, and humans. Plastic is ubiquitous, and production and emissions continue to rise. Micro- and nano-plastics are widely detected in surface water such as oceans, rivers, lakes, air, and soil. According to the Global Plastics Outlook: Economic Drivers, Environmental Impacts, and Policy Options published by OECD, the global plastic production soared from 234 million tons in 2000 to 460 million tons in 2019, and plastic waste increased from 156 million tons in 2000 to 353 million tons in 2019. Among them, polystyrene is the fourth largest general-purpose plastic in China, and is widely used to produce foam lunch boxes, water cups, etc., which easily generates microplastics and enters the human body through diet, threatening health.

[0003] Microorganisms have the characteristics of wide distribution, strong vitality, low cost, separability, environmental protection, etc., and the use of microorganisms to degrade microplastics is an important method for removing and controlling microplastics in the environment. Enriching plastic-degrading bacteria is a key cornerstone of biodegrading plastics, and the current screening and domestication of plastic-degrading bacteria may only be the "tip of the iceberg" of environmental microbial dark matter. The large amount and wide range of plastic pollution in the environment still has an important demand for degrading bacteria. SUMMARY

[0004] Therefore, the present disclosure provides a Stenotrophomonas maltophilia, which is Stenotrophomonas maltophilia QY1 (CCTCC No: M 20241862).

[0005] In another aspect, the present disclosure also provides a microbial inoculant comprising the Stenotrophomonas maltophilia QY1 described herein.

[0006] In another aspect, the application also provides a use of the Stenotrophomonas maltophilia QY1 described herein or the microbial agent described herein in degrading polystyrene. The strain can grow well and proliferate rapidly when cultured with polystyrene as the sole carbon source, and can tolerate 1-5000 mg / L of polystyrene. After 7 days of treatment with the Stenotrophomonas maltophilia QY1 strain, the concentration of the plastic is reduced as detected by a fluorescence microplate reader, the molecular weight of the plastic is reduced as detected by gel permeation chromatography, and the plastic degradation monomers are identified by a gas chromatograph-mass spectrometer, indicating that the strain has the ability to degrade polystyrene.

[0007] In another aspect, the application also provides a method for degrading polystyrene, comprising co-culturing the Stenotrophomonas maltophilia described herein or the microbial agent described herein with polystyrene.

[0008] In another aspect, the application also provides a method for enriching plastic-degrading bacteria, comprising the following steps:

[0009] 1) Culturing mixed strains in the sample in mineral water to form a bacterial solution;

[0010] 2) Culturing the strains in the bacterial solution with a liquid plastic-degrading bacteria enrichment medium (PEM medium);

[0011] 3) Culturing the surviving strains in step 2) with a solid plastic-degrading bacteria purification medium (PPM medium) supplemented with plastic as the sole carbon source to obtain strains that can survive and grow well;

[0012] 4) Diluting the strains obtained in step 3) and further culturing them in a microwell plate containing a solid plastic-degrading bacteria purification medium (PPM medium) supplemented with plastic as the sole carbon source to screen strains that can degrade plastic.

[0013] The application provides a Stenotrophomonas maltophilia, which is named Stenotrophomonas maltophilia QY1. It is preserved in the China Center for Type Culture Collection, located at No. 299, Bayi Road, Wuchang District, Wuhan City, Hubei Province, China, and the preservation date is August 28, 2024. The preservation number is CCTCC No: M 20241862.

[0014] Compared with the prior art, the application has the following beneficial effects:

[0015] (1) The plastic-degrading strain enrichment method provided by the application can address the difficulties in plastic-degrading bacteria enrichment, create an enrichment environment that is conducive to stimulating growth and gradual domestication, and has the advantages of simple operation, low cost, and high-throughput enrichment of plastic-degrading strains.

[0016] (2) The Stenotrophomonas maltophilia QY1 strain provided in the application can grow rapidly with nanometer polystyrene as the sole carbon source, can significantly reduce the concentration and molecular weight of plastics, and can degrade polystyrene into styrene monomer. The widespread plastic pollution in the environment still has a wide demand for degrading bacteria, and the present technology enriches the plastic degrading bacterial resource library.

[0017] (3) The Stenotrophomonas maltophilia QY1 strain provided in the application can provide a basis for in-depth study of the microbial degradation mechanism of polystyrene and the improvement of the degradation function through genetic engineering.

