Application of pseudomonas aeruginosa in degradation of polypropylene plastic and method for degrading polypropylene plastic

Abstract

The invention relates to the technical field of microbial degradation, and discloses application of pseudomonas aeruginosa in degradation of polypropylene plastic and a method for degrading the polypropylene plastic. The pseudomonas aeruginosa is preserved in the China General Microbiological Culture Collection Center (CGMCC), and the preservation number is CGMCC NO: 27456. The pseudomonas aeruginosa has relatively high degradation efficiency and relatively high degradation rate on polypropylene plastics, and has a good market application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of microbial degradation, and specifically, to the application of Pseudomonas aeruginosa in degrading polypropylene plastics and a method for degrading polypropylene plastics. Background Art

[0002] While plastic products bring convenience to people's lives and agriculture, excessive plastic products can also cause environmental pollution and ecological damage. Especially after a large amount of agricultural plastic films are used, due to the inability to effectively collect and process them, these waste plastic films will accumulate in the soil and are difficult to degrade.

[0003] Currently, the treatment method for all plastics such as polypropylene plastics is still mainly incineration for power generation (accounting for about 42% of the total plastic volume), the recovery rate is only about 35%, and 23% is still landfilled. Incinerating plastics for power generation will produce pollutants and greenhouse gas substances such as dioxins, sulfur dioxide, and a large amount of carbon dioxide; landfilling plastics not only occupies a large area, but also releases toxic and harmful substances such as plasticizers and heavy metal ions that pollute groundwater and soil under high temperature and direct sunlight; at the same time, plastics that have not been completely degraded will turn into microplastics. Microplastics can adsorb other toxic and harmful substances and enter the human body or organisms through food chains and other channels, causing a series of diseases or ecological disasters.

[0004] Microbial treatment of plastic pollution is currently the most environmentally friendly and economical method, but due to the long treatment cycle, slow rate, and single source, it has not been widely promoted. Currently, the degrading bacteria of plastics are all from the bacterial flora systems of landfill sites or microplastic-aggregated waters, and the degradation rates of polypropylene plastics (the highest degradation rate of polypropylene plastic films doped with starch within 120 days is only 19% (Journal of Applied Polymer Science, 2019)) and microplastics (the highest degradation rate of polypropylene microplastics within 40 days is only 6.4% (Marine Pollution Bulletin, 2018)) without ultraviolet irradiation or other pretreatment are relatively low.

[0005] The above-mentioned bacterial strains cannot meet the requirements of rapid treatment, greatly limiting the popularization and application of microbial treatment of polypropylene plastic pollution. Therefore, it is necessary to provide a degrading bacterium with high efficiency and high degradation rate for polypropylene plastic films and polypropylene microplastics. Summary of the Invention

[0006] The purpose of the present invention is to overcome the defects of low degradation efficiency and low degradation rate of existing polypropylene plastic degrading bacteria.

[0007] To achieve the above object, the inventors of the present invention conducted a large number of screening experiments and screened a Pseudomonas aeruginosa with high degradation efficiency and high degradation rate for polypropylene plastics. Therefore, in the first aspect of the present invention, there is provided the use of Pseudomonas aeruginosa XJ16 in degrading polypropylene plastics. This Pseudomonas aeruginosa is preserved in the General Microbiology Center of the China Committee for Culture Collection of Microorganisms, and the preservation number is CGMCC NO: 27456.

[0008] In the second aspect of the present invention, there is provided a method for degrading polypropylene plastics, which includes: contacting the Pseudomonas aeruginosa XJ16 described in the first aspect above with polypropylene plastics to degrade the polypropylene plastics.

[0009] The Pseudomonas aeruginosa XJ16 provided by the present invention has a degradation rate of up to 23.5% for polypropylene plastic films doped with carbon powder and up to 11.1% for polypropylene microplastics within 120 days. It can be used to treat a large amount of waste polypropylene plastic films and polypropylene microplastics, alleviating the current situation of few degradation strains and low degradation efficiency for polypropylene plastic films and polypropylene microplastics, and has good market application prospects.

[0010] Biological preservation

[0011] The Pseudomonas aeruginosa of the present invention was preserved in the General Microbiology Center of the China Committee for Culture Collection of Microorganisms (Address: No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences, Postcode: 100101) (the abbreviation of the preservation unit is CGMCC) on May 25, 2023, and the preservation number is CGMCC: 27456. Detailed implementation manners

[0012] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0013] As mentioned above, in the first aspect of the present invention, there is provided the use of Pseudomonas aeruginosa XJ16 in degrading polypropylene plastics. This Pseudomonas aeruginosa is preserved in the General Microbiology Center of the China Committee for Culture Collection of Microorganisms, and the preservation number is CGMCC NO: 27456.