[0018] Other features and advantages of the present application will be set forth in the specification, and in part will become apparent from the specification, or can be learned by practice of the present application. Other advantages of the present application can be realized and obtained by the embodiments described in the specification and drawings. BRIEF DESCRIPTION OF DRAWINGS

[0019] The accompanying drawings are included to provide an understanding of the present application technical solution, and constitute a part of the specification, and together with the embodiments of the present application are used to explain the present application technical solution, and do not constitute a limitation on the present application technical solution.

[0020] Figure 1 The growth of Stenotrophomonas maltophilia QY1 with polystyrene as the sole carbon source in an embodiment of the present application.

[0021] Figure 2 In the degradation system of an embodiment of the present application, the laser confocal high-content imaging microscope graph showing the change in the number of Stenotrophomonas maltophilia QY1 cells. The left graph is 0h, and the right graph is 7d.

[0022] Figure 3 In the degradation system of an embodiment of the present application, Stenotrophomonas maltophilia QY1 grows in tolerance to different concentrations of polystyrene plastics. The upper graph is 3d, and the lower graph is 7d.

[0023] Figure 4 In the degradation system of an embodiment of the present application, the polystyrene degradation monomer detected by pyrolysis mass spectrometry.

[0024] Figure 5 In the degradation system of an embodiment of the present application, the graph of the change in the concentration of polystyrene.

[0025] Figure 6 In the degradation system of an embodiment of the present application, the graph of the change in the molecular weight of polystyrene. DETAILED DESCRIPTION

[0026] Technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains unless specifically defined otherwise. When referring to a quantity, concentration, or other value or parameter, the use of the term "about" in connection with a range, preferably a range that is expressed as a number, preferably a number that is an upper limit or a number that is a lower limit, is meant to encompass not only the precise value specified, but also values or ranges that are approximately or reasonably close to the stated value within normal experimental error. Numerical ranges that list a range of values are intended to include the endpoints of the range and all integers and fractions (decimals) within the range, unless otherwise indicated.

[0027] The terms "about" and "approximately" when used in connection with a numerical value, generally mean that the recited numerical value and all numerical values within experimental error of the recited numerical value (e.g., within a 95% confidence interval of the mean) or within ±10% of the stated numerical value, or within a broader range.

[0028] The expressions "comprising" or "comprise," and "containing" or "contain," and "including" or "include," and the like are open-ended, and do not exclude additional, unrecited elements, steps, or ingredients. The expression "consisting of" excludes any element, step, or ingredient not specified. The expression "consisting essentially of" means that the range is limited to the specified elements, steps, or ingredients, plus optional elements, steps, or ingredients that do not materially affect the basic and novel characteristic(s) of the claimed subject matter. It is understood that the expression "comprising" encompasses the expressions "consisting of" and "consisting essentially of."

[0029] The expressions "at least one" or "one or more" mean 1, 2, 3, 4, 5, 6, 7, 8, 9, or more.

[0030] The present application belongs to the field of microbial resource mining and development, and provides a method for high-throughput screening and enrichment of plastic-degrading bacterial strains. The application of the enrichment method is illustrated by taking polystyrene as an example, and the degradation of polystyrene by the enriched strain is proved. The strain can grow and metabolically degrade polystyrene as the sole carbon source, and has been identified as Stenotrophomonas maltophilia by 16S rRNA sequencing. The proliferation of the strain in the polystyrene carbon source is observed by using a laser confocal high-content imaging microscope, and the plastic is reduced; the concentration of polystyrene is detected to be low under the action of the strain by using a multifunctional enzyme marker; the polystyrene degradation monomer styrene is detected by using a lysing mass spectrometer; and the number-average, weight-average and Z-average molecular weights of the plastic are all reduced by using gel permeation chromatography. In summary, the strain can grow by using plastic and has the ability to degrade polystyrene. The present application provides a scientific basis for the mining of new species of microorganisms and their application in degrading polystyrene.

[0031] In one aspect, the present application provides a Stenotrophomonas maltophilia, which is Stenotrophomonas maltophilia QY1 (CCTCC No: M 20241862).

[0032] In another aspect, the present application also provides a microbial agent comprising the Stenotrophomonas maltophilia QY1 described herein.

[0033] In another aspect, the present application also provides a use of the Stenotrophomonas maltophilia QY1 described herein or the microbial agent described herein in degrading polystyrene.