[0014] The Pseudomonas aeruginosa with the preservation number of CGMCC NO: 27456 in the present invention is derived from the reservoir environment and is obtained by isolation and purification through the method of streaking on a plate. The colony of this Pseudomonas aeruginosa is beige, and the surface of the colony is moist. At the same time, the total RNA of strain XJ16 is extracted, and 16S rRNA gene sequence analysis is carried out. After comparison with the DNA sequence database (Genbank), it is determined that this bacterium is Pseudomonas aeruginosa. This Pseudomonas aeruginosa is preserved in the General Microbiology Center of the China Committee for Culture Collection of Microorganisms, with the preservation number of CGMCC NO: 27456.

[0015] The Pseudomonas aeruginosa provided by the present invention can produce a large number of live cells of Pseudomonas aeruginosa after cultivation. It should be noted that the present invention has no special requirements for the cultivation method, as long as it can enable the proliferation of the Pseudomonas aeruginosa. For example, the live cells of Pseudomonas aeruginosa can be inoculated into the R2A liquid medium at an inoculation amount of 10 7 CFU / mL, and after culturing at a temperature of 30 - 40 °C for 12 - 48 h, a culture solution is obtained.

[0016] It should be noted that the present invention has no special limitations on the cultivation conditions of Pseudomonas aeruginosa. Those skilled in the art can select according to the known technical means in the art. An exemplary specific implementation manner is provided in the present invention, and those skilled in the art should not understand it as a limitation to the present invention. For example, the composition of the R2A liquid medium used for cultivation can be: 0.5 g / L of yeast extract powder; 0.25 g / L of tryptone; 0.75 g / L of peptone; 0.5 g / L of glucose; 0.5 g / L of soluble starch; 0.3 g / L of K 2 HPO 4 ; 0.024 g / L of MgSO 4 ; 0.3 g / L of sodium pyruvate; the rest is water, pH = 7. The composition of the inorganic salt medium used for cultivation can be: 3 g / L of KNO 3 ; 3 g / L of Na 2 HPO 4 ; 0.5 g / L of MgSO 4 ; 12 g / L of Na 2 EDTA·2H 2 O, 10 g / L of Na 2 SO 4 ; 5 g / L of FeSO 4 ·7H 2 O, 0.5 g / L of CuSO 4 ·5H 2 O; the rest is water, pH = 7.

[0017] As described above, the second aspect of the present invention provides a method for degrading polypropylene plastics, which includes: contacting Pseudomonas aeruginosa XJ16 with polypropylene plastics to degrade the polypropylene plastics.

[0018] Preferably, the polypropylene plastics are polypropylene microplastics and / or polypropylene plastic films doped with carbon powder.

[0019] More preferably, the particle size of the polypropylene microplastics is 100 - 1000 μm, preferably 780 - 920 μm. The inventors of the present invention have found that when the particle size of the polypropylene microplastics is 780 - 920 μm, a higher degradation efficiency is achieved.

[0020] Further preferably, the thickness of the polypropylene plastic film is 0.1 - 2.0 mm, preferably 1.0 - 1.1 mm.

[0021] It should be noted that the present invention does not have any special limitations on the content of carbon powder in the polypropylene plastic film doped with carbon powder, and various commercially available polypropylene plastic films doped with carbon powder can be used.

[0022] According to a preferred embodiment, relative to 1 g of the polypropylene plastics, the dosage of Pseudomonas aeruginosa XJ16 is 0.3 - 2.3 L of a bacterial liquid with an OD 600 value of 0.1 - 2.5. Particularly preferably, relative to 1 g of the polypropylene plastics, the dosage of Pseudomonas aeruginosa XJ16 is 0.3 - 2.3 L of a bacterial liquid with an OD 600 value of 0.5 - 2.0.

[0023] According to another preferred embodiment, the conditions for the contact include: performing under stirring conditions, and the stirring speed is 100 - 250 rpm, preferably 120 - 150 rpm; the temperature is 20 - 45 °C, preferably 30 - 40 °C.

[0024] The present invention will be described in detail below through examples.

[0025] In the following examples, unless otherwise specified, the raw materials used are all commercially available.

[0026] In the present invention, the degradation rate of polypropylene plastics = (weight of polypropylene plastics before degradation - weight of polypropylene plastics after degradation) / weight of polypropylene plastics before degradation × 100%.

[0027] Polypropylene plastic film doped with carbon powder: Obtained from the Bamboo Research and Development Center of the National Forestry and Grassland Administration.

[0028] Preparation example: Preparation of Pseudomonas aeruginosa bacterial liquid

[0029] The Pseudomonas aeruginosa with the preservation number of CGMCC NO: 27456 of the present invention was inoculated into the R2A liquid medium sterilized at 121 °C for 20 min, and cultured with a shaker at 120 rpm and 35 °C for 24 h to obtain a seed culture solution; the obtained seed culture solution was inoculated into 100 mL of an inorganic salt medium at an inoculation amount of 2% by volume to obtain a bacterial solution with an OD 600 value of 0.7.