[0034] In some embodiments, the degradation is that the Stenotrophomonas maltophilia QY1 grows with polystyrene as the sole carbon source and colonizes on the surface of polystyrene, gradually degrading the plastic.

[0035] In another aspect, the present application also provides a method for degrading polystyrene, comprising co-culturing the Stenotrophomonas maltophilia QY1 described herein or the microbial agent described herein with polystyrene.

[0036] In some embodiments, the polystyrene is a granular material, a film or a powder of polystyrene. In some embodiments, the polystyrene comprises at least one of various particle sizes and specifications.

[0037] In some embodiments, the present application also provides a method for degrading polystyrene plastic, comprising co-culturing the Stenotrophomonas maltophilia QY1 described herein or the microbial agent described herein with polystyrene plastic. In some embodiments, the plastic comprises plastics of various types and sources. In some embodiments, the polystyrene plastic comprises at least one of various particle sizes and specifications.

[0038] In some embodiments, the polystyrene is degraded by the Stenotrophomonas maltophilia QY1 in different water bodies (e.g. river water, lake water, sea water or sewage).

[0039] In another aspect, the present application also provides a method for enriching plastic-degrading bacteria, comprising the following steps:

[0040] 1) cultivating mixed strains in the sample in mineral water to form a bacterial solution;

[0041] 2) cultivating the strains in the bacterial solution with a liquid plastic-degrading bacteria enrichment medium (PEM medium);

[0042] 3) The strains survived in step 2) are cultured in Plastic Degrading Bacteria Purification Medium (PPM medium) with solid plastic as the sole carbon source to obtain strains that can survive and grow well;

[0043] 4) The strains obtained in step 3) are diluted and further cultured in micro- well plates containing Plastic Degrading Bacteria Purification Medium (PPM medium) with solid plastic as the sole carbon source to screen strains that can degrade plastic.

[0044] In some embodiments, the formula of the liquid plastic-degrading bacteria enrichment medium is: 3 g (NH4)2SO4, 0.05 g KNO3, 0.0085 g NaCl, 0.0001 g C5H 14 ClNO, 0.0001 g C 18 H 32 CaN2O 10 , 0.0001 g C 19 H 19 N7O6, 0.0001 g C6H6N2O, 0.0001 g C8H9NO3, 0.00001 g C 17 H 20 N4O6, 0.0001 g C 12 H 17 ClN4OS·HCl and 0.0002 g C6H 12 O6, 1 g KH2PO4, 3 g K2HPO4·3H2O, 0.2 g MgSO4, 1 g NaCl, 0.01 g CaCl2, 0.006 g Na2SeO3·5H2O, 0.008 g Na2WO4·2H2O, 0.0005 g EDTA, 0.0002 g 7H2O·Fe2SO4, 0.00001 g 7H2O·ZnSO4, 0.000003 g 4H2O·MnCl2, 0.00003 g H3BO3, 0.00002 g 6H2O·CoCl2, 0.000001 g 2H2O·CuCl2, 0.000002 g 6H2O·NiCl2, 0.000003 g 2H2O·NaMoO4, and 1 L ultrapure water.

[0045] In some embodiments, the formulation of the solid plastic-degrading bacteria purification medium without carbon source is 1 g KH2PO4, 3 g K2HPO4·3H2O, 0.2 g MgSO4, 1 g NaCl, 0.01 g CaCl2, 0.006 g Na2SeO3·5H2O, 0.008 g Na2WO4·2H2O, 0.5 g EDTA, 0.2 g 7H2O·Fe2SO4, 0.01 g 7H2O·ZnSO4, 0.003 g 4H2O·MnCl2, 0.03 g H3BO3, 0.02 g 6H2O·CoCl2, 0.001 g 2H2O·CuCl2, 0.002 g 6H2O·NiCl2, 0.003 g 2H2O·NaMoO4, 15 g agar, and 1 L ultrapure water. Plastic can be added to the solid plastic-degrading bacteria purification medium without carbon source to obtain a solid plastic-degrading bacteria purification medium with plastic as the sole carbon source.

[0046] In some embodiments, the sample can have various sources. In some embodiments, the sample can be a soil sample of a contaminated site. In some embodiments, the sample can be a wastewater sample. In some embodiments, the sample can be a plastic waste buried in environmental soil. In some embodiments, the sample can be a sediment sample in various water bodies, such as the ocean.

[0047] In some embodiments, the plastic is an aged plastic.

[0048] In some embodiments, the aged plastic is plastic in the form of nanoparticles. In some embodiments, the aged plastic is prepared into a plastic stock solution at a certain concentration and added to the PPM medium described herein for the screening and purification of plastic-degrading bacteria. The concentration of the plastic stock solution can be adjusted according to the type of strain to be isolated or the type of plastic.

[0049] In some embodiments, step 4) is repeated one or more times to isolate and purify individual strains.

[0050] In some embodiments, the plastic is polystyrene plastic.

[0051] The present application provides a high-throughput plastic-degrading bacteria enrichment method, which first adds mineral water to shake and activate 24 h of contaminated site soil to prepare a bacterial suspension; then adds the activated bacterial solution to a liquid plastic-degrading bacteria enrichment medium (PEM medium), adds a pretreated polystyrene solution, and shakes and acclimates for 48 h; and finally further separates and purifies polystyrene-degrading bacteria in a solid plastic-degrading bacteria purification medium (PPM medium) with polystyrene as the sole carbon source. The relevant specific treatments are as follows.

[0052] Wherein, the polystyrene pretreatment, in 100 mL water, add polystyrene nano plastic to prepare 10 g / L of plastic mother liquor; under the LED lamp (395 nm wavelength) simulating natural ultraviolet irradiation, the beaker is placed in the magnetic stirrer under constant stirring to simulate environmental aging, 25℃ room temperature incubation for 7 days.

[0053] The formula of liquid plastic degradation bacteria enrichment medium (PEM medium) is 3g (NH4) 2SO4, 0.05g KNO3, 0.0085g NaCl, 0.0001g C5H 14 ClNO, 0.0001g C 18 H 32 CaN2O 10 , 0.0001g C 19 H 19 N7O6, 0.0001g C6H6N2O, 0.0001g C8H9NO3, 0.00001g C 17 H 20 N4O6, 0.0001g C 12 H 17 ClN4OS·HCl and 0.0002g C6H 12 O6, 1g KH2PO4, 3g K2HPO4·3H2O, 0.2g MgSO4, 1g NaCl, 0.01g CaCl2, 0.006g Na2SeO35H2O, 0.008g Na2WO42H2O, 0.0005g EDTA, 0.0002g 7H2O·Fe2SO4, 0.00001g 7H2O·ZnSO4, 0.000003g 4H2O·MnCl2, 0.00003g H3BO3, 0.00002g 6H2O·CoCl2, 0.000001g 2H2O·CuCl2, 0.000002g 6H2O·NiCl2, 0.000003g 2H2O·NaMoO4and 1L ultrapure water.

[0054] Preparation of plastic addition solid plastic-degrading bacteria purification medium (PPM medium) with plastic as the sole carbon source: weigh 1 g KH2PO4, 3 g K2HPO4·3H2O, 0.2 g MgSO4, 1 g NaCl, 0.01 g CaCl2, 0.006 g Na2SeO3·5H2O, 0.008 g Na2WO4·2H2O, 0.5 g EDTA, 0.2 g 7H2O·Fe2SO4, 0.01 g 7H2O·ZnSO4, 0.003 g 4H2O·MnCl2, 0.03 g H3BO3, 0.02 g 6H2O·CoCl2, 0.001 g 2H2O·CuCl2, 0.002 g 6H2O·NiCl2, 0.003 g 2H2O·NaMoO4, 15 g agar, then mix well and make up to 1 L of ultrapure water. After high-temperature high-pressure sterilization, add plastic mother liquor and mix well, pour into the microwell plate holes, and cool and solidify for use.

[0055] The present application describes a number of embodiments, but the description is exemplary rather than limiting, and it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the embodiments described in the present application. Although a number of possible combinations of features have been set forth in the accompanying figures and discussed above, many other combinations of the disclosed features are possible. Unless specifically intended otherwise, any feature of any embodiment can be used in combination with any other feature of any other embodiment, or in replacement of any other feature of any other embodiment.

[0056] The present application includes and contemplates combinations of features known to those of ordinary skill in the art. The embodiments and features disclosed in the present application can also be combined with any conventional features to form unique inventive solutions defined by the claims. Any feature of any embodiment can also be combined with features from other inventive solutions to form another unique inventive solution defined by the claims. Therefore, it should be understood that any feature shown and / or discussed in the present application can be implemented alone or in any appropriate combination. Accordingly, the embodiments are not limited by any other limitation other than those imposed with the appended claims and their equivalents. Furthermore, various modifications and changes can be made within the scope of the appended claims.