[0030] Example 1

[0031] 49.6 ± 0.1 mg of polypropylene plastic film doped with carbon powder (both the length and width are 0.5 cm, and the thickness is 1 mm) was added to 100 mL of the bacterial solution obtained in the preparation example, and cultured with a shaker at 120 rpm and 35 °C. The total culture time was 28 d. During this period, the polypropylene plastic film doped with carbon powder was taken out every 7 d, dried to a constant weight at 65 °C, and then weighed. The parallel test was carried out 3 times; and

[0032] 50.2 ± 0.1 mg of carbon powder (particle size is 430 μm) was added to 100 mL of the bacterial solution obtained in the preparation example, and cultured with a shaker at 120 rpm and 35 °C. The total culture time was 28 d. During this period, the carbon powder was taken out every 7 d, dried to a constant weight at 65 °C, and then weighed. The parallel test was carried out 3 times.

[0033] Example 2

[0034] 302.2 ± 0.1 mg of polypropylene plastic film doped with carbon powder (both the length and width are 3.0 cm, and the thickness is 1 mm) was added to 100 mL of the bacterial solution obtained in the preparation example, and cultured with a shaker at 120 rpm and 35 °C. The total culture time was 120 d. During this period, the polypropylene plastic film doped with carbon powder was taken out every 30 d, dried to a constant weight at 65 °C, and then weighed. The parallel test was carried out 3 times; and

[0035] 300.6 ± 0.1 mg of carbon powder (particle size is 430 μm) was added to 100 mL of the bacterial solution obtained in the preparation example, and cultured with a shaker at 120 rpm and 35 °C. The total culture time was 120 d. During this period, the carbon powder was taken out every 30 d, dried to a constant weight at 65 °C, and then weighed. The parallel test was carried out 3 times.

[0036] Example 3

[0037] Add 50.6 ± 0.1 mg of polypropylene microplastics (particle size: 850 μm) to 100 mL of the bacterial solution obtained in Preparation Example, and perform shaking culture using a shaker at 120 rpm and 35 °C. The total culture time is 28 days. During this period, take out the polypropylene microplastics every 7 days, dry them to a constant weight at 65 °C, and then weigh them. Conduct 3 parallel tests.

[0038] Example 4

[0039] Add 303.6 ± 0.1 mg of polypropylene microplastics (particle size: 850 μm) to 100 mL of the bacterial solution obtained in Preparation Example, and perform shaking culture using a shaker at 120 rpm and 35 °C. The total culture time is 120 days. During this period, take out the polypropylene microplastics every 30 days, dry them to a constant weight at 65 °C, and then weigh them. Conduct 3 parallel tests.

[0040] Example 5

[0041] Add 50 ± 0.1 mg of polypropylene microplastics doped with carbon powder (particle size: 510 μm) to 100 mL of the bacterial solution obtained in Preparation Example, and perform shaking culture using a shaker at 120 rpm and 35 °C. The total culture time is 28 days. During this period, take out the polypropylene plastic film doped with carbon powder every 7 days, dry it to a constant weight at 65 °C, and then weigh it. Conduct 3 parallel tests.

[0042] Table 1

[0043]

[0044]

[0045] As can be seen from the results in Table 1, the Pseudomonas aeruginosa provided by the present invention has a high degradation rate for both the polypropylene plastic film doped with carbon powder and polypropylene microplastics.

[0046] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. Application of Pseudomonas aeruginosa XJ16 in degrading polypropylene plastics, characterized in that, the preservation number of the Pseudomonas aeruginosa is CGMCC NO: 27456.

2. The application according to claim 1, wherein, the polypropylene plastic is polypropylene microplastics and / or a polypropylene plastic film doped with carbon powder.

3. The application according to claim 1 or 2, wherein, the particle size of the polypropylene microplastics is 100 - 1000 μm.

4. The application according to any one of claims 1 - 3, wherein, the thickness of the polypropylene plastic film is 0.1 - 2.0 mm.

5. A method for degrading polypropylene plastics, characterized in that, the method comprises: contacting Pseudomonas aeruginosa XJ16 with the polypropylene plastic to degrade the polypropylene plastic.

6. The method according to claim 5, wherein, the polypropylene plastic is polypropylene microplastics and / or a polypropylene plastic film doped with carbon powder.

7. The method according to claim 6, wherein, the particle size of the polypropylene microplastics is 100 - 1000 μm.

8. The method according to claim 6 or 7, wherein, the thickness of the polypropylene plastic film is 0.1 - 2.0 mm.

9. The method according to any one of claims 4 - 8, wherein, The dosage of the Pseudomonas aeruginosa XJ16 is a bacterial liquid with an OD value of 0.1-2.5 in an amount of 0.3-2.3 L relative to 1 g of the polypropylene plastic. 600 The value is 0.1-2.5 of the bacterial liquid.

10. The method according to any one of claims 4 - 9, wherein, the conditions of the contact include: carried out under stirring conditions, and the stirring speed is 100 - 250 rpm, and the temperature is 20 - 45 °C.

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