[0057] Furthermore, in describing representative embodiments, the specification can have presented the method and / or process as a particular sequence of steps. However, to the extent that the method or process depends on the performance of such steps, the method or process should not be limited to the

[0058] The experimental methods in the following examples, unless otherwise specified, were generally in accordance with the national standards. The experimental materials in the following examples, unless otherwise specified, were all commercially available raw materials. The equipment used in each step in the following examples was all conventional equipment. If there is no corresponding national standard, it is carried out according to the general international standard, the conventional condition, or according to the conditions suggested by the manufacturer. Unless otherwise defined or explained, all professional and scientific terms used in this application have the same meaning as those familiar to those skilled in the art. In addition, any method and material similar or equivalent to that described can be applied to the method of the present application.

[0059] Examples

[0060] The relevant materials used in the examples are as follows:

[0061] 1. Reagents, materials

[0062] (NH4)2SO4, KNO3, NaCl, C5H 14 ClNO, C 18 H 32 CaN2O 10 , C 19 H 19 N7O6, C6H6N2O, C8H9NO3, C 17 H 20 N4O6, C 12 H 17 ClN4OS·HCl and C6H 12O6, KH2PO4, K2HPO4·3H2O, MgSO4, NaCl, CaCl2, Na2SeO35H2O, Na2WO42H2O, EDTA, 7H2O·Fe2SO4, 7H2O·ZnSO4, 4H2O·MnCl2, H3BO3, 6H2O·CoCl2, 2H2O·CuCl2, 6H2O·NiCl2, 2H2O·NaMoO4, and the like medium formula reagents are all of analytical purity, purchased from the National Pharmaceutical Group, Macklin, Aladdin, Sigma, and the like. Agar is purified agar. Microplastics are 20 nm red fluorescent microplastics (Jiangsu Zhichuan Science and Technology).

[0063] 2. Instruments

[0064] Routine operation culture instruments include high-temperature and high-pressure sterilization pots, super-clean workbenches, shaking tables, constant-temperature incubators, and the like. A wavelength of 395 nm LED ultraviolet lamp tube is used to irradiate aged microplastics. Detection instruments include multifunctional enzyme label instruments (TECAN, Spark), laser confocal high-content imaging microscopes (PerkinElmer, Opera Phenix), gel permeation chromatographs (Waters, Breeze2), and the like.

[0065] Example 1. High-throughput plastic degrading bacteria screening method separates polystyrene degrading bacteria

[0066] This example takes polystyrene as an example to illustrate the process of separating plastic-degrading bacteria by the well plate plastic enrichment method of the application. First, 10 g of plastic-polluted site soil (isolated from the garbage dump in Xiaowa Town, Aohan Banner, Inner Mongolia) and 100 mL of Nongfushanquan Changbaishan mineral water were added to a conical flask, and a soil bacterial suspension was prepared by incubating at 30°C and 180 rpm / min on a shaking table for 24 h. Then, 100 μL of the soil bacterial suspension and 800 μL of a low-nutrient plastic-degrading bacterial enrichment medium PEM medium were added to each well of a 48-well plate, and the mixture was shaken and activated for 24 h. Then, 100 μL of an aged 20 nm polystyrene stock solution (1000 mg / L) was added, and the mixture was incubated at 30°C and 80 rpm / min on a shaking table for 48 h to further acclimate the degrading bacteria. Finally, polystyrene stock solution was added to the plastic-degrading bacterial purification medium PPM medium, and the degrading bacteria acclimated in the previous step were inoculated onto the solid PPM medium without adding polystyrene as a carbon and nitrogen-free control. The medium was incubated at 30°C for 7-20 d, and the growth of bacterial colonies was observed and photographed. Bacteria that could form colonies on PPM plates with polystyrene as the sole carbon source but could not grow on solid PPM medium without plastic were determined to have plastic-degrading potential. Single colonies with plastic-degrading potential were selected and purified multiple times to obtain a polystyrene-degrading pure bacterium. After identification by 16S rRNA sequencing (the 16S rRNA sequence is shown in SEQ ID NO: 1), the polystyrene-degrading pure bacterium was identified as a Stenotrophomonas maltophilia strain. It has high similarity with the Stenotrophomonas maltophilia strain ZT1, and is named Stenotrophomonas maltophilia QY1. It was preserved at the China Center for Type Culture Collection, located at No. 299, Bayi Road, Wuchang District, Wuhan City, Hubei Province, on August 28, 2024. The preservation number is CCTCC No: M 20241862.

[0067] Example 2. Growth of degrading bacteria in polystyrene medium

[0068] Growth of degrading bacteria in solid medium. The growth of degrading bacteria in PPM plastic-degrading bacterial purification microplate solid medium with polystyrene plastic as the sole carbon source was investigated. Single colonies of Stenotrophomonas maltophilia QY1 strain were streaked on PPM solid medium, and incubated at 30°C in an incubator for 2-7 d. The growth of bacterial colonies was photographed and recorded. The results showed that no colony proliferation was observed in the control without adding plastic, while the number of colonies of degrading bacteria increased significantly in the wells with added plastic, and obvious colonies were formed on the second day. Figure 1

[0069] ​Growth of degrading bacteria in liquid culture medium. *Stenotrophomonas maltophilia* strain QY1 was inoculated at a ratio of 1% into LB medium and cultured overnight at 30°C and 180 rpm / min to activate and rejuvenate the bacteria, obtaining a highly active *Stenotrophomonas maltophilia* strain QY1 in the logarithmic growth phase. The LB medium was then removed by centrifugation at 8000 rpm / min, and the bacteria were resuspended in sterile ultrapure water, vortexed, and washed three times by centrifugation to remove nutrients. The washed bacterial cells were added to PPM liquid medium containing 1000 mg / L fluorescent polystyrene nanoparticles as the sole carbon source to adjust the OD. 600 =0.2, and then cultured in a shaker at 30℃ and 180 rpm / min. The culture solution was then observed under a laser confocal high-content imaging microscope to examine the changes in the degrading bacteria and plastic. The results showed that ( Figure 2 After 7 days of cultivation, the number of bacteria increased and the amount of plastic decreased, indicating that the strain was able to grow and reproduce in polystyrene medium.

[0070] Example 3. Growth of degrading bacteria in polystyrene culture medium and tolerance thresholds to different concentrations of polystyrene.

[0071] The tolerance threshold of degrading bacteria to different concentrations of polystyrene was verified in 9cm petri dishes. Different plastic concentrations (0, 1 mg / L, 20 mg / L, 100 mg / L, 1000 mg / L, 5000 mg / L, 20000 mg / L) were set. Single colonies of *Stenotrophomonas maltophilia* strain QY1 were streaked onto plates and incubated at 30℃ in a shaker for 2-10 days. Colony growth was observed and photographed to determine the range of plastic concentrations in which colonies could grow. The results showed that ( Figure 3 The *Stenotrophomonas maltophilia* strain QY1 could not grow in a carbon-nitrogen-free medium without plastic. It showed no difference in growth on plastics at concentrations of 1 mg / L, 20 mg / L, and 100 mg / L. However, the number of colonies that could form on plastics at concentrations of 1000 mg / L, 5000 mg / L, and 20000 mg / L decreased with increasing plastic concentration. This indicates that *Stenotrophomonas maltophilia* strain QY1 can grow using polystyrene as the sole carbon source and can tolerate polystyrene plastic concentrations ranging from 1 to 5000 mg / L.

[0072] Example 4. Changes in plastics in the degradation system

[0073] 1. Detection of plastic concentration

[0074] Liquid culture of *Stenotrophomonas maltophilia* QY1 grown with polystyrene as the sole carbon source at different incubation times was collected. Fluorescence (excitation 310 nm, emission 680 nm) was detected using a multi-functional microplate reader. The fluorescence intensity reflected the changes in polystyrene concentration in the bacterial culture. The results showed that ( Figure 4), the fluorescence intensity of polystyrene plastic detected decreased with the increase of time, indicating that the concentration of plastic in the culture system decreased.

[0075] 2. Detection of plastic monomers

[0076] When detecting the degradation monomers of plastic, about 3 mg of powder was weighed after the bacterial liquid treated by the strain for 7 days was collected and freeze-dried, and the degradation monomers of polystyrene plastic were detected by pyrolysis chromatography mass spectrometry. Figure 5 By comparing the spectrum library to identify the characteristic peaks, it was found that the strain could degrade polystyrene plastic into monomer styrene.

[0077] 3. Gel permeation chromatography detection

[0078] In the PPM medium added with polystyrene plastic, the bacterial liquid after 7 days of reaction of the treatment group of Stenotrophomonas maltophilia QY1 and the control group without the addition of Stenotrophomonas maltophilia QY1 was taken, then the dried polystyrene plastic was dissolved with N,N-dimethylformamide, and the changes of weight average, Z average and peak molecular weight were detected by gel permeation chromatography. Figure 6 The results showed that during the growth of Stenotrophomonas maltophilia QY1 strain in the medium with polystyrene as the sole carbon source, the weight average, Z average and peak molecular weight of polystyrene plastic detected decreased with the increase of time, indicating that the plastic in the culture system was degraded.

Claims

1. A Stenotrophomonas maltophilia, characterized in that, The Stenotrophomonas maltophilia is Stenotrophomonas maltophilia QY1 Stenotrophomonas maltophilia QY1, and the preservation number is CCTCC No: M 20241862.

2. An inoculant comprising the Stenotrophomonas maltophilia QY1 of claim 1.

3. Use of the Stenotrophomonas maltophilia QY1 of claim 1 or the inoculant of claim 2 in degrading polystyrene.

4. Use according to claim 3, characterized in that, The degradation is that the Stenotrophomonas maltophilia QY1 grows with polystyrene as the sole carbon source and colonizes on the surface of polystyrene, gradually degrading the plastic.

5. A method of degrading polystyrene, characterized by, The Stenotrophomonas maltophilia QY1 of claim 1 or the inoculant of claim 2 is co-cultured with polystyrene.

6. The method of claim 5, wherein, The polystyrene is a granular material, a film or a powder of polystyrene.

7. The method of claim 5, wherein, The polystyrene is degraded by the Stenotrophomonas maltophilia QY1 in different water bodies.

8. A method for enriching plastic-degrading bacteria, characterized in that, The method comprises the following steps: 1) cultivating mixed strains in the sample in mineral water to form a bacterial solution; 2) cultivating the strains in the bacterial solution with a liquid plastic-degrading bacterial enrichment medium; 3) cultivating the surviving strains in step 2) with a solid plastic-degrading bacterial purification medium added with plastic as the sole carbon source to obtain strains that can survive and grow well; 4) dilute the strain obtained in step 3) and inoculate into a microplate containing solid plastic-degrading bacteria purification medium with added plastic as the sole carbon source for further cultivation, and screen for strains capable of degrading plastic; wherein the formula of the liquid plastic-degrading bacteria enrichment medium is: 3g (NH4)2SO4, 0.05g KNO3, 0.0085g NaCl, 0.0001g C5H 14 ClNO, 0.0001g C 18 H 32 CaN2O 10 , 0.0001g C 19 H 19 N7O6, 0.0001g C6H6N2O, 0.0001g C8H9NO3, 0.00001g C 17 H 20 N4O6, 0.0001g C 12 H 17 ClN4OS·HCl and 0.0002g C6H 12 O6, 1g KH2PO4, 3g K2HPO4·3H2O, 0.2g MgSO4, 1g NaCl, 0.01g CaCl2, 0.006g Na2SeO35H2O, 0.008g Na2WO42H2O, 0.0005g EDTA, 0.0002g 7H2O·Fe2SO4, 0.00001g 7H2O·ZnSO4, 0.000003g 4H2O·MnCl2, 0.00003g H3BO3, 0.00002g 6H2O·CoCl2, 0.000001g 2H2O·CuCl2, 0.000002g 6H2O·NiCl2, 0.000003g 2H2O·NaMoO4and 1L ultrapure water, and the formula of the solid plastic-degrading bacteria purification medium is 1g KH2PO4, 3g K2HPO4·3H2O, 0.2g MgSO4, 1g NaCl, 0.01g CaCl2, 0.006g Na2SeO35H2O, 0.008g Na2WO42H2O, 0.5g EDTA, 0.2g 7H2O·Fe2SO4, 0.01g 7H2O·ZnSO4, 0.003g 4H2O·MnCl2, 0.03g H3BO3, 0.02g 6H2O·CoCl2, 0.001g 2H2O·CuCl2, 0.002g 6H2O·NiCl2, 0.003g 2H2O·NaMoO4, 15g agar and 1L ultrapure water.

9. The method of claim 8, wherein, Step 4) is repeated one or more times to isolate and purify individual strains.

10. The method according to claim 8 or 9, characterized in that, The plastic is a polystyrene plastic.

